HomeMy WebLinkAbout04-04-07 Agenda Item 7a Integrated Water Resources PlanOtay Water District
Integrated Water Resources Plan
March 2, 2007
March 2, 2007 i
Contents
Executive Summary..............................................................................................................ES-1
Section 1 Introduction.............................................................................................................1-1
1.1 Project Background ..................................................................................................1-1
1.1.1 District Characteristics..............................................................................1-1
1.1.2 Imported Water Supply............................................................................1-2
1.2 Problem Statement ...................................................................................................1-4
1.3 Purpose of the Integrated Resources Plan ............................................................1-4
Section 2 Existing Water Supply...........................................................................................2-1
2.1 Water Supply Systems.............................................................................................2-1
2.2 Potable Water Supply ..............................................................................................2-4
2.2.1 San Diego County Water Authority Imported Supply........................2-4
2.2.2 City of San Diego’s Otay WTP.................................................................2-5
2.2.3 Helix Water District’s Levy WTP............................................................2-5
2.3 Recycled Water Supply............................................................................................2-6
2.3.1 Ralph W. Chapman Water Reclamation Facility..................................2-6
2.3.2 City of San Diego South Bay Water Reclamation Plant.......................2-6
2.4 Summary of Existing Supply..................................................................................2-7
Section 3 Projected Water Supply Gap................................................................................3-1
3.1 Future Water Demands ...........................................................................................3-1
3.1.1 Annual Average Demand Projections....................................................3-1
3.1.2 Weather Impacts and Peaking.................................................................3-3
3.1.2.1 Annual Weather Impacts............................................................3-3
3.1.2.2 Seasonal (Monthly) Impacts.......................................................3-4
3.1.2.3 Peak Day Demands.....................................................................3-6
3.2 Supply Gap Analysis................................................................................................3-7
Section 4 Evaluation Framework..........................................................................................4-1
4.1 Evaluation Process....................................................................................................4-1
4.1.1 Objectives and Performance Measures ..................................................4-2
4.1.2 Weighting Objectives................................................................................4-4
4.1.3 Identify Options and Create Portfolios..................................................4-5
4.2 Portfolio Evaluation Method ..................................................................................4-6
Section 5 Water Supply Options ..........................................................................................5-1
5.1 Water Conservation..................................................................................................5-4
5.2 Groundwater Options..............................................................................................5-6
5.2.1 Middle Sweetwater Conjunctive Use.....................................................5-8
5.2.2 Lower Sweetwater Brackish Groundwater Demineralization..........5-10
5.2.3 Santee/El Monte Basin...........................................................................5-11
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Otay Water District Integrated Resource Plan
ii March 2, 2007
5.2.3.1 Santee/El Monte Conjunctive Use..........................................5-12
5.2.3.2 Santee/El Monte Brackish Groundwater
Demineralization.....................................................................................5-14
5.2.3.3 Santee/El Monte Brackish Combined Conjunctive Use and
Brackish Groundwater Demineralization............................................5-15
5.2.4 San Diego Formation Brackish Groundwater Demineralization .....5-16
5.2.5 Tijuana River Valley Aquifer Reclaimed Water Storage ...................5-17
5.2.6 Other Groundwater Wells......................................................................5-18
5.2.6.1 Otay Mountain Well..................................................................5-18
5.3 Additional Recycled Options................................................................................5-19
5.3.1 Spring Valley Stripping Plant................................................................5-20
5.3.2 Chula Vista Stripping Plant...................................................................5-20
5.3.3 Additional Purchases from South Bay WRP.......................................5-21
5.3.4 Expansion of South Bay WRP................................................................5-21
5.3.5 Ralph W. Chapman Water Reclamation Facility (RWCWRF) and /or
Spring Valley Stripping Plant Recycled Water to Lower Sweetwater
Basin and Downstream Well Recovery................................................5-22
5.3.6 North District Recycled Water Concept...............................................5-22
5.3.7 Expansion of Ralph W. Chapman Water Reclamation Facility
(RWCWRF) and Sewer Collection System...........................................5-23
5.4 Ocean Desalination Options .................................................................................5-23
5.4.1 Poseidon’s Carlsbad Seawater Desalination Project ..........................5-25
5.4.2 Southern California Partnership: Sweetwater/City of San Diego South
Bay Project................................................................................................5-25
5.4.3 Bi-National Partnership: Rosarito Financial Partnership with In-lieu
Colorado River Water.............................................................................5-26
5.4.4 Other Desalination Options...................................................................5-27
5.5 Additional Imported Water Options with Local Treatment Agreements......5-28
5.5.1 Expansion of Capacity Rights from Helix Water District’s
Levy WTP.................................................................................................5-28
5.5.2 Expansion of Capacity at City of San Diego’s Otay WTP..................5-29
5.5.3 Imported Water from Sweetwater Authority’s Perdue WTP ...........5-29
5.5.4 Imported Water from the City of San Diego’s Alvarado WTP.........5-30
5.6 Imported Raw Water from SDCWA Pipeline No. 3 for Irrigation..................5-30
5.7 Imported Treated Water from SDCWA Pipeline No. 4 ....................................5-31
5.8 Water Transfers and Water Banking....................................................................5-32
Section 6 Water Supply Portfolio Development................................................................6-1
Section 7 Systems Simulation Model ..................................................................................7-1
7.1 Conceptual Model....................................................................................................7-1
7.2 Model Elements........................................................................................................7-1
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Otay Water District Integrated Resource Plan
March 2, 2007 iii
7.2.1 Demands.....................................................................................................7-1
7.2.2 Water Supply .............................................................................................7-2
7.2.3 Performance Measures .............................................................................7-6
7.2.3.1 Qualitative Performance Measures...........................................7-6
7.2.3.2 Quantitative Performance Measures........................................7-7
7.3 Simulation Process ...................................................................................................7-9
Section 8 Portfolios Evaluation and Screening..................................................................8-1
8.1 Evaluation Process Overview.................................................................................8-1
8.2 Portfolio Evaluation Results....................................................................................8-1
8.2.1 Water Quality Evaluation ........................................................................8-1
8.2.2 Water Supply Reliability Evaluation......................................................8-4
8.2.3 Cost Evaluation..........................................................................................8-7
8.2.4 Diversity and Flexibility Evaluation.....................................................8-10
8.2.5 Environmental and Institutional Constraints Evaluation .................8-12
8.2.6 Portfolio Performance Summary...........................................................8-13
8.3 Portfolios Ranking..................................................................................................8-13
8.4 Preferred Portfolios................................................................................................8-14
8.5 Sensitivity Analysis................................................................................................8-16
8.6 Common Elements among the Preferred Portfolios..........................................8-16
Section 9 Implementation Plan.............................................................................................9-1
9.1 Strategic Implementation of Projects.....................................................................9-1
9.2 Short-Term Actions..................................................................................................9-2
Section 10 References............................................................................................................10-1
Appendices
Appendix A Objectives Weighting Results
Appendix B Supply Options Rating and Schematics
Appendix C Supply Option Cost Estimates
Appendix D Portfolio Summary and Performance
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Otay Water District Integrated Resource Plan
iv March 2, 2007
Tables
2-1 Comparison of 2006 and 2010 Water Facility Capacities and
Agreements..........................................................................................2-7
3-1 Otay Water District Total Demand Projections..............................3-1
3-2 Projected Demand Distributions by System for Potable and
Recycled Uses......................................................................................3-2
3-3 Total Supply Peak Day Demand Projections..................................3-6
4-1 OWD Objectives, Sub-objectives and Performance Measures .....4-3
5-1 SDCWA 2007 Imported Water Rates...............................................5-2
6-1 Matrix of Supply Option Yields included in Portfolios.................6-3
7-1 Potential Baseline Supply Yield in System Model .........................7-3
7-2 System Model Prioritization for Use of Non-Potable Supply
Options.................................................................................................7-5
7-3 System Model Prioritization for Use of Potable Supply
Options.................................................................................................7-5
8-1 Portfolio Performance Summary....................................................8-18
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Otay Water District Integrated Resource Plan
March 2, 2007 v
Figures
ES-1 Otay Water District Service Area................................................... ES-1
ES-2 IRP Portfolio Evaluation Process................................................... ES-3
ES-3 Average Weight Assigned by Staff and Bard Members to
IRP Objectives................................................................................... ES-4
ES-4 OWD IRP Implementation Plan .................................................... ES-7
1-1 Otay Water District Service Area......................................................1-1
2-1 North, Central Area, and Otay Mesa Systems................................2-2
2-2 Baseline System Schematic................................................................2-3
3-1 Otay Water District Projected Annual Demands...........................3-2
3-2 Annual Hydrologic Demand Factors...............................................3-4
3-3 Monthly Seasonal Potable Demand Factors....................................3-5
3-4 Monthly Seasonal Recycled Demand Factors.................................3-6
3-5 Projected Baseline Supply Mix over Time.......................................3-7
4-1 “Why” and “How” Parallel Paths in the IRP..................................4-1
4-2 Example Objective Weighting for One Stakeholder......................4-4
4-3 Comparison of Average Objective Weightings..............................4-5
4-5 Multi-Attribute Rating Method ........................................................4-7
5-1 Projected SDCWA Imported Water Rates (including
transportation charges)......................................................................5-3
5-2 Projected Conservation Water Savings by System.........................5-5
5-3 Projected Conservation Costs by System ........................................5-5
5-4 Location of Groundwater Basins......................................................5-7
5-5 Middle Sweetwater Conjuntive Use Option Schematic................5-9
5-6 Lower Sweetwater Brackish Groundwater Demineralization
Option Schematic..............................................................................5-11
5-7 Santee/ El Monte Conjunctive Use Option Schematic................5-13
5-8 Santee/El Monte Brackish Groundwater Demineralization
Option Schematic..............................................................................5-14
5-9 San Diego Formation Brackish Groundwater Desalination
Option Schematic..............................................................................5-16
5-10 Bi-National Partnership: Rosarito Financial Partnership
with In-lieu Colorado River Water Option Schematic ................5-27
5-11 Projected Water Transfers Costs.....................................................5-34
7-1 Model Representation of a Groundwater Basin.............................7-3
7-2 Portion of the System Model Management Panel........................7-10
8-1 Portfolios Evaluation Process............................................................8-1
8-2 Portfolio Salinity (Total Dissolved Solids) ......................................8-2
8-3 Portfolio Compatibility and DBP Scores .........................................8-4
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Otay Water District Integrated Resource Plan
vi March 2, 2007
8-4 Cumulative Deficit under Extreme Drought Conditions
(a measure of Portfolio Reliability)...................................................8-6
8-5 Portfolio Reliability under Emergency Seismic Conditions .........8-7
8-6 Portfolio Capital Costs.......................................................................8-8
8-7 Portfolio NPV Unit Cost ....................................................................8-9
8-8 Number of Take Points and Contracts in Portfolio......................8-11
8-9 Percent Contribution of Largest Source to Total Supply in
Portfolio..............................................................................................8-11
8-10 Portfolio Scores for Environmental and Institutional
Constraints.........................................................................................8-12
8-11 Portfolio Ranking for Average Stakeholder Weights..................8-14
8-12 Number of Times a Portfolio was Ranked Number 1.................8-15
8-13 Number of Times a Portfolio was Ranked Number 1, 2, or 3.....8-15
9-1 OWD IRP Implementation Plan .......................................................9-4
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Otay Water District Integrated Resource Plan
March 2, 2007 vii
Acronyms
AFY Acre-feet per year
AFM Acre-feet per month
BMP Best Management Practices
CDM Camp Dresser & McKee
CDP Criterium Decision Plus
CEQA California Environmental Quality Act
CFS Cubic feet per second
CIP Capital Improvement Program
CRA Colorado River Aqueduct
CUWCC California Urban Water Conservation Council
CVP Central Valley Project
DHS Department of Health Services
DBP Disinfection By-Product
FCF Flow control facility
GW Groundwater
HAA Haloacetic acid
IRP Integrated (Water) Resources Plan
LMSE La Mesa-Sweetwater Extension
mg/l Milligrams per liter
MGD Million gallons per day
MOU Memorandum of Understanding
MWD Metropolitan Water District of Southern California
NPV Net present value
O&M Operation and maintenance
OWD Otay Water District
RO Reverse Osmosis
RWCWRF Ralph W. Chapman Water Reclamation Facility
RWQCB Regional Water Quality Control Board
SANDAG San Diego Association of Governments
SBWRP South Bay Water Reclamation Plant
STELLA Systems Thinking Experimental Learning Laboratory with
Animation
SDCWA San Diego County Water Authority
SWP State Water Project
SWRCB State Water Resources Control Board
TDS Total Dissolved Solids
THM Tri-halomethane
TOC Total organic carbon
UV Ultraviolet
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Otay Water District Integrated Resource Plan
viii March 2, 2007
UWMP Urban Water Management Plan
WBIC Weather-Based Irrigation Controller
WTP Water Treatment Plant
WRP Water Reclamation Plant
A ES-1
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Figure ES-1
Otay Water District Service Area
Executive Summary
The Otay Water District (OWD) provides water and wastewater services to
approximately 179,000 customers throughout its service area in southern San Diego
County. OWD delivers potable and reclaimed water supplies to portions of Bonita,
Chula Vista, Eastlake, El Cajon, Jamul, La Mesa, Otay Mesa, Rancho San Diego, and
Spring Valley (Figure ES-1).
Currently, OWD relies on imported water to satisfy all of its potable water demands
and most of its non-potable demands. With uncertainty surrounding imported water
supplies due to potential shortages during drought or seismic emergency conditions,
as well as the rising costs of imported water, OWD’s dependence on imported water
as their main source of supply potentially poses challenges to meet water demands
reliably and cost-effectively. OWD has taken a number of short-term actions that will
help diversify its water supply portfolio by the year 2010, but significant needs will
still exist to reduce imported water dependence after the implementation of these
short-term actions.
For these reasons, OWD has undertaken the development of an Integrated Resources
Plan (IRP) to examine potential, future supply options and their performance with
respect to a set of long-term, comprehensive water resource objectives developed as
part of the IRP process. The development of the IRP followed a process that resulted
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in a comprehensive and defensible implementation strategy to meet the OWD
objectives and allow flexibility to adapt to changes in the water industry and market
and regulatory conditions.
OWD Background
Total OWD water demands are anticipated to double in the next 25 years from
approximately 40,000 AFY to over 80,000 AFY. This is due to the fact that a large
percentage of undeveloped land with residential, commercial, and industrial land use
denominations will be developed. The current population of approximately 179,000 is
expected to grow to approximately 273,000 people at ultimate built-out conditions. Of
the total water demand, the demand for recycled water is expected to increase from
about 3,500 AFY to 7,300 AFY in 2030.
Supply for OWD primarily comes from imported water provided by the SDCWA
(treated and untreated). Some local agreements with neighboring agencies allow for
alternate water supplies in the case that treated water from the SDCWA aqueduct is
unavailable. Additionally, OWD owns and operates the Ralph W. Chapman Water
Reclamation Plant and delivers recycled water supplies to the Central Area and Otay
Mesa Systems. By the spring of 2007 these systems are expected to also receive
recycled water from the City of San Diego South Bay Water Reclamation Plant
(SBWRP).
Challenges to Meet Future Needs
Otay Water District faces a number of challenges in meeting future growing water
demands. Almost all of OWD’s supply is imported water supply from SDCWA; this is
expected to continue if no action is taken to develop local supplies. Because OWD
significantly relies on imported water to meet its water demands, it has greater risk in
terms of potential extreme droughts and seismic events that could reduce the amount
of imported water available. Additionally, because of the significant investments
being made by MWD and SDCWA to improve supply reliability, imported water
costs are expected to increase significantly.
Therefore, OWD needs to systematically evaluate a number of supply options to
define the best supply portfolio for the future, consistent with its mission to “provide
safe, reliable water and wastewater services to our community with innovation, in a
cost-efficient, water-wise and environmentally responsible manner.”
Integrated Resources Planning Process
An IRP is uniquely and collaboratively developed through the framework of a
systematic decision making process which takes into account multiple system
objectives and perspectives from multiple stakeholders (including OWD senior staff
and board members). An IRP involves the identification of the values and objectives
of an organization, and then looks at possible supply-side and demand-side water
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Figure ES-2
IRP Portfolio Evaluation Process
management options in a consensus-building process to develop a comprehensive
plan to meet the defined objectives.
Through the development of the IRP, planning objectives were defined and weighted
by stakeholders to account for the difference in their relative importance. In addition,
at least one performance measure was established for each objective.
Parallel to the definition of the objectives and performance measures, water supply
options were defined and combined into water supply portfolios. These portfolios
were evaluated using a systems model that simulated the behavior of the OWD water
system through the year 2030 providing information about raw portfolio performance
with respect to OWD’s objectives. Portfolio evaluation
was an iterative process where the performance results
of a set of portfolios were used to refine the next set until
preferred portfolios were identified (Figure ES-2).
Raw performance of the simulated portfolios was
translated to overall, objective-based performance and
the portfolios were ranked using a technique known as
the Multi-Attribute Rating Technique. The results of the
portfolio analysis and rankings were used to develop
preliminary recommendations for a future
implementation strategy for OWD. These
recommendations were discussed during a workshop
with the OWD and new portfolios were developed and
analyzed to develop a final implementation strategy.
Integrated Resource Plan Results
As part of the IRP process, OWD staff and board members defined the IRP objectives
and their relative importance. The six primary water resource objectives identified for
this IRP are:
Meet or Exceed Water Quality Standards and Guidelines
Achieve Reliability
Maintain Affordability
Increase Flexibility
Increase Diversity
Address Environmental and Institutional Constraints
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Figure ES-3
Average Weight Assigned by Staff and Bard Members to IRP Objectives
The relative importance of the objectives for senior staff members and OWD Board is
presented in Figure ES-3. Achieving reliability, meeting and exceeding water quality
standards and increasing diversity are important OWD objectives that will need to be
achieved by a program resulting from the IRP process.
Over 20 water supply portfolios were analyzed and the performance was measured
against their ability to meet the IRP objectives.
Throughout the analysis, the options that consistently showed in the top ranked
portfolios and that were ultimately considered feasible include the following:
Additional Conservation
Central Valley and Land Fallowing Transfers
Groundwater projects (Demineralization and Conjunctive Use)
5-10 MGD Ocean Desalination (Poseidon, or Sweetwater/City of SD’s South Bay
project)
Stripping Plant along Spring Valley Trunk Line
North District Recycled Water Concept
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Other options that could be considered for implementation are those that were in at
least one of the top three performing portfolios. These options are:
SD17 Agreement with City of San Diego to treat raw water at Alvarado WTP
Additional Purchases from South Bay WRP
North of Delta Transfers
The options listed above are projects, programs and contractual agreements that have
shown to best accomplish OWD’s goals when combined in a supply mix for the
future. Therefore, these projects are recommended for consideration in the IRP
implementation strategy.
Implementation Strategy
This IRP identifies an implementation path to keep OWD on track to accomplish its
long-term goals while strategically making investments only if and when necessary
(Figure ES-4). It is recognized that, due to the high-level planning and policy nature of
the IRP, some uncertainties on the technical or implementation aspects of the projects
can result in their unfeasibility. For example, some events may make the
implementation of a groundwater conjunctive use or desalination project more or less
feasible or cost effective. The implementation strategy accounts for these uncertainties
and provides an adaptable path that still allows OWD to accomplish it goals. The
implementation path is consistent with the IRP’s recommendations for a long-term
local supply mix. The implementation strategy identifies some short-term, mid-term,
and long-term actions and decisions that will take place during implementation.
The implementation path defines potential triggers and the potential actions that
could follow. OWD, however, can begin short-term steps immediately, which will
bring them closer to achieving longer term goals.
Projects, programs and contractual arrangements included in the short-term actions
are:
Additional conservation measures
SD17 agreement with the City of San Diego
Additional purchases from SBWRP
North District recycled water concept
Water banking agreements
These actions will serve as the foundation for the rest of the plan strategy.
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Implementation Costs
The different end points in the implementation paths presented in the implementation
strategy could result in a range of capital investment from approximately $117 million
to around $318 million. The top three IRP portfolios ranged from $132 million to $381
million, so the different implementation paths would result in costs comparable to
any of the three best scoring portfolios. What is important to recognize is that any of
the resulting paths in the implementation strategy would represent a diverse water
supply portfolio including projects, programs, and contractual agreements that have
shown to best accomplish OWD’s goals when combined in a supply mix for the
future.
Sensitivity Analyses
Two of the greatest long-term water management concerns for OWD are the
reliability and increasing cost associated with imported water purchases (raw or
treated) from the SDCWA. In order to test the robustness of the IRP decision, the
sensitivity of these two factors was analyzed to determine how the portfolio rankings
would change if: (1) imported water were 100 percent reliable even under severe
droughts, and (2) the projected cost of imported water were lower than the cost
projections used in the main analysis of this IRP. The sensitivity analysis showed that
the rankings of the preferred portfolios would remain the same, which indicates that
results of the portfolio rankings are robust and that the supply projects and programs
included in the top scoring portfolios are likely to achieve the OWD’s objectives.
Conclusions
The recommendations in the IRP will help Otay Water District achieve its mission to:
“provide safe, reliable water and wastewater services to our community with innovation, in a
cost-efficient, water-wise and environmentally responsible manner.”
The implementation strategy developed in the IRP will help OWD to confront the
uncertainties surrounding imported water supplies by reducing their dependence on
imported water. The plan will help the OWD achieve its objectives of achieving
reliability, maintaining affordability, increasing flexibility, increasing diversity, and
addressing environmental and institutional constraints.
LEGEND
Implement Project
Minimal Capital Cost Project
Maximum Capital Cost Project
Implement
Additional Conservation
SD17 Agreement with City of
San Diego to treat raw water at
Alverado WTP
Additional purchases from
SBWRP
North District Recycled Water
Concept
Water banking (5000 AFY)
•
•
•
•
•
Implement 5,000 AFY
ocean desalination project<
(Southern California
Partnership (SCP) preferred
over Poseidon)
Implement Chula Vista
stripping plant option<
Are ocean
desalination projects
feasible?
Yes
N
o
Implement
Additional or new ocean
desalination project
5,000 AFY
(Poseidon or SCP)
Spring Valley Stripping
plant option=
•
•No Action
Implement water
transfers (5,000 AFY)
Implement GW conjunctive
use project (Santee/El Monte?
or Middle Sweetwater)
Implement Brackish GW
Demineralization project
(Santee/El Monte>? or
Lower Sweetwater)
Is new supply
implemented to
date less than
25,000 AFY?
Yes
N
o
Yes
N
o
Are groundwater
conjunctive
use projects
feasible?
Implement additional ocean
desalination (if total yield of ocean
desalination projects implemented
to date is less than 5,000 AFY)
2007 2010 2015 2020 2030
NOTES
< If ocean desalination projects and stripping options are not feasible, implement Santee/El Monte brackish groundwater demineralization (with the use of the LMSE).
= If Chula Vista stripping plant is not already in place.
> If not already in place.
? Assumes use of LMSE pipeline.
Implement Brackish GW
Demineralization Project
(Santee/El Monte>? or
Lower Sweetwater)
Figure ES-4 OWD IRP Implementation Plan
TIMELINE
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Figure 1-1
Otay Water District Service Area
Section 1
Introduction
1.1 Project Background
1.1.1 District Characteristics
The Otay Water District (OWD) is located within San Diego County, east of the City
of San Diego on the U.S. – Mexican border in Southern California. OWD has a
planned service area of 143 square miles (126 square miles within its boundaries and
17 square miles within its area of influence). OWD provides water and wastewater
service to parts of the following communities: Bonita, Chula Vista, Eastlake, El Cajon,
Jamul, La Mesa, Otay Mesa, Rancho San Diego, and Spring Valley. Figure 1-1 shows
the OWD service area.
The OWD was formed in 1956 by local residents and landowners in response to the
need to address declining quality and quantity of water supplies in the arid region of
San Diego County. Since that time, OWD has been managing water and wastewater
services to meet the needs of its growing population of customers. The population
served by the OWD in 1980 was 48,300 people, and in 2005 the population was
179,000 (OWD et. al., 2005). The San Diego Association of Governments (SANDAG)
estimates that the population served by OWD in the year 2030 will be 273,150.
Section 1
Introduction
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The long term population growth rate has historically been about 3 percent per year.
The growth rate has been faster in recent years due to development in eastern Chula
Vista, and growth is expected to continue at an accelerated rate for another five to ten
years. In the long-term future, the growth rate is expected to slow as the amount of
undeveloped land decreases (OWD et. al., 2005).
According to OWD’s 2005 Urban Water Management Plan (UWMP), approximately
90% of OWD’s customers are single-family residences, and much of the anticipated
development will also be single-family residential. The relative composition of
OWD’s customers is expected to remain constant, since the commercial, industrial,
and institutional sectors will grow proportionally in order to support the residential
development.
The climate in San Diego County is characterized as Mediterranean, with mild
temperatures and low annual rainfall. Temperatures are mild on the pacific coast
year-round, and tend to be slightly more extreme inland at OWD – with warmer
temperatures in the summer and cooler temperatures in the winter. Average annual
rainfall for OWD is approximately 9.4 inches.
1.1.2 Imported Water Supply
OWD is a member agency of the San Diego County Water Authority (SDCWA),
which is in turn a member of the Metropolitan Water District of Southern California
(MWD). Together, SDCWA and MWD provide imported water from Northern
California and the Colorado River to their member agencies throughout Southern
California. MWD augments its imported water supplies with water transfers and
groundwater banking programs. SDCWA augments its imported water supplies with
water transfers and is planning other programs such as seawater desalination,
additional transfers, and/or groundwater programs.
Currently, OWD relies on imported water to satisfy all of its potable water demands
and most of its non-potable demands. This imported supply is delivered both treated
and untreated (raw) through the SDCWA aqueducts. The raw water is treated at local
water treatment plants through agreements with neighboring water agencies.
Reliability of Imported Water
Because OWD significantly relies on imported water to meet its water demands, it has
greater risk in terms of potential droughts and seismic events that could reduce or
terminate the amount of imported water available. Although both SDCWA and MWD
have long-range water supply plans that indicate they will be able to meet full-service
water demands of their member water agencies through 2025, these plans make a
number of important assumptions, as explained below.
In 2003, MWD released its update to its 1996 Integrated Water Resources Plan (IRP).
This IRP update concluded that MWD has enough water to meet full service demands
through 2025.
Section 1
Introduction
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However, this reliability assessment was based on the following assumptions:
1. Over 145,000 AFY of additional (beyond what was planned in the 1996 IRP)
local water conservation implemented by 2020
2. Approximately 250,000 of additional (beyond what was planned in the 1996
IRP) local recycled water, groundwater recover and seawater desalination
3. Seventy-seven years of historical hydrology for determining the reliability of
imported water from the State Water Project and Colorado River
4. An assumed solution for the Bay-Delta, the source of water for the State Water
Project
5. Full implementation of the California Settlement for the Colorado River
Many of these assumptions have been invalidated by one of the worst droughts on
record for the Western United States. Several reports prepared by the United States
Geological Survey (USGS) indicate that the recent droughts in the West have been the
worst in 500 years (based on tree ring analysis)1. This suggests that only using 77
years of historical hydrology to determine supply reliability might be inadequate in
explaining the real risk of drought.
The recent drought for the Colorado River (1998-present) is the worst drought on
record in terms of annual water supply. Prior to this drought, the average flow
volume of the Colorado River was approximately 15 million acre-feet (for the last 30
years); while the flow volume of the Colorado River since 1999 has averaged only 7.1
million acre-feet1.
Also, the CALFED record of decision, which will pave the way for the improvements
to the State Water Project has faced legal challenges in the past and is likely to have
some additional challenges in the future. This could result in even more local water
supply development being necessary in Southern California.
If the recent drought experienced for the Colorado River, along with reduced State
Water Project supplies due to legal challenges and increasing environmental
restrictions were to occur in the future, MWD’s assumption of 100 percent reliability
for imported water may not hold true.
Therefore, it is prudent for OWD to explore expanding its local resources
development as a way to hedge against supply risk for imported water.
1 USGS Fact Sheet 2004-3062 (August, 2004).
Section 1
Introduction
1-4 A
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Raising Costs of Imported Water
Because of the significant investments being made by MWD and SDCWA to improve
supply reliability, imported water costs are expected to increase significantly.
SDCWA’s Draft Water Facilities Master Plan (December 2002) evaluated three
alternatives for its CIP ranging from $2 to $6 billion. The most likely scenario is a $4
billion plus CIP that includes the emergency storage project, Twin Oaks Water
Treatment Plant, and a seawater desalination plant. MWD’s CIP is also about $4
billion, including several retrofits and expansions to its treatment plants, the Inland
Feeder Project, and other major conveyance systems.
1.2 Problem Statement
Given the uncertainties surrounding imported water supplies as a result of potential
drought shortages or emergency seismic conditions, as well as the rising costs of
imported water, the reliance of OWD on imported water as their main supply source
potentially poses challenges to fulfilling their organizational mission statement as
stated below:
To provide safe, reliable water and wastewater services to our community with innovation, in
a cost-efficient, water-wise and environmentally responsible manner.2
OWD, like many similar agencies in Southern California, is looking to reduce their
dependence on imported water, and in doing so, to reduce operational costs and
provide greater local control over their water resources and water management
systems. To do this, OWD needs to systematically evaluate a number of supply
options and define the best supply portfolio for the future.
1.3 Purpose of the Integrated Resources Plan
The Integrated Resources Plan (IRP) developed for OWD is a flexible, long-term
strategy for the implementation of key facilities, management, and inter-agency
agreements needed to expand and operate the OWD water system consistent with
OWD’s mission and values. An IRP is uniquely developed through the framework of
a systematic decision making process which takes into account multiple system
objectives and perspectives from multiple stakeholders. An IRP involves the
identification of the values and objectives of an organization, and then looks at
possible supply-side and demand-side water management options in a consensus-
building process to develop a comprehensive plan to meet the defined objectives.
The IRP uses computer-based systems and decision models as tools in the planning
process to simulate the operation of different supply options and then to quantify the
relative performance of different combinations of options (portfolios) as measured
against stated objectives.
2 Source: 2005 OWD Urban Water Management Plan prepared by OWD and MWH Americas, Inc.
Section 1
Introduction
A 1-5
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These modeling tools allow large amounts of data and complex system relationships
to be incorporated into the decision process while also giving proper consideration to
different, and often conflicting, values and perspectives among multiple stakeholders.
The result is a defensible plan for the future development and management of the
OWD that considers important objectives such as cost, reliability, environmental
protection, and water quality and that provides flexibility for changes and adaptation
in the future.
A 2-1
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Section 2
Existing Water Supply
Supply for the OWD primarily comes from imported water provided by the SDCWA.
Some local agreements with neighboring agencies allow for alternate water supplies
in the case that treated water from the SDCWA aqueduct is unavailable. However,
these alternate supplies themselves are heavily reliant on imported raw water.
Currently, OWD does not use any local sources, such as groundwater or seawater, to
meet potable customer demands. The only recycled supply currently available is from
OWD’s Ralph W. Chapman Water Reclamation Facility, although OWD has an
agreement with the City of San Diego to receive effluent from the South Bay Water
Reclamation Plant.
Upgrades and expansions to the current (2006) water supply system have already
been planned, and implementation has begun. This includes some new, higher-
capacity pipelines, larger pump stations in certain areas, and interconnection facilities
between the subsystems of the service area. Given the goals of the IRP of identifying
new supply options in the development of a long-term water supply strategy,
planned facilities expansions and upgrades through the year 2010 were included in
the baseline, or “existing”, system, while the focus of this IRP was to identify and
evaluate options that went beyond the already planned level of improvements for the
system.
2.1 Water Supply Systems
The OWD service area is divided into five subsystems. These systems are known as:
La Presa System, the Regulatory System, the Hillside System, the Central Area
System, and the Otay Mesa System. The Presa, Regulatory, and Hillsdale systems are
grouped together into what is known as the North District. The Central Area and
Otay Mesa systems make up the South District.
For the purposes of modeling in this study, the OWD service area is considered to be
divided into three systems: North, Central Area, and Otay Mesa. These systems are
geographically separated and operationally distinct (See Figure 2-1 for the geographic
locations). Each system receives imported water from one or more flow control
facilities (FCF) on the SDCWA aqueduct. Each has its own storage and pumping
facilities, as well as its own demands to serve.
Section 2
Existing Water Supply
2-2 A
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Figure 2-1
North, Central Area, and Otay Mesa Systems
Figure 2-2 shows a schematic of the entire OWD system as it is expected to exist in
2010. This schematic represents the major facilities and conveyance infrastructure
from the source to system demands. For purposes of the IRP, details of the facilities
associated with the distribution system are not shown on this schematic.
North System
The North System uses Flow Control Facility (FCF) No. 11 to divert water by gravity
from San Diego County Water Authority (SDCWA) Pipeline No. 4 to the 640 and 520
reservoirs. Water then flows by gravity or is pumped from the reservoirs to La Presa,
the Regulatory, and the Hillsdale systems of the service area. Flow Control Facility
No. 11 has a meter capacity of 38.8 million gallons per day (MGD), or 60 cubic feet per
second (cfs).
In addition to receiving treated imported water purchases through Pipeline No. 4, the
North System can also receive water from Helix Water District’s Levy Water
Treatment Plant through a pipeline expected to replace the existing La Mesa-
Sweetwater Extension (LMSE) by March 2010.
Section 2
Existing Water Supply
A 2-3
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Central Area System
The Central Area System receives treated water from FCF No. 10 and FCF No. 12 on
Pipeline No. 4 which is delivered to the 624 reservoirs. FCF No. 10 has a capacity of
18.1 MGD (or 28 cfs), and FCF No. 12 has a capacity of 38.8 MGD (or 60 cfs).
In addition, water treated at the City of San Diego’s Otay Water Treatment Plant
(WTP) can be delivered to the Central Area System. OWD has an agreement with the
City of San Diego to treat 10 MGD of raw water purchased from the SDCWA at the
Otay WTP. This agreement is discussed in more detail later in this section.
Otay Mesa System
The Otay Mesa System receives treated imported water from FCF No. 13 on Pipeline
No. 4. This water flows by gravity into the 571 storage reservoir from which it is
pumped to reservoirs at a higher elevation to serve water demands. FCF No. 13 has a
capacity of 25.9 MGD (or 40 cfs).
Figure 2-2
Baseline System Schematic
14
.
4
m
g
d
ca
p
a
c
i
t
y
Pumped from
Central to
North
Central
Area
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
RWCWRF
FCF No. 11 38.8 mgd
capacity
Helix
WTP
SD
C
W
A
P
L
N
o
.
4
(
T
r
e
a
t
e
d
)
Reservoirs
300
1.1 mgd (pum ped to 9 44)FCF No. 10 18.1 mgd
capacity
FCF No. 12 38.8 mgd
capacity
FCF No. 13 25.9 mgd
capacity
SD
C
W
A
P
L
N
o
.
3
(
R
a
w
)
Assume sufficient capacity to
meet Otay Mesa projected
recycled demands
Tijuana Emergency Interconnect
(Federal Treaty Water)
Not included in model
Permanent Pump Station: 30 mgdCity of SD
Otay WTP
6 mgd
(pumped to 450 and
potentially 944)
SDCWA 1st Aqueduct
(Raw )
C a p a c it y:
•1 2 m g d o n p e a k
•1 6 m g d o ff p e a k
O W D i s o b li g a te d t o t a k e
1 0 ,0 0 0 af y
N e w 3 6 ”Pi p eli n e
F C F N o . 1 4
640/520
624
571
Potable Facilities
Raw Facilities
Recycled Facilities
Emergency Facilities (Potable)
Note: Facilities with red font are
planned.
Agreement for up to 10 mgd
• Summer Operation: 8 mgd
• Winter Operation: 10 mgd
450/944
450
100
14
.
4
m
g
d
ca
p
a
c
i
t
y
Pumped from
Central to
North
Central
Area
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
RWCWRF
FCF No. 11 38.8 mgd
capacity
Helix
WTP
SD
C
W
A
P
L
N
o
.
4
(
T
r
e
a
t
e
d
)
Reservoirs
300
1.1 mgd (pum ped to 9 44)FCF No. 10 18.1 mgd
capacity
FCF No. 12 38.8 mgd
capacity
FCF No. 13 25.9 mgd
capacity
SD
C
W
A
P
L
N
o
.
3
(
R
a
w
)
Assume sufficient capacity to
meet Otay Mesa projected
recycled demands
Tijuana Emergency Interconnect
(Federal Treaty Water)
Not included in model
Permanent Pump Station: 30 mgdCity of SD
Otay WTP
6 mgd
(pumped to 450 and
potentially 944)
SDCWA 1st Aqueduct
(Raw )
C a p a c it y:
•1 2 m g d o n p e a k
•1 6 m g d o ff p e a k
O W D i s o b li g a te d t o t a k e
1 0 ,0 0 0 af y
N e w 3 6 ”Pi p eli n e
F C F N o . 1 4
640/520
624
571
Potable Facilities
Raw Facilities
Recycled Facilities
Emergency Facilities (Potable)
Note: Facilities with red font are
planned.
Agreement for up to 10 mgd
• Summer Operation: 8 mgd
• Winter Operation: 10 mgd
450/944
450
100
Section 2
Existing Water Supply
2-4 A
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Similar to the Central Area System, the Otay Mesa System also received water treated
at the City of San Diego’s Otay WTP.
Recycled Water Facilities
In addition to the potable water infrastructure described above, recycled water
supplies are also delivered to the Central Area and Otay Mesa Systems through
pipelines from the Ralph W. Chapman Water Reclamation Plant (owned and operated
by OWD), and are expected to be delivered to these systems from the City of San
Diego South Bay Water Reclamation Plant (SBWRP) by the spring of 2007. The
recycled water system is also shown on the schematic in Figure 2-2, and is further
described in Section 2.3 below. Currently there is no system for recycled water in the
North System.
Alternative Supply/Emergency Interconnections
An interconnection pipeline between the Central Area and Otay Mesa Systems
currently exists, and an interconnection between the Central Area and North District
is expected to be in place after 2010. These interconnections permit the transfer of
water between systems and provide flexibility in the management of demands in the
case of an emergency, such as an earthquake, that disrupts the normal operation of
the SDCWA aqueduct. The interconnections are not intended for normal operating
conditions. Additionally there exists a 13 MGD emergency interconnect between
OWD and the city of Tijuana in Mexico. This interconnect can be used to deliver
international treaty waters to Mexico, but was not modeled in the IRP because the
emergency transfer of water is not obligatory.
2.2 Potable Water Supply
2.2.1 San Diego County Water Authority Imported Supply
Imported water from SDCWA is the primary source of water for OWD. OWD takes
both treated water and raw water from SDCWA. Treated water from SDCWA is
directly delivered to OWD’s reservoirs through four flow control facilities on Pipeline
No. 4. Raw water from SDCWA is first delivered to the Helix Water District’s Levy
Water Treatment Plant (WTP) or the City of San Diego’s Otay WTP for treatment and
then it is conveyed to the OWD service area.
The SDCWA is a member agency of the Metropolitan Water District of Southern
California (MWD). MWD is the regional water wholesaler for Southern California,
providing supplemental water to over 17 million people in Los Angeles, Orange,
Riverside, San Bernardino, San Diego, and Ventura Counties.
MWD owns and operates the Colorado River Aqueduct (CRA), along with major
reservoirs such as Diamond Valley Lake and Lake Skinner, 5 regional water treatment
plants, and large transmission pipelines to move imported water to its 26 public
member agencies. Over the last few years CRA supply, historically providing over 1.2
million AFY to the region, has been severely cut. This was due to the development of
Section 2
Existing Water Supply
A 2-5
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the California Plan for Colorado River, which forces California to live within its 4.4
million AF entitlement of Colorado River. MWD does have programs in place and is
working on others in order to maximize supplies from the CRA and in certain years
get back to the 1.2 million AFY level.
MWD is also the largest State Water Contractor, with a contract of 2.0 million acre-feet
for State Water Project (SWP) supply. The SWP is subject to extreme variability in
hydrology due to a lack of storage. Although MWD has a contract for 2.0 million AF,
it rarely has received that (only in the very wettest of years). Average deliveries have
been closer to 1.2 million AFY. In severe droughts, SWP supplies to MWD have been
less than 0.5 million AFY.
MWD augments its imported water from the CRA and SWP with stored water in
water banks such as Semitropic and Arvin-Edison, conjunctive use storage in local
basins, and voluntary water transfers during certain dry years. MWD’s IRP (1996) and
IRP Update (2003) indicate that MWD will have the supplemental water to meet all of
its member agencies’ water needs through 2025, even during a repeat of the 1987-1992
drought condition, although this is based on a number of assumptions that may not
hold true as discussed in Section 1.
2.2.2 City of San Diego’s Otay WTP
The City of San Diego’s Otay WTP has a rated capacity of 40 MGD with an effective
capacity of 34 MGD, of which 20 MGD is currently used by the City of San Diego. In
1999, OWD entered into an agreement with the City of San Diego to be provided with
10 MGD of treatment capacity from the Otay Water Treatment Plant, if such surplus is
available. Typically, OWD receives only 8 MGD during summer months, in which
water demands are the highest. Current trailer-mounted pumping facilities have
capacity to deliver 6-20 MGD from the Otay plant to the OWD distribution system.
Potential upgrades to a permanent pump station would allow for a conveyance
capacity of 30 MGD.
OWD purchases raw water from the SDCWA for treatment at the Otay WTP.
2.2.3 Helix Water District’s Levy WTP
A SDCWA Board of Directors commitment dating back to 1976 entitles OWD to be
provided with 8 MGD of treated water by SDCWA through a pipeline known as the
La Mesa-Sweetwater Extension (LMSE). To fulfill this obligation, SDCWA acquired
capacity from the Helix Water District at their R.M. Levy WTP for treated water to be
conveyed through the LMSE to OWD.
Although the current (2006) rated conveyance capacity of the LMSE is 12 MGD, the
effective capacity is limited to 3.4 MGD due to hydraulic limitations. In the future, the
LMSE pipeline is expected to either be converted for use in raw water delivery to
Sweetwater Authority or else abandoned. In the case that the pipeline is abandoned,
it was assumed that it could be used for conveyance in some of the supply options
Section 2
Existing Water Supply
2-6 A
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described in Section 5. A new 36-inch pipeline that will replace the LMSE is planned
to be operational by March 2010 with a conveyance capacity of 16 MGD. In addition,
FCF No. 14 will be upgraded to a capacity of 16 MGD to convey water from Levy
WTP to the new pipeline for delivery to OWD. Per the terms of the recent agreement
between SDCWA and OWD regarding implementation of the East County Regional
Treated Water Improvement Program (ECRTWIP), the supply to OWD from the Levy
WTP via FCF No. 14 and the new pipeline will be up to 12 MGD on-peak and 16
MGD off-peak. Once the new pipeline is operational, the LMSE is expected to be
abandoned or converted to raw water service by SDCWA.
Per the terms of the ECRTWIP, OWD must purchase a minimum of 10,000 acre-feet
per year (AFY) of treated water from Helix’s Levy WTP beginning in March 2010.
2.3 Recycled Water Supply
2.3.1 Ralph W. Chapman Water Reclamation Facility
OWD owns and operates the Ralph W. Chapman Water Reclamation Facility
(RWCWRF). This facility provides tertiary treated wastewater effluent that meets Title
22 requirements for non-restricted impoundments, spray irrigation of food crops, and
the broadest category of landscape irrigation. Wastewater treated at RWCWRF comes
from the OWD and the Spring Valley Sanitation District. Effluent from this plant that
is not further treated and put to beneficial re-use is disposed of via the Rancho San
Diego Outfall. The RWCWRF has a current rated capacity of 1.3 MGD (approximately
1,460 AFY), although in terms of water quality, the reliable continuous treatment
capacity of this facility is approximately 1.1 MGD (1,230 AFY) (OWD et. al., 2005).
2.3.2 City of San Diego South Bay Water Reclamation Plant
The South Bay Water Reclamation Plant (SBWRP) is owned and operated by the City
of San Diego’s Metropolitan Wastewater Department. The plant became operational
in May 2002, and has a rated treatment capacity of 15 MGD with an effective capacity
of approximately 14 MGD. The effluent receives either secondary treatment for
discharge into the Pacific Ocean, or tertiary treatment to meet Title 22 requirements
for reclaimed water use. The design allows for tertiary treatment of all flows (14
MGD); of which, 10 MGD is available for reclaimed use by other water agencies.
In October 2003, OWD entered into an agreement with the City of San Diego to
receive at least 6 MGD of treated effluent from the SBWRP. In addition, the agreement
presents a minimum purchase schedule for OWD on an annual basis. For purposes of
this analysis, the supply from SBWRP to OWD was limited to 6 MGD.
Due to the seasonal fluctuation in reclaimed water demands, it should be noted that
the supply from SBWRP will need to exceed 6 MGD during peak summer months in
order to satisfy the minimum purchase agreement on an annual basis. However, any
supply exceeding 6 MGD is not promised to OWD, and is not reliable for planning
purposes. Therefore, the minimum annual purchases required in the agreement were
Section 2
Existing Water Supply
A 2-7
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not enforced in this analysis. Rather, supply from SBWRP was limited to the
minimum of reclaimed water demands or 6 MGD, whichever was lower.
2.4 Summary of Existing Supply
Upgrades and expansions to the current (2006) system have already been planned.
These include some new, higher-capacity pipelines, larger pump stations in certain
areas, and interconnection facilities between the subsystems of the service area. Table
2-1 compares the current (2006) system with the system as it is expected to exist in the
year 2010.
Given the goals of the IRP to identify new supply options and develop a long-term
water supply strategy, planned facilities expansions and upgrades through the year
2010 were included in the baseline, or “existing”, system for purposes of the IRP. For
reference, the baseline (2010) facilities in Table 2-1 are consistent with the system
schematic in Figure 2-2.
Table 2-1
Comparison of 2006 and 2010 Water Facility Capacities and Agreements
Supply Source 2006 Current Yield 2010 baseline Yield
Imported
Treated water from SDCWA
through Pipeline # 4
121.5 MGD
[Capacity]
121.5 MGD
[Capacity]
City of San Diego’s
Otay WTP
10 MGD
[Agreement]
10 MGD
[Agreement]
Helix’s Levy WTP 3.4 MGD [Capacity]
8 MGD [Agreement]
12 MGD On-Peak,
16 MGD Off-Peak [Agreement]
Recycled
OWD’s Chapman WRP 1.1 MGD [Capacity] 1.1 MGD [Capacity]
City of San Diego’s
South Bay WRP
0 MGD 6 MGD
[Agreement]
A 3-1
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Section 3
Projected Water Supply Gap
3.1 Future Water Demands
Future water demand projections provide the context for the evaluation of water
supply alternatives, and support the development of the IRP. In addition, water
demand projections can be used to schedule the timing of water supply investments
in order to minimize unnecessary costs. The following is a description of the projected
demands used for this IRP for the North, Central Area, and Otay Mesa Systems
within OWD.
3.1.1 Annual Average Demand Projections
The total OWD water demand projections for potable and recycled uses are based on
estimates in the OWD’s 2005 Urban Water Management Plan (UWMP), and
summarized in Table 3-1. These demands were prepared by the San Diego County
Water authority (SDCWA) using the CWA-MAIN model, which applies input data
for population, demographics, climate, economic forecasts, and other variables to
estimate future water use. The total demand projections in the UWMP are higher than
the demand projections estimated in the 2002 Water Resources Master Plan, but OWD
has elected to use them for the IRP to maintain consistency with planning work by the
SDCWA (OWD et. al., 2005).
Table 3-1
Otay Water District Total Demand Projections
Potable Water Use Recycled
Water Use2 Total Water Use1 Forecast
Year afy afy afy
2005 35,288 3,485 38,773
2010 45,772 4,040 49,812
2015 52,349 4,684 57,033
2020 59,799 5,430 65,229
2025 66,560 6,294 72,854
2030 75,108 7,297 82,405
1 Source: 2005 Urban Water Management Plan, page 15. 2 Source: 2005 Urban Water Management Plan, pages 33-34.
For purposes of the IRP, the total OWD demands were divided into demands for the
North, Central Area, and Otay Mesa Systems (described in Section 2) based on
demand distributions delineated in the 2002 Water Resources Master Plan. The
projected distribution of total demand to each system for the years 2016 and 2030 are
shown in Table 3-2, and annual rates of change were assumed to be linear throughout
the planning horizon. The resulting projected demands for each system (North,
Central Area, and Otay Mesa) that were used for the IRP are shown in Figure 3-1.
Section 3
Projected Water Supply Gap
3-2 A
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Table 3-2
Projected Demand Distributions by System for Potable and Recycled Uses
Potable1 Recycled2
Forecast Year
NORTH CENTRAL AREA OTAY MESA CENTRAL AREA OTAY MESA
2006 41% 51% 8% 89% 11%
2016 37% 54% 9% 84% 16%
2035 33% 52% 15% 77% 23% 1 Source: Adapted from 2002 Water Resources Master Plan, page 4-9. 2 Source: Adapted from 2002 Water Resources Master Plan, page 11-12.
As shown in Figure 3-1, total OWD demands are anticipated to double in the next 25
years from approximately 40,000 AFY to over 80,000 AFY. This is due to the fact that a
large percentage of undeveloped land is being converted from agricultural use to
higher water consuming residential, commercial, and industrial uses. In addition, the
current population of approximately 179,000 persons is expected to grow to
approximately 273,000 persons at ultimate built-out conditions (OWD et. al., 2005).
The land use changes and population growth translate into a significant increase in
projected water demands through the year 2030.
It is also clear from Figure 3-1 that the Central Area System represents the majority of
demands, and has the largest increase in demands over time. According to the 2005
Figure 3-1
Otay Water District Projected Annual Demands
Section 3
Projected Water Supply Gap
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UWMP, the Central area is comprised primarily of major residential developments,
while the Otay Mesa area is expected to develop almost exclusively as industrial with
very small commercial and residential land uses.
3.1.2 Weather Impacts and Peaking
Water demands are not uniform over time. Rather, water demands at nearly all
municipal water agencies exhibit variability on an annual, monthly, and daily basis.
Annual and seasonal changes in weather affect water demands, and people’s lifestyles
and business habits affect water demand throughout the day. This variability is
subject to random processes, but inherent patterns can be observed over time and
used in the planning and management of water supply systems. Annual, monthly,
and daily water use patterns can be described; and although weather is unpredictable,
understanding its range of effects can improve management of water resources.
3.1.2.1 Annual Weather Impacts
When projecting future water demands, it is important to recognize that demands
fluctuate year-to-year based on local weather. Water demands are greater in dry-
weather years than in average-weather years, due to increased landscape irrigation
needs and other uses. Additionally, there is uncertainty due to weather and
hydrology regarding the amount of imported water available from year to year. In
order to account for the variability caused by different hydrological conditions,
demand factors were generated. The factors are multipliers to be applied to the base
demand projections (average annual value). A demand multiplier equal to 1.0 would
represent the average annual hydrology condition, while a multiplier greater than 1.0
would apply to dry-weather years with higher demand. Inversely a demand
multiplier less than 1.0 would represent wet-weather years with lower demand. These
factors account for fluctuations in demand related to local weather and the availability
of imported water supply.
Local weather factors for water demand were obtained from the Metropolitan Water
District (MWD), which developed them statistically from their long-term planning
efforts. These demand factors were shared with and reviewed by the SDCWA in
previous studies.
Imported water from the SDCWA and MWD is one of the most variable sources of
water supply. This variation is mainly due to hydrology in northern California, which
is not always correlated to hydrology in San Diego County. The imported water
variability from the Colorado River is tempered by the massive storage within the
system (which has over 10 times the storage as the SWP system). Weather factors for
imported water were also obtained by MWD.
The resultant factors, which account for fluctuation in demand due to local weather
and imported water supply, were assigned to each year of hydrologic record and are
shown in Figure 3-2. Of the 77 historical hydrologic years of record from 1922 to 1998,
38 years (or 49 percent) were normal, 21 years (or 27 percent) were dry, and 18 years
(or 23 percent) were wet.
Section 3
Projected Water Supply Gap
3-4 A
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3.1.2.2 Seasonal (Monthly) Impacts
Water demands not only vary from year-to-year, but also from season-to-season (for
instance, irrigation demands increase during dry summer months). To account for
these seasonal fluctuations in demand, monthly demand factors were developed
based on historical water use patterns for the OWD. The following is a description of
the method for calculating the monthly demand factors.
OWD’s historical monthly SDCWA purchases were available for the period from July
1992 through June 2005 for the North, Central Area, and Otay Mesa Systems. In
addition, historical total recycled water demands were available from January 1996
through December 2005. Because historical recycled water demands have exceeded
the potential supply from RWCWRF in the past, SDCWA treated water purchases
have historically been used to meet recycled water demands.
In order to develop seasonal factors for potable demands only, historical monthly
recycled water demands (assuming 1.1 MGD supply from OWD’s RWCWRF) were
subtracted from the total SDCWA purchases. The remaining SDCWA purchases were
assumed for potable uses.
Figure 3-2
Annual Hydrologic Demand Factors
Section 3
Projected Water Supply Gap
A 3-5
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Monthly potable demand factors could then be calculated based on the ratio of
monthly potable water use variations to the annual average month water use. The
calculated potable monthly demand factors for each system are shown in Figure 3-3.
The factors are multipliers to be applied to the base demand projections (average
annual value). A demand multiplier equal to 1.0 would represent the average month
demand, while a multiplier greater than 1.0 would apply to peak demand months. On
the contrary, a demand multiplier less than 1.0 would represent low demand months.
These factors account for fluctuations in demand related to seasonal water use
patterns.
Monthly seasonal factors for recycled water demands were given in the 2002 Water
Resources Master Plan, and are shown in Figure 3-4. These seasonal variations for
recycled water demand originated from the City of San Diego Clean Water Program
Reports.
Figure 3-3
Monthly Seasonal Potable Demand Factors
Section 3
Projected Water Supply Gap
3-6 A
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3.1.2.3 Peak Day Demands
The peak day factor for potable water demands was derived from figure 4-1 in the
2002 Water Resources Master Plan, which illustrates the relationship between peak
day factors and average annual demands. In general, peak day factors decrease as
annual average demands increase. Since the annual average demand projections for
each system increase over time, projected peak day factors were adjusted accordingly.
Over the planning horizon, the North System peak day factor remains at 1.8, while the
Central Area System peak day factor ranges between 1.75-1.8, and the Otay Mesa
System peak day factor ranges from 1.9-2.2. The peak day factor for recycled water
demands is given as 2.6 in the 2002 Water Resources Master Plan.
The total supply peak day demands are summarized in Table 3-3.
Table 3-3
Total Supply Peak Day Demand Projections
Annual Total Demand Average Annual Day
Total Demand
Peak Day Total
Demand1 Forecast Year
afy mgd mgd
2005 38,773 35 66
2010 49,812 44 84
2015 57,033 51 95
2020 65,229 58 108
2025 72,854 65 121
2030 82,405 74 136
1 Potable demand peak factors for each system are based on Master Plan (Figure 4-1).
Peak factor of 2.6 for recycled water demands is based on Master Plan (page 11-7).
Figure 3-4
Monthly Seasonal Recycled Demand Factors
Section 3
Projected Water Supply Gap
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Because the capacity of existing water supply facilities discussed in Section 2 exceeds
the estimated 2030 peak day total water demand, there are no projected peak day
capacity shortages for OWD under normal operating conditions.
3.2 Supply Gap Analysis
There is currently sufficient capacity to meet all OWD future demands through
purchases of imported water from SDCWA. In that sense, there is no projected supply
gap. Figure 3-5 below shows the projected supply mix for OWD assuming the
baseline water supply as discussed in Section 2, where imported water purchases are
assumed to increase to meet system demands. As can be seen with this baseline case,
most of the water used by OWD will come from imported SDCWA water. The OWD
objectives for this IRP, however, which will be described further in Section 4, place
emphasis on reliability, flexibility, and diversity and point toward decreasing the
dependence on imported SDCWA water supplies. These three objectives and the
potential issues associated with the reliability of imported supply (discussed in
Section 1), create an opportunity for OWD to develop a more diverse water supply
portfolio.
Figure 3-5
Projected Baseline Supply Mix over Time
A 4-1
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Figure 4-1
“Why” and “How” Parallel Paths in the IRP
Section 4
Evaluation Framework
4.1 Evaluation Process
The IRP proceeded initially along two parallel paths: the objectives path and the
supply options path. The objectives path develops the “why’s” in the IRP – why is the
planning being undertaken?, why would one option be selected over another?, etc. These
questions are answered by explicitly defining planning objectives. Planning objectives
are of fundamental importance to a successful IRP as they describe, in this case, what
OWD aims to achieve with regard to its long-term management of water resources.
The supply options path develops the “how’s” in the IRP – these are the specific
alternatives that OWD can choose from as means of meeting its water supply needs.
Individual supply options can be projects, programs, or contracts with other agencies
and the water supplies for these options can be from sources such as groundwater,
recycled water, ocean desalination, etc. Since no single supply option is going to be
able to meet all of OWD’s objectives, separate supply options must be combined into
portfolios. The portfolios, because of their multiple sources, can increase diversity and
can better meet multiple objectives.
In order to be able to use the objectives and supply options together, there needs to be
a means of quantifying the importance of the objectives relative to one another, as
well as a means of quantifying how well different supply options satisfy those
objectives. Characterizing the relative importance of the objectives is done by giving
them weights. Quantifying the ability of the supply options to satisfy the objectives is
done by defining performance measures, which are specific and measurable attributes
related to the objectives.
All of the planning objectives, weights, and
performance measures are put together in
an IRP in what is known as a value model.
Here, goals are explicitly stated and
elaborated with the objectives, and the
importance of the objectives relative to
one another is characterized by the objective
weighting. Portfolios (or different
combinations of supply options) can be
evaluated against the objectives through the
specific performance measures. Ultimately,
the analysis results in the selection of a
preferred portfolio. Figure 4-1 depicts the
generic process followed in an IRP. This
process is further described in the
sections that follow.
Section 4
Evaluation Framework
4-2 A
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4.1.1 Objectives and Performance Measures
As part of the IRP, the OWD Board and senior staff worked on defining planning
objectives consistent with the OWD’s strategic planning goals, but specific to the
development of the IRP. The objectives serve as the goals or reasons “why” the IRP is
being undertaken.
Objectives are usually categorized into primary and secondary (with the secondary
objectives being termed sub-objectives). Primary objectives are more general; while
secondary help define the primary objectives in more specific terms.
For each sub-objective, a performance measure is required. The performance measure
is used to indicate whether an objective is being achieved.
The following example illustrates the hierarchy of objectives, sub-objectives, and
performance measures.
Primary Objective Sub-objectives Performance Measures
Maximize number of sources Total number of sources
Increase Diversity Reduce contribution of largest
source
Percent contribution of the largest
source to total supply
Principles of good decision-making indicate that primary objectives should be
developed such that they are:
Distinctive: objectives should be developed to distinguish between one project (or
portfolio) and another
Measurable: objectives should be able to be measured, either quantitatively or
qualitatively, in order to determine if they are being achieved
Non-Redundant: objectives should not overlap with each other
Understandable: objectives should be easily explainable
Concise: objectives should be kept to manageable numbers
The objectives, sub-objectives and performance measures defined by OWD are shown
in Table 4-1. Some of the objectives apply to the individual supply options (such as
“Meet or Exceed Water Quality Standards and Guidelines” and “Address
Environmental and Institutional Constraints”) while other objectives are more
applicable to the overall combination of supply options included in an specific
portfolio. This distinction is represented in the analysis.
Section 4
Evaluation Framework
A 4-3
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Table 4-1
OWD Objectives, Sub-objectives and Performance Measures
Objective Sub-objective Performance Measure
1a) Meet current and future drinking water
standards Compliance
1b) Address compatibility of new sources
with current imported supply Compatibility Score
Average TDS of all Potable
Sources 1c) Meet total dissolved solids (TDS) goals
for recycled water, potable water and
Basin Plan Average TDS of all Non-
potable Sources
1) Meet or Exceed Water Quality
Standards and Guidelines
1d) Minimize potential issues due to
disinfection method
Disinfection By-Products (DBP)
Score
2a) Meet demands under average hydrology
conditions
2030 Annual Deficit;
evaluated under average
hydrology conditions
2b) Meet demands under drought imported
shortage conditions
Cumulative Deficit over all
shortage years; 2) Achieve Reliability
2c) Minimize impacts under emergency
conditions
2030 Deficit during a three
month emergency period
3a) Minimize impacts to an average single-
family customer Present Value $/AF
3) Maintain Affordability
3b) Manage Capital Costs Capital costs ($)
4) Increase Flexibility 4a) Increase Number of Take Points and
Alternative Flow Routes Total Number of Take Points
5a) Maximize number of sources Total Number of Contracts
5) Increase Diversity
5b) Reduce contribution of largest source
2030 percent contribution of
the largest source to total
supply
6a) Minimize environmental permitting
requirements Permitting Score
6b) Minimize institutional coordination and
implementation requirements
(local/State/Federal/International)
Institutional Coordination Score
6c) Maximize customer acceptance Customer Acceptance Score
6d) Minimize regulatory constraints Regulatory Constraints Score
6) Address Environmental and
Institutional Constraints
6e) Minimize technology uncertainty Technology Uncertainty Score
Section 4
Evaluation Framework
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Figure 4-2
Example Objective Weighting for One Stakeholder
4.1.2 Weighting Objectives
In any decision-making process, the objectives are generally not equally important for
every stakeholder. Some objectives may be more relevant for one stakeholder than
others (e.g., for a given individual, operational flexibility may be more important than
environmental and institutional constraints). Thus, weighting objectives is necessary
to better reflect the values and preferences of stakeholders and decision-makers.
For the IRP, the objectives were weighted using a method known as “forced-paired
comparison.” This method simplifies the comparison of numerous planning
objectives by looking at the relative importance of only two objectives at a time. This
relative comparison is performed for all the possible pairs of objectives, and the
results can be aggregated using simple algorithms to determine the overall
importance of every objective. Overall weights can be obtained for each individual
participant, as well as for the group as a whole. For the case of the IRP, objectives
were weighed individually by each stakeholder (see Appendix A for the results of this
exercise). Each stakeholder’s individual weightings for the objectives were preserved
and used to rank portfolios (later described in Section 8).
Figure 4-2 presents an example result from this exercise for one stakeholder, where:
(1) the vertical line represents the range of weights assigned to each objective by all
stakeholders; (2) the horizontal line marker shows the average weight for all
stakeholders; and (3) the diamond marker represents the weight for this example
decision maker. The minimum and maximum weights of the group of stakeholders
indicate that there is a very large spread in terms of objective importance.
Section 4
Evaluation Framework
A 4-5
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Since the results of the weighting exercise were maintained for each stakeholder, the
IRP planning team developed 13 different (5 board members and 7 senior staff)
profiles for the objective weightings. For comparison purposes only, the IRP planning
team aggregated results into two set of weights: Board members and senior staff
members (see Figure 4-3).
In general, the weights appear to be similar for the Board members and the senior
staff for issues related to reliability, affordability, flexibility, and diversity. There are
however large differences between Board members and staff members regarding
water quality and environmental and institutional constraints. These differences
exhibit a consistency with the roles and responsibilities of each. For example, Board
members, whose main responsibilities include setting policy, tend to be more
interested in water quality, which is related to quality of life. In contrast, staff
members, whose main responsibility is executing policy, tend to be more interested in
implementation issues related to environmental permitting and institutional
coordination.
4.1.3 Identify Options and Create Portfolios
The planning objectives represent essential reasons or purposes “why” OWD is
undertaking the IRP; however, they do not specify “how” OWD should move
forward to meet these objectives. Supply options represent the individual projects and
programs that are the potential means for accomplishing the planning objectives. The
IRP used these options as building blocks to develop integrated portfolios with the
potential to meet the planning objectives.
Figure 4-3
Comparison of Average Objective Weightings
Section 4
Evaluation Framework
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Even with a relatively small number of options, the different combinations to form
portfolios could be fairly large. Therefore, initial portfolios are developed that tend to
push the boundaries of the objectives. In other words, the first round of portfolios is
developed to optimize specific objectives. But since the purpose of an IRP is to find a
solution that balances all the objectives, it is understood that these initial portfolios
may not be the best overall performers.
By examining the performance of these initial portfolios, trade-offs can be seen, such
as maximizing supply reliability but at very high cost. Understanding these trade-offs
can be useful in developing final portfolios, which take the best elements from top-
scoring initial portfolios in order to create better performing portfolios.
4.2 Portfolio Evaluation Method
After developing objectives and portfolios, the next step in the planning process is to
evaluate each portfolio. The IRP planning team developed and used a systems model
programmed with the commercial software STELLA® to evaluate the IRP portfolios.
In general, the systems model simulates water demands and supplies under different
hydrologic and operating scenarios. The systems model can output raw performance,
such as supply reliability, cost, water quality, etc. in order to see how well a specific
portfolio meets the objectives.
Because the systems model outputs raw performance measured in different units
(e.g., reliability measured in AFY, cost measured in dollars, and water quality
measured in milligram per unit volume), another decision tool is often needed to rank
the portfolios.
The IRP planning team used the commercial software Criterium Decision Plus (CDP),
developed by Infoharvest Inc., to rank the portfolios. This software tool converts raw
performance measured in different units into standardized scores so that the
performance measures can be added together in order to rank portfolios. This
technique is called Multi-Attribute Rating and is illustrated in Figure 4-5.
Step 1 is to compare the raw performance of a given objective for all the portfolios. In
this example, Portfolio 6 has a raw cost (or performance) of $10 million.
Step 2 standardizes the raw performance score for each objective into comparable
numeric scores (the higher the score the better the performance). In this example,
Portfolio 6 has relatively high costs when compared to the other portfolios, so the
standardized score for this objective (between 0 and 10) is 3.4, a fairly low
performance.
Section 4
Evaluation Framework
A 4-7
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Steps 3 and 4 calculate the partial score for the portfolio, based on the standardized
score and the weight for the objective being calculated. In this example, the cost
objective was given a weight of 9 percent (out of a possible 100 percent). The partial
score for this objective is represents the standardized score (3.4) multiplied by the
objective weight (0.09) which equals 0.306.
Step 5 plots the partial score of 0.306 for Portfolio 6, and this procedure repeats for all
of the other objectives for Portfolio 6 until a total score for the project is calculated [see
Step 6].
The IRP planning team used this process to develop overall scores for each portfolio
and using each stakeholder’s unique objective weights in order to get 13 different
rankings. In this way, the number of times a portfolio was ranked as the Top 1, 2,or 3
could be calculated to determine the top performing portfolios.
Figure 4-5
Multi-Attribute Rating Method
A 5-1
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Section 5
Water Supply Options
Parallel to the definition and development of planning objectives, water supply
options were identified that could be used by Otay Water District (OWD) to meet
their long term water management objectives. The process of developing supply
options was collaborative between OWD and CDM. Potential options were identified
by both parties; and through discussion and refinement, a diverse list of realistic
options was agreed upon. Supply options can be projects, programs, or contractual
arrangements with other agencies; they are the building blocks for the water supply
portfolios (discussed in Section 6). The potential options can be broken down into
categories based on the source of the water and the processes required before the
water can be used. The categories of supply options include: conservation,
groundwater, water banking and water transfers, ocean desalination, and recycled
water. Additionally, different options were identified for the expansion of treatment
agreements with local agencies.
Following the identification of potential supply options, each option was
characterized in terms of the conceptual mode of operation, facilities required for
implementation, expected reliable yield, capital and operating costs, and issues
related to water quality, environmental impact, and institutional coordination. It
should be noted that the costs, yields, and other characteristics of the supply options
are intended for planning level analysis and modeling. Although every attempt was
made to obtain reasonable data, in some cases, certain estimates had to be made based
on prior studies and/or professional engineering judgment. Before any supply option
is actually implemented, a detailed investigation may be required.
In the sections that follow, the potential supply options are described. A list of all the
options evaluated, along with information regarding their yields and costs, is
provided in a summary table located in Appendix B. Specific and detailed cost
estimates for each option can be found in Appendix C.
In addition to developing yields and costs, each supply option was evaluated for its
performance with respect to two of the planning objectives (i.e. “Water Quality” and
“Addressing Environmental and Institutional Constraints”). The option scores for
performance measures of “Water Quality” and “Environmental and Institutional
Constraints” are shown in Appendix B.
The supply option ratings summarized in Appendix B are later used to calculate
overall scores for the water supply portfolios.
Option Unit Cost Calculation
The unit cost (dollar per acre-foot) was calculated for each option, and incorporates
both capital and operation and maintenance (O&M) costs. The method used to
calculate option unit cost differs from the method to calculate portfolio unit cost
Section 5
Water Supply Options
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discussed in Section 7. For options, in order to compare them independently for
portfolio development, the unit cost is calculated based on the entire potential yield of
the option. Also, the operation and maintenance in today’s dollars was used, rather
than inflating the O&M costs over time. The option capital cost was amortized at a 6%
interest rate, assuming a payment period of 30 years. The total annual cost (capital
and O&M) was then divided by the option’s potential annual yield to calculate the
unit cost in dollars per acre-foot.
For portfolios, several options are used in conjunction with each other to meet future
demands, and a particular option may not necessarily be used to its full capacity at all
times. In order to account for varying use of options over time, the unit cost of the
portfolios was calculated assuming the net present value of incremental costs of new
water over the entire planning horizon.
Imported Water Costs
Imported water from the San Diego County Water Authority (SDCWA) is currently
OWD’s only potable water supply. OWD purchases both treated and raw (untreated)
imported water. The cost of imported water is greatly influenced by the capital
improvement programs of the Metropolitan Water District of Southern California
(MWD) and the SDCWA. MWD’s capital improvement program has been estimated
to be between $1 and $2 billion over the next 20 years. SDCWA’s capital improvement
program has been estimated to range between $2 and $4 billion. Rising energy costs
and O&M costs for conveyance of water from the Bay-Delta and regional treatment
are also expected to increase imported water costs.
The SDCWA imported water rates in 2007 are shown in the table below.
Table 5-1
SDCWA 2007 Imported Water Rates
Purchase Rate
[$/AF]
Transport Rate
[$/AF]
Total
[$/AF]
Untreated M&I supply rate 365 60 425
Treated M&I supply rate 515 60 575
Untreated groundwater replenishment rate 238 60 298
For OWD, the total commodity rate that would have to be paid for purchasing treated
imported water would be $575/acre-foot ($60 transportation rate + $515 treated
supply rate). OWD also has to pay its share of SDCWA’s fixed costs, which include:
customer service charge; storage charge; infrastructure access charge; and a parcel or
standby charge.
MWD offers a discount in its water rates, of which the SDCWA can take advantage of,
for groundwater storage. Currently the SDCWA directly passes this water rate to any
local agency that can replenish groundwater and store the water for a period of at
least one year. The SDCWA transportation rate would be added to this groundwater
Section 5
Water Supply Options
A 5-3
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replenishment rate. A number of the groundwater conjunctive use options that OWD
is exploring could take advantage of MWD’s discounted water rate, which would
reduce imported water costs.
SDCWA has projected treated M&I water rates to the year 2016, which indicate that
there will be a 72 percent increase over current rates.1 To project SDCWA water rates
from 2017 to 2040, CDM used rate projections from MWD and SDCWA, as well as CIP
costs for both agencies to determine an annual percentage increase which would be
applied to the 2016 SDCWA projected water rate. These annual percentage increases
in water rates are:
Transportation rate 3.5 percent annual increase
Treated M&I supply rate 6.7 percent annual increase
Untreated M&I supply rate 8.0 percent annual increase
Untreated groundwater replenishment 3.5 percent annual increase
These water rate projections include inflation, which is currently averaging 2.5
percent per year. Projecting water rates more than 30 years into the future is highly
uncertain, but based on current SDCWA and MWD CIPs, it is certain that imported
water costs will increase much faster than inflation. Figure 5-1 summarizes the
projections for the total treated, untreated, and groundwater replenishment water
rates including transportation charges.
1 Projections of SDCWA water rates provided by Mr. Jeff Garvey of the Water Authority on July 6,
2006.
Figure 5-1
Projected SDCWA Imported Water Rates (including transportation charges)
Section 5
Water Supply Options
5-4 A
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5.1 Water Conservation
In 1992, OWD adopted a Memorandum of Understanding (MOU) from the California
Urban Water Conservation Council (CUWCC) that includes Best Management
Practices (BMPs) for reducing long-term urban water demands (OWD et. al., 2005).
The 14 BMPs are aimed at conserving water by reducing consumption, providing
incentives for consumers to participate (i.e. rebates on plumbing retrofits),
establishing education and information programs about the importance of water
conservation, as well as addressing conservation at the institutional and managerial
levels.
During Fiscal Year 2005, OWD is estimated to have saved approximately 1,087 acre-
feet of water. Current water conservation programs implemented by OWD include
(OWD et. al., 2005):
Cash for Plants Landscape Retrofit Program
Signage Grant Received to Highlight Waterwise Model Homes
Water Conservation Programs for New Homes
Outreach Efforts to Otay Customers
Commercial Water Conservation Programs
Large Landscape Programs
Residential ULFT Program-$75 and $95 Vouchers
Residential High Efficiency Clothes Washer Program
School Education Program
Residential Weather-Based Irrigation Controller (WBIC) Incentive Program
The future conservation goals for OWD are provided in the 2005 UWMP, and were
distributed to the North, Central Area, and Otay Mesa Systems based on land use
projections in the 2002 Master Plan. The cost per acre-foot saved for each BMP was
obtained from OWD staff members. The projected conservation goals and
corresponding costs for each system are shown in Figures 5-2 and 5-3, respectively.
Section 5
Water Supply Options
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Figure 5-2
Projected Conservation Water Savings by System
Figure 5-3
Projected Conservation Costs by System
Figure 5-2 shows the conservation
savings in the North System decreasing
over time, even though the total overall
savings are increasing. This is because
the Central Area System currently
represents 50% the single-family
residential sector, while the North
System represents the other 50%. In
future build-out conditions, the single
family sector is anticipated to gradually
transition to only 11% in the North
System, and 89% in the Central Area
System. This projected decrease of the
single family residential sector from
50% to 11% in the North System
explains why the projected savings in
the North System decrease, since a
majority of total conservation savings
come from BMP’s associated with the
single-family residential sector and
landscape irrigation.
Section 5
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5.2 Groundwater Options
Groundwater resources are a promising local supply option, providing more localized
control and potentially lower treatment and conveyance costs. Two general types of
groundwater options were considered: 1) safe-yield groundwater extraction with
demineralization, and 2) conjunctive-use storage of imported water providing a dry
year supply. Groundwater extraction and demineralization will provide OWD with a
new local water source, improve system reliability, and contribute toward a gradual
improvement in the quality of the basin. Conjunctive use consists of recharging
imported water during periods of high availability and lower cost (by taking
advantage of MWD’s replenishment rates) and recovery during high-demand periods
(i.e. summer months), drought, or emergency conditions. This type of project will
enhance the reliability of the OWD system.
Several basins were considered for potential groundwater projects because of their
proximity to Otay Water District. These include: the Middle Sweetwater basin, the
Lower Sweetwater basin, the Santee/El Monte basin, the San Diego Formation
aquifer, and the Tijuana River Valley aquifer. Figure 5-4 shows the location of the
basins in relation to the OWD service area. Additionally, a number of small well
projects were considered. These include a new well northeast of the Otay Mesa Yard
well, the Rancho del Rey Well, the Daley Ranch well, and the Otay Mountain well
site. The Daley Ranch well, new well northeast of Otay Mesa Yard well, and the
Rancho del Rey well were eliminated from further consideration however, due to
institutional concerns, their high unit cost, and/or poor water quality.
A schematic figure showing the relationship between the groundwater supply options
and the OWD water supply system is shown in Appendix B.
A
Location of Groundwater Basins
Figure 5-4
Otay Water District
Otay - Integrated Water
Resources Plan (IRP)"
Chapman
WRP
§¨¦ 5
§¨¦805
·|}þ 94
·|}þ125
·|}þ 94
§¨¦ 8
§¨¦905
·|}þ 54
§¨¦ 15
§¨¦805
·|}þ125
Mi d d le Sweetwate r B asin
Santee El M o n t e B a si n
M i s s i o n S a n D i e g o B a s i n
San Die g o F ormation
Tiajuana River Valley
SB
WRP
Helix's Levy
WTP
Approximate Location
of SDCWA PCF #14
P
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Lower Otay R eservoir
S w e e t wate r Reservoir
L o v el and Res ervoir
Lake
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North
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Central
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Otay Mesa
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L o w e r Swee
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wa t e r Ba s i n
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Mexico
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15,000 0 15,0007,500
Feet
Legend
× Water Recycling Plant
+C Water Treatment Plant
Pipeline
El Monte Pipeline
Groundwater Basin
Otay Mountain Well"
Spring Valley Trunk Sewer
Mission Gorge Trunk Sewer
La Mesa Sweetwater Extension
SDCWA Pipeline No. 3 (Raw)
SDCWA Pipeline No. 4 (Filtered)
System Boundary
Section 5
Water Supply Options
A 5-8
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5.2.1 Middle Sweetwater Conjunctive Use
The Middle Sweetwater basin is defined as the 17-mile reach of the Sweetwater River
between Loveland and Sweetwater Reservoirs. The basin is located mostly within the
OWD service area. This is an alluvial aquifer with a thickness of 20-30 feet in the
upstream section, 60-150 feet in the middle section, and 10-20 feet in the downstream
sections. The depth to the water table is shallow. Its tributary system includes
additional alluvial aquifers. The alluvial sediments in the basin are coarse sand and
gravel having moderate to high permeability. The alluvium is bordered by slightly-
fractured crystalline bedrock which is generally impermeable.
Alluvial storage is approximately 29,000 acre-ft: approximately 17,000 AF above
Singing Hills Golf Course, and 12,000 AF downstream.
Recharge to the basin is from surface water, such as the Sweetwater River (approx
2,000 AFY) as well as stormwater and irrigation return flows (approx. 1,600 AFY).
Boyle (1993) estimated a net recharge of 750 AFY. As of 1991, approximately 1,560
AFY were being extracted from the basin for golf course irrigation and residential use.
No recent water quality information has been obtained for the Middle Sweetwater
basin. However in 1993, total dissolved solids (TDS) concentrations in the upper basin
were under 600mg/l; and in the lower basin were between 500mg/l to 1500 mg/l. It is
assumed that water quality has deteriorated over time, and that TDS concentrations
would be higher at this time.
Potential Project
In this concept project, groundwater extraction would occur during dry years to help
OWD meet demands in drought conditions. During this time, the water table would
be allowed to drop so that the aquifer could be recharged with imported water at a
later time. The advantage of this configuration would be that OWD could meet
demand in extremely dry years and recharge with less expensive imported water
using MWD replenishment rates. It is assumed that pumping efficiency decreases
as the basin is depleted.
For planning purposes, it is assumed that a 5,000 AFY conjunctive use project may be
implemented. Recovered water may be delivered to the North System of the service
area. Filtered replenishment water may be obtained from the abandoned La Mesa-
Sweetwater Extension (LMSE) if this option is available and proves less expensive, as
it would require less conveyance infrastructure (see Section 2.2.3). Alternatively,
unfiltered water from the San Diego Aqueduct Pipeline No. 3 could be obtained. For
purposes of this analysis, it was assumed that recovered groundwater quality is
sufficient for delivery without demineralization. A conceptual schematic of this
option is shown in Figure 5-5.
Section 5
Water Supply Options
5-9 A
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Figure 5-5
Middle Sweetwater Conjuntive Use Option Schematic
The facilities/project components required for this option include:
Conveyance of water to Middle Sweetwater Basin for recharge
Infiltration basins
Extraction wells
Monitoring wells
Conveyance of recovered water (pipeline and pumping)
Land acquisition
Imported raw water purchases from SDCWA (at the groundwater replenishment
rate)
Assuming the use of the LMSE to convey water for groundwater recharge, the total
capital cost of this option is estimated at $44,950,000, and the annual operation and
maintenance costs are approximately $2,655,000/year. The unit cost of this option is
$1,184/AF.
If the LMSE is not available for use, additional conveyance infrastructure would be
required to bring raw water from the SDCWA Pipeline No. 3 to the basin for recharge.
In this case, the total capital cost of this option is estimated at $65,187,000, and the
annual operation and maintenance costs are approximately $3,307,400/year. The unit
cost of this option is $1,609/AF.
Extraction
Wells
North System
(Regulatory)
Pump
Station
Infiltration
Basins
5000 AFY
5000 AFY
5000 AFY
L M S E
Pipeline
No. 3
Option 2: No LMSE
5000 AFY
Extraction
Wells
North System
(Regulatory)
Pump
Station
Infiltration
Basins
5000 AFY
5000 AFY
5000 AFY
L M S E
Pipeline
No. 3
Option 2: No LMSE
5000 AFY
Section 5
Water Supply Options
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To implement this option, OWD would need to coordinate with the Sweetwater
Authority to ensure that adverse impacts are not created, and potentially to discuss
partnering opportunities. In addition, OWD would need to coordination with
SDCWA for delivery of replenishment water at replenishment rates.
Potential issues to be considered include adverse impacts to Sweetwater Authority
and private wells as well as adverse impacts to riparian habitat dependent on
groundwater. In addition, it may need to be confirmed by more extensive research
that recovered groundwater demineralization will indeed not be needed.
Groundwater demineralization will increase cost and create the need for brine
management.
5.2.2 Lower Sweetwater Brackish Groundwater Demineralization
The Lower Sweetwater basin is defined as the 8-mile reach of the Sweetwater River
between Sweetwater Reservoir and San Diego Bay, and is located outside of the OWD
service area. The basin consists of an alluvial aquifer and the underlying San Diego
Formation. There is approximately 13,000 acre-ft of storage in the basin, including the
underlying San Diego Formation. The alluvial aquifer consists of sand and gravel, and
the depth to groundwater is in the range of 0-20 ft. The net recharge to the alluvial
aquifer is estimated to be approximately 1,100 AFY. Boyle (1993) estimated that up to
1,500 AFY could be extracted from the basin.
Salinity in the alluvial aquifer varies from 1,700 to 3,100 mg/l, while TDS
concentrations in the urban runoff recharge water is approx 2,500 mg/l.
Potential Project
Under this option, 1,500 AFY of brackish groundwater would be extracted and treated
with reverse osmosis (RO). Assuming a treatment efficiency of 85%, 1,275 AFY of
treated water would be conveyed to the Central Area System. The RO treatment
would generate 225 AFY of brine which could be disposed of in the San Diego
County’s Spring Valley Trunk Sewer, which ultimately flows to the Point Loma
Wastewater Treatment Plant. A conceptual schematic of this option is shown in
Figure 5-6.
The facilities/project components required for this option include:
Extraction wells
Monitoring wells
RO treatment plant
Conveyance for treated water (pipeline and pumping)
Conveyance for brine disposal
Land acquisition
Section 5
Water Supply Options
5-11 A
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The total capital cost of this option is estimated at $11,250,000, and the annual
operation and maintenance costs are approximately $942,000/year. The unit cost of
this option is $1,184/AF.
Potential issues for the implementation of this project include the need to coordinate
with Sweetwater Authority and possibly the City of Chula Vista to obtain access to
the basin and locate the required facilities. In addition, OWD needs to coordinate with
the City of San Diego and the County of San Diego for the use of the sewer system for
brine disposal. Brine disposal may in turn impact the salinity of Point Loma effluent
and require significant environmental review.
5.2.3 Santee/El Monte Basin
The Santee/El Monte basin is located outside of OWD’s service area along the San
Diego River and mostly in the City of Santee and Lakeside (Padre Dam Municipal
Water District). See Figure 5-4. The basin includes an alluvial unit with total storage
volume of 55,000 AF, composed of gravel, sand, silt and clay. This unit is capable of
storing and transmitting large quantities of water. It is assumed that 50% of this
volume would be available for potential storage use by OWD since use of the basin is
also proposed by the City of San Diego and Padre Dam MWD. The thickness of the
aquifer ranges from 50 to 230 feet. The water table is shallow (between 15 and 30 feet
below the surface).
Groundwater has in the past been pumped by Helix WD, Lakeside WD and
Riverview WD; however, recent groundwater production information has not been
obtained.
Extraction
Wells
Central SystemPump
Station
RO
Plant
Spring Valley Trunk Sewer
(to Point Loma WWTP)
Brine
Waste
1500 AFY
225 AFY
1275 AFY
Extraction
Wells
Central SystemPump
Station
RO
Plant
Spring Valley Trunk Sewer
(to Point Loma WWTP)
Brine
Waste
1500 AFY
225 AFY
1275 AFY
Figure 5-6
Lower Sweetwater Brackish Groundwater Demineralization Option Schematic
Section 5
Water Supply Options
A 5-12
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The most recent water quality information obtained (1985) indicates that TDS
concentrations in the eastern portion of the basin are in the order of 500 mg/l,
although much higher concentrations (1,500 mg/l) have been observed.
Water quality in the western portion of the basin is worse, with TDS concentrations
ranging from 1,500 to 2,000 mg/l.
Estimates of the safe yield of the basin range from 1,650 to 5,500 AFY.
Previous studies have estimated that between 8,700 and 11,700 AFY of imported
water could be stored in the eastern portion of the basin (Woodward-Clyde 1990,
Black and Veatch 1994). The most favorable conditions for recharge and storage
appear to be near Lakeside, Moreno Valley and El Monte.
Three supply options for the OWD IRP were considered: imported water conjunctive
use, brackish groundwater demineralization, and a combined project of both
conjunctive use and brackish demineralization.
5.2.3.1 Santee/El Monte Conjunctive Use
With this option, 5,000 AF of imported water would be recharged to the basin in
wetter years and recovered during high demand periods, droughts, or emergency
conditions. Recharge water could be obtained from one of the following sources: 1)
raw water from the San Vicente Reservoir via the El Monte Pipeline; 2) raw or treated
water from the Second San Diego Aqueduct (Pipeline No. 3 raw water or Pipeline No.
4 treated water); or 3) La Mesa Sweetwater Extension (LMSE). Of these options, the El
Monte pipeline and the LMSE are closer to the basin and would require less
conveyance infrastructure. However, there may be limitations due to conveyance
capacity.
For cost estimating purposes, it was assumed that the basin would be recharged with
raw water from the San Vicente Reservoir conveyed via the El Monte pipeline. The
replenishment water would percolate into the ground through infiltration basins and
then be extracted and conveyed to the Regulatory System in the North System. It is
assumed that pumping efficiency decreases as the basin is depleted.
Recovered water could be conveyed to OWD through any of the three conveyance
facilities (i.e. San Diego Aqueduct, El Monte pipeline, LMSE); each with relative
advantages and disadvantages. Pipeline No. 4 and the LMSE convey treated water, so
the recovered water could go to one these two lines. However, conveyance to Pipeline
No. 4 would require significant pumping to pressurize the new water to the operating
pressure of the aqueduct. The LMSE has a capacity of 12 MGD, but is currently
constrained to 3.4 MGD due to hydraulic limitations (OWD, 2002). The LMSE pipeline
is to be converted to raw water conveyance for Sweetwater Authority or else
abandoned by 2010. If it is abandoned, it was assumed that the pipeline would be
available for options considered in the IRP. For cost estimating purposes, conveyance
via the LMSE was used for this option, and it was assumed that current hydraulic
Section 5
Water Supply Options
5-13 A
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Figure 5-7
Santee/ El Monte Conjunctive Use Option Schematic
limitations will be eliminated when this option is implemented. Because OWD does
not own the LMSE and its use is proposed by other new water supply options, cost
estimates were also developed assuming the LMSE is not available for use. A
conceptual schematic of this option is shown in Figure 5-7.
The facilities/ project components required for this option include:
Conveyance of replenishment water
Infiltration basins
Extraction wells
Monitoring wells
Conveyance of recovered water (pipeline and pumping)
Land acquisition
Imported raw water purchases from SDCWA (at the groundwater replenishment
rate)
Assuming the use of the LMSE to convey recovered water to the North System, the
total capital cost of this option is estimated at $41,950,000, and the annual operation
and maintenance costs are approximately $2,675,000/year. The unit cost of this option
is $1,145/AF.
If the LMSE is not available for use, additional conveyance infrastructure would be
required from the basin to the North System. In this case, the total capital cost of this
Extraction
Wells
North System
(Regulatory)
Pump
Station
Infiltration
Basins
5000 AFY
5000 AFY
El Monte Pipeline
San Vicente
Reservoir
L M S E o r new p i peline
Extraction
Wells
North System
(Regulatory)
Pump
Station
Infiltration
Basins
5000 AFY
5000 AFY
El Monte Pipeline
San Vicente
Reservoir
L M S E o r new p i peline
Section 5
Water Supply Options
A 5-14
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Figure 5-8
Santee/El Monte Brackish Groundwater Demineralization Option Schematic
option is estimated at $64,009,600, and the annual operation and maintenance costs
are approximately $3,160,000/year. The unit cost of this option is $1,562/AF.
Given the distance from the basin to OWD’s service area and the need to convey wet
water, OWD could consider partnering with other water districts for the
implementation of projects in a way in which OWD participates financially but
receives in-lieu water from a different source.
Potential implementation issues for this concept project include the need to
coordinate with the city of San Diego, Padre Dam MWD and other jurisdictions
located within the basin for the use of the basin and to address any potential water
rights issues. Coordination with SDCWA will also be required for obtaining
replenishment water and for potentially using some of its infrastructure.
5.2.3.2 Santee/El Monte Brackish Groundwater Demineralization
This concept project entails extracting and treating brackish groundwater throughout
the year. According to available literature, the safe yield of the basin ranges from
1,650 to 5,500 AFY. Approximately 5,600 AFY of groundwater is currently being
extracted from the basin by municipal (1,600 AFY) and agricultural users (4,000 AFY).
Under this option it is assumed that 5,000 AFY will be extracted from the ground and
treated by reverse osmosis (RO). Assuming a treatment efficiency of 85% for brackish
demineralization, 4,250 AFY would be delivered to the OWD distribution system and
750 AFY of brine concentrate could be disposed of in the City of San Diego
Metropolitan Wastewater District (Metro) Mission Gorge Sewer Line, and ultimately
discharge at the Point Loma Ocean Outfall.
The treated groundwater would be delivered to the North System either by the LMSE,
if available for use, or by new conveyance facilities. A conceptual schematic of this
option is shown in Figure 5-8.
Extraction
Wells
North SystemPump
Station
RO
Plant
Mission Gorge Sewer Line
(to Point Loma WWTP)
Brine
Waste
5000 AFY
750 AFY
4250 AFY
L M S E
If LMSE not available, new
conveyance facilities would
be required.
Extraction
Wells
North SystemPump
Station
RO
Plant
Mission Gorge Sewer Line
(to Point Loma WWTP)
Brine
Waste
5000 AFY
750 AFY
4250 AFY
L M S E
If LMSE not available, new
conveyance facilities would
be required.
Section 5
Water Supply Options
5-15 A
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The facilities/project components required for this option include:
Extraction wells
RO treatment plant and brine disposal facilities
Conveyance of treated water (pipeline and pumping)
Monitoring wells
Land acquisition
Assuming the use of the LMSE to convey recovered water to the North System, the
total capital cost of this option is estimated at $32,390,000, and the annual operation
and maintenance costs are approximately $2,863,000/year. The unit cost of this option
is $688/AF.
If the LMSE is not available for use, additional conveyance infrastructure would be
required from the basin to the North System. In this case, the total capital cost of this
option is estimated at $63,702,000, and the annual operation and maintenance costs
are approximately $3,593,000/year. The unit cost of this option is $1,084/AF.
The ability for OWD to extract and treat groundwater would depend on the actual
current safe yield and use of the basin. Additionally, there might be water rights
issues precluding OWD from obtaining this water. This issue might be resolved by
extracting brackish groundwater for demineralization and replenishing the aquifer
with better-quality imported water. This configuration will over time improve the
quality of the aquifer.
Given the distance from the basin to OWD’s service area and the need to convey
water, OWD could consider partnering with other water districts for the
implementation of projects in a way in which OWD participates financially but
receive in-lieu water from a different source.
Brine disposal will be an important consideration for project implementation and will
require significant environmental review and coordination with the city of San Diego
Metropolitan Wastewater Department. Also of concern is the high cost for capacity
through the Metropolitan Wastewater Department.
5.2.3.3 Santee/El Monte Brackish Combined Conjunctive Use and Brackish
Groundwater Demineralization
This option combines the Conjunctive Use and Brackish Groundwater
Demineralization projects described above, although each project would operate
independently of the other. As there would be no shared infrastructure (other than
the conveyance to the North System), the capital and O&M costs for a combined
project would essentially be a summation of the total costs for the conjunctive use
project and the total costs for the groundwater demineralization project. By having a
mechanism for replenishment water recharge, this configuration could address
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Water Supply Options
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Figure 5-9
San Diego Formation Brackish Groundwater Desalination Option Schematic
potential site need and water rights issues associated with a stand-alone
demineralization project.
If the use of the LMSE is not available for use, the new conveyance infrastructure
required to bring product water to the North System should be sized for the
combined flow of the Conjunctive Use and Brackish Groundwater Demineralization
projects.
5.2.4 San Diego Formation Brackish Groundwater
Demineralization
The San Diego Formation aquifer underlies the South Bay and extends approximately
two miles north and inland to Mission Bay. The aquifer is outside of the OWD service
area. Refer to Figure 5-4 for the groundwater basin location.
The aquifer is between 800-2400 ft thick, with transmissivity between 2100-5300
ft2/day. Well yields in the basin range from 400-800 gpm/well (Boyle 1999).
However, the aquifer is highly heterogeneous, so large variation in individual well
yields exist.
Salinity ranges from 500-2100 mg/l; and thus, extracted water would likely require
demineralization for potable use. The capacity of a demineralization project would
depend on the safe yield of the aquifer.
The option considered for the IRP is to extract 2,500 AFY of groundwater from the San
Diego formation for demineralization by reverse osmosis, of which 2,125 AFY would
be delivered by pipeline to the Central Area System, and 375 AFY would be disposed
of as brine concentrate. The brine waste would be sent to the San Diego County’s
Spring Valley Outfall, and ultimately discharge at the Point Loma Ocean Outfall.
A conceptual schematic of this option is shown in Figure 5-9.
Extraction
Wells
Central SystemPump
Station
RO
Plant
Spring Valley Trunk Sewer
(to Point Loma WWTP)
Brine
Waste
2500 AFY
375 AFY
2175 AFY
Extraction
Wells
Central SystemPump
Station
RO
Plant
Spring Valley Trunk Sewer
(to Point Loma WWTP)
Brine
Waste
2500 AFY
375 AFY
2175 AFY
Section 5
Water Supply Options
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The facilities/project components required for this option include:
Extraction wells
RO treatment plant (with brine disposal facilities)
Conveyance to distribution system (pipeline and pumping)
Monitoring wells
Land acquisition
The total capital cost of this option is estimated at $22,525,000, and the annual
operation and maintenance costs are approximately $1,679,000/year. The unit cost of
this option is $1,362.
Potential issues for project implementation include seawater intrusion, interference
with other users of the basin, such as Sweetwater Authority, and brine disposal.
Additional extraction from the Formation has been considered by Sweetwater
Authority and the City of San Diego. Brine may affect the salinity of the Point Loma
effluent.
Brine disposal will be an important consideration for project implementation and will
require significant environmental review and coordination with the city of San Diego
Metropolitan Wastewater Department.
5.2.5 Tijuana River Valley Aquifer Reclaimed Water Storage
The Tijuana River basin is a coastal alluvial aquifer located north of the U.S./Mexico
border in the City of San Diego (see Figure 5-4). This site was initially considered for
the storage of reclaimed water from the City of San Diego’s South Bay Water
Reclamation Plant for use during peak summer months. The amount of available
storage would be in the order of 500 AF. If this water is recovered over a 6-month
period, the basin could produce approximately 1 MGD of reclaimed water.
This option was eliminated from further consideration due to a number of factors.
First, water quality is an issue in terms of salinity and runoff in the Tijuana River. TDS
concentrations in the aquifer range from 850 to 9,000 mg/l. Extraction without
artificial replenishment may result in seawater intrusion, further degrading the
quality of the aquifer. The potential for storage of high quality imported water would
be limited by the amount of storage availability.
Additionally, there are some issues that would complicate the implementation of this
project. The California Department of Health Services (DHS) requires recharge
reclaimed water to have TDS and total organic carbon (TOC) concentrations lower
that those of the South Bay effluent. If a waiver cannot be obtained, effluent would
require membrane treatment prior to recharge, thus significantly increasing the cost of
the project.
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Water Supply Options
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5.2.6 Other Groundwater Wells
Four smaller, local groundwater well projects were initially considered in the IRP.
These projects included groundwater extraction wells and conveyance facilities to the
OWD distribution system from the following sites: Rancho del Rey well, Daley Ranch
well, northeast of the Otay Mesa Yard well, and the Otay Mountain well site. For the
Rancho del Rey, and northeast of Otay Mesa Yard well sites, limited information was
available, but there was strong concern about poor water quality (in the form of high
TDS concentrations) at those sites. Advanced treatment with reverse osmosis would
be required for these wells, which is very expensive for such a small yield. For the
Daley Ranch site, there was concern about institutional coordination and wildlife
losses. For these reasons, these three well projects were eliminated from further
analysis in the IRP. The Otay Mountain wells site was considered for evaluation.
5.2.6.1 Otay Mountain Well
Information for the Otay Mountain well site is based on an agreement between OWD
and D&D Landholdings for the exploration, production, and sale of potable water
and water rights. The Otay Mountain well is located near the intersection of Otay
Mesa Rd. and Alta Rd. The water quality at this well is characterized by high TDS and
would thus require demineralization treatment before the water could be used.
Under this option, 1,612 AFY of water would be extracted from the ground and
treated by reverse osmosis for use in the non-potable supply for OWD. Assuming a
treatment plant efficiency of 85%, 1,370 AFY of treated water would be conveyed to
the 860 reservoir for recycled water use in the Otay Mesa System. Also, 242 AFY of
brine concentrate would be produced. It is assumed that this waste can be disposed of
either in a sanitary sewer close to the location of the well, or else via a dedicated brine
disposal line connected to the City of San Diego’s South Bay Ocean Outfall. Initially in
the analysis, brine disposal in a local sanitary sewer was assumed; a dedicated brine
line would add to the cost of the option and decrease its attractiveness. The
performance of this option in later analysis indicated that even without the added cost
of the dedicated brine line, this option was not favored.
The facilities/project components required for this option include:
Extraction well
RO treatment plant (with brine disposal facilities)
Conveyance to 860 Reservoir (pipeline and pumping)
Land acquisition
The total capital cost of this option is estimated at $12,380,000, and the annual
operation and maintenance costs are approximately $970,000/year. The unit cost of
this option is $1,364.
Section 5
Water Supply Options
5-19 A
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Brine disposal will be an important consideration for project implementation and will
require significant environmental review and coordination with the City of San Diego
Metropolitan Wastewater Department.
5.3 Additional Recycled Options
Recycled or reclaimed water can be used to meet select irrigation demands in place of
potable water at considerable cost savings and while utilizing an otherwise discarded
resource. Otay Water District currently owns and operates the Ralph W. Chapman
Water Reclamation Facility (RWCWRF) which produces 1,230 AFY of recycled water.
Additionally, OWD has entered into agreement with the City of San Diego to receive
approximately 6,700 AFY of recycled water from the South Bay Water Reclamation
Plant (SBWRP). Recycled water supplies can be used for the irrigation of golf courses,
municipal parks, school grounds, highway medians, housing developments, and
other large landscaped areas.
As part of the IRP process, OWD considered options for expanding its use of recycled
water by identifying further demands and additional supplies. It is estimated that
OWD’s demand for recycled water uses in 2005 was 3,485 AF (OWD et. al., 2005). This
value will continue to grow into the future (refer to Section 3 for projected recycled
water demands). There are, however, limitations on the application of recycled water
to the land within OWD’s service area. According to the Water Resources Master Plan
(OWD et. al., 2001):
“The use of recycled water within any watershed tributary to surface water
storage reservoirs that provide supply for potable domestic water uses is
prohibited by the San Diego Regional Water Quality Control Board
(RWQCB) to protect water quality in the reservoirs. These land areas
include the entire North District [or North System] and a portion of the
South District [mainly the Central Area System]. The three surface water
storage reservoirs that restrict the size of the recycled water irrigation area
are the Sweetwater Reservoir, Upper Otay Reservoir, and Lower Otay
Reservoir. The tributary land areas are consequently excluded from the
recycled water planning area.”
Types of options for expanding OWD’s use of recycled water include: the expansion
of existing recycled water facilities or agreements, the construction of or purchase
agreement for wastewater stripping plants, and potential extension of recycled supply
for demands in the North System. The use of recycled water to meet irrigation
demands in the North System would be conditional upon the permitting decision of
the RWQCB and the California DHS, per reasons stated above.
A schematic figure showing the relationship between the additional recycled supply
options and the OWD water supply system is shown in Appendix B.
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5.3.1 Spring Valley Stripping Plant
Under this potential supply option, OWD would construct a 5 MGD (5600 AFY)
stripping plant in the Sweetwater Valley along the San Diego County’s Spring Valley
Outfall. Wastewater would be siphoned off the trunk sewer and treated to produce
recycled water for re-use in the Central Area System and a waste stream that would
be returned to the trunk sewer.
The wastewater in the trunk sewer currently flows from the City of Chula Vista to the
Point Loma WWTP where it is treated. Chula Vista is expected to need additional
wastewater capacity that exceeds the current system capacity by 5 MGD, and this
option would help to alleviate the capacity problem by removing wastewater flows in
the system. As such, it is assumed that OWD could be compensated by other agencies
for providing the benefit of removing flows from the wastewater system.
Infrastructure required for this option includes:
5 MGD stripping plant
Pump station and 24-inch transmission pipeline to convey recycled water from
the Spring Valley Stripping Plant to the Central Area System
Land acquisition
The unit cost of this option is $1,117/AF. Total capital costs would be approximately
$63,900,000 with annual O&M costs of about $1,600,000.
Execution of this option would require coordination with the City of Chula Vista, the
City of San Diego, the County of San Diego, Lemon Grove, and Spring Valley
Sanitation District for taking wastewater from the sewer and returning a smaller but
more concentrated flow after treatment.
5.3.2 Chula Vista Stripping Plant
This option is similar to the Spring Valley Stripping Plant option described above
except that this option assumes that the treatment plant would be owned by Chula
Vista and Otay would only purchase recycled water but not be responsible for the
construction or operation of the stripping plant. Treated effluent from this plant
would be delivered to serve the Central Area System’s recycled water demands.
Infrastructure required for this option includes a pump station and a transmission
pipeline to convey recycled water from the CVSP to the Central Area System.
The unit cost of this option is $756/ AF. Total capital costs would be approximately
$12,500,000 with annual O&M costs of about $3,300,000.
This option would require coordination with the City of Chula Vista, the City of San
Diego, as well as the County of San Diego.
Section 5
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5.3.3 Additional Purchases from South Bay WRP
Otay Water District has an existing agreement with the City of San Diego to receive at
least 6 MGD of recycled water produced at the SBWRP2 (refer to Section 2 for a
description of the existing agreement). Under this option, OWD would acquire an
additional 4 MGD (4,500 AFY) of SBWRP recycled water (for a total of 10 MGD). The
SBWRP currently has a recycled water production capacity of 15 MGD; of which, 10
MGD is available for reclaimed use by other water agencies.
The City of San Diego is providing OWD with transmission capacity in a 4,000 foot, 30
inch transmission system through the Dairy Mart Road Bridge -- which is assumed to
be sufficient for the additional flows. OWD is responsible for the construction of
conveyance infrastructure from the City’s pipeline to the 450 Zone Reservoirs, per the
terms of the existing agreement.
No infrastructure would be required for the additional purchase of recycled water
from SBWRP; however, a one-time capacity charge would be exacted in order to
augment the allotment of plant capacity for OWD’s use. Annual purchase and
operation costs would also exist, which are equivalent to costs incurred for the
existing agreement on a per unit basis.
The unit cost per acre-foot for this option is estimated at $633. Total capital costs
would be approximately $2,400,000 with annual O&M costs of about $2,700,000.
Additional coordination would be required with the City of San Diego for this option.
5.3.4 Expansion of South Bay WRP
This option is similar to the Additional Purchases from South Bay WRP option.
However, under this option OWD would contribute funds to the cost of an expansion
of the SBWRP in order to obtain rights to an additional 4 MGD (4,500 AFY) of
recycled water capacity. Implementing this option would provide OWD with a total
of 10 MGD of recycled water from the City of San Diego SBWRP. Per the terms of the
existing agreement (refer to Section 2), the City of San Diego is providing OWD with
transmission capacity in a 4,000 foot, 30 inch transmission system through the Dairy
Mart Road Bridge -- which is assumed to be sufficient for this option’s expanded flow.
OWD is responsible for constructing conveyance infrastructure from the pipeline to
the 450 Zone Reservoirs.
2 The existing agreement between the City of San Diego and Otay Water District for reclaimed water
from SBWRP is a 20 year agreement. For the purposes of planning and modeling supply options, it was
assumed that this agreement would be extended under the same terms through the end of the IRP
planning horizon (i.e. 2030). For reference, see the agreement in Appendix D of the 2005 Urban Water
Management Plan (OWD et. al., 2005).
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Costs for this option are associated with the expansion of the SBWRP to provide 4
MGD to OWD, and operational (pumping) costs for conveyance to OWD. It is
assumed that OWD would have rights to the additional 4 MGD of effluent, and
would not have to pay a purchase fee to the City of San Diego for use of the source.
The unit cost of this option is $1,137/ AF. Total capital costs would be approximately
$40,000,000 with annual O&M costs of about $2,200,000.
Coordination would be required with the City of San Diego for this option.
5.3.5 Ralph W. Chapman Water Reclamation Facility (RWCWRF)
and /or Spring Valley Stripping Plant Recycled Water to Lower
Sweetwater Basin and Downstream Well Recovery
The Lower Sweetwater Basin is defined as the 8-mile reach of the Sweetwater River
between Sweetwater Reservoir and San Diego Bay, and is located outside of the OWD
service area. The basin consists of an alluvial aquifer and the underlying San Diego
Formation. The alluvial aquifer consists of sand and gravel. The basin has
approximately 13,000 acre-ft of storage, including the underlying San Diego
Formation. Depth to groundwater is in the range of 0-20 ft. Net recharge to the
alluvial aquifer is estimated at approximately 1100 AFY. Salinity in the alluvial
aquifer varies from 1700 to 3100 mg/l, while TDS concentration in the urban runoff
recharge water is approx 2500 mg/l.
Groundwater could be recharged with recycled water from 1) OWD’s RWCWRF or 2)
a new stripping plant along the Spring Valley Outfall (if constructed). The recharged
effluent would be traded with Sweetwater Authority for extraction and treatment at
their groundwater demineralization facility. In exchange, Sweetwater Authority
would provide potable water to OWD from another source.
This option was eliminated from further consideration since there is no real incentive
for Sweetwater Authority to participate in this type of agreement. This option is not
likely to be implemented in terms of inter-agency coordination.
5.3.6 North District Recycled Water Concept
Under this option, OWD would identify 1.1 MGD of recycled water demands in the
North System, which would be served by Otay Water District’s existing Ralph W.
Chapman Water Reclamation Facility (RWCWRF). A description of the existing
RWCWRF is provided in Section 2. Effluent from the RWCWRF is currently pumped
by OWD to irrigate golf courses, parks and open space in Eastern Chula Vista, which
is in the Central Area System and at a higher elevation than the North System. This
option would reduce the conveyance costs that are currently incurred in pumping
recycled water from the RWCWRF to Eastern Chula Vista. Existing recycled water
users in Chula Vista would have to be provided with an alternate supply.
Section 5
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Infrastructure required for this option includes conveyance to the North System.
The unit cost of this option is $711/AF. Total capital costs would be approximately
$7,900,000 with annual O&M costs of about $300,000. Note that these values do not
accurately reflect the true costs of the option, as the costs for an alternative water
supply to the users in Eastern Chula Vista are not included.
Inter-agency coordination will be required for this option with the Regional Water
Quality Control Board, DHS, and Sweetwater Authority. Additionally, coordination
with the City of Chula Vista would be required.
5.3.7 Expansion of Ralph W. Chapman Water Reclamation
Facility (RWCWRF) and Sewer Collection System
This option involves an expansion of the production capacity of the Otay Water
District’s RWCWRF in order to obtain additional recycled water. The RWCWRF
currently has a reliable Title 22 treatment capacity of 1.1 MGD (total capacity 1.3
MGD), as discussed in Section 2. This option includes expanding the RWCWRF in 1.3
MGD increments up to an ultimate capacity of 3.9 MGD. This is a long term option
given that the sewer collection generation growth rate is less than 1% per year. The
ultimate capacity is estimated based on the total projected ultimate OWD tributary
sewer flow (3.2 MGD) and a portion of the ultimate Spring Valley tributary sewer
flow (0.853 MGD). Implementation would be carried out in two phases. Phase One
would be an expansion to a capacity of 2.6 MGD, and Phase Two would expand
capacity to the ultimate 3.9 MGD. The total additional yield from this option is 2.6
MGD (3,000 AFY). Any additional sewer flows beyond the 3.9 MGD to be treated at
RWCWRF will be bypassed to the Point Loma Treatment Plant.
The infrastructure required for this option includes the two phases of plant facilities
expansion and a pipeline to convey the additional volume of recycled water from
RWCWRF.
The unit cost of this option is $1,036/AF. Total capital costs would be approximately
$30,500,000 with annual O&M costs of about $800,000.
5.4 Ocean Desalination Options
Desalination is the process whereby dissolved mineral (salts and others) are removed
from seawater or brackish groundwater. Historically, desalination technology was
focused on removal of salts from seawater and used in countries where no other
solutions were feasible. Given other alternatives, the cost of desalination in the United
States was considered too high. However, because of new technologies, desalination
is being examined by coastal water agencies around the country. Desalination offers
improved water quality (low salinity), and, as a more local source, can help protect
against supply vulnerabilities due to droughts and earthquakes.
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Although seawater is a seemingly unlimited resource, the high cost of developing this
supply tends to restrict the total capacity developed. Issues such as siting, energy
availability, environmental impacts, and the distribution costs needed to move the
water from treatment to delivery all impose constraints on how much seawater can be
treated. Of primary concern in all desalination projects is the disposal of the
concentrated brine solution which is left over after treatment. Managing the brine
waste can add considerable cost to desalination projects. Typical disposal methods
include large evaporation ponds (land-intensive with environmentally concerns) or
disposal by ocean outfall (costly to construct and maintain). Regionally, these issues
are becoming more pronounced as more brine waste is produced and existing outfalls
reach their capacities.
Although OWD is close to the Pacific Ocean, it is not immediately on the coast, and so
conveyance costs for ocean desalination projects can be high. This fact motivates the
cooperation between water agencies in the region. Several of the desalination options
considered in the IRP involve OWD entering into agreements with other agencies to
be provided with in-lieu water from their respective desalination plants. Under these
agreements, OWD would either pay for capacity in a desalination plant or simply for
a volume of product water. The desalinated water would be used to meet demands
local to the plant, and other water from a different source would be provided to OWD
in exchange.
For planning level purposes, conceptual desalination options or exchanges were
considered and it was assumed that coordination with the necessary agencies would
be possible in the future. The seawater desalination option concepts evaluated
include:
OWD purchases desalinated seawater from another agency (where OWD does not
contribute to the construction of the desalination plant). This concept was
evaluated with the Poseidon’s Carlsbad Seawater Desalination Plant.
OWD partners with other local agencies to construct a regional seawater
desalination plant. This concept was evaluated assuming an agreement with the
Sweetwater Authority and the City of San Diego (i.e. South Bay Project).
OWD partners with Mexican water agencies to construct a seawater desalination
plant in Mexico, by which OWD would receive Colorado River water in-lieu. This
concept was evaluated assuming a bi-national partnership to construct a seawater
desalination plant in Rosarito, Mexico.
A schematic figure showing the relationship between the ocean desalination supply
options and the OWD water supply system is shown in Appendix B.
Section 5
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5.4.1 Poseidon’s Carlsbad Seawater Desalination Project
This option represents the concept that OWD would purchases seawater from another
agency, and OWD would not contribute to the construction of a desalination plant.
For evaluation purposes, the Poseidon’s Seawater Desalination Project was
considered.
Poseidon Resources is a private corporation in the process of developing a
desalination plant in the City of Carlsbad. The proposed plant has a design capacity of
50 MGD which is planned to serve the cities of Carlsbad and Oceanside. Additional
capacity will also be available for other communities in the region who would like to
participate. Under this option, OWD would pay to have 10 MGD (11,200 AFY) of
potable water delivered to their distribution system from a third party, such as
SDCWA. In exchange, the third party would receive an equal amount of desalinated
water from the plant at a different point in their system.
Conveyance infrastructure may be necessary for the third party to receive the
desalinated water. It is assumed that OWD would receive in-lieu water through the
SDCWA treated water Pipeline No. 4.
A per-acre-foot unit cost of $1,300 was assumed for this option. This includes the
operational seawater treatment costs and the in-lieu exchange transportation costs.
There would be no capital costs associated with this option. Conveyance costs may be
necessary to deliver the desalinated water to the third party, but are not included for
this evaluation.
This option would require considerable inter-agency coordination for
implementation, including coordination among: Poseidon Resources, the potential
exchange partners (such as SDCWA), and any other project participants (Carlsbad
Municipal Water District, Valley Center Municipal Water District, Ricon Diablo
Municipal Water District, Olivenhain Municipal Water District, and Sweetwater
Authority).
The desalination plant still needs to obtain a permit from the California Coastal
Commission.
5.4.2 Southern California Partnership: Sweetwater/City of San
Diego South Bay Project
This option would involve other local agencies to construct a regional seawater
desalination plant. This option was evaluated assuming a potential agreement with
Sweetwater Authority and the City of San Diego in the construction of a desalination
plant at the South Bay site. Otay Water District would contribute funds to the
construction of the plant proportional to a capacity of up to 20 MGD (22,400 AFY) for
their use. A pipeline and pump station would need to be constructed to convey the
desalinated ocean water from the South Bay plant to OWD’s service area. In addition,
there would be capital and O&M costs for brine disposal.
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The unit cost of this option is approximately $2,800/AF. Assuming an agreement for
20 MGD, the total capital costs would be approximately $186,164,400 with annual
O&M costs of about $49,185,000. Cost estimates were also developed for projects
involving plant capacities of 5 MGD and 10 MGD. These estimates can be found
Appendix C.
Siting and permitting of this plant would require extensive environmental review,
especially as it relates to the construction of an ocean intake and an outfall for brine
disposal. Originally, it was envisioned that the desalination plant could share the
intake and outfall of an existing power generation plant in the South Bay. However,
this plant may be taken out of operation in the near future.
5.4.3 Bi-National Partnership: Rosarito Financial Partnership with
In-lieu Colorado River Water
Under this option, OWD would help to fund the construction of an ocean desalination
plant in Rosarito, Mexico. Desalinated ocean water would be used locally but Mexico
would provide a volume of its Colorado River water allotment to OWD in exchange –
in an amount equal to OWD’s capacity at the desalination plant. The in-lieu water
from the Colorado River would have to be conveyed through the MWD and SDCWA
systems to be delivered to OWD through their turnouts on Pipeline No. 4, and would
be subject to those agencies’ transportation and wheeling charges.
For this option, an initial plant capacity to provide 5MGD (5,600 AFY) would be
supported by funds from OWD with the possibility to expand in the long-term. A
conceptual schematic of this option is shown in Figure 5-10.
This option would not require any infrastructure other than OWD paying for its
portion of the capacity of the desalination plant. All of the necessary conveyance
infrastructure for the in-lieu exchange from the Colorado River is already in place.
The operational and maintenance costs for the seawater plant are approximately
$870/AF. It was assumed that OWD would pay this unit O&M cost to Mexico --
minus the cost of transportation, wheeling, and treatment costs which it would pay to
SDCWA to receive the in-lieu Colorado River water.
The overall unit cost of this option is $897 / AF. Total capital costs would be
approximately $36,349,000 with annual (2006) O&M costs of about $4,865,555.
Section 5
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Figure 5-10
Bi-National Partnership: Rosarito Financial Partnership
with In-lieu Colorado River Water Option Schematic
This option would require considerable coordination among numerous local, state,
and national agencies in both countries. The exchange of Colorado River water will
require significant negotiation efforts. The desalination plant will need to comply
with all Mexican regulatory standards.
5.4.4 Other Desalination Options
Two other potential desalination supply options initially considered were a joint
facility with Rosarito, Mexico and a partnership with Sweetwater/City of San Diego
for the treatment of water from ocean wells on the Otay River. However, both of these
options were eliminated from consideration.
The joint facility with Rosarito would have involved OWD jointly owning and
operating a desalination plant in Rosarito, Mexico. Ocean water would be treated at
the plant in Rosarito and a portion of the product water would have been conveyed
across the border to OWD. This option was deemed to have too many regulatory and
inter-agency coordination issues to be feasible—particularly with drinking water
crossing an international border.
OWD System
RO
Plant
Ocean Outfall
Brine
Waste
11,200 AFY
5600 AFY
Pacific
Ocean
(for OWD)
(for OWD)
5600 AFY (in lieu)
MWD/SDCWA Conveyance
To local
Rosarito
uses
Colorado
River
U.S.
MEXICO
5600 AFY
WTP*
* Raw water could be treated at the City of San
Diego’s Otay WTP, or treated at MWD/SDCWA
treatment plants.
OWD System
RO
Plant
Ocean Outfall
Brine
Waste
11,200 AFY
5600 AFY
Pacific
Ocean
(for OWD)
(for OWD)
5600 AFY (in lieu)
MWD/SDCWA Conveyance
To local
Rosarito
uses
Colorado
River
U.S.
MEXICO
5600 AFY
WTP*
* Raw water could be treated at the City of San
Diego’s Otay WTP, or treated at MWD/SDCWA
treatment plants.
*Raw water could be treated at MWD/SDCWA
treatment plants or at the City of San Diego’s Otay
WTP or potentially the Alvarado WTP
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The ocean wells project with Sweetwater/City of San Diego would have involved
extracting seawater from the ground at the mouth of the Otay River, treating the
seawater, and conveying the treated effluent to OWD. Due to the proposed inland
location of these wells, there may be difficulties in obtaining the required yield from
those wells. Therefore, this option was determined infeasible, and eliminated from
further evaluation.
5.5 Additional Imported Water Options with Local
Treatment Agreements
Otay Water District currently has agreements with neighboring water agencies to
receive SDCWA water treated by such agencies. Agreements exist for up to 12 MGD
(on-peak) of treatment at Helix Water District’s Levy WTP and up to 10 MGD of
treatment at the City of San Diego’s Otay WTP.
As part of the IRP process, options for obtaining additional treated imported water
from neighboring agencies for normal operational use were identified. These local
treatment options included: expanding agreements for Helix Water District’s Levy
WTP and the City of San Diego’ Otay WTP, forming agreements with Sweetwater
Authority for treated water from their Perdue WTP and with the City of San Diego for
water from its Alvarado WTP.
Although these options still rely on imported SDCWA water as a source, they could
provide more system flexibility for OWD, and in some cases, could utilize existing
infrastructure.
Refer to Figure 5-1 for the projected imported raw water purchase rates from
SDCWA, which are discussed in the following sections. A schematic figure showing
the relationship between the additional imported supply options and the OWD water
supply system is shown in Appendix B.
5.5.1 Expansion of Capacity Rights from Helix Water District’s
Levy WTP
Under this option, OWD would obtain rights to an additional 4 MGD, beyond the
existing agreement for 12 MGD on-peak, 16 MGD off-peak capacity (refer to Section
2). For this option it is assumed that the treated Levy WTP water would be conveyed
to the Regulatory Site 520 reservoir in the North District using FCF #8 and the LMSE
pipeline (which are scheduled to be abandoned when FCF #14 is on-line).
Costs for this option would include the expanded plant capacity participation
purchase at Levy WTP, and the cost for imported SDCWA purchases treated at Levy
which is equivalent to the SDCWA treated water rate. The unit cost of this option is
$744 / AF. Total capital costs would be approximately $12,300,000 with annual O&M
costs for the purchase of imported water of about $2,400,000.
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5.5.2 Expansion of Capacity at City of San Diego’s Otay WTP
Under this option, OWD would contribute funds for the expansion of the City of San
Diego’s Otay WTP. The current effective capacity of the Otay WTP is 40 MGD; of
which, the City of San Diego typically uses 20 MGD for its own demands. Otay Water
District currently has an agreement with the City of San Diego for 10 MGD from the
Otay WTP; however, typical operations currently provide approximately 8 MGD in
high-demand summer months and 10 MGD in winter months (refer to Section 2).
Expansion of the facility would provide up to an additional 20 MGD to OWD. Water
from the Otay WTP is currently supplied to the Otay Mesa and Central Area Systems
via a temporary pump station with a capacity ranging between 6-21 MGD. A
permanent pump station is already planned, which will have a capacity of 30 MGD
(OWD et. al., 2002). It is assumed that there will be sufficient conveyance capacity
already in place before implementation of this option.
For this option, a plant capacity to provide 20MGD (22,400 AFY) would be supported
by funds from OWD. This option would not require any infrastructure other than
OWD paying for its portion of the capacity expansion of Otay WTP. It is assumed that
there will be sufficient conveyance capacity already in place for this option.
Operational costs associated with this option include imported raw water purchases
from SDCWA, and pumping conveyance costs from Otay WTP to the OWD
distribution system.
The unit cost of this option is $694 / AF. Total capital costs would be approximately
$49,000,000 for with annual O&M costs of about $12,000,000.
It is important to note that this option is mutually exclusive with Alvarado WTP
option because the City does not have enough water demands or funding to justify
expansion of two water treatment plants.
5.5.3 Imported Water from Sweetwater Authority’s Perdue WTP
Under this option, OWD would purchase additional raw water from SDCWA and
pay the Sweetwater Authority for treatment at the Perdue WTP. Under this option, 4
MGD of treatment capacity would be available to OWD. Otay Water District would
pump treated water from Perdue WTP into the existing 36-inch transmission main to
the North System via a new pump station and 24-inch pipeline (OWD et. al., 2002).
Capital costs associated with this option include the participation charge for 4 MGD
of treatment capacity at Perdue WTP, and the 24-inch pipeline and pump station for
conveyance to the existing 36-inch transmission main.
Operation and maintenance costs include treatment costs, pipeline maintenance,
pumping (energy) costs for conveyance, and imported raw water purchases from
SDCWA.
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The net present value unit cost of this option is $878 / AF. Total capital costs would
be approximately $16,200,000 with annual O&M costs of about $2,700,000.
5.5.4 Imported Water from the City of San Diego’s Alvarado WTP
Under this option, OWD would purchase additional raw water from SDCWA and
pay the City of San Diego for treatment at the Alvarado WTP. Capacity available for
purchase could be up to 30 MGD. The treated water from Alvarado WTP would be
delivered to OWD through SDCWA Pipeline No. 4. Otay Water District diverts water
from SDCWA Pipeline No. 4 at a number of points, including: FCF No. 11 to the
North System, FCF No. 10 and 12 to the Central Area System, and FCF No. 13 to the
Otay Mesa System.
Capital costs associated with this option include the SD17 pump station and the
participation purchase for 30 MGD capacity at Alvarado WTP. The operational costs
for this option are imported raw water purchases from SDCWA, treatment at
Alvarado WTP, and energy costs at the SD17 pump station.
The unit cost of this option is $733 / AF. Total capital costs would be approximately
$82,400,000 with annual O&M costs including the purchase of imported water of
about $18,600,000. [Information since the IRP analysis has indicated that there would be no
participation/purchase cost for the Alvarado imported water option. This supply option
performed well regardless of the initially assumed participation cost, and its newer lower cost
would only help its performance.]
It is important to note that this option is mutually exclusive with Otay WTP option
because the City does not have enough water demands or funding to justify
expansion of two water treatment plants.
5.6 Imported Raw Water from SDCWA Pipeline No. 3 for
Irrigation
SDCWA Pipeline No. 3 provides raw water to Sweetwater Authority’s Perdue WTP,
Sweetwater Reservoir, City of San Diego Otay WTP, and Lower Otay Reservoir.
Under this option, Otay Water District would construct diversion facilities and
purchase additional raw water to meet irrigation demands in their service area
currently being met with treated water. For this option it is assumed that the yield
would be 5 MGD over 6 months to help meet irrigation needs in high-demand
summer months. The raw water would be diverted from SDCWA Pipeline No. 3 into
the 680 Reservoir for delivery to OWD customers.
It is assumed that there is sufficient capacity in Pipeline No. 3 for this option. The
SDCWA Pipeline No. 3 right of way is located adjacent to the 680 pressure zone
reservoir. It was assumed that the turnout would be located near this point at an
elevation above 680 ft and that no pumping and only a small length of pipe would be
required. Filtering of the raw water may be required, but for this analysis it was
assumed that the water could be used directly. The uncertainty of treatment
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requirements was captured in this option’s Compatibility Score (see Section 4). A
more detailed analysis would be required if this option were to be implemented.
OWD would need to construct a tie-in to Pipeline No. 3 for diversions. In addition,
because the proposed flow for this option is relatively small compared with the large
capacity of SDCWA Pipeline No. 3, several modifications would be necessary to
control the flow in Pipeline No. 3. The size of the current valves and other
appurtenances are too large to allow only 5 MGD to pass through. Necessary
modifications to SDCWA facilities include flow balancing structures on SDCWA
Pipelines No. 3 & 4, as well as modifications to the San Diego 5 take-off structure. It
should be noted that these modifications would only be necessary if the flow from
this option in Pipeline No. 3 was not supplemented by other flows being delivered
downstream for other uses. There are seasonal storage flows in Pipeline No. 3 that
would prevent the need for the modifications. However, these occur during October
through May, which is not when irrigation demands are high. For purposes of this
analysis, it was assumed that this option could be operated independently from other
flows.
Operational costs for this option include the imported raw water purchases from
SDCWA, which are shown in Figure 5-1. The SDCWA requires a minimum flow of 2
CFS be discharged to Lower Otay Reservoir, to ensure that the pipeline is operating
correctly. It is conceivable that OWD could treat this flow at the City of San Diego’s
Otay WTP through an agreement in the future. However, this required minimum
flow was added to the imported raw water purchases for this option, and considered
a “sunk” cost for OWD in this analysis.
The unit cost of this option is $590/AF. Total capital costs would be approximately
$2,400,000 with annual O&M costs including the purchase of imported water of about
$1,500,000.
5.7 Imported Treated Water from SDCWA Pipeline No. 4
In this analysis, treated water purchases from SDCWA are the default supply option
used to meet any remaining demands after all other supply options have been
exhausted. It is also considered the baseline supply source that could meet OWD’s
projected future water demands, under normal conditions, if no other options are
implemented. The capacity of Pipeline No. 4 is sufficient to meet OWD’s demands
through the planning year 2030. However, OWD is interested in reducing its reliance
on imported water supplies, gaining greater local control of their water resources, and
avoiding uncertainty about the cost and reliability of imported water in the future.
There are no capital costs for this option, since all the necessary infrastructure is
already in place. The projected purchase rates of imported treated water from the
SDCWA are discussed at the beginning of this section, and shown in Figure 5-1.
Section 5
Water Supply Options
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5.8 Water Transfers and Water Banking
OWD could engage in water transfers to increase their water supply. Water transfers
are the voluntary exchange of water between a willing buyer and a willing seller. Both
State and Federal law contain provisions that authorize, acknowledge, and support
water transfers. The California Water Code protects legal users of water during water
transfers through the “no injury rule,” which states that a change in a water right may
not cause injury to any legal user of the water involved. The Water Code also requires
that a transfer: (1) avoid any unreasonable effects to fish and wildlife; and (2) does not
cause unreasonable economic impacts to the county from which the water is
transferred.
Water transfers can be short-term or long-term. Short-term water transfers are
typically a one-time purchase of water, usually on an as-needed basis to offset the
effects of drought. Short-term transfers are generally exempt from CEQA; the Water
Code relies on notice to the affected parties and findings made by the State Water
Resources Control Board (SWRCB). Long-term transfers are those that take place over
a period of more than 1 year. Long-term transfers are subject to the requirements of
CEQA and must also comply with the standard SWRCB public noticing and protest
process. The California Water Bank, established during the 1988-92 drought, is an
example of a short-term water transfer.
Short-term and long-term transfers can be made through an options agreement,
where buyers have the “option” to purchase a certain amount of water any time
during the life of the agreement. An “option” payment would be made each and very
year to secure the right to transfer the water. When the water is called, then the buyer
would pay the water transfer cost for that amount of supply needed in that year.
Water transfers can occur through various mechanisms including stored water
purchases, groundwater substitution, or crop idling agreements. Water can be
purchased from water districts north of the Sacramento-San Joaquin Delta, in the
Central Valley, or the Colorado River Basin. OWD would have to negotiate a price,
transfer amount, and delivery schedule with the seller.
OWD could also participate in a water banking agreement. Water banking involves
storing water underground for future use, especially during dry periods. Several
water agencies have established a formal groundwater bank. Semitropic Water
District in Kern County operates a groundwater bank with a storage capacity in
excess of 1 million acre-feet. Multiple agencies already participate in the bank,
including MWD and Santa Clara Valley Water District. Semitropic Water District is
currently increasing their banking operation and has storage and pumpback capacity
available for new banking partners. The Kern Water Bank, is another example of an
established water bank. And finally, the San Bernardino Municipal Water District is
also a potential water banking partner.
Section 5
Water Supply Options
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For the purposes of OWD’s IRP analysis, three general types of water transfers were
explored: (1) short-term, North of Delta; (2) Land fallowing or Option, in the Central
Valley or Colorado River Basin; and (3) Groundwater banking in the Central Valley
(or Southern California region). There are advantages and disadvantages to each of
these types of transfers, which include:
Water Transfer Advantage Disadvantage
Short-Term, North of Delta
(e.g., California Water
Bank)
Lowest cost, no CEQA
required
Any Bay-Delta restrictions
would likely affect these
supplies as well
Land Fallowing or Option
Contracts, Central Valley
or Colorado River Basin
(e.g., Palos Verdes
Irrigation District)
High reliability, lots of
flexibility in cost structure
and how/when transfer
water is taken
Third party impacts could
be high, CEQA issues
likely, and negotiations
more complex
Groundwater Banking,
Central Valley (e.g.,
Semitropic Banking
Program)
Highest reliability,
especially if a pumpback
provision is made
CEQA issues, ensuring
adequate pumpback
capability, and highest up
front costs (for capital)
Costs
Estimating costs for water transfers is extremely speculative due to the nature of the
water transfer market. The more sellers of water transfers, the lower the expected
costs, while the fewer sellers, the greater the expected costs. The California water
market is ever changing. However, for this IRP analysis, water transfer costs were
estimated based on most recent water transfers involving MWD, SDCWA, Palos
Verdes Irrigation District, Imperial Irrigation District, and Semitropic Water Bank.
The current water transfer costs (in 2007 dollars) were estimated to be:
Water Transfer
Fixed Cost ($/AF)
(capital or option payment)
Variable Cost ($/AF)
Short-Term Transfers None $80
Land Fallowing $100 $150
Groundwater Banking $180 $100
Section 5
Water Supply Options
A 5-34
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Figure 5-11
Projected Water Transfers Costs
In addition to water transfer costs, there are costs associated with delivery and
treatment of the water. Delivering the transferred water would require the use of
other agencies water conveyance infrastructure, also known as wheeling.3 Other
infrastructure usually involved in the transfer of water includes: State Water Project
(SWP), Central Valley Project (CVP), MWD, and SDCWA. The California Water Code
states that an agency must allow wheeling if excess capacity is available, given that
fair compensation is paid for use of the system. For this analysis, it was assumed that
any water transfer to OWD would involve paying both SDCWA and MWD for
wheeling. The current wheeling costs for 2007 are estimated to be:
MWD Wheeling 4 $260/acre-foot
SDCWA Wheeling 5 $60/acre-foot
Total Wheeling $320/acre-foot
Figure 5-11 shows the projected water transfer costs for the three types of transfers
that include the fixed, variable and wheeling costs.
3 Wheeling is the use of an agency’s distribution system to move non-agency water between a willing
seller and buyer. 4 Based on MWD’s Long Range Finance Plan (July 23, 2004, Table 6). 5 Based on SDCWA transportation rate (http://www.sdcwa.org/news/finances.phtml#current)
Section 5
Water Supply Options
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The transferred water could be treated by the City of San Diego at the Otay WTP or
potentially the Alvarado WTP, or else treated by MWD with payment of the
treatment surcharge. The cost of treatment at Otay WTP is approximately $90/AF. In
addition, OWD would need to pay approximately $25/AF for pumping conveyance
from Otay WTP to OWD’s distribution system. It was assumed that the treatment
cost for water transfers would be the same as imported raw water purchases from
SDCWA.
If the transfers are delivered through Pipeline No. 4 assuming treatment by MWD, the
treatment surcharge was assumed as the difference between the SDCWA treated and
raw water purchase rate projections, which are shown in Figure 5-1.
North of Sacramento-San Joaquin Delta Water Transfers
The transfers from north of the Delta are considered the least expensive transfers.
However, they are likely the least reliable since the water must be conveyed through
the Bay-Delta area, which is prone to environmental restrictions and drought
uncertainty. For this analysis, it was assumed that OWD would purchase up to 5,000
AFY of transfers from north of the Delta groundwater. The use of this supply source
would be only during extreme drought years when the SDCWA could potentially
impose imported water supply reductions.
Central Valley Groundwater Banking
The Central Valley groundwater is considered the most reliable source of transfers. It
is estimated that approximately 200,000-500,000 afy is available for use through the
Central Valley Water Project and agricultural projects in the Delta. For this analysis, it
was assumed that a yield of up to 15,000 AFY would be purchased throughout the
planning horizon and used in dry years. The Central Valley groundwater banking
opportunities appear attractive due to reliability in drought conditions, but they are
generally more expensive than other transfer/banking opportunities.
Land Fallowing in Central Valley or the Colorado River Basin
Land fallowing refers to an agricultural rotating crop program, which would make
agricultural water rights available for other uses on an as-needed basis. Potential
suppliers of water through land fallowing could be in the Central Valley, or the
Imperial Irrigation District, or the Pales Verdes Irrigation District. This water is more
reliable than north of Delta short-term transfers, but has more complexities in
negotiations due to potential third party impacts, CEQA issues, and political
obstacles. Transfers along the Colorado Basin may also be difficult to acquire since the
Coachella Valley Water District, SDCWA and MWD have first priority for purchase
before other water agencies. For this analysis, it was assumed that up to 15,000 AFY
would be purchased throughout the planning horizon and used in dry years.
Other Transfers/Banking Options Considered
Other potential types of water transfers include purchasing or leasing Indian water
rights and regional water transfers/banking. Indian water rights are generally the
Section 5
Water Supply Options
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most senior water rights in California. They are also likely the most expensive and
difficult to negotiate. Few examples of Indian water rights being transferred to urban
water districts exist. However, OWD should engage a water rights attorney to
conduct a search to see if such rights might be available.
Regional water transfers may also present an opportunity for OWD. The most
promising is the San Bernardino Valley Municipal Water District, which has
significant water storage potential in the Bunker Hill Basin and is also a State Water
Contractor. OWD might be able to purchase a water storage account in the basin to
store SWP water, transfer water or purchased groundwater.
A 6-1
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Section 6
Water Supply Portfolio Development
This section describes the water supply portfolio development process followed in the
IRP, and lists the final set of portfolios used for ranking.
Portfolio Development Process
The process followed the basic approach described in Section 4, and illustrated in
Figure 4-1. The portfolio development process is iterative, in that supply options,
portfolios, and performance measures are refined after initial evaluation. The initial
portfolio results show “why” and “how” a portfolio did well, or poorly, in meeting
performance measures. The iterative process allows for adjustment and fine-tuning in
order to create better performing portfolios and also to ensure that the best
performance measures are being used to compare portfolios.
There are several methods that can be used to develop portfolios. For this IRP, the
portfolios were developed with an objective-based method, where each portfolio is
based on a specific IRP objective defined in Section 4. With this method, the new
supply options that maximize a specific IRP objective are grouped together in a
portfolio. For example, one of the objectives is “Flexibility.” To create a portfolio with
emphasis in this objective, supply options are grouped together that would increase
OWD’s operational flexibility by increasing the number of take points into the system.
Portfolios were developed for all of the objectives, except for the objective to “Address
Environmental and Institutional Constraints.” This objective was not used for a
portfolio since it was not weighted heavily by the group of stakeholders.
In order to compare the objective-based portfolios with the “no project” scenario, the
baseline condition was also evaluated as a portfolio.
In this IRP, the CDM planning team developed initial portfolios and discussed them
with OWD senior staff prior to systems analysis and ranking. With consensus of the
initial portfolios and portfolio development method, the initial portfolios were
evaluated and the results were reviewed collaboratively by the CDM planning team
and OWD staff. The initial results provided insight needed to refine the analysis, and
final portfolios were developed for evaluation.
Summary of Portfolios
The following is a description of the portfolios that were included in the final
evaluation. A matrix summary of the supply options included in each portfolio is
shown Table 6-1, with the portfolios across the top of the matrix. A list of the
available supply options and their corresponding yields is shown on the left side of
the matrix.
The supply options included in each portfolio are indicated within the matrix by their
potential yields (in acre-feet per year). If a cell within the matrix is blank, it means the
Section 6
Water Supply Portfolio Development
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option was not included in the portfolio. Note that the existing, or baseline, supply
was included in every portfolio along with the potential water supply options.
For reference, a schematic of the portfolios and a list of the options included in each
portfolio are included Appendix D.
Water Quality A: This portfolio was developed with the objective of improving water
quality by minimizing the potential for presence of disinfection by-products (DBP’s).
Water Quality B: Options included in this portfolio were intended to improve water
quality by minimizing the concentration of Total Dissolved Solids (TDS) in the
system.
Reliability A: The objective of this portfolio was to increase reliability under drought
conditions that could result in imported water shortages.
Reliability B: Options included in this portfolio were intended to increase reliability
under seismic conditions. The assumed seismic condition involves an interruption of
imported water supply caused by SDCWA Pipelines No.3 and No. 4 being offline. In
addition, all recycled water supply is assumed to be offline.
Affordability: This portfolio was developed with the lowest cost options based on
their dollar per acre-foot unit cost.
Baseline: This portfolio represented the “no project” scenario, and utilized all of
OWD’s existing (or already planned) supply sources, as they would exist in the year
2010.
Diversity A: The objective of this portfolio was to increase the diversity of supply
sources.
Diversity B: This portfolio was developed with the objective of increasing the
diversity of supply sources, and also focuses on expanded the use of existing (or
already planned) sources.
Flexibility: The objective of this portfolio was to increase OWD’s operational
flexibility by increasing the number of take points into the system.
The performance of these portfolios against the IRP objectives, as well as the
comparison of their performance against each other, is discussed in Section 8. The top
scoring portfolios were used to select water supply options in an implementation
strategy described in Section 9.
Supply Option
Annual Yield
[AFY]
Peak Day
[MGD]
Water Quality
A: DBP
Water Quality
B: TDS
Reliability A:
Drought
Reliability B:
Seismic Affordability Baseline Diversity A
Diversity B:
Expand
Existing Flexibility
I. Existing Supply (Baseline = 2010 System)
Ia. Imported
SDCWA Pipeline # 4 Up to capacity of existing
turnouts [136,106 AFY].
Up to capacity of existing
turnouts [121.5 MGD].Use as last
priority source
Use as last
priority source
Use as last
priority source
Use as last
priority source
Use as last
priority source
Use as last
priority source
Use as last
priority source
Use as last
priority source
Use as last
priority source
City of San Diego’s Otay WTP 10,100 AFY 10 MGD in winter,
8 MGD in summer 10,100 10,100 10,100 10,100 10,100 10,100 10,100 10,100 10,100
Helix’s Levy WTP 13,400 AFY base load.
Minimum of 10,000 AFY.
12 MGD
13,400 13,400 13,400 13,400 13,400 13,400 13,400 13,400 13,400
Ib. Recycled
OWD’s Ralph W. Chapman WRP 1230 AFY 1.1 MGD 0 1,232 0 1,232 0 1,232 1,232 0 1,232
City of San Diego’s South Bay WRP 6,720 AFY 6 MGD 6,722 6,722 6,722 6,722 6,722 6,722 6,722 6,722 6,722
II. Potential Additional Supply Options
IIa. Additional Imported/Local Treatment Agreements
Helix’s Levy WTP 4,480 AFY 4 MGD 4,480 4,480
Sweetwater Authority’s Perdue WTP 4,480 AFY 4 MGD 4,480 4,480
City of San Diego’s Otay WTP 22,400 AFY 20 MGD 22,400
SD17 Agreement with City of San Diego to treat
raw SDCWA water at Alvarado WTP
33,600 AFY 30 MGD
33,600 33,600
IIb. Additional Non-Potable
Imported Water from Pipeline No. 3. (Raw)2,800 AFY 5 MGD over 6 months 2,800 2,800 2,800 2,800
Spring Valley Stripping Plant (along Sweetwater
River)
5,600 AFY 5 MGD
5,600
Chula Vista Stripping Plant 5,600 AFY 5 MGD 5,600 5,600
South Bay WRP (Additional Purchase Only)4,480 AFY for additional
purchase only. Potential to
expand SBWRP to obtain
more effluent.
4 MGD
4,480 4,480 4,480
Expansion of South Bay WRP
RWCWRF and/or Spring Valley Stripping Plant
effluent bypassing Sweetwater Res and pumped
at Sweetwater’s Demineralization Plant for In-lieu
exchange
RWCWRF: 1230 AFY
SVSP: 5,600 AFY
Chap: 1.1 MGD
SVSP: 5 MGD
North District Recycled Water Concept (uses
existing RWCWRP capacity)
Shift 1230 AFY supply from
Central Area to North.
Central Area demands
would need to be met by
another source.
1.1 MGD
1,230 1,230 1,230 1,230
Expansion of RWCWRF and Sewer Collection
System
1,681 AFY
3,137 AFY
1.5 MGD
2.8 MGD 3,137 3,137 3,137
Table 6-1
Matrix of Supply Option Yields (in AFY) included in Portfolios
Portfolios
Table 6-1
Matrix of Supply Option Yields included in Portfolios
Supply Option
Annual Yield
[AFY]
Peak Day
[MGD]
Water Quality
A: DBP
Water Quality
B: TDS
Reliability A:
Drought
Reliability B:
Seismic Affordability Baseline Diversity A
Diversity B:
Expand
Existing Flexibility
Table 6-1
Matrix of Supply Option Yields (in AFY) included in Portfolios
Portfolios
IIc. Groundwater
Middle Sweetwater Groundwater Conjunctive Use 5,000 AFY
Recharge for 6 months in
winter of wet years, extract
for 6 months in summer of
drought years
8.9 MGD
5,000 5,000 5,000 5,000 5,000
Lower Sweetwater Brackish Groundwater
Demineralization
1,500 AFY 1.3 MGD 1,500 1,500 1,500 1,500
Santee/ El Monte Conjunctive Use 5,000 AFY
Recharge for 6 months in
winter of wet years, extract
for 6 months in summer of
drought years
8.9 MGD
5,000 5,000 5,000 5,000
Santee/El Monte Brackish Groundwater
Demineralization
4,250 AFY extract year-
round 4,250 4,250 4,250 4,250
San Diego Formation Brackish Groundwater
Demineralization
2,125 AFY
(assumes 85% RO
efficiency)
1.897 MGD
2,125 2,125 2,125 2,125
Otay Mountain Well for Recycled Use 1,370 AFY
(assumes 85% RO
efficiency)
1.22 MGD (1000 gpm)
1,370 1,370
IId.Ocean Desalination
SDCWA or Poseidon (in-lieu)
Assume 28,000 AFY
available to OWD
Up to 25 MGD
(to OWD)
11,200
Binational Partnership: Rosarito Joint Facility in
lieu CR Assume 28,000 AFY
available to OWD
Up to 25 MGD
(to OWD)
5,600 5,600
Southern California Partnership: Sweetwater/City
of SD’s South Bay project Assume 28,000 AFY
available to OWD
Up to 25 MGD
(to OWD)
5,600 11,200 22,400 5,600 5,600
IIe. Conservation
Conservation 5,390 5,390 5,390 5,390 5,390
IIf. Transfers
North of Delta Banking Up to 5,000 AFY Up to 4.5 MGD 5,000
Central Valley Groundwater Up to 15,000 AFY Up to 13.4 MGD 7,500 15,000 5,000 5,000
Land Fallowing Up to 15,000 AFY Up to 13.4 MGD 7,500 15,000 5,000
Table 6-1
Matrix of Supply Option Yields included in Portfolios
A 7-1
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Section 7
Systems Simulation Model
A systems model was created to simulate the performance of OWD’s water resources
portfolios for the next 25 years, until the planning year 2030. The systems model is
built on the STELLA® programming environments. STELLA (Systems Thinking
Experimental Learning Laboratory with Animation), developed by Isee Systems, Inc.
is a systems modeling standard. This modeling platform was selected because of its
flexible and relatively simple programming environment.
In STELLA, models are constructed by dragging and dropping pre-defined elements
of a system and it can be used to represent one or several elements of a water
resources system. A model in STELLA can be as complex or simple as the user wants
and can represent several different types of systems interactively working together,
such as a water flow model combined with a mass balance for water quality. In
addition, the STELLA software provides graphical interfaces that create an engaging
virtual environment, increasing the ability of the programmers to share their
understanding of the system with technical staff, decision-makers, and stakeholders.
7.1 Conceptual Model
This model is designed to simulate a 25 year sequential time series from 2005 through
2030, with calculations performed on a monthly time step to analyze the seasonality
elements of supply and demand for OWD’s system. In addition, the model evaluates
peak-day demands versus system capacity throughout the planning horizon. The
model may be simulated with four different types of hydrologic sequences: critical
dry, dry, normal, and wet.
For the purposes of modeling in this study, the OWD service area is considered to be
divided into three systems: North, Central Area, and Otay Mesa, which are discussed
in Section 2. These systems are geographically separated and operationally distinct
(See Figure 2-1 for the geographic locations and Figure 2-2 for the system schematic).
Each system has its own demands to serve, and its own existing and potential future
supply options.
7.2 Model Elements
The model elements include: projected water demands (refer to Section 3), baseline
water supplies (refer to Section 2), potential water supply options (refer to Section 5),
and all portfolio performance measures, such as cost and water quality (refer to
Section 4).
7.2.1 Demands
The projected annual average potable and recycled water demands described in
Section 3 (see Figure 3-1) were modeled for each of the three systems (North, Central
Section 7
Systems Simulation Model
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Area, and Otay Mesa). Annual and seasonal fluctuations were applied, as well as a
peak day demand factor, to annual average potable and recycled demands.
Annual hydrologic demand factors were generated for each year on record, which are
illustrated in Figure 3-2. In order to test the system with various demand fluctuations,
four types of hydrologic sequences and their corresponding demand factors were
extracted from the period of record: critical dry, dry, normal, and wet:
Dry: 1967 - 1996
Critical Dry: 1986-1998, 1922-1938 (wrapped sequence)
Normal: 1951 - 1980
Wet: 1956 – 1985
The annual demand factors apply to both potable and recycled water demands, as
well as the additional conservation option (if it is included in the portfolio).
Seasonal demand factors used in the model are shown in Figure 3-2 and 3-4, and the
peak day demands are shown in Table 3-3.
7.2.2 Water Supply
One of the key attributes of the model is that it incorporates many water resources
components (water treatment plants, groundwater wells, wastewater treatment plant
effluent, etc.) into one model. All of the components, and their inter-relationships, are
programmed with the use of three main types of variables in systems dynamics
software:
Stocks: used to represent elements that can accumulate over time (such as
groundwater basins with conjunctive use projects)
Flows: used to represent elements that feed or drain stock, and elements that can
be represented as rates (such as groundwater well extractions from the aquifer, or
treated water deliveries from the SDCWA Pipeline No. 4)
Converters: used to establish more detailed mathematical relationships between
stock and flows, and used for constants or independent variables
In STELLA, stocks are represented as rectangles, flows are represented as arrows with
a circular valve, and converters are simply a circle. Figure 7-1 is a screenshot of a
simple stock/flow system that conceptually represents the Middle Sweetwater
groundwater basin with recharge and pumping.
Section 7
Systems Simulation Model
A 7-3
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The red arrows in the figure (called “connectors” in STELLA) indicate the relationship
between variables. For example, the variable “Middle Sweetwater Pumping Capacity”
is a function of “Middle Sweetwater Supply to North” as indicated by the red
connector.
Baseline System
The baseline water supply system, as it is expected to exist in 2010, was programmed
into the model. The baseline system in the model is illustrated schematically in Figure
2-2, and is represented by the following supply options in table 7-1. The potential
yield modeled for each of these existing supply options is also listed in Table 7-1.
Table 7-1
Potential Baseline Supply Yield in System Model
Baseline Supply Option Potential Yield
Imported
Treated water from SDCWA
through Pipeline # 4
121.5 MGD
[Capacity]
City of San Diego’s
Otay WTP
10 MGD in winter months,
8 MGD in summer months
Helix’s Levy WTP 12 MGD
Recycled
OWD’s RWCWRF 1.1 MGD
City of San Diego’s
South Bay WRP
6 MGD
Figure 7-1
Model Representation of a Groundwater Basin
Section 7
Systems Simulation Model
7-4 A
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The “potential yield” is representative of the constraining factor among the facility
capacity, contractual agreements, or typical availability based on operational patterns.
It should be mentioned that the potential yield does not necessarily represent the
calculated actual supply from each option in the model, since supply from each
option in a water supply portfolio is a function of demand. The priority order in
which supply options are used to meet demands is discussed below.
To evaluate calculations on a monthly time step, the daily potential yield in MGD was
converted to a monthly yield in acre-feet per month (AFM). For the baseline supply
options, the yield was assumed to be available at a constant rate. Therefore, they are
all represented by “flow” variables in the system model.
New Supply Options
New water supply options discussed in Section 5 were also programmed into the
model. A list of all of the new supply options, along with their potential yield, is
provided in Appendix B. Again, to evaluate calculations on a monthly time step, the
daily potential yield in MGD was converted to a monthly yield in acre-feet per month
(AFM).
The system served (North, Central Area, or Otay Mesa) by each option can be seen in
the schematics included in Appendix B. Options that propose the use of SDCWA
Pipeline No. 4 for treated water conveyance can potentially serve all three systems.
All options, except for Middle Sweetwater Conjunctive Use and Santee/El Monte
Conjunctive Use, are represented by “flow” variables in the system model. In order to
track groundwater recharge and recovery over time, the groundwater conjunctive use
projects were modeled with “stock” variables.
The conjunctive use projects follow an annual schedule indicating which years to
“recharge” and “recover” water, depending on the hydrology condition of that year.
In general, water is recharged in wetter years, and recovered in drier years.
Similarly, two of the water transfers and water banking options follow an annual
schedule for use. The Central Valley and Land Fallowing transfer options are used
only in dry years of the hydrology sequences. However, this schedule of use is
overruled by the drought imported shortage condition, discussed later in Section
7.1.3. In this case, transfer options may be used in any year there is a deficit under
drought imported shortage conditions.
The North of Delta transfer option does not follow the annual use schedule, and
should be used only to meet remaining deficits during an imported water shortage
condition.
Prioritization of Supply Use
Each system (North, Central Area, and Otay Mesa) was modeled with its own
demands. Accordingly, as shown schematically in Figure 2-2 and Appendix B, each
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system also was model with its own supply options. Priorities were set to establish an
order in which supply options (existing and new) are used to satisfy each system’s
demand. This is necessary for the model to cease using additional supply once it has
satisfied demand, and compute the portfolio’s supply mix and output for
performance measures. Tables 7-2 and 7-3 show the prioritization of supply options
used to meet recycled and potable demands that was programmed in the model for
each system.
The priorities for the use of the water supply options are generally based on the
typical operating cost per unit volume, as well as the type of supply option
considering OWD’s interest in reducing dependence on imported water supply.
Table 7-2
System Model Prioritization for Use of Non-Potable Supply Options *
North System Central Area System Otay Mesa System
1 North District Recycled
Water Concept
RWCWRF RWCWRF
2 N/A Spring Valley Stripping Plant Spring Valley Stripping Plant
3 N/A Chula Vista Stripping Plant Chula Vista Stripping Plant
4 N/A South Bay WRP South Bay WRP
5 N/A Otay Mountain Well Imported Raw Water from Pipeline
No. 3 for Irrigation
6 N/A Potable Supply Option Potable Supply Option
*Options described in Section 5 that were eliminated from further evaluation were not programmed in system model.
N/A No option available.
Table 7-3
System Model Prioritization for Use of Potable Supply Options*
North System Central Area System Otay Mesa System
1 Conservation Conservation Conservation
2 Helix’s Levy WTP City of San Diego’s Otay WTP City of San Diego’s Otay WTP
3 SD17 Agreement with City
of San Diego (Alvarado
WTP)
SD17 Agreement with City of
San Diego (Alvarado WTP)
SD17 Agreement with City of San
Diego (Alvarado WTP)
4 Central Valley and Land
Fallowing Transfers (via
Pipeline No. 4)
Central Valley and Land
Fallowing Transfers (first via City
of San Diego’s Otay WTP, then
via Pipeline No. 4)
Central Valley and Land Fallowing
Transfers (first via City of San
Diego’s Otay WTP, then via
Pipeline No. 4)
5 Sweetwater Authority’s
Perdue WTP
Poseidon Ocean Desalination
(via Pipeline No. 4)
Poseidon Ocean Desalination (via
Pipeline No. 4)
6 Poseidon Ocean
Desalination (via Pipeline
No. 4)
Southern California Ocean
Desalination Partnership:
Sweetwater Authority/City of San
Diego South Bay Project
Bi-national Partnership: Rosarito
Ocean Desal in-lieu Colorado
River (first via Otay WTP, then via
Pipeline No. 4)
7 Middle Sweetwater
Groundwater Conjunctive
Use
Bi-national Partnership: Rosarito
Ocean Desal in-lieu Colorado
River (first via Otay WTP, then
via Pipeline No. 4)
Imported Treated water purchases
from SDCWA
8 Santee/El Monte
Groundwater Conjunctive
Use and/or Brackish GW
Demineralization
San Diego Formation Brackish
GW Demineralization
North of Delta Transfers (first via
City of San Diego’s Otay WTP,
then via Pipeline No. 4)
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Table 7-3 (cont.)
System Model Prioritization for Use of Potable Supply Options*
North System Central Area System Otay Mesa System
9 Bi-national Partnership:
Rosarito Ocean Desal in-lieu
Colorado River (via Pipeline
No. 4)
Rancho Del Ray Well* N/A
10 Imported Treated water
purchases from SDCWA
Lower Sweetwater Brackish GW
Demineralization
N/A
11 North of Delta Transfers (via
Pipeline No. 4)
Imported Treated water
purchases from SDCWA
N/A
12 N/A North of Delta Transfers (first via
City of San Diego’s Otay WTP,
then via Pipeline No. 4)
N/A
*Options described in Section 5 that were eliminated from further evaluation were not programmed in system model.
N/A No option available.
Emergency Interconnects between Systems
The baseline system includes bi-directional interconnects to convey water between the
systems (refer to Figure 2-2). However, these interconnect pipelines are intended for
emergency use only. For purposes of the IRP, the use of the interconnect pipelines
was only activated in the seismic emergency condition, which is discussed in Section
7.1.3. During a seismic emergency condition, any remaining “unused” supply from
each system may be transferred to meet supply deficits in other systems.
7.2.3 Performance Measures
Performance measures are used to indicate whether an objective is being achieved.
They generally answer the question “How well is a portfolio meeting the objectives?”
and can be either quantitative or qualitative in nature. Refer to Table 4-1 for a list of
the objectives and associated performance measures that were established for this
IRP. The following discussion explains how the portfolio score was calculated for the
performance measures, both qualitatively and quantitatively.
7.2.3.1 Qualitative Performance Measures
For the model to provide output for the qualitative performance measures, a scoring
system was established to quantify the performance measure.
Qualitative scores were used for the following performance measures: Compatibility,
Disinfection By-Product (DBP) potential, Environmental Permitting, Institutional
Coordination, Customer Acceptance, Environmental Compliance, and Technological
Uncertainty. The qualitative performance measure has a rating scale of 1-5 (1 being
the worst and 5 being the best). The portfolio score for the qualitative performance
measures is calculated as the weighted average of the ratings (or scores) for the
options.
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The weighted average is based upon the annual potential yield of the options
included in the portfolio. See Appendix B of the individual options ratings.
∑
=
++∗=N
i
iOption
NOptionNOptionOptionOption
Flow
FlowScoreFlowScorecorePortfolioS
1
)(
)()()1()1(
)(
)(*)(...)()(
7.2.3.2 Quantitative Performance Measures
The calculation methods of the portfolio scores for the quantitative performance
measures differ from one another, and are discussed as follows:
Potable and Non-potable Total Dissolved Solids (TDS)
A TDS value in mg/L is calculated for the potable and non-potable supply in each
portfolio, based on a mass balance. The TDS concentration assigned to a particular
water supply option is multiplied by the option’s simulated monthly supply, to
calculate the monthly TDS load. The supply from each option is dependent on the
projected water demands, and the priority of use to meet demands in relation to other
supply options.
The total monthly TDS load was then divided by the portfolio’s water supply (total
potable or non-potable) to obtain the TDS concentration. The following formula was
used to calculate the TDS of the potable and non-potable supply in the portfolio:
∑
=
++∗=N
i
iOption
NOptionNOptionOptionOption
Flow
FlowTDSFlowTDSDSPortfolioT
1
)(
)()()1()1(
)(
)(*)(...)()(
The non-potable and potable TDS values represent the average TDS values over time,
and the average of the simulated hydrology conditions (critical dry, dry, normal, wet)
since the use of some supply options are hydrology-dependent, as mentioned in
Section 7.1.2.
2030 Annual Deficit under Average Conditions
The monthly deficit, or water supply shortage relative to demands, was calculated to
measure reliability of each portfolio. The monthly deficits that occur in 2030 are added
together to calculate the annual deficit (in acre-feet), and the average annual deficit is
calculated among the four hydrology conditions.
It should be mentioned that all portfolios are capable of meeting demands under
average conditions through the 2030 planning year, with imported water purchases
from SDCWA. Therefore, this performance measure was essentially a “non-
discriminator” in terms of decision-making. To put more emphasis on performance
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measures that differentiate the portfolios, the average condition performance measure
was not given any weight under the reliability objective in the decision model.
Instead, all of the weight for the reliability objective was placed on the performance of
the portfolio measured by imported water shortage conditions and seismic emergency
conditions.
Cumulative Deficit under Imported Water Shortage Conditions
The system reliability of the portfolio was evaluated under imported water shortage
conditions with critically dry hydrology. The portfolio’s monthly deficit (in acre-feet)
was calculated over time, and summed at the end of the simulation.
Though the 2030 planning year, the imported water shortages during critically dry
hydrology years are assumed to be up to 30% of imported water purchases (treated or
raw) from SDCWA. This reduction applies to any existing or new supply option that
relies on imported water from SDCWA as a source. The assumed projected imported
water reductions vary year-to-year depending on the forecast year and the historical
hydrology year modeled in the critically dry time series. For purposes of the model,
the largest imported water shortage (30% reduction) was assumed to occur in the 2030
planning year. The imported water shortage condition assumes that shortages will be
distributed proportionally to demands of all member agencies, and do not account for
preferential rights.
2030 Deficit during a Three-Month Emergency Period
Reliability of the system during a three-month emergency period was measured by
the cumulative monthly supply deficit (in acre-feet), assuming 2030 planning year
demands under normal hydrology conditions. The assumed seismic condition is
defined as an interruption of raw and treated imported water supply caused by
SDCWA Pipelines No. 3 (raw) and No. 4 (treated) being completely out of service.
Therefore, there is no supply from existing or new supply options that rely on these
SDCWA facilities for transportation. In addition, there is no supply from recycled
water options in this scenario. The measured supply deficit does not assume any
mitigation by SDCWA that would be provided from the Emergency Storage Project.
Net Present Value $/AF
To evaluate the affordability of each portfolio, the net present value (NPV) unit cost in
$/AF was calculated. The NPV unit cost is representative of the incremental cost of
water over the entire planning horizon, and includes both capital and operation and
maintenance (O&M) costs.
For purposes of portfolio comparison, implementation of the supply options was
assumed to occur at the same time, and at the start of the planning period. Therefore,
the NPV capital costs for the options are equivalent to today’s dollars.
An annual inflation rate of 3% was assumed for the O&M costs of all options, except
imported SDCWA water purchases and transfers/banking purchases. The projected
purchase rates for imported SDCWA water and transfer/banking options are
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anticipated to increase at a different rate, as discussed in Section 5. The total annual
O&M costs were discounted back to today’s dollars at an annual rate of 6% to
calculate the NPV annual O&M costs, and the cumulative NPV O&M costs accrued
over the entire planning horizon.
Similarly, a discount rate of 6% was used to calculate the NPV of the total annual
yield, and the cumulative NPV total yield over the planning horizon.
To calculate the $/AF unit cost, the sum of the NPV capital and cumulative NPV
O&M costs were divided by the NPV cumulative yield over the planning horizon.
Capital Costs
This performance measure for affordability was calculated by adding the capital cost
(in today’s dollars) of all new supply options included in the portfolio.
Total Number of Take Points
System flexibility of the portfolio was measured by the number of take points, or
major conveyance routes, to receive water. In some cases, several sources of water
may be conveyed by one pipeline for delivery. For example, all supply options that
rely on SDCWA Pipeline No. 4 for treated water conveyance have one take point.
Total Number of Contracts
System diversity of the portfolio was measured by the number of contractual
agreements for water. For options that involved the expanded use of an existing
supplies (i.e. Additional purchases from the City of San Diego’s South Bay WRP), the
expanded use contract was not counted as a separate agreement. In other words, only
one contractual agreement was counted for both the existing contractual supply and
the new (expanded use) supply option.
2030 Percent Contribution of Largest Source to Total Supply
Diversifying the supply sources can help OWD in the event that one of the supply
sources is unavailable, such as imported water purchases from SDCWA. By
increasing the number of sources for OWD, the reliance on one particular source is
reduced. This performance measure is calculated as the percentage of the largest
potential annual yield from a source to the total annual supply, assuming critically
dry hydrology conditions in the 2030 planning year. For this performance measure, all
imported water purchases from SDCWA (raw or treated) are considered one source,
regardless of where the water is treated.
7.3 Simulation Process
The input process for the systems model is facilitated by the use of a graphical
interface based on switches that turn options ON and OFF. Figure 7-2 shows a portion
of the graphical management panel developed for the systems model.
Section 7
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The management decisions required selection of:
Hydrologic condition (critical dry, dry, normal, wet)
Imported water shortage condition (switch ON or OFF)
Emergency condition (switch ON or OFF)
Water supply options and associated yields to be included in the portfolio
(groundwater, ocean desalination, additional imported water with local treatment
agreements, water transfers/banking, additional recycled water, and
conservation).
To run the model, the user selects the desired options for simulating the portfolio by
clicking the appropriate buttons (the green square in the middle of the switch
indicates that the option is ON. Each portfolio has a unique set of inputs to the model,
represented by different combinations water supply options, that is entered into the
model with use of the management panel.
Figure 7-2
Portion of the System Model Management Panel
Section 7
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Each portfolio is simulated under the following conditions, in order to generate
results for every performance measure evaluated:
Critical Dry Hydrology with Imported SDCWA Water Shortage Conditions
Dry Hydrology Condition
Normal Hydrology Condition
Wet Hydrology Condition
Normal Hydrology Condition with a Three month Seismic Emergency Condition
in 2030
The model output is translated into an Excel spreadsheet that can be updated at the
end of each simulation, processed further, and linked dynamically to the scorecard
summary file. The scorecard summary file is then input to the decision model to rank
the portfolios based the stakeholders’ objective weightings.
Section 8 presents a comparison of the raw performance of the portfolios based on the
systems model results, and then discusses the rankings of the portfolios.
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Section 8
Portfolio Evaluation and Screening
8.1 Evaluation Process Overview
Water supply portfolios were evaluated and ranked
using the approach described in Section 4. A systems
model was developed for OWD and was the primary
tool for determining the raw performance of each
portfolio in terms of supply reliability, cost, water
quality, diversity, flexibility, and other objectives.
This information from the systems model was then
standardized using a multi-attribute rating tool in
order to determine a portfolio’s overall score. Finally,
portfolios were compared and ranked. Figure 8-1
illustrates the portfolio evaluation process. Initial
portfolios were evaluated first, and based on their
performance; final portfolios were developed and
evaluated.
8.2 Portfolio Evaluation Results
This section describes the raw performance of the portfolios, regardless of the
stakeholder’s importance or weight placed on the planning objectives. Later, Section
8.3 describes how the raw portfolio performance is used in conjunction with the
objective weights to rank the portfolios. Appendix D presents the summary of the raw
performance of each portfolio.
It is important to recognize that the portfolio results are not predictive, but are rather
a measure of their relative performance under various conditions.
8.2.1 Water Quality Evaluation
For this IRP, the water quality objective was considered in four ways: (1) meeting
current and future water regulations, (2) salinity management, (3) compatibility with
other sources for blending prior to distribution, and (4) potential for disinfection by-
products.
Current and Future Water Regulations
For the first performance measure, it is assumed that all supply options will be
designed to comply with all current and future water regulations. In this case, all
portfolios will receive the same score.
Figure 8-1
Portfolios Evaluation Process
Section 8
Portfolio Evaluation and Screening
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Figure 8-2
Portfolio Salinity (Total Dissolved Solids)
Salinity Management
In the systems model, each water supply option has an average salinity, measured in
total dissolved solids (TDS), which can be tracked. Refer to Appendix B for the
assumed TDS levels of each option. Using mass-balance calculations, the overall
salinity of the potable and non-potable water supply can be estimated for any
portfolio.
Figure 8-2 shows the average salinity for potable and non-potable supply, measured
in total dissolved solids. Again, these values are not predictive. They are simply used
to accurately compare the performance of the portfolios against each other.
It is apparent in Figure 8-2 that the salinity is relatively the same for all portfolios. The
Flexibility portfolio has a slightly lower non-potable TDS level because it includes the
Raw Water from Pipeline No. 3 for Irrigation option, which comes from imported
water purchases through SDCWA. The TDS levels of raw imported water
(approximately 500 mg/L) are much lower than wastewater treatment plant effluent,
which typically has a TDS of approximately 900-1000 mg/L in Southern California.
The Water Quality B and Reliability B portfolios have slightly lower potable TDS
levels because they include a significant supply from the local ocean desalination
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partnership with Sweetwater Authority and/or the City of San Diego (South Bay
Project).
Compatibility with Other Sources and Potential for Disinfection By-products
The performance of portfolios for salinity management was measured
quantitatively—meaning that performance could be measured on a continuous scale.
However, not all performance can be measured quantitatively. Some of the IRP
objectives had to be measured using a constructed scale or more qualitative
measurement. This is not to say that these performance measures are less important,
but merely that at the time of the IRP analysis, they could not be precisely measured
on a continuous scale.
Qualitative scales are described in Section 7, and the qualitative scores for each supply
option are summarized in Appendix B. The qualitative scores for each option were
used to calculate an overall portfolio score based on the weighted average of the
annual potential yield of the options included in the portfolio.
Figure 8-3 illustrates the qualitative scores for water quality related to (1)
compatibility with OWD’s existing water supply system, and (2) the potential for
disinfection by-products based on the supply mix in the portfolio. The results show
that all portfolios score well in terms of supply compatibility. The Reliability B
portfolio scored slightly lower because it has a large supply from the local ocean
desalination partnership with Sweetwater Authority and/or the City of San Diego
(South Bay Project), as well as brackish groundwater demineralization options in the
Lower Sweetwater, Santee El/Monte, and San Diego Formation Basins. These projects
scored lower in terms of compatibility because they introduce new source water
(desalinated seawater and groundwater) into the distribution system, which currently
only contains imported water from SDCWA. The compatibility of desalinated
seawater and groundwater with imported water is unknown and further
investigation may be required prior to implementation.
In terms of potential disinfection by-products, all of the portfolios scored on the
higher end of the scale. The portfolios that scored better for the DBP performance
measure include more supply from groundwater projects, and/or the local ocean
desalination partnership with Sweetwater Authority and/or the City of San Diego
(South Bay Project). In other words, the portfolios that scores well rely less on supply
from surface water treatment.
Section 8
Portfolio Evaluation and Screening
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Figure 8-3
Portfolio Compatibility and DBP Scores
Disinfection by-products, such as tri-halomethane (THM) and haloacetic acid (HAA),
are created when water that is high in bromate or total organic content (TOC) receives
treatment from a plant that uses chlorine as a primary disinfection method. Most
surface water treatment plant in the Southern California region that supply water to
OWD already have, or are planning to, upgrade to include ultraviolet (UV) or ozone
disinfection methods to comply with safe drinking water standards. Therefore, none
of the supply options had a DBP score less than 3, on a qualitative scale of 1 to 5 (with
5 being the best score).
8.2.2 Water Supply Reliability Evaluation
One of the main objectives of the IRP is to improve supply reliability. The ability of
each portfolio to meet projected future demands was evaluated under various
hydrology conditions. In addition, portfolios were evaluated under extreme drought
conditions involving imported water shortages, as well as emergency seismic
conditions in which the SDCWA Second San Diego Aqueduct (Pipelines No. 3 and
No. 4) that conveys raw and treated water are offline.
Initial portfolio results shows that all portfolios could reliably meet demands on the
peak day, and also under “average” conditions (meaning normal hydrology, non-
emergency conditions). OWD currently has enough system capacity to meet projected
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2030 demands through imported water purchases from SDCWA. In this case, the peak
day reliability performance measure is considered a “non-discriminator” in terms of
decision-making, since all portfolios could meet the peak day demand. Therefore, the
peak day performance was not used for final evaluation.
Similarly, all portfolios were capable of meeting demands under normal hydrology,
non-emergency conditions through imported water purchases from SDCWA.
Therefore, the performance measure to reliably meet demands under “average”
conditions was not used to rank the portfolios, since all of the portfolios would have
the same score.
For final evaluation, all of the importance to score portfolios on their reliability was
instead placed on meeting demands under (1) extreme drought conditions (with
imported water shortages) and (2) seismic emergency conditions.
Deficits under Extreme Drought Conditions with Imported Water Shortages
Water demands are typically higher under critically dry conditions than normal
hydrology conditions, since natural rainfall is not available for irrigation. The
evaluated extreme drought condition accounts for these annual increases in demands
based on historical correlations between demands and hydrology for the San Diego
area, which are discussed in Section 3.
In addition to higher demands, it was assumed that under extreme drought
conditions annual imported water supply from SDCWA would be reduced by up to
30% of the baseline, or “no project,” throughout the planning horizon. The estimated
reductions vary over time depending on the planning year and the corresponding
historical hydrology year in the time series. The reductions apply to all purchases of
raw or treated imported water from the SDCWA, even if it is treated locally.
It should be noted that this evaluation does not predict future imported water
shortages, but rather is for purposes of relative comparison of portfolio performance
in a given shortage scenario. The assumption is that the percentage of shortage would
be distributed equally to all member agencies, and preferential rights would not be
enforced. In addition, this analysis does not include any drought supply from sources
such as the Emergency Storage Project.
Figure 8-4 shows the cumulative deficit over all shortage years in the critically dry
hydrology sequence. Water supply drought reliability increases under each portfolio
relative to the No Project Portfolio. All portfolios can be considered drought reliable
except for the Water Quality A, Water Quality B, and the Baseline Portfolios. The
smaller drought deficits can be considered negligible, since they could probably be
met through system operational decisions to optimize the available supply, or
through drought emergency sources such as the Emergency Storage Project.
Section 8
Portfolio Evaluation and Screening
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The portfolios that performed well in this scenario have a large portion of supply
from local sources, such as groundwater, seawater, recycled, and conservation
savings. In addition, portfolios with water transfer and water banking options would
benefit in this scenario.
Deficits under Emergency Seismic Conditions
The evaluated seismic emergency condition assumed that all supply options relying
on conveyance through the SDCWA Second San Diego Aqueduct would be offline.
This means there would be no supply from options that use raw water from Pipeline
No. 3 or treated water from Pipeline No. 4, even if it is treated locally through
agreements with neighboring agencies. In addition, all recycled water supply would
be offline, since there would be a potable water supply emergency shortage.
The deficit under the seismic emergency condition was evaluated over a three month
period, assuming 2030 projected demands under normal hydrology conditions.
Figure 8-5 shows the deficit over the three month period for each portfolio. Although
there is a large deficit in every portfolio, the size of the deficit is the smallest in the
Reliability B Portfolio. This portfolio includes several groundwater projects and the
local ocean desalination partnership with Sweetwater Authority and/or the City of
Figure 8-4
Cumulative Deficit under Extreme Drought Conditions (a measure of Portfolio Reliability)
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San Diego (South Bay Project), which do not propose the use of the SDCWA Second
San Diego Aqueduct for conveyance.
The Baseline Portfolio fails completely to meet demand under the assumed seismic
emergency condition, since most supply comes from imported raw and treated water
purchase through SDCWA, and a small recycled water supply from OWD’s Ralph W.
Chapman WRP and the City of San Diego’s South Bay WRP.
The portfolios that performed well in the seismic scenario have a large portion of
supply from local sources that do not use SDCWA conveyance facilities, such as
groundwater and conservation savings. The only seawater project that provides
benefit in this scenario is the partnership with Sweetwater Authority and the City of
San Diego to build a local desalination plant, since the other seawater options rely on
in-lieu water conveyed through SDCWA Pipeline No. 4.
8.2.3 Cost Evaluation
The performance of the portfolios in terms of affordability was measured with total
capital costs, as well as the net present value (NPV) unit cost in dollars per acre-foot
($/AF). For portfolio comparison purposes, it was assumed that all projects would be
implemented at the same time. Therefore, the capital costs are presented in today’s
Figure 8-5
Portfolio Reliability under Emergency Seismic Conditions
Section 8
Portfolio Evaluation and Screening
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dollars (without inflation). Once the preferred portfolios have been selected, the
timing of project implementation will be evaluated, to help minimize costs and
develop the implementation plan described in Section 9.
For purposes of portfolio evaluation, any existing or planned capital costs associated
with the baseline (2010) system were not included in the cost of the water supply
portfolio. Therefore, only the capital costs incurred with new supply options are
shown. The total capital costs for each portfolio are presented in Figure 8-6.
The portfolios with the highest capital costs are the Reliability B and Diversity A
Portfolios, which perform very well in terms of reliability under extreme drought
conditions and emergency seismic condition. These portfolios are very reliable, but at
a high capital cost, because they include groundwater projects which require new
conveyance infrastructure and demineralization plants, and they include the
construction of a new ocean desalination plants. Although the Diversity A has a much
smaller ocean desalination supply than Reliability B, it has more supply from non-
potable options and additional imported options (through local treatment
agreements), which have a high cumulative capital cost.
Figure 8-6
Portfolio Capital Costs
Section 8
Portfolio Evaluation and Screening
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The net present value (NPV) unit cost is representative of the cost of new water over
the entire planning horizon, and includes both capital and O&M costs. In order to
calculate the NPV unit costs, the annual cost of new water is calculated, as well as the
cumulative cost over time; then, the cumulative costs are discounted at a rate of 6%,
and divided by the cumulative supply, which is also discounted at the same rate.
The annual capital cost is calculated with a debt financing plan over 30 years,
assuming a 6% annual interest rate. The annual O&M costs are inflated annually at
3% over time. The annual costs also include imported water purchases from SDCWA
and water transfer/banking purchases, which increase at a different assumed rate
(see Section 5). A more detailed discussion of the NPV unit cost of portfolio is
provided in Section 7.
The NPV unit cost of each portfolio is shown in Figure 8-7. The results show that the
Baseline portfolio is the least expensive in terms of $/AF, but the Affordability
portfolio is the least expensive reliable portfolio. The Affordability portfolio performs
very well under extreme drought conditions (when there are imported water
shortages from SDCWA), while maintaining a relatively low capital cost and NPV
unit cost. This is because the Affordability portfolio includes a substantial supply
from water transfers or water banking opportunities. The water transfers and water
banking options do, however, rely on the SDCWA 2nd Aqueduct for conveyance; and
therefore, do not perform well under seismic emergency conditions.
Figure 8-7
Portfolio NPV Unit Cost
Section 8
Portfolio Evaluation and Screening
8-10 A
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The portfolio with the highest NPV unit cost is the Reliability B portfolio, which also
has a very high capital cost. For portfolios with a very high capital cost, it is
anticipated that the NPV unit cost could be significantly reduced with careful
scheduling of project implementation. The annual capital cost for a new option does
not contribute to the NPV unit cost until it is implemented, which may not be
required until the long-term, especially if other options are implemented in the near-
term.
It is interesting to see that the NPV unit cost for the Diversity A portfolio is
significantly lower than the Reliability B portfolio, since these portfolios had
approximately the same capital cost. This means that the annual O&M cost of the
Reliability B portfolio is much higher that of the Diversity A portfolio, which can be
attributed to the annual O&M cost for the local ocean desalination partnership with
Sweetwater Authority and/or the City of San Diego (South Bay Project). This project
is very expensive to operate since it involves seawater desalination with typically
high power costs, pumping conveyance costs to the OWD’s distribution system, and
high-priced brine disposal costs.
8.2.4 Diversity and Flexibility Evaluation
System diversity and flexibility are important attributes of a water supply portfolio.
These objective help to improve overall operational reliability by increasing the
number of water sources, contractual rights for water use, and take points into the
system. Diversity and flexibility reduce the system’s dependence on one source or
facility, respectively. If a source or facility is offline, overall water system could still
potentially satisfy all demands with the use of other supply options in the portfolio.
The flexibility of the portfolio was measured by the number of take points into the
system. The diversity was measured in two ways: (1) number of contracts for water
use, and (2) percent contribution of largest source to total supply. The portfolio scores
for these performance measures are shown in Figures 8-8 and 8-9.
In Figure 8-8, it is clear that all portfolios increase the number of take points and
number of contracts over the Baseline Portfolio. The portfolio with the largest number
of take points and contracts is the Diversity A portfolio. The supply options included
in this portfolio are listed in Table 6-1 and Appendix D.
Figure 8-9 shows that all portfolios reduce the percent contribution of the largest
source from the Baseline Portfolio. In this case, a lower percentage is viewed as a
better score. The portfolios that scored well in this performance measure typically
relied less on imported raw and treated water purchases from SDCWA, since
imported water purchases are counted as a single source regardless of where the
water is treated.
Section 8
Portfolio Evaluation and Screening
A 8-11
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Figure 8-8
Number of Take Points and Contracts in Portfolio
Figure 8-9
Percent Contribution of Largest Source to Total
Supply in Portfolio
Section 8
Portfolio Evaluation and Screening
8-12 A
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8.2.5 Environmental and Institutional Constraints Evaluation
For this objective, five performance measures were evaluated to compare the
portfolios: (1) minimize environmental permitting requirements, (2) minimize
institutional coordination, (3) maximize customer acceptance, (4) minimize regulatory
constraints, and (5) minimize technological uncertainty. A qualitative scale was used
for these performance measures, as discussed in Section 7, and a higher score
indicates that the portfolio performed well. The scores for these performance
measures are shown in Figure 8-10.
In general, most of the portfolios score well for these performance measures.
However, the Reliability B portfolio has the lowest score in every case and clearly
scores poorly for environmental permitting obstacles. The qualitative scores are
related to the potential annual yield of the options. Therefore, the large portion of
supply from ocean desalination projects in the Reliability B portfolio is impacting the
environmental permitting score. The local ocean desalination partnership with
Sweetwater Authority and/or the City of San Diego (South Bay Project) has a very
low score for environmental permitting, primarily because it requires approval from
the California Coastal Commission the San Diego County Regional Water Quality
Control Board, and the California DHS.
Figure 8-10
Portfolio Scores for Environmental and Institutional Constraints
Section 8
Portfolio Evaluation and Screening
A 8-13
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8.2.6 Portfolio Performance Summary
A summary of the raw performance scores for every portfolio is presented in Table 8-
1, as shown at the end of this section. Section 8.3 discusses how these raw scores were
used in conjunction with stakeholder’s objective weightings (refer to Section 4) to rank
the portfolios.
8.3 Portfolios Ranking
Using the portfolio raw performance scores in Table 8-1, the portfolios were ranked
with the multi-attribute rating method described in Section 4. A ranking of the
portfolios was developed for each stakeholder, based on the raw performance
measures discussed in Section 8.2 and the relative weights that the stakeholder placed
on each objective. This method allows individual results to be tracked in order to see
where consensus was reached. This approach can be very powerful, as a majority of
stakeholders can arrive at the same conclusion for very different reasons. If an overall
average weight for each objective was used for all stakeholders and applied to the raw
performance, one single ranking of portfolios would result. In this case it would be
difficult to know for sure if the results actually represented any stakeholder’s
individual preferences.
Figure 8-11 shows the rankings of portfolios for the average weightings of the entire
group of stakeholders, and illustrates how the ranking results are created for one set
of weights. The figure not only indicates which portfolio had the greatest overall
score, but also the make-up of that score. Each color segment represents the major
objectives discussed in Section 4.
Two factors determine the size of each color segment for a given bar, or portfolio: (1)
the raw performance of the portfolio for that objective; and (2) the weight of the
objective assigned by the stakeholders. In general, if the color segment is larger, then
the raw performance was better, and the objective was given a relatively high weight
of importance. However, if the color segment is smaller, it could be because of poor
performance, or a low weight of importance, or both.
The top three portfolios for the average of the stakeholders are:
Diversity A
Reliability A
Water Quality A
Section 8
Portfolio Evaluation and Screening
8-14 A
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8.4 Preferred Portfolios
The chart shown in Figure 8-11 illustrates how ranking results are created for one set
of weights. In order to determine the preferred portfolio and see if consensus truly
exists among stakeholders, analysis is required of all of the individual stakeholders’
rankings. To do this, the number of times a portfolio was ranked number 1, number 2,
or number 3 by all stakeholders was counted1. This is shown in Figures 8-12 and 8-13.
The top three preferred portfolios in Figure 8-13 are clearly Diversity A, Reliability A,
and Water Quality A. In this case, the results are the same as those obtained from the
average stakeholder weights.
1 In one stakeholder’s case, the Reliability B portfolio was tied with Water Quality A for the number 3 ranking. Therefore, they
were both counted as being ranked number 3. This is why the total number of times counted in Figure 8-13 does not equal 39
(which is the product of 13 stakeholders x 3 portfolios counted per stakeholder).
Figure 8-11
Portfolio Ranking for Average Stakeholder Weights
Section 8
Portfolio Evaluation and Screening
A 8-15
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Figure 8-12
Number of Times a Portfolio was Ranked Number 1
Figure 8-13
Number of Times a Portfolio was Ranked Number 1, 2, or 3
Section 8
Portfolio Evaluation and Screening
8-16 A
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8.5 Sensitivity Analysis
In the development of this IRP, two of the greatest concerns for OWD are the
indefinite reliability and increasing cost associated with imported water purchases
(raw or treated) from the SDCWA. The sensitivity of these two factors was analyzed
to determine how the rankings would change if (1) imported water reductions under
drought conditions were not as severe, and (2) the projected cost of imported water
was not as high.
If the imported water reductions over time were only up to 15% (instead of 30%) of
the baseline demand for raw or treated water purchases, the top 3 ranked portfolios
would not change. In other words, by improving the performance of portfolios that
had deficits under extreme drought conditions, the rankings of the preferred
portfolios would remain the same.
Similarly, if the cost of projected imported water costs was reduced by up to 20%, the
top 3 ranked portfolios would not change. In this case, portfolios which rely on
imported water purchases from SDCWA would have a lower NPV unit cost, but the
rankings of the preferred portfolios would still remain the same.
Therefore, it is concluded that the portfolio rankings are robust.
8.6 Common Elements among the Preferred Portfolios
The options that consistently show up in the top ranked portfolios should be
considered for implementation. The following options are included in at least two of
the top three preferred portfolios:
Additional Conservation
Central Valley and Land Fallowing Transfers
Groundwater projects (Demineralization and Conjunctive Use)
5-10 MGD Ocean Desalination (Poseidon, or Sweetwater/City of SD’s South Bay
project)
Raw CWA imported water for Irrigation Use
Stripping Plant along Spring Valley Trunk Line
North District Recycled Water Concept
Expand Ralph W. Chapman Water Reclamation Facility
Other options that could be considered for implementation are those that were in at
least one of the top three performing portfolios. These options are:
Section 8
Portfolio Evaluation and Screening
A 8-17
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Perdue WTP
SD17 Agreement with City of San Diego to treat raw water at Alvarado WTP
Additional Purchases from South Bay WRP
North of Delta Transfers
The options listed above are projects, programs and contractual agreements that have
shown to best accomplish OWD’s goals when combined in a supply mix for the
future. Therefore, these projects are recommended for consideration in the IRP
implementation plan, which is presented in Section 9.
Objective/Sub-objective Performance
Measure
Water Quality
A: DBP
Water Quality
B: TDS
Reliability A:
Drought
Reliability B:
Seismic Affordability Baseline Diversity A
Diversity B:
Expand Existing Flexibility
Objective 1 -Meet or Exceed Water Quality Standards and Guidelines
1a) Meet current and future drinking water standards All portfolios will
comply 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0
1b) Address compatibility of new sources with current imported supply Compatability Score 4.1 4.2 4.3 3.4 4.9 5.0 4.6 4.8 4.6
Potable TDS (mg/L)426 406 490 388 492 492 483 492 484
Non-potable TDS
(mg/L)968 990 990 990 990 990 990 990 912
1d) Minimize potential issues due to disinfection method DBP Score 4.5 3.8 3.7 4.8 3.2 3.0 3.7 3.3 3.5
Objective 2 – Achieve Reliability
2a) Meet demands under average hydrology conditions Average Annual
Deficit (AFY)251 455 0 118 68 1066 0 113 1
2b) Meet demands under drought imported shortage conditions
Cumulative Deficit
(AF/ all shortage
years)9037 21862 0 2833 2983 110864 0 908 18
2c) Minimize impacts under emergency conditions
Shortage during a
three month
emergency - AF 20101 24367 23813 16242 26887 29137 21921 27790 24894
Objective 3 – Maintain Affordability
3a) Minimize impacts to an average single-family customer NPV Unit costs --
$/AF 1,465 1,562 1,197 1,940 1087 952 1,440 1,019 1,329
3b) Manage Capital Costs NPV Capital costs --
$266,585,000 163,975,000 131,906,000 380,065,000 52,092,000 - 380,707,000 150,341,000 245,265,000
Objective 4 – Increase Flexibility
4a) Increase Number of Take Points and Alternative Flow Routes Total Number of
Take Points 12 9 9 10 6 5 13 6 10
Objective 5 – Increase Diversity
5a) Maximize number of sources Total number of
contracts 12 9 12 11 8 5 17 8 11
5b) Reduce contribution of largest source 2030 contribution of
the largest source to
total supply - %54% 70% 34% 34% 47% 91% 38% 59% 78%
Objective 6 – Address Environmental and Institutional Constraints
6a) Minimize environmental permitting requirements Permitting Score 3.3 3.0 3.9 2.2 3.7 4.0 3.5 3.9 3.6
6b) Minimize institutional coordination and implementation requirements
(local/State/Federal/International)Institutional
Coordination Score 3.7 3.6 3.2 3.1 3.3 4.0 3.7 3.8 3.8
6c) Maximize customer acceptance Customer
Acceptance Score 4.2 4.6 4.6 3.9 4.9 5.0 4.6 4.6 4.8
6d) Minimize regulatory constraints Regulatory
Constraints Score 3.8 4.0 4.1 2.9 4.8 5.0 3.9 4.6 3.8
6e) Minimize technology uncertainty Technology
Uncertainty Score 4.0 4.5 4.4 3.8 4.8 5.0 4.5 4.8 4.7
1c) Meet TDS goals for recycled water, potable water and Basin Plan
Table 8-1
Portfolio Performance Summary
Table 8-1
Portfolio Performance Summary
A 9-1
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Section 9
Implementation Plan
It is important to have a flexible and adaptive water resources implementation
strategy to react to future opportunities and changes. The implementation strategy
defined for OWD’s IRP and described in this section proposes a phased
implementation of projects over the planning horizon to meet growing future water
demands, while making adjustments as necessary to respond to changing technology,
supply levels, regulations, market conditions, costs, or partnership opportunities.
The evaluations described in Section 8 compare the performance and rankings of
several water supply portfolios. The results of the rankings are dependent on the raw
portfolios performance and the planning objective weightings, which were developed
by the group of OWD stakeholders.
The three top-scoring portfolios were Diversity A, Reliability A, and Water Quality A.
These portfolios are described in Section 6. Section 8.6 discusses the recommended
water supply options that consistently showed up in the top ranked portfolios and
should be considered for implementation. These options combined into water supply
portfolios are likely to help OWD achieve the objectives defined in the IRP.
While reviewing the results of the portfolio rankings, OWD staff members expressed
concern regarding the feasibility of some water supply options that were included in
top three ranked portfolios. These supply options were not included in
implementation plan for reasons described below:
Raw CWA imported water for Irrigation Use – This option was not included in the
implementation plan due to the OWD’s concern with water quality compatibility
with other water sources in the recycled water distribution system.
Expand Ralph W. Chapman Water Reclamation Facility (RWCWRF) - This option
was not included in the implementation plan due to the OWD’s concern that there
would not be sufficient wastewater flows into the RWCWRF unless OWD
allocates resources to wastewater collection system expansions.
Perdue WTP - This option was not included in the implementation plan due to the
OWD’s concern that there would not be sufficient capacity at Perdue WTP.
The options that consistently showed in the top ranked portfolios and that were
ultimately considered feasible include the following:
Additional Conservation
Central Valley and Land Fallowing Transfers
Groundwater projects (Demineralization and Conjunctive Use)
Section 9
Implementation Plan
9-2 A
March 2, 2007 P:\Otay Water District 2607\IRPP 50683\7.0 ProjDoc\7.3 Final Documents\Section 9 Implementation Plan 3_2_07.doc
5-10 MGD Ocean Desalination (Poseidon, or Sweetwater/City of SD’s South Bay
project)
Stripping Plant along Spring Valley Trunk Line
North District Recycled Water Concept
SD17 Agreement with City of San Diego to treat raw water at Alvarado WTP
Additional Purchases from South Bay WRP
North of Delta Transfers
9.1 Strategic Implementation of Projects
With the implementation of this integrated water resources plan, OWD will be taking
significant steps to achieve its objectives of improving system reliability, flexibility,
and diversity. In order for this to occur, it is important for OWD to revise its current
CIP to reflect the recommended supply options, and begin assessing the feasibility of
projects to meet phased targets proposed in the implementation plan. The top ranked
portfolios represent a long-term vision for OWD, and the implementation strategy
represents a feasible way to achieve that vision.
The implementation strategy is presented in Figure 9-1. The strategy is based on
actions, triggers, and decisions followed by new actions, all of which span a timeline
of 25 years. Triggers are related to the feasibility to implement ocean desalination, the
development of demands compared to the supply available in between 2015 and 2020,
and the feasibility and need to implement groundwater conjunctive use projects.
At some points in the implementation, OWD could be faced with the impossibility or
impracticability to implement a specific project. In those cases the implementation
strategy delineates alternative projects. In other cases, OWD will have the possibility
to implement more than one project when only one is necessary. In those cases,
conditions at the time will dictate which project is more convenient, cost effective and
practical. This results in different possible scenarios of investment.
The different implementation paths could result in a maximum capital investment of
approximately $318 million, and the minimum exposure would be around $117
million. If conditions allow for the implementation of the least costly option, the
resulting portfolio would be essentially the Reliability A portfolio (See Table 6-1 for a
list of options included in each portfolio), with a yield of approximately 72,000 AFY.
Conversely, if conditions were such that the highest level of investment is required,
the resulting portfolio would be closer to the Diversity A portfolio, with lower capital
costs and slightly lower annual yield (about 76,000 AFY vs. 88,000 AFY). What is
important to recognize is that any of the resulting paths in the implementation
strategy would include projects, programs, and contractual agreements that have
Section 9
Implementation Plan
A 9-3
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shown to best accomplish OWD’s goals when combined in a supply mix for the
future.
9.2 Short-Term Actions
The three top performing portfolios, Diversity A, Water Quality A and Reliability A,
represent viable and desirable future water supply mixes for OWD. The
implementation strategy shows different ways to obtain that supply mix and accounts
for future uncertainty on project implementation. The strategy, however, is clear in
the short-term. Projects presented in Figure 9-1 as short-term implementation projects
will require concrete steps for implementation that OWD will need to take to develop
the foundations of the future supply mix. Projects, programs and contractual
arrangements included in the short-term actions are:
Additional conservation
SD17 agreement with the City of San Diego
Additional purchases from SBWRP
North District recycled water concept
Water banking agreements
Implementing these short-term projects constitutes the largest step in the
implementation strategy, but they are considered more likely to be achieved in the
short-term than the complex and capital-intensive projects scheduled later in the
strategy, since opportunity currently exists for partnerships and agreements and, in
some cases, the implementation has already begun with minimum capital
improvements required. These initial projects represent the most achievable projects
in the short-term to firm the supply for OWD and improve system flexibility,
diversity and cost efficiency.
The strategy presented in Figure 9-1 was designed to achieve OWD’s goals under any
of the resulting implementation scenarios. The projects implemented by OWD under
this strategy will result in portfolios that have shown by the IRP analysis to be the
most likely to accomplish OWD’s objectives for the future.
LEGEND
Implement Project
Minimal Capital Cost Project
Maximum Capital Cost Project
Implement
Additional Conservation
SD17 Agreement with City of
San Diego to treat raw water at
Alverado WTP
Additional purchases from
SBWRP
North District Recycled Water
Concept
Water banking (5000 AFY)
•
•
•
•
•
Implement 5,000 AFY
ocean desalination project<
(Southern California
Partnership (SCP) preferred
over Poseidon)
Implement Chula Vista
stripping plant option<
Are ocean
desalination projects
feasible?
Yes
N
o
Implement
Additional or new ocean
desalination project
5,000 AFY
(Poseidon or SCP)
Spring Valley Stripping
plant option=
•
•No Action
Implement water
transfers (5,000 AFY)
Implement GW conjunctive
use project (Santee/El Monte?
or Middle Sweetwater)
Implement Brackish GW
Demineralization project
(Santee/El Monte>? or
Lower Sweetwater)
Is new supply
implemented to
date less than
25,000 AFY?
Yes
N
o
Yes
N
o
Are groundwater
conjunctive
use projects
feasible?
Implement additional ocean
desalination (if total yield of ocean
desalination projects implemented
to date is less than 5,000 AFY)
2007 2010 2015 2020 2030
NOTES
< If ocean desalination projects and stripping options are not feasible, implement Santee/El Monte brackish groundwater demineralization (with the use of the LMSE).
= If Chula Vista stripping plant is not already in place.
> If not already in place.
? Assumes use of LMSE pipeline.
Implement Brackish GW
Demineralization Project
(Santee/El Monte>? or
Lower Sweetwater)
Figure 9-1
OWD IRP Implementation Plan
TIMELINE
A 10-1
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Section 10
References
Boyle Engineering Corporation, 1993. Lower Sweetwater River Basin Groundwater
Studies. Prepared for Sweetwater Authority.
Boyle Engineering Corporation, 1999. Aquifer Storage and Recovery Project: San Diego
Formation. Phase I Technical Report. Prepared for the San Diego County Water
Authority.
OWD & MWH Americas, Inc. 2005. Urban Water Management Plan.
OWD, 2002. Water Resources Master Plan.
City of San Diego, 2001. Long-Range Water Resources Plan.
Woodward-Clyde Consultants, 1990. Groundwater Basin Evaluation. San Diego County
Water Authority Optimal Storage Study. Prepared for James M. Montgomery,
Consulting Engineers, Inc.
Appendix A
Objectives Weighting Results
A A-1
C:\Documents and Settings\MeyersAM\Desktop\Otay Appendices\Practice\App A Intro.doc
Appendix A
Objectives Weighting Results
Appendix A presents the overall objectives weighting results for the group of OWD
stakeholders, and the individual weighting results for each stakeholder. The
stakeholders included both OWD senior staff and the Board of Directors. The
objectives were weighted using a method known as “forced-paired comparison.” This
method consists of comparing the relevant importance of two objectives in all the
possible pair of objectives.
The individual stakeholder results were used to calculate the minimum, maximum,
and average weight of each objective for the group of stakeholders, as shown in the
stock chart on the next page. On average, “Water Quality”, Reliability”, and
“Diversity” objectives are the three most important. However, the minimum and
maximum results show that there is a very large spread in terms of objective
importance among the stakeholders. Therefore, the average may not be representative
of any individual preferences.
In order to show overall group results that accurately reflect individual preferences,
the number of times an objective was determined as the Top 1 (or most important)
objective was counted for each stakeholder. Similarly, the number of times an
objective was within the Top 3 most important objectives were counted. The results in
the bar charts show that the “Water Quality”, “Reliability”, and “Affordability”
objectives are rated the three most important objectives among all of the stakeholders.
Objectives Weighting (Min, Max, Average)
0%
5%
10%
15%
20%
25%
30%
35%
Meet or Exceed
Water Quality
Standards and
Guidelines
Achieve
Reliability
Maintain
Affordability
Increase
Flexibility
Increase
Diversity
Address
Environmental
and Institutional
Constraints
Number of Times the Objective is the Top 1
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Meet or Exceed
Water Quality
Standards and
Guidelines
Achieve Reliability Maintain Affordability Increase Flexibility Increase Diversity Address
Environmental and
Institutional
Constraints
Number of Times the Objective is in the Top 3
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Meet or Exceed
Water Quality
Standards and
Guidelines
Achieve Reliability Maintain Affordability Increase Flexibility Increase Diversity Address
Environmental and
Institutional
Constraints
Otay Water District Integrated Water Resources Plan
Name: Stakeholder 1
1
1
12
123
1
555
12345
123456Objective Number
Objective/Sub-Objective Weighting Results
These results seem to indicate that the objectives and sub-objectives for you
rank as follows:
Meet or Exceed Water Quality Standards and Guidelines 33%
Increase Diversity 27%
Achieve Reliability 20%
Maintain Affordability 13%
Increase Flexibility 7%
Address Environmental and Institutional Constraints 0%
The chart below shows the weights you have assigned by sub-objective
Percentage of All Matches
To be completed by CDM
33% 20% 13% 7% 27% 0%
0
Weighting Grid - Objectives
Meet or Exceed Water Quality Standards and Guidelines
Achieve Supply Reliability
6
5 Increase Supply Diversity
4
Address Environmental and Institutional Constraints
2
5
Increase System Flexibility
3 Maintain Affordability
3214 Number of Times Circled
(Total = 15)
20%
7%
3% 3%
8% 8%
4%
7% 7% 7%
27%
0% 0% 0% 0% 0%0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
1a 1b 1c 1d 2a 2b 2c 3a 3b 4a 5a 6a 6b 6c 6d 6e
1 of 2
Otay Water District Integrated Water Resources Plan
Objective 1 - Meet or Exceed Water Quality Standards and Guidelines
Points Sub-objective
60 1a) Meet current and future drinking water standards
20 1b) Address compatibility of new sources with current imported supply
10 1c) Meet TDS goals for recycled water, potable water and Basin Plan
10 1d) Minimize potential issues due to disinfection method
Total Pts (Must equal 100)
Objective 2 - Achieve Reliability
Points Sub-objective
40 2a) Meet demands under normal conditions
40 2b) Meet demands under drought conditions
20 2c) Minimize impacts under emergency conditions
Total Pts (Must equal 100)
Objective 3 - Maintain Affordability
Points Sub-objectives
50 3a) Minimize impacts to an average single-family customer
50 3b) Manage capital costs
Total Pts 100 (Must equal 100)
Objective 4 - Increase Flexibility
Points Sub-objectives
100 4a) Increase number of take points and alternative flow routes
Total Pts 100 (Must equal 100)
Objective 5 - Increase Diversity
Points Sub-objectives
100 5a) Maximize number of sources and/or reduce contribution of largest source
Total Pts 100 (Must equal 100)
Objective 6 - Address Environmental and Institutional Constraints
Points Sub-objectives
10 6a) Minimize environmental permitting requirements
10 6b) Minimize institutional coordination and implementation requirements (local/State/Federal/International)
50 6c) Maximize customer acceptance
10 6d) Minimize regulatory constraints
20 6e) Minimize technology uncertainty
Total Pts 100 (Must equal 100)
Weighting - Sub-Objectives
2 of 2
Otay Water District Integrated Water Resources Plan
Name: Stakeholder 2
1
1
12
12
4
1
555
12345
123456Objective Number
Objective/Sub-Objective Weighting Results
These results seem to indicate that the objectives and sub-objectives for you
rank as follows:
Meet or Exceed Water Quality Standards and Guidelines 33%
Increase Diversity 27%
Achieve Reliability 20%
Increase Flexibility 13%
Maintain Affordability 7%
Address Environmental and Institutional Constraints 0%
The chart below shows the weights you have assigned by sub-objective
5
Increase System Flexibility
3 Maintain Affordability
3124 Number of Times Circled
(Total = 15)
Weighting Grid - Objectives
Meet or Exceed Water Quality Standards and Guidelines
Achieve Supply Reliability
6
5 Increase Supply Diversity
4
Address Environmental and Institutional Constraints
2
Percentage of All Matches
To be completed by CDM
33% 20% 7% 13% 27% 0%
0
20%
3%
7%
3%
12%
6%
2%
5%
2%
13%
27%
0% 0% 0% 0% 0%0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
1a 1b 1c 1d 2a 2b 2c 3a 3b 4a 5a 6a 6b 6c 6d 6e
1 of 2
Otay Water District Integrated Water Resources Plan
Objective 1 - Meet or Exceed Water Quality Standards and Guidelines
Points Sub-objective
60 1a) Meet current and future drinking water standards
10 1b) Address compatibility of new sources with current imported supply
20 1c) Meet TDS goals for recycled water, potable water and Basin Plan
10 1d) Minimize potential issues due to disinfection method
Total Pts (Must equal 100)
Objective 2 - Achieve Reliability
Points Sub-objective
60 2a) Meet demands under normal conditions
30 2b) Meet demands under drought conditions
10 2c) Minimize impacts under emergency conditions
Total Pts (Must equal 100)
Objective 3 - Maintain Affordability
Points Sub-objectives
70 3a) Minimize impacts to an average single-family customer
30 3b) Manage capital costs
Total Pts 100 (Must equal 100)
Objective 4 - Increase Flexibility
Points Sub-objectives
100 4a) Increase number of take points and alternative flow routes
Total Pts 100 (Must equal 100)
Objective 5 - Increase Diversity
Points Sub-objectives
100 5a) Maximize number of sources and/or reduce contribution of largest source
Total Pts 100 (Must equal 100)
Objective 6 - Address Environmental and Institutional Constraints
Points Sub-objectives
30 6a) Minimize environmental permitting requirements
20 6b) Minimize institutional coordination and implementation requirements (local/State/Federal/International)
30 6c) Maximize customer acceptance
10 6d) Minimize regulatory constraints
10 6e) Minimize technology uncertainty
Total Pts 100 (Must equal 100)
Weighting - Sub-Objectives
2 of 2
Otay Water District Integrated Water Resources Plan
Name: Stakeholder 3
1
1
12
12
4
1
555
1234
6
123456Objective Number
Objective/Sub-Objective Weighting Results
These results seem to indicate that the objectives and sub-objectives for you
rank as follows:
Meet or Exceed Water Quality Standards and Guidelines 33%
Achieve Reliability 20%
Increase Diversity 20%
Increase Flexibility 13%
Maintain Affordability 7%
Address Environmental and Institutional Constraints 7%
The chart below shows the weights you have assigned by sub-objective
Percentage of All Matches
To be completed by CDM
33% 20% 7% 13% 20% 7%
1
Weighting Grid - Objectives
Meet or Exceed Water Quality Standards and Guidelines
Achieve Supply Reliability
6
5 Increase Supply Diversity
4
Address Environmental and Institutional Constraints
2
5
Increase System Flexibility
3 Maintain Affordability
3123 Number of Times Circled
(Total = 15)
20%
10%
3%
0%
10%
5% 5%5%
2%
13%
20%
1%1%
3%
1% 1%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
1a 1b 1c 1d 2a 2b 2c 3a 3b 4a 5a 6a 6b 6c 6d 6e
1 of 2
Otay Water District Integrated Water Resources Plan
Objective 1 - Meet or Exceed Water Quality Standards and Guidelines
Points Sub-objective
60 1a) Meet current and future drinking water standards
30 1b) Address compatibility of new sources with current imported supply
10 1c) Meet TDS goals for recycled water, potable water and Basin Plan
0 1d) Minimize potential issues due to disinfection method
Total Pts (Must equal 100)
Objective 2 - Achieve Reliability
Points Sub-objective
50 2a) Meet demands under normal conditions
25 2b) Meet demands under drought conditions
25 2c) Minimize impacts under emergency conditions
Total Pts (Must equal 100)
Objective 3 - Maintain Affordability
Points Sub-objectives
70 3a) Minimize impacts to an average single-family customer
30 3b) Manage capital costs
Total Pts 100 (Must equal 100)
Objective 4 - Increase Flexibility
Points Sub-objectives
100 4a) Increase number of take points and alternative flow routes
Total Pts 100 (Must equal 100)
Objective 5 - Increase Diversity
Points Sub-objectives
100 5a) Maximize number of sources and/or reduce contribution of largest source
Total Pts 100 (Must equal 100)
Objective 6 - Address Environmental and Institutional Constraints
Points Sub-objectives
20 6a) Minimize environmental permitting requirements
10 6b) Minimize institutional coordination and implementation requirements (local/State/Federal/International)
50 6c) Maximize customer acceptance
10 6d) Minimize regulatory constraints
10 6e) Minimize technology uncertainty
Total Pts 100 (Must equal 100)
Weighting - Sub-Objectives
2 of 2
Otay Water District Integrated Water Resources Plan
Name: Stakeholder 4
1
2
12
123
1234
12345
123456Objective Number
Objective/Sub-Objective Weighting Results
These results seem to indicate that the objectives and sub-objectives for you
rank as follows:
Achieve Reliability 33%
Meet or Exceed Water Quality Standards and Guidelines 27%
Maintain Affordability 20%
Increase Flexibility 13%
Increase Diversity 7%
Address Environmental and Institutional Constraints 0%
The chart below shows the weights you have assigned by sub-objective
4
Increase System Flexibility
3 Maintain Affordability
5321 Number of Times Circled
(Total = 15)
Weighting Grid - Objectives
Meet or Exceed Water Quality Standards and Guidelines
Achieve Supply Reliability
6
5 Increase Supply Diversity
4
Address Environmental and Institutional Constraints
2
Percentage of All Matches
To be completed by CDM
27% 33% 20% 13% 7% 0%
0
8%
4%
7%
8%
13%
10% 10%
14%
6%
13%
7%
0% 0% 0% 0% 0%0.00%
2.00%
4.00%
6.00%
8.00%
10.00%
12.00%
14.00%
16.00%
1a 1b 1c 1d 2a 2b 2c 3a 3b 4a 5a 6a 6b 6c 6d 6e
1 of 2
Otay Water District Integrated Water Resources Plan
Objective 1 - Meet or Exceed Water Quality Standards and Guidelines
Points Sub-objective
30 1a) Meet current and future drinking water standards
15 1b) Address compatibility of new sources with current imported supply
25 1c) Meet TDS goals for recycled water, potable water and Basin Plan
30 1d) Minimize potential issues due to disinfection method
Total Pts (Must equal 100)
Objective 2 - Achieve Reliability
Points Sub-objective
40 2a) Meet demands under normal conditions
30 2b) Meet demands under drought conditions
30 2c) Minimize impacts under emergency conditions
Total Pts (Must equal 100)
Objective 3 - Maintain Affordability
Points Sub-objectives
70 3a) Minimize impacts to an average single-family customer
30 3b) Manage capital costs
Total Pts 100 (Must equal 100)
Objective 4 - Increase Flexibility
Points Sub-objectives
100 4a) Increase number of take points and alternative flow routes
Total Pts 100 (Must equal 100)
Objective 5 - Increase Diversity
Points Sub-objectives
100 5a) Maximize number of sources and/or reduce contribution of largest source
Total Pts 100 (Must equal 100)
Objective 6 - Address Environmental and Institutional Constraints
Points Sub-objectives
10 6a) Minimize environmental permitting requirements
10 6b) Minimize institutional coordination and implementation requirements (local/State/Federal/International)
40 6c) Maximize customer acceptance
15 6d) Minimize regulatory constraints
25 6e) Minimize technology uncertainty
Total Pts 100 (Must equal 100)
Weighting - Sub-Objectives
2 of 2
Otay Water District Integrated Water Resources Plan
Name: Stakeholder 5
1
1
1
3
123
123
5
12345
123456Objective Number
Objective/Sub-Objective Weighting Results
These results seem to indicate that the objectives and sub-objectives for you
rank as follows:
Meet or Exceed Water Quality Standards and Guidelines 33%
Maintain Affordability 27%
Achieve Reliability 20%
Increase Diversity 13%
Increase Flexibility 7%
Address Environmental and Institutional Constraints 0%
The chart below shows the weights you have assigned by sub-objective
Percentage of All Matches
To be completed by CDM
33% 20% 27% 7% 13% 0%
0
Weighting Grid - Objectives
Meet or Exceed Water Quality Standards and Guidelines
Achieve Supply Reliability
6
5 Increase Supply Diversity
4
Address Environmental and Institutional Constraints
2
5
Increase System Flexibility
3 Maintain Affordability
3412 Number of Times Circled
(Total = 15)
17%
10%
3% 3%
10%
6%
4%
13% 13%
7%
13%
0% 0% 0% 0% 0%0.00%
2.00%
4.00%
6.00%
8.00%
10.00%
12.00%
14.00%
16.00%
18.00%
1a 1b 1c 1d 2a 2b 2c 3a 3b 4a 5a 6a 6b 6c 6d 6e
1 of 2
Otay Water District Integrated Water Resources Plan
Objective 1 - Meet or Exceed Water Quality Standards and Guidelines
Points Sub-objective
50 1a) Meet current and future drinking water standards
30 1b) Address compatibility of new sources with current imported supply
10 1c) Meet TDS goals for recycled water, potable water and Basin Plan
10 1d) Minimize potential issues due to disinfection method
Total Pts (Must equal 100)
Objective 2 - Achieve Reliability
Points Sub-objective
50 2a) Meet demands under normal conditions
30 2b) Meet demands under drought conditions
20 2c) Minimize impacts under emergency conditions
Total Pts (Must equal 100)
Objective 3 - Maintain Affordability
Points Sub-objectives
50 3a) Minimize impacts to an average single-family customer
50 3b) Manage capital costs
Total Pts 100 (Must equal 100)
Objective 4 - Increase Flexibility
Points Sub-objectives
100 4a) Increase number of take points and alternative flow routes
Total Pts 100 (Must equal 100)
Objective 5 - Increase Diversity
Points Sub-objectives
100 5a) Maximize number of sources and/or reduce contribution of largest source
Total Pts 100 (Must equal 100)
Objective 6 - Address Environmental and Institutional Constraints
Points Sub-objectives
20 6a) Minimize environmental permitting requirements
10 6b) Minimize institutional coordination and implementation requirements (local/State/Federal/International)
50 6c) Maximize customer acceptance
10 6d) Minimize regulatory constraints
10 6e) Minimize technology uncertainty
Total Pts 100 (Must equal 100)
Weighting - Sub-Objectives
2 of 2
Otay Water District Integrated Water Resources Plan
Name: Stakeholder 6
1
2
2
3
2
44
2
555
23 5
66
123456Objective Number
Objective/Sub-Objective Weighting Results
These results seem to indicate that the objectives and sub-objectives for you
rank as follows:
Achieve Reliability 33%
Increase Diversity 27%
Maintain Affordability 13%
Increase Flexibility 13%
Address Environmental and Institutional Constraints 13%
Meet or Exceed Water Quality Standards and Guidelines 0%
The chart below shows the weights you have assigned by sub-objective
Percentage of All Matches
To be completed by CDM
0% 33% 13% 13% 27% 13%
2
Weighting Grid - Objectives
Meet or Exceed Water Quality Standards and Guidelines
Achieve Reliability
6
5 Increase Diversity
4
Address Environmental and Institutional Constraints
2
0
Increase Flexibility
3 Maintain Affordability
5224 Number of Times Circled
(Total = 15)
0% 0% 0% 0%
3%
13%
17%
7% 7%
13%
27%
1%2%
7%
1%3%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
1a 1b 1c 1d 2a 2b 2c 3a 3b 4a 5a 6a 6b 6c 6d 6e
1 of 2
Otay Water District Integrated Water Resources Plan
Objective 1 - Meet or Exceed Water Quality Standards and Guidelines
Points Sub-objective
25 1a) Meet current and future drinking water standards
25 1b) Address compatibility of new sources with current imported supply
25 1c) Meet TDS goals for recycled water, potable water and Basin Plan
25 1d) Minimize potential issues due to disinfection method
Total Pts (Must equal 100)
Objective 2 - Achieve Reliability
Points Sub-objective
10 2a) Meet demands under normal conditions
40 2b) Meet demands under drought conditions
50 2c) Minimize impacts under emergency conditions
Total Pts (Must equal 100)
Objective 3 - Maintain Affordability
Points Sub-objectives
50 3a) Minimize impacts to an average single-family customer
50 3b) Manage capital costs
Total Pts 100 (Must equal 100)
Objective 4 - Increase Flexibility
Points Sub-objectives
100 4a) Increase system redundancy
Total Pts 100 (Must equal 100)
Objective 5 - Increase Diversity
Points Sub-objectives
100 5a) Maximize number of sources and/or reduce contribution of largest source
Total Pts 100 (Must equal 100)
Objective 6 - Address Environmental and Institutional Constraints
Points Sub-objectives
5 6a) Minimize environmental permitting requirements
15 6b) Minimize institutional coordination and implementation requirements (local/State/Federal/International)
50 6c) Maximize customer acceptance
10 6d) Minimize regulatory constraints
20 6e) Minimize technology uncertainty
Total Pts 100 (Must equal 100)
Weighting - Sub-Objectives
2 of 2
Otay Water District Integrated Water Resources Plan
Name: Stakeholder 7
1
1
1
3
123
13
55
12345
123456Objective Number
Objective/Sub-Objective Weighting Results
These results seem to indicate that the objectives and sub-objectives for you
rank as follows:
Meet or Exceed Water Quality Standards and Guidelines 33%
Maintain Affordability 27%
Increase Diversity 20%
Achieve Reliability 13%
Increase Flexibility 7%
Address Environmental and Institutional Constraints 0%
The chart below shows the weights you have assigned by sub-objective
5
Increase Flexibility
3 Maintain Affordability
2413 Number of Times Circled
(Total = 15)
Weighting Grid - Objectives
Meet or Exceed Water Quality Standards and Guidelines
Achieve Reliability
6
5 Increase Diversity
4
Address Environmental and Institutional Constraints
2
Percentage of All Matches
To be completed by CDM
33% 13% 27% 7% 20% 0%
0
20%
5% 5%
3%
8%
3% 3%
16%
11%
7%
20%
0% 0% 0% 0% 0%0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
1a 1b 1c 1d 2a 2b 2c 3a 3b 4a 5a 6a 6b 6c 6d 6e
1 of 2
Otay Water District Integrated Water Resources Plan
Objective 1 - Meet or Exceed Water Quality Standards and Guidelines
Points Sub-objective
60 1a) Meet current and future drinking water standards
15 1b) Address compatibility of new sources with current imported supply
15 1c) Meet TDS goals for recycled water, potable water and Basin Plan
10 1d) Minimize potential issues due to disinfection method
Total Pts 100 (Must equal 100)
Objective 2 - Achieve Reliability
Points Sub-objective
60 2a) Meet demands under normal conditions
20 2b) Meet demands under drought conditions
20 2c) Minimize impacts under emergency conditions
Total Pts 100 (Must equal 100)
Objective 3 - Maintain Affordability
Points Sub-objectives
60 3a) Minimize impacts to an average single-family customer
40 3b) Manage capital costs
Total Pts 100 (Must equal 100)
Objective 4 - Increase Flexibility
Points Sub-objectives
100 4a) Increase system redundancy
Total Pts 100 (Must equal 100)
Objective 5 - Increase Diversity
Points Sub-objectives
100 5a) Maximize number of sources and/or reduce contribution of largest source
Total Pts 100 (Must equal 100)
Objective 6 - Address Environmental and Institutional Constraints
Points Sub-objectives
25 6a) Minimize environmental permitting requirements
25 6b) Minimize institutional coordination and implementation requirements (local/State/Federal/International)
15 6c) Maximize customer acceptance
25 6d) Minimize regulatory constraints
10 6e) Minimize technology uncertainty
Total Pts 100 (Must equal 100)
Weighting - Sub-Objectives
2 of 2
Otay Water District Integrated Water Resources Plan
Name: Stakeholder 8
1
2
33
23
4
23
55
12345
123456Objective Number
Objective/Sub-Objective Weighting Results
These results seem to indicate that the objectives and sub-objectives for you
rank as follows:
Maintain Affordability 33%
Achieve Reliability 27%
Increase Diversity 20%
Increase Flexibility 13%
Meet or Exceed Water Quality Standards and Guidelines 7%
Address Environmental and Institutional Constraints 0%
The chart below shows the weights you have assigned by sub-objective
Percentage of All Matches
To be completed by CDM
7% 27% 33% 13% 20% 0%
0
Weighting Grid - Objectives
Meet or Exceed Water Quality Standards and Guidelines
Achieve Reliability
6
5 Increase Diversity
4
Address Environmental and Institutional Constraints
2
1
Increase Flexibility
3 Maintain Affordability
4523 Number of Times Circled
(Total = 15)
2%1%
3%
1%
8%
13%
5%
23%
10%
13%
20%
0% 0% 0% 0% 0%0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
1a 1b 1c 1d 2a 2b 2c 3a 3b 4a 5a 6a 6b 6c 6d 6e
1 of 2
Otay Water District Integrated Water Resources Plan
Objective 1 - Meet or Exceed Water Quality Standards and Guidelines
Points Sub-objective
30 1a) Meet current and future drinking water standards
10 1b) Address compatibility of new sources with current imported supply
50 1c) Meet TDS goals for recycled water, potable water and Basin Plan
10 1d) Minimize potential issues due to disinfection method
Total Pts 100 (Must equal 100)
Objective 2 - Achieve Reliability
Points Sub-objective
30 2a) Meet demands under normal conditions
50 2b) Meet demands under drought conditions
20 2c) Minimize impacts under emergency conditions
Total Pts 100 (Must equal 100)
Objective 3 - Maintain Affordability
Points Sub-objectives
70 3a) Minimize impacts to an average single-family customer
30 3b) Manage capital costs
Total Pts 100 (Must equal 100)
Objective 4 - Increase Flexibility
Points Sub-objectives
100 4a) Increase system redundancy
Total Pts 100 (Must equal 100)
Objective 5 - Increase Diversity
Points Sub-objectives
100 5a) Maximize number of sources and/or reduce contribution of largest source
Total Pts 100 (Must equal 100)
Objective 6 - Address Environmental and Institutional Constraints
Points Sub-objectives
20 6a) Minimize environmental permitting requirements
10 6b) Minimize institutional coordination and implementation requirements (local/State/Federal/International)
30 6c) Maximize customer acceptance
20 6d) Minimize regulatory constraints
20 6e) Minimize technology uncertainty
Total Pts 100 (Must equal 100)
Weighting - Sub-Objectives
2 of 2
Otay Water District Integrated Water Resources Plan
Name: Stakeholder 9
1
2
2
3
123
5555
23 5
66
123456Objective Number
Objective/Sub-Objective Weighting Results
These results seem to indicate that the objectives and sub-objectives for you
rank as follows:
Increase Diversity 33%
Achieve Reliability 27%
Maintain Affordability 20%
Address Environmental and Institutional Constraints 13%
Meet or Exceed Water Quality Standards and Guidelines 7%
Increase Flexibility 0%
The chart below shows the weights you have assigned by sub-objective
1
Increase Flexibility
3 Maintain Affordability
4305 Number of Times Circled
(Total = 15)
Weighting Grid - Objectives
Meet or Exceed Water Quality Standards and Guidelines
Achieve Reliability
6
5 Increase Diversity
4
Address Environmental and Institutional Constraints
2
Percentage of All Matches
To be completed by CDM
7% 27% 20% 0% 33% 13%
2
1%
3%
1% 1%0%
5%
21%
14%
6%
0%
33%
1%
4%
7%
1%1%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
35.00%
1a 1b 1c 1d 2a 2b 2c 3a 3b 4a 5a 6a 6b 6c 6d 6e
1 of 2
Otay Water District Integrated Water Resources Plan
Objective 1 - Meet or Exceed Water Quality Standards and Guidelines
Points Sub-objective
10 1a) Meet current and future drinking water standards
50 1b) Address compatibility of new sources with current imported supply
20 1c) Meet TDS goals for recycled water, potable water and Basin Plan
20 1d) Minimize potential issues due to disinfection method
Total Pts 100 (Must equal 100)
Objective 2 - Achieve Reliability
Points Sub-objective
0 2a) Meet demands under normal conditions
20 2b) Meet demands under drought conditions
80 2c) Minimize impacts under emergency conditions
Total Pts 100 (Must equal 100)
Objective 3 - Maintain Affordability
Points Sub-objectives
70 3a) Minimize impacts to an average single-family customer
30 3b) Manage capital costs
Total Pts 100 (Must equal 100)
Objective 4 - Increase Flexibility
Points Sub-objectives
100 4a) Increase system redundancy
Total Pts 100 (Must equal 100)
Objective 5 - Increase Diversity
Points Sub-objectives
100 5a) Maximize number of sources and/or reduce contribution of largest source
Total Pts 100 (Must equal 100)
Objective 6 - Address Environmental and Institutional Constraints
Points Sub-objectives
5 6a) Minimize environmental permitting requirements
30 6b) Minimize institutional coordination and implementation requirements (local/State/Federal/International)
50 6c) Maximize customer acceptance
10 6d) Minimize regulatory constraints
5 6e) Minimize technology uncertainty
Total Pts 100 (Must equal 100)
Weighting - Sub-Objectives
2 of 2
Otay Water District Integrated Water Resources Plan
Name: Stakeholder 10
1
2
2
3
444
5555
245
66
123456Objective Number
Objective/Sub-Objective Weighting Results
These results seem to indicate that the objectives and sub-objectives for you
rank as follows:
Increase Diversity 33%
Increase Flexibility 27%
Achieve Reliability 20%
Address Environmental and Institutional Constraints 13%
Maintain Affordability 7%
Meet or Exceed Water Quality Standards and Guidelines 0%
The chart below shows the weights you have assigned by sub-objective
Percentage of All Matches
To be completed by CDM
0% 20% 7% 27% 33% 13%
2
Weighting Grid - Objectives
Meet or Exceed Water Quality Standards and Guidelines
Achieve Reliability
6
5 Increase Diversity
4
Address Environmental and Institutional Constraints
2
0
Increase Flexibility
3 Maintain Affordability
3145 Number of Times Circled
(Total = 15)
0% 0% 0% 0%
14%
3% 3%2%
5%
27%
33%
4%
1%3% 3% 3%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
35.00%
1a 1b 1c 1d 2a 2b 2c 3a 3b 4a 5a 6a 6b 6c 6d 6e
1 of 2
Otay Water District Integrated Water Resources Plan
Objective 1 - Meet or Exceed Water Quality Standards and Guidelines
Points Sub-objective
10 1a) Meet current and future drinking water standards
80 1b) Address compatibility of new sources with current imported supply
5 1c) Meet TDS goals for recycled water, potable water and Basin Plan
5 1d) Minimize potential issues due to disinfection method
Total Pts 100 (Must equal 100)
Objective 2 - Achieve Reliability
Points Sub-objective
70 2a) Meet demands under normal conditions
15 2b) Meet demands under drought conditions
15 2c) Minimize impacts under emergency conditions
Total Pts 100 (Must equal 100)
Objective 3 - Maintain Affordability
Points Sub-objectives
30 3a) Minimize impacts to an average single-family customer
70 3b) Manage capital costs
Total Pts 100 (Must equal 100)
Objective 4 - Increase Flexibility
Points Sub-objectives
100 4a) Increase system redundancy
Total Pts 100 (Must equal 100)
Objective 5 - Increase Diversity
Points Sub-objectives
100 5a) Maximize number of sources and/or reduce contribution of largest source
Total Pts 100 (Must equal 100)
Objective 6 - Address Environmental and Institutional Constraints
Points Sub-objectives
30 6a) Minimize environmental permitting requirements
10 6b) Minimize institutional coordination and implementation requirements (local/State/Federal/International)
20 6c) Maximize customer acceptance
20 6d) Minimize regulatory constraints
20 6e) Minimize technology uncertainty
Total Pts 100 (Must equal 100)
Weighting - Sub-Objectives
2 of 2
Otay Water District Integrated Water Resources Plan
Name: Stakeholder 11
1
1
12
12
4
12 4
5
12 4 6
66
123456Objective Number
Objective/Sub-Objective Weighting Results
These results seem to indicate that the objectives and sub-objectives for you
rank as follows:
Meet or Exceed Water Quality Standards and Guidelines 33%
Achieve Reliability 27%
Increase Flexibility 20%
Address Environmental and Institutional Constraints 13%
Increase Diversity 7%
Maintain Affordability 0%
The chart below shows the weights you have assigned by sub-objective
031 Number of Times Circled
(Total = 15)
Weighting Grid - Objectives
Meet or Exceed Water Quality Standards and Guidelines
Achieve Reliability
5 Increase Diversity
4 Increase Flexibility
3 Maintain Affordability
Address Environmental and Institutional Constraints
2
Percentage of All Matches
To be completed by CDM
33% 27% 0% 20% 7% 13%
254
20%
7%
0%
7%
9% 9% 9%
0% 0%
20%
7%
0%
7%
0% 0%
7%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
1a 1b 1c 1d 2a 2b 2c 3a 3b 4a 5a 6a 6b 6c 6d 6e
1 of 2
Otay Water District Integrated Water Resources Plan
Objective 1 - Meet or Exceed Water Quality Standards and Guidelines
Points Sub-objective
60 1a) Meet current and future drinking water standards
20 1b) Address compatibility of new sources with current imported supply
0 1c) Meet TDS goals for recycled water, potable water and Basin Plan
20 1d) Minimize potential issues due to disinfection method
Total Pts 100 (Must equal 100)
Objective 2 - Achieve Reliability
Points Sub-objective
33.333 2a) Meet demands under normal conditions
33.333 2b) Meet demands under drought conditions
33.333 2c) Minimize impacts under emergency conditions
Total Pts 100 (Must equal 100)
Objective 3 - Maintain Affordability
Points Sub-objectives
80 3a) Minimize impacts to an average single-family customer
20 3b) Manage capital costs
Total Pts 100 (Must equal 100)
Objective 4 - Increase Flexibility
Points Sub-objectives
100 4a) Increase system redundancy
Total Pts 100 (Must equal 100)
Objective 5 - Increase Diversity
Points Sub-objectives
100 5a) Maximize number of sources and/or reduce contribution of largest source
Total Pts 100 (Must equal 100)
Objective 6 - Address Environmental and Institutional Constraints
Points Sub-objectives
0 6a) Minimize environmental permitting requirements
50 6b) Minimize institutional coordination and implementation requirements (local/State/Federal/International)
0 6c) Maximize customer acceptance
0 6d) Minimize regulatory constraints
50 6e) Minimize technology uncertainty
Total Pts 100 (Must equal 100)
Weighting - Sub-Objectives
2 of 2
Otay Water District Integrated Water Resources Plan
Name: Stakeholder 12
1
2
2
3
12
4
12
55
1234
6
123456Objective Number
Objective/Sub-Objective Weighting Results
These results seem to indicate that the objectives and sub-objectives for you
rank as follows:
Achieve Reliability 33%
Meet or Exceed Water Quality Standards and Guidelines 20%
Maintain Affordability 13%
Increase Flexibility 13%
Increase Diversity 13%
Address Environmental and Institutional Constraints 7%
The chart below shows the weights you have assigned by sub-objective
3
Increase Flexibility
3 Maintain Affordability
5222 Number of Times Circled
(Total = 15)
Weighting Grid - Objectives
Meet or Exceed Water Quality Standards and Guidelines
Achieve Reliability
6
5 Increase Diversity
4
Address Environmental and Institutional Constraints
2
Percentage of All Matches
To be completed by CDM
20% 33% 13% 13% 13% 7%
1
4%
8%
6%
2%
10%
20%
3%
5%
8%
13% 13%
1% 1% 1% 1% 1%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
1a 1b 1c 1d 2a 2b 2c 3a 3b 4a 5a 6a 6b 6c 6d 6e
1 of 2
Otay Water District Integrated Water Resources Plan
Objective 1 - Meet or Exceed Water Quality Standards and Guidelines
Points Sub-objective
20 1a) Meet current and future drinking water standards
40 1b) Address compatibility of new sources with current imported supply
30 1c) Meet TDS goals for recycled water, potable water and Basin Plan
10 1d) Minimize potential issues due to disinfection method
Total Pts 100 (Must equal 100)
Objective 2 - Achieve Reliability
Points Sub-objective
30 2a) Meet demands under normal conditions
60 2b) Meet demands under drought conditions
10 2c) Minimize impacts under emergency conditions
Total Pts 100 (Must equal 100)
Objective 3 - Maintain Affordability
Points Sub-objectives
40 3a) Minimize impacts to an average single-family customer
60 3b) Manage capital costs
Total Pts 100 (Must equal 100)
Objective 4 - Increase Flexibility
Points Sub-objectives
100 4a) Increase system redundancy
Total Pts 100 (Must equal 100)
Objective 5 - Increase Diversity
Points Sub-objectives
100 5a) Maximize number of sources and/or reduce contribution of largest source
Total Pts 100 (Must equal 100)
Objective 6 - Address Environmental and Institutional Constraints
Points Sub-objectives
20 6a) Minimize environmental permitting requirements
20 6b) Minimize institutional coordination and implementation requirements (local/State/Federal/International)
20 6c) Maximize customer acceptance
20 6d) Minimize regulatory constraints
20 6e) Minimize technology uncertainty
Total Pts 100 (Must equal 100)
Weighting - Sub-Objectives
2 of 2
Otay Water District Integrated Water Resources Plan
Name: Stakeholder 13
1
1
33
123
123
5
123
66
123456Objective Number
Objective/Sub-Objective Weighting Results
These results seem to indicate that the objectives and sub-objectives for you
rank as follows:
Maintain Affordability 33%
Meet or Exceed Water Quality Standards and Guidelines 27%
Achieve Reliability 20%
Address Environmental and Institutional Constraints 13%
Increase Diversity 7%
Increase Flexibility 0%
The chart below shows the weights you have assigned by sub-objective
Percentage of All Matches
To be completed by CDM
27% 20% 33% 0% 7% 13%
2
Weighting Grid - Objectives
Meet or Exceed Water Quality Standards and Guidelines
Achieve Reliability
6
5 Increase Diversity
4
Address Environmental and Institutional Constraints
2
4
Increase Flexibility
3 Maintain Affordability
3501 Number of Times Circled
(Total = 15)
7% 7% 7% 7%
12%
2%
6%
17% 17%
0%
7%
3%
1%
7%
1% 1%
0.00%
2.00%
4.00%
6.00%
8.00%
10.00%
12.00%
14.00%
16.00%
18.00%
1a 1b 1c 1d 2a 2b 2c 3a 3b 4a 5a 6a 6b 6c 6d 6e
1 of 2
Otay Water District Integrated Water Resources Plan
Objective 1 - Meet or Exceed Water Quality Standards and Guidelines
Points Sub-objective
25 1a) Meet current and future drinking water standards
25 1b) Address compatibility of new sources with current imported supply
25 1c) Meet TDS goals for recycled water, potable water and Basin Plan
25 1d) Minimize potential issues due to disinfection method
Total Pts 100 (Must equal 100)
Objective 2 - Achieve Reliability
Points Sub-objective
60 2a) Meet demands under normal conditions
10 2b) Meet demands under drought conditions
30 2c) Minimize impacts under emergency conditions
Total Pts 100 (Must equal 100)
Objective 3 - Maintain Affordability
Points Sub-objectives
50 3a) Minimize impacts to an average single-family customer
50 3b) Manage capital costs
Total Pts 100 (Must equal 100)
Objective 4 - Increase Flexibility
Points Sub-objectives
100 4a) Increase system redundancy
Total Pts 100 (Must equal 100)
Objective 5 - Increase Diversity
Points Sub-objectives
100 5a) Maximize number of sources and/or reduce contribution of largest source
Total Pts 100 (Must equal 100)
Objective 6 - Address Environmental and Institutional Constraints
Points Sub-objectives
20 6a) Minimize environmental permitting requirements
10 6b) Minimize institutional coordination and implementation requirements (local/State/Federal/International)
50 6c) Maximize customer acceptance
10 6d) Minimize regulatory constraints
10 6e) Minimize technology uncertainty
Total Pts 100 (Must equal 100)
Weighting - Sub-Objectives
2 of 2
Appendix B
Supply Options Rating and Schematics
1 TDS values shown are not predictive. They are for comparison purposes only. On average, current TDS levels from the Combined Skinner Plants and the Helix Levy WTP are 501 mg/L and 435 mg/L, respectively, per the 2006 OWD Consumer Confidence Report.
According to OWD staff members, TDS levels have ranged up to 650 mg/l periodically. 2 TDS values are those assumed after treatment, i.e. the TDS value of water supplied to the OWD distribution system from each source.
3 Qualitative Scale of 1-5, with 1 being the worst and 5 being the best. 4 All costs are in current dollars. N/A Not applicable. Qualitative scores were only applied to new supply options.
Table B-1 Supply Options Rating
Supply Source Description Water Quality Yield Affordability/Cost4 Environmental/ Institutional Scores3
TDS1,2
[mg/L]
Compat.
Score3
DBP
Score3 [AFY]
TC = Total Capital,
OM = operation./ maint.
IW = Imported Purchases
UN= unit (per acre-ft) Permitting Institut.
Coord.
Customer
Acceptance
Regulatory
Constraints
Technolog.
Uncertainty
I. Existing Supply
Ia. Imported
SDCWA Pipeline # 4
Turnout #11 (40 MGD) supplies the North Xystem.
Turnouts #10 (18 MGD) and #12 (40 MGD) supply the
Central System.
Turnout #13 (26 MGD) supplies the Otay Mesa System.
(OWD, 2002 Figure 5-1)
492 N/A N/A
Up to capacity of
existing
turnouts.
UN = $545 /AF N/A N/A N/A N/A N/A
City of San Diego’s Otay WTP
The current effective capacity of the Otay WTP is 34
MGD, of which the City of San Diego’s typical demand
is 20 MGD. OWD has an agreement with the City of
San Diego for 10 MGD from the Otay WTP. Water is
supplied to the Otay Mesa and Central systems via a
temporary pump station with a capacity ranging
between 6-21 MGD. Current operations typically
provide up to 8 MGD in summer months and 10 MGD
in winter months to OWD.
(OWD, 2002 pg. 1-5)
492 N/A N/A 11,200 AFY
UN = $535 /AF
Two payments: one for
SDCWA raw water
($420/AF); the other for
treatment ($115/AF)
N/A N/A N/A N/A N/A
Helix’s Levy WTP
The Levy WTP supplies water to the North System. SDCWA
is obligated to provide 12 MGD on-peak, and up to 16 MGD
off-peak to OWD through a new pipeline that will replace the
LMSE and expected to be operational by 2010.
(Helix Agreement)
492 N/A N/A
13,440 AFY
base load.
Minimum of
10,000 AFY.
UN = $545 /AF N/A N/A N/A N/A N/A
Ib. Recycled
OWD’s Chapman WRP
Recycled water supply is pumped to the Central system. The
Chapman WRP capacity is approximately 1.1 MGD.
(OWD, 2002 pg. 11-3)
990 N/A N/A 1230 AFY Fixed OM: $700,000/year
Variable OM: $250/AF N/A N/A N/A N/A N/A
City of San Diego’s South Bay WRP
OWD has a contract to receive at least 6 MGD from the
SBWRP. The capacity of the SBWRP is 15 MGD.
(SBWRP Agreement)
990 N/A N/A 6,720 AFY $595/AF N/A N/A N/A N/A N/A
II. Potential Supply Options
IIa. Additional Imported/Local
Treatment Agreements
Helix’s Levy WTP
Obtain additional 4 MGD water rights, beyond the current 12
MGD, to supply North District.
Assume LMSE can be used for conveyance in this option.
492 5 3 4,480 AFY
TC = $12,227,000
OM =$0/year
IWP= $2,442,000/year
UN = $744 /AF
4 4 5 5 5
Sweetwater Authority’s Perdue WTP
Obtain 4 MGD water rights to supply North System.
SDCWA Pipeline No. 3 supplies raw water to Perdue WTP.
OWD would pump water from Perdue WTP into the existing
North District 36 inch transmission main via a new pump
station and 24 inch pipeline (OWD 2002 p 8-3)
492 5 3 4,480 AFY
TC = $16,233,000
OM =$872,000/year
IWP=$1,882,000/year
UN = $878 /AF
4 4 5 5 5
City of San Diego’s Otay WTP
Contribute to expansion of the Otay WTP to 60 MGD
capacity, and gain an additional 20 MGD of water rights to
supply Otay Mesa and Central systems. A permanent pump
station is planned for conveyance, which will have a capacity
of 30 MGD.
(OWD, 2002 pg. 1-5,6)
492 5 3 22,400 AFY
TC = $49,001,000
OM =$2,576,000/year
IWP=$9,409,000/year
UN = $694 /AF
4 4 5 5 5
1 TDS values shown are not predictive. They are for comparison purposes only. On average, current TDS levels from the Combined Skinner Plants and the Helix Levy WTP are 501 mg/L and 435 mg/L, respectively, per the 2006 OWD Consumer Confidence Report.
According to OWD staff members, TDS levels have ranged up to 650 mg/l periodically. 2 TDS values are those assumed after treatment, i.e. the TDS value of water supplied to the OWD distribution system from each source.
3 Qualitative Scale of 1-5, with 1 being the worst and 5 being the best. 4 All costs are in current dollars. N/A Not applicable. Qualitative scores were only applied to new supply options.
Table B-1 Supply Options Rating
Supply Source Description Water Quality Yield Affordability/Cost4 Environmental/ Institutional Scores3
TDS3,4
[mg/L]
Compat.
Score3
DBP
Score3 [AFY]
TC = Total Capital,
OM = operation./ maint.
IW = Imported Purchases
UN= unit (per acre-ft)
Permitting Institut.
Coord.
Customer
Acceptance
Regulatory
Constraints
Technolog.
Uncertainty
SD17Agreement with City of San
Diego to treat raw SDCWA water at
Alvarado WTP
Raw water purchased from SDCWA would be treated at
Alvarado WTP through an agreement with the City of San
Diego. Treated water would be delivered via SDCWA
Pipeline No. 4.
492 5 3 33,600AFY
TC = $82,445,000
OM =$4,537,000/year
IWP=$14,114,000/year
UN = $733 /AF
4 4 5 4 5
Imported Water from Pipeline No. 4 Buy filtered water from SDCWA to meet demands
throughout the District’s service area. 492 5 3
Up to capacity of
existing
turnouts.
See Imported Water
Projected Rate Schedule
Section 5
4 4 5 5 5
IIb. Additional Non-potable
Imported Water from Pipeline No. 3 Buy raw water from SDCWA to meet irrigation demands in
the Central System. 492 3 5 2,800 AFY
TC = $2,438,000
IWP =$1,476,000/year
UN = $590 /AF
5 4 5 4 5
Spring Valley Stripping Plant
OWD would construct a 5 MGD stripping plant along the
Spring Valley sewer trunk upstream of the Point Loma
WWTP, to alleviate the existing capacity limitation. This is
not in conjunction with the City of Chula Vista’s plan for a
stripping plant.
990 5 3 5,600 AFY
TC = $63,900,000
OM =$1,600,000/year
UN = $1,117 /AF
2 4 5 3 4
Chula Vista Stripping Plant
OWD would obtain effluent rights to the City of Chula
Vista’s proposed stripping plant along the Spring Valley
trunk sewer.
990 5 3 5,600 AFY
TC = $12,480,000
OM =$3,328,750/year
UN = $756 /AF
2 4 5 3 4
City of San Diego’s South Bay WRP
Additional purchases only Obtain up to 4 MGD additional delivery of SBWRP effluent. 990 5 3 4,480 AFY
Purchases Only:
TC = $2,412,000
OM =$2,663,000/year
UN = $633 /AF
5 4 5 5 5
City of San Diego’s South Bay WRP
Plant Expansion
Contribute funds to the expansion of SBWRP, to receive an
additional 4 MGD of effluent. 990 5 3 4,480 AFY
TC = $40,000,000
OM =$2,190,000/year
UN = $1,137 /AF
3 4 5 3 5
North District Recycled Water Concept
Create up to 1 MGD of recycled water demands in North
District, which would be served by the OWD Chapman WRP.
This would reduce conveyance costs that are currently
incurred by pumping effluent from the Chapman WRP to the
Central system. Current demands met by the Chapman WRP
in the Central system would need to be satisfied by another
supply option.
990 5 5
Shift 1230 AFY
supply from
Central to North.
TC = $7,920,000
OM =$301,125/year
UN = $711 /AF
4 3 4 3 5
Expansion of Chapman WRP and
sewer collection system (RWCWRP)
Expand plant from 1.1 to 2.6 MGD capacity, and ultimately
3.9 MGD capacity. 990 5 5
2,910 AFY
(phase I)
4,370 AFY
(phase II)
TC = $30,500,000
OM =$801,750/year
UN = $1,036 /AF
4 5 4 4 5
Chapman or SVSP effluent bypassing
Sweetwater Reservoir with in-lieu
exchange
(This option was not evaluated in model.)
XX XX XX XX XX XX XX XX XX XX XX
1 TDS values shown are not predictive. They are for comparison purposes only. On average, current TDS levels from the Combined Skinner Plants and the Helix Levy WTP are 501 mg/L and 435 mg/L, respectively, per the 2006 OWD Consumer Confidence Report.
According to OWD staff members, TDS levels have ranged up to 650 mg/l periodically. 2 TDS values are those assumed after treatment, i.e. the TDS value of water supplied to the OWD distribution system from each source.
3 Qualitative Scale of 1-5, with 1 being the worst and 5 being the best. 4 All costs are in current dollars. N/A Not applicable. Qualitative scores were only applied to new supply options.
Table B-1 Supply Options Rating
Supply Source Description Water Quality Yield Affordability/Cost4 Environmental/ Institutional Scores3
TDS5,6
[mg/L]
Compat.
Score3
DBP
Score3 [AFY]
TC = Total Capital,
OM = operation./ maint.
IW = Imported Purchases
UN= unit (per acre-ft)
Permitting Institut.
Coord.
Customer
Acceptance
Regulatory
Constraints
Technolog.
Uncertainty
IIIc. Groundwater
Middle Sweetwater
Conjunctive use of basin for drought groundwater storage.
Recharge imported raw water purchased from SDCWA in
wetter years. Extract groundwater in drier years.
492 4 5 5,000 AFY –
(over 6 months)
w/ LMSE
TC = $44,950,000
OM =$2,655,000/year
IWP = $2,100,000/year
UN = $1,184 /AF
No LMSE
TC = $62,200,000
OM =$3,300,,000/year
IWP = $2,400,000/year
UN = $1,600 /AF
3 3 4 3 3
Lower Sweetwater Brackish groundwater demineralization. 200 3 5
1,275 AFY
(assumes 85%
plant efficiency)
TC = $11,250,000
OM =$942,000/year
UN = $1,184 /AF
2 3 4 3 3
Santee/ El Monte Conjunctive Use
Conjunctive use of basin for drought groundwater storage.
Recharge imported raw water purchased from SDCWA in
wetter years. Extract groundwater in drier years.
492 4 5 5,000 AFY
(over 6 months)
w/ LMSE
TC = $41,950,000
OM =$2,675,000/year
IWP = $2,100,000/year
UN = $1,145 /AF
No LMSE
TC = $64,000,000
OM =$3,160,000/year
IWP = $2,100,000/year
UN = $1,562 /AF
3 3 4 3 3
Santee/El Monte Brackish
Groundwater Demineralization
Brackish groundwater demineralization.
200 3 5
4,250 AFY
(assumes 85%
plant efficiency)
w/ LMSE
TC = $32,390,000
OM =$2,863,000/year
UN = $688 /AF
No LMSE
TC = $63,702,000
OM =$3,593,000/year
UN = $1,084 /AF
2 3 4 3 3
San Diego Formation Brackish
Groundwater Demineralization
Brackish groundwater demineralization.
200 3 5
2,175 AFY
(assumes 85%
plant efficiency)
TC = $22,525,000
OM =$1,679,000/year
UN = $1,362 /AF
2 3 4 3 3
Otay Mountain Well for Recycled Use Minimum yield of 1000 gpm (1,612 AFY) ,
per Agreement between OWD and D&D Landholdings. 200 3 5 1,612 AFY TC = $12,380,000
OM =$970,000/year
UN = $1,364 /AF
3 4 4 3 3
Tijuana River Valley Aquifer
Reclaimed Water Storage And
Recovery
(This option was not evaluated in model)
XX XX XX XX XX XX XX XX XX XX XX
New well NE of Otay Mesa Yard Well
(This option was not evaluated in model) XX XX XX XX XX XX XX XX XX XX XX
1 TDS values shown are not predictive. They are for comparison purposes only. On average, current TDS levels from the Combined Skinner Plants and the Helix Levy WTP are 501 mg/L and 435 mg/L, respectively, per the 2006 OWD Consumer Confidence Report.
According to OWD staff members, TDS levels have ranged up to 650 mg/l periodically. 2 TDS values are those assumed after treatment, i.e. the TDS value of water supplied to the OWD distribution system from each source.
3 Qualitative Scale of 1-5, with 1 being the worst and 5 being the best. 4 All costs are in current dollars. N/A Not applicable. Qualitative scores were only applied to new supply options.
References
OWD. 2005. Urban Water Management Plan.
OWD. 2002. Water Resources Master Plan.
“Helix Agreement.” 2005. Agreement between the San Diego County Water Authority and Otay Water district Regarding Implementation of the East County Regional Treated Water Improvement Program.
“SBWRP Agreement.” 2003. Agreement between the Otay Water District and the City of San Diego for Purchase of Reclaimed Water from the South Bay Water Reclamation Plant.
Table B-1 Supply Options Rating
Supply Source Description Water Quality Yield Affordability/Cost4 Environmental/ Institutional Scores3
TDS7,8
[mg/L]
Compat.
Score3
DBP
Score3 [AFY]
TC = Total Capital,
OM = operation./ maint.
IW = Imported Purchases
UN= unit (per acre-ft)
Permitting Institut.
Coord.
Customer
Acceptance
Regulatory
Constraints
Technolog.
Uncertainty
Rancho Del Rey Well
(This option was not evaluated in model) XX XX XX XX XX XX XX XX XX XX XX
Daley Ranch Well (North District)
((This option was not evaluated in model) XX XX XX XX XX XX XX XX XX XX XX
IIId. Ocean Desalination
Poseidon’s Carlsbad Seawater
Desalination Project (in lieu)
OWD to participate in regional desalination project.
Purchase water from Poseidon Resources desal plant to be
delivered “in lieu” as SDCWA water through Pipeline No. 4.
492 3 3 11,200 AFY UN = $1,300/AF 5 2 5 4 5
Southern California Partnership:
Sweetwater/City of SD’s South Bay
project next to power plant
OWD to participate in regional desalination project.
Contribute funds for capacity at South Bay desal plant.
Conveyance infrastructure required. Varying degrees of
participation possible – 20 MGD assumed here.
200 3 5
Varies
22,400 AFY
11,200 AFY
or
5,600 AFY
20 MGD
TC = $186,164,400
OM =$49,185,000/year
UN = $2,800 /AF
10 MGD
TC = $98,509,600
OM =$24,700,076/year
UN = $2,850 /AF
5 MGD
TC = $55,307,200
OM =$12,460,038/year
UN = $2,950 /AF
1 3 4 2 4
Binational Partnership: Rosarito
Financial Partnership with In-lieu
Colorado River water
OWD to contribute funds for capacity at Rosarito
desalination plant. Ocean water would be treated and used
locally in Rosarito. OWD would be provided with in lieu
water from Mexican allocation of Colorado River water.
492 3 3 5,600 AFY
TC = $36,349,000
OM =$4,865,555/year
UN = $897 /AF
3 2 4 4 5
Binational Partnership: Rosarito Joint
Facility
(This option was not evaluated in model)
XX XX XX XX XX XX XX XX XX XX XX
Southern California Partnership:
Sweetwater/City of SD Otay River
ocean wells
(This option was not evaluated)
XX XX XX XX XX XX XX XX XX XX XX
IIIe. Conservation
Reduce long-term urban water demands by reducing
consumption, providing incentives for consumers,
establishing education/information programs, and
addressing conservation at institutional/managerial levels.
200 5 5
See Water
Conservation
Section 5.1
See Water Conservation
Cost Schedule
Section 5.1
5 5 3 5 4
IIIf. Water Transfers/Banking Long term water exchanges during dry years.
North of Delta Banking Least expensive, yet potentially unreliable due to conveyance
through environmentally sensitive Bay-Delta. 492 5 3 5,000 AFY 5 3 5 5 5
Central Valley Groundwater Generally more expensive, but also more reliable. Exchange
water available from agricultural programs. 492 5 3 Up to 15,000 AFY 4 3 5 5 5
Land Fallowing Annual availability of agricultural water rights for other uses.
Generally reliable, but OWD would not have priority access. 492 5 3 Up to 15,000 AFY
See Imported Water
Projected Rate Schedule
Section 5
3 3 5 5 5
Central
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
Chapman WRP
#11
Helix WTP
SD
C
W
A
P
L
#
4
(
F
i
l
t
e
r
e
d
)
Reservoirs
#10
#12
#13
SD
C
W
A
P
L
#
3
(
R
a
w
)
Tijuana Emergency
Interconnect
(Federal Treaty Water)
Not in model
City of SD
Otay WTP
SDCWA 1st Aqueduct (Raw )Groundwater Resources Options
Existing (in model) Potable Facilities
Existing (in model) Raw/Recycled Facilities
Proposed Facilities
Expanded Use of Existing Facilities
Santee/ El Monte
Basin Demin Plant
San Vicente
Reservoir
Options:
1. Middle Sweetwater Conjunctive Use
2. Lower Sweetwater Brackish GW Demineralization
3. Santee/El Monte Conjunctive Use
4. Santee/El Monte Brackish GW Desal
5. (eliminated)
6. (eliminated)
7. San Diego Formation Brackish GW Desal
8. Otay Mountain Well
9. (eliminated)
10. (eliminated)
11. (eliminated)
Middle Sweetwater
Basin
Lower Sweetwater
BasinRO Plant
Well
San Diego
Formation
Demin Plant
1
2
3
3
4
7
8
Imported Raw
Water for
Recharge
Central
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
Chapman WRP
#11
Helix WTP
SD
C
W
A
P
L
#
4
(
F
i
l
t
e
r
e
d
)
Reservoirs
#10
#12
#13
SD
C
W
A
P
L
#
3
(
R
a
w
)
Tijuana Emergency Interconnect (Federal Treaty Water)
Not in model
City of SD
Otay WTP
SDCWA 1st Aqueduct (Raw )
Existing (in model) Potable Facilities
Existing (in model) Raw/Recycled Facilities
Proposed Facilities
Expanded Use of Existing Facilities
Additional Imported Water Options
Options:
1. Expansion of Capacity Rights from Helix WD’s Levy WTP
2. Expand Capacity at Sweetwater Authority’s Perdue WTP
3. Expand City of San Diego’s Otay WTP
4. Imported Water from Pipeline No. 3 (Raw)
5. Imported Water from Pipeline No. 4 (Treated)
6. Agreement with City of San Diego to treat imported
water at Alvarado WTP
Perdue WTP
1
2
3
4
5,6
5,6
5,6
5,6
Central
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
Chapman WRP
#11
Helix WTP
SD
C
W
A
P
L
#
4
(
F
i
l
t
e
r
e
d
)
Reservoirs
#10
#12
#13
SD
C
W
A
P
L
#
3
(
R
a
w
)
Tijuana Emergency Interconnect (Federal Treaty Water)
Not in model
City of SD
Otay WTP
SDCWA 1st Aqueduct (Raw )Ocean Desalination Options
Existing (in model) Potable Facilities
Existing (in model) Raw/Recycled Facilities
Proposed Facilities
Expanded Use of Existing Facilities
Options:
1. Poseidon Desal Plant (In-lieu)
2. Binational Partnership: Rosarito Desal Plant in-lieu Colorado
River water
3. Southern California Partnership (Sweetwater/City of SD’s
South Bay project)
1,2
1,2
1,2
1,2
Desal Plant
3
Central
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
Chapman WRP
#11
Helix WTP
SD
C
W
A
P
L
#
4
(
F
i
l
t
e
r
e
d
)
Reservoirs
(p u m pe d t o C e nt ra l)#10
#12
#13
SD
C
W
A
P
L
#
3
(
R
a
w
)
Assume sufficient
capacity to meet
Otay Mesa project
recycled demands
Tijuana Emergency Interconnect (Federal Treaty Water)
Not in model
City of SD
Otay WTP
Assume sufficient
capacity for 18+
mgd
SDCWA 1st Aqueduct (Raw )
Options:
1. Stripping Plant
2. Additional Effluent from South Bay WRP
3. North District Recycled Water Concept
4. Expansion of Chapman WRP
Additional Reclaimed Water
Existing (in model) Potable Facilities
Existing (in model) Raw/Recycled Facilities
Proposed Facilities
Expanded Use of Existing Facilities
Stripping Plant
1
2
1.1 m
gd3
4
Appendix C
Supply Option Cost Estimates
A C-1
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Appendix C
Supply Option Cost Estimates
Planning level cost estimates were developed for all of the supply options considered
in the IRP. For each option, the costs of major infrastructure and facilities components
were estimated, including: conveyance (pipelines, pumping), storage, treatment and
waste disposal, and service connections and meters. Additionally, operational costs
were estimated, including: imported water purchases, energy costs, and capacity fees.
In the sections that follow, the major facilities and infrastructure required for the
supply options are tabulated with their respective capital and annual O&M costs.
Relevant notes concerning the specific cost estimates are also included.
The cost estimates for other options were developed using recent experience with
similar projects for the given facility or piece of infrastructure (i.e. pipelines, pump
stations, RO plants, ocean outfalls, etc.). Table C-1 shows a list of the major unit cost
assumptions used in the estimates.
Table C-1
Per unit Cost Assumptions
Capital Cost Assumptions
$20 per inch diameter, per foot of pipe (loaded)
$2,500 per horsepower capacity
$3 per gal per day of brackish groundwater RO treatment (loaded)
$6 per gal per day of ocean RO desalination treatment (loaded)
$750,000 per new extraction well (excluding site acquisition costs)
$1,435 per meter of ocean outfall line
$700,000 per acre for land acquisition
85% Efficiency of RO treatment for brackish groundwater desalination
50% Efficiency of RO treatment for ocean desalination
O&M Cost Assumptions
2% of Capital cost for pipe maintenance
2% of Capital cost for pump maintenance
$0.11 per kw-hr pumping costs
$400 per AFY of brackish groundwater RO treatment (loaded)
$850 per AFY of ocean RO desalination treatment (loaded)
$725,000 per MG (operating cost for brine discharge)
Option Unit Cost Calculation
The unit cost (dollar per acre-foot) was calculated for each option, which incorporates
both capital and operation and maintenance (O&M) costs. The method used to
calculate option unit cost differs from the method later discussed in Section 7 to
calculate portfolio unit cost. For portfolios, several options are used in conjunction
with each other to meet future increasing demands, and a particular option may not
necessarily be used to its full capacity at all times. In order to account for varying use
of options over time, the unit cost of the portfolios was calculated assuming the net
present value of incremental costs of new water over the entire planning horizon.
Appendix C
Supply Option Cost Estimates
C-2 A
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For options, in order to compare them independently for portfolio development, the
unit cost is calculated based on the entire potential yield of the option. Also, the
operation and maintenance in today’s dollars was used, rather than inflating the
O&M costs over time. The option capital cost was amortized at a 6% interest rate,
assuming a payment period of 30 years. The total annual cost (capital and O&M) was
then divided by the option’s potential annual yield to calculate the unit cost in dollars
per acre-foot.
Imported Water Costs
See Section 5 for a discussion on imported water costs.
C.1 Conservation of Water
See discussion in Section C.1.
C.2 Groundwater Options
C.2.1 Middle Sweetwater Conjunctive Use
The La Mesa Sweetwater Extension (LMSE) is a pipeline that runs from Helix Water
District’s Levy WTP through OWD’s North District and to the Sweetwater Reservoir.
Currently the LMSE delivers potable water from the Levy plant to OWD as an
alternative source when Pipeline No. 4 is out of service. In the future, the LMSE may
become available for use with other supply options, including: Middle Sweetwater
and Santee/El Monte.
Assuming the use of the LMSE to convey water for groundwater recharge, the total
capital cost of this option is estimated at $44,950,000, and the annual operation and
maintenance costs are approximately $2,655,000/year. The unit cost of this option is
$1,184/AF.
If the LMSE is not available for use, additional conveyance infrastructure would be
required to bring raw water from the SDCWA Pipeline No. 3 to the basin for recharge.
In this case, the total capital cost of this option is estimated at $65,187,000, and the
annual operation and maintenance costs are approximately $3,307,400/year. The unit
cost of this option is $1,609/AF.
The capital and O&M components of the options with and without use of the LMSE
are presented in Table C-2 and Table C-3.
Appendix C
Supply Option Cost Estimates
A C-3
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Table C-2
Cost Summary: Middle Sweetwater Conjunctive Use (with LMSE)
unit description Capital [$] O&M [$/yr]
Conjuctive Use
Conveyance to Middle Sweetwater Basin 16,000 ft of 24 in pipe $7,680,000 $150,000
Infiltration Basins 2 basins, 40 acres $1,480,000 $30,000
Extraction
Extraction Wells 6 @ 1,000 gpm $4,500,000 $210,000
Conveyance of Recovered Water 2,500 ft of 22 in pipe; 300 HP pump $1,850,000 $125,000
Monitoring Wells 2 @ 4 in dia. $40,000 $40,000
Land Acquisition 42 acres $29,400,000
Cost of Imported Water 5,000 AFY $2,100,000
TOTAL $44,950,000 $2,655,000
Table C-3
Cost Summary: Middle Sweetwater Conjunctive Use (No LMSE)
unit description Capital [$] O&M [$/yr]
Conjuctive Use
Tie-in to Pipelin No. 3 1 $500,000
Conveyance to Middle Sweetwater Basin 54,900 ft of 24 in pipe $26,357,760 $530,000
Infiltration Basins 2 basins, 40 acres $1,480,000 $30,000
Extraction
Extraction Wells 6 @ 1,000 gpm $4,500,000 $210,000
Conveyance of Recovered Water 5,280 ft of 24 in pipe; 150 HP pump $2,909,400 $97,500
Monitoring Wells 2 @ 4 in dia. $40,000 $40,000
Land Acquisition 42 acres $29,400,000
Cost of Imported Water 5,714 AFY $2,399,901
TOTAL $65,187,160 $3,307,401
C.2.2 Lower Sweetwater Brackish Groundwater Demineralization
The total capital cost of this option is estimated at $11,250,000, and the annual
operation and maintenance costs are approximately $942,000/year. The unit cost of
this option is $1,184/AF. The capital and O&M components of the option are
presented in Table C-4 below.
Table C-4
Costs Summary: Lower Sweetwater Brackish Groundwater Demineralization
unit description Capital [$] O&M [$/yr]
Desalination
Extraction Wells 1 @ 1,000 gpm $750,000 $50,000
RO Plant 1.1 MGD $3,410,000 $510,000
Conveyance of Recovered Water 5,000 ft of 10 in pipe; 80 HP pump $1,200,000 $64,000
Brine Removal (0.2 MGD) 5,000 ft of 4 in pipe; 20 HP pump $4,467,067 $298,000
Land Acquisition 2 acres $1,400,000
Monitoring Wells 1 @ 4 in dia. $20,000 $20,000
TOTAL $11,247,067 $942,000
Appendix C
Supply Option Cost Estimates
C-4 A
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C.2.3 Santee/El Monte Basin
The La Mesa Sweetwater Extension (LMSE) is a pipeline that runs from Helix Water
District’s Levy WTP through OWD’s North District and to the Sweetwater Reservoir.
Currently the LMSE delivers potable water from the Levy plant to OWD as an
alternative source when Pipeline No. 4 is out of service. In the future, the LMSE may
become available for use with other supply options, including: Middle Sweetwater
and Santee/El Monte.
C.2.3.1 Santee/El Monte Conjunctive Use
Assuming the use of the LMSE to convey recovered water to the North system, the
total capital cost of this option is estimated at $41,950,000, and the annual operation
and maintenance costs are approximately $2,675,000/year. The unit cost of this option
is $1,145/AF.
If the LMSE is not available for use, additional conveyance infrastructure would be
required from the basin to the North system. In this case, the total capital cost of this
option is estimated at $64,009,600, and the annual operation and maintenance costs
are approximately $3,160,000/year. The unit cost of this option is $1,562/AF.
The capital and O&M components of the options with and without use of the LMSE
are presented in Table C-5 below and Table C-6 on the following page.
Table C-5
Cost Summary: Santee/El Monte Conjunctive Use (with LMSE)
unit description Capital [$] O&M [$/yr]
Conjunctive Use
Conveyance to Basin*,** 2,500 ft of 24 in pipe $1,200,000 $20,000
Infiltration Basins 2 basins, 40 acres $1,480,000 $30,000
Extraction Wells 6 @ 1,000 gpm $4,500,000 $250,000
Conveyance of Recovered Water** 8,500 ft of 24 in pipe; 500 HP pump $5,330,000 $235,000
Cost of Imported Water 5,000 AFY $2,100,000
Land Acquisition 42 acres $29,400,000
Monitoring Wells 2 @ 4 in dia. $40,000 $40,000
TOTAL $41,950,000 $2,675,000
* Assume zero costs for existing infrastructure
** Assume pumping costs are zero for existing infrastructure
Appendix C
Supply Option Cost Estimates
A C-5
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Table C-6
Cost Summary: Santee/El Monte Conjunctive Use (No LMSE)
unit description Capital [$] O&M [$/yr]
Conjunctive Use
Conveyance to Basin*,** 2,500 ft of 24 in pipe $1,200,000 $20,000
Infiltration Basins 2 basins, 40 acres $1,480,000 $30,000
Extraction Wells 6 @ 1,000 gpm $4,500,000 $250,000
Conveyance of Recovered Water** 56,000 ft of 24 in pipe; 200 HP pump $27,389,600 $720,000
Cost of Imported Water 5,000 AFY $2,100,000
Land Acquisition 42 acres $29,400,000
Monitoring Wells 2 @ 4 in dia. $40,000 $40,000
TOTAL $64,009,600 $3,160,000
* Assume zero costs for existing infrastructure
** Assume pumping costs are zero for existing infrastructure
C.2.3.2 Santee/El Monte Brackish Groundwater Demineralization
Assuming the use of the LMSE to convey recovered water to the North system, the
total capital cost of this option is estimated at $32,390,000, and the annual operation
and maintenance costs are approximately $2,863,000/year. The unit cost of this option
is $688/AF.
If the LMSE is not available for use, additional conveyance infrastructure would be
required from the basin to the North system. In this case, the total capital cost of this
option is estimated at $63,702,000, and the annual operation and maintenance costs
are approximately $3,593,000/year. The unit cost of this option is $1,084/AF.
The capital and O&M components of the options with and without use of the LMSE
are presented in Table C-7 and Table C-8 on the following page.
Table C-7
Cost Summary: Santee/El Monte Brackish Groundwater Demineralization (with LMSE)
unit description Capital [$] O&M [$/yr]
Desalination
Extraction Wells 3@ 1,000 gpm $2,250,000 $120,000
RO Plant 3.8 MGD $11,380,000 $1,700,000
Conveyance of desalinated water 10,000 ft of 16 in pipe; 60 HP pump $3,350,000 $83,000
Brine Removal (0.7 MGD) 4,000 ft of 6 in pipe; 40 HP $13,970,225 $920,000
Land Acquisition 2 acres $1,400,000
Monitoring Wells 2 @ 4 in dia. $40,000 $40,000
TOTAL $32,390,225 $2,863,000
Appendix C
Supply Option Cost Estimates
C-6 A
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Table C-8
Cost Summary: Santee/El Monte Brackish Groundwater Demineralization (No LMSE)
unit description Capital [$] O&M [$/yr]
Desalination
Extraction Wells 3@ 1,000 gpm $2,250,000 $120,000
RO Plant 3.8 MGD $11,380,000 $1,700,000
Conveyance of desalinated water 57,520 ft of 30 in pipe; 60 HP pump $34,662,000 $813,000
Brine Removal (0.7 MGD) 4,000 ft of 6 in pipe; 40 HP $13,970,225 $920,000
Land Acquisition 2 acres $1,400,000
Monitoring Wells 2 @ 4 in dia. $40,000 $40,000
TOTAL $63,702,225 $3,593,000
C.2.3.2 Santee/El Monte Brackish Combined Conjunctive Use and Brackish
Groundwater Demineralization
This option combines the Conjunctive Use and Brackish Groundwater
Demineralization projects described above, although each project would operate
independently of the other. As there would be no shared infrastructure (other than
the conveyance to the North system), the capital and O&M costs for a combined
project would essentially be a summation of the total costs for the conjunctive use
project and the total costs for the groundwater desalination project.
If the use of the LMSE is not available for use, the new conveyance infrastructure
required to bring product water to the North system should be sized for the combined
flow of the Conjunctive Use and Brackish Groundwater Demineralization projects.
C.2.3 San Diego Formation Brackish Groundwater Desalination
The total capital cost of this option is estimated at $22,525,000, and the annual
operation and maintenance costs are approximately $1,679,000/year. The unit cost of
this option is $1,362. The capital and O&M components of the option are presented in
Table C-9 below.
Table C-9
Cost Summary: San Diego Formation Brackish Groundwater Desalination
unit description Capital [$] O&M [$/yr]
Desalination
Extraction Wells 3 @ 500 gpm $4,500,000 $210,000
RO Plant 1.9 MGD $5,690,000 $850,000
Conveyance of Recovered Water 18,500 ft of 10 in pipe; 100 HP pump $3,950,000 $115,000
Brine Removal (0.3 MGD) 2,500 ft of 4 in pipe; 20 HP pump $6,945,112 $464,000
Land Acquisition 2 acres $1,400,000
Monitoring Wells 2 @ 4 in dia. $40,000 $40,000
TOTAL $22,525,112 $1,679,000
Appendix C
Supply Option Cost Estimates
A C-7
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C.2.4 Tijuana River Valley Aquifer Reclaimed Water
Conjunctive Use
This option was not evaluated. See Section C.2.4.
C.2.5 Other Groundwater Wells
C.2.5.1 Otay Mountain Well
The total capital cost of this option is estimated at $12,380,000, and the annual
operation and maintenance costs are approximately $970,000/year. The unit cost of
this option is $1,364. The capital and O&M components of the option are presented in
Table C-10 below.
Table C-10
Cost Summary: Otay Mountain Well
unit description Capital [$] O&M [$/yr]
Extraction Wells 1 @ 1,000 gpm $750,000 $40,000
RO Treatment 1.2 MGD $3,670,000 $550,000
Conveyance of Recovered Water 12,200 ft of 10 in pipe; 200 HP pump $2,940,000 $90,000
Brine Removal (0.2 MGD) assume disposal sanitary sewer $4,317,008 $290,000
Land Acquisition 1 acre $700,000
TOTAL $12,377,008 $970,000
C.3 Additional Recycled Options
C.3.1 Spring Valley Stripping Plant
The unit cost of this option is $1,117/AF. Total capital costs would be approximately
$63,900,000 with annual O&M costs of about $1,600,000. The capital and O&M
components of the option are presented in Table C-11 below.
Table C-11
Cost Summary: Spring Valley Stripping Plant
unit description Capital [$] O&M [$/yr]
Stripping Plant 5 MGD $50,000,000 $1,368,750
Land Acquisition 2 acres $1,400,000
Piping to Central System 26,000 ft of 24 in pipe $12,480,000 $249,600
TOTAL $63,880,000 $1,618,350
C.3.2 Chula Vista Stripping Plant
The unit cost of this option is $756/ AF. Total capital costs would be approximately
$12,500,000 with annual O&M costs of about $3,300,000. The capital and O&M
components of the option are presented in Table C-12.
Appendix C
Supply Option Cost Estimates
C-8 A
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Table C-12
Cost Summary: Chula Vista Stripping Plant
unit description Capital [$] O&M [$/yr]
Purchase of RW from City of Chula Vista 5,600 AFY $1,960,000
24-inch piping to Central System 26,000 ft of 24 in pipe $12,480,000 $1,368,750
TOTAL $12,480,000 $3,328,750
C.3.3 Additional Purchases from South Bay WRP
The unit cost per acre-foot for this option is estimated at $633. Total capital costs
would be approximately $2,400,000 with annual O&M costs of about $2,700,000. The
capital and O&M components of the option are presented in Table C-13 below.
Table C-13
Cost Summary: Additional Purchases from South Bay WRP
unit description Capital [$] O&M [$/yr]
Agreement with City of San Diego $0 $0
Purchase of RW from SBWRP 4,480 AFY $1,568,000
Capacity Reservation Charge (One Time) 4,480 AFY $2,412,000 $0
Pumping from SBWRP to Reservoir 450-1
based on $1.50/1000 gallons--half of
flow $1,095,000
TOTAL $2,412,000 $2,663,000
C.3.4 Expansion of South Bay WRP
The unit cost of this option is $1,137/ AF. Total capital costs would be approximately
$40,000,000 with annual O&M costs of about $2,200,000. The capital and O&M
components of the option are presented in Table C-14 below.
Table C-14
Cost Summary: Expansion of South Bay WRP
unit description Capital [$] O&M [$/yr]
South Bay Plant Expansion 4 MGD $40,000,000 $1,095,000
Pumping from SBWRP to Reservoir 450-1
based on $1.50/1000 gallons--half of
flow $1,095,000
TOTAL $40,000,000 $2,190,000
C.3.5 Chapman WRP and /or Spring Valley Stripping Plant
Recycled Water to Lower Sweetwater Basin and Downstream
Well Recovery:
This option was not evaluated. See Section C.3.5.
C.3.6 North District Recycled Water Concept
The unit cost of this option is $711/AF. Total capital costs would be approximately
$7,900,000 with annual O&M costs of about $300,000. Note that these values do not
Appendix C
Supply Option Cost Estimates
A C-9
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accurately reflect the true costs of the option, as the costs for an alternative water
supply to the users in Eastern Chula Vista are not included. The capital and O&M
components of the option are presented in Table C-15 below.
Table C-15
Cost Summary: North District Recycled Water Concept
unit description Capital [$] O&M [$/yr]
Piping to Central System 33,000 ft of 12 in pipe $7,920,000 $301,125
TOTAL $7,920,000 $301,125
C.3.7 Expansion of Chapman WRP and Sewer Collection System
The unit cost of this option is $1,036/AF. Total capital costs would be approximately
$30,500,000 with annual O&M costs of about $800,000. The capital and O&M
components of the option are presented in Table C-16 below.
Table C-16
Cost Summary: Expansion of Chapman WRP and Sewer Collection System
unit description Capital [$] O&M [$/yr]
R.W. Chapman Plant Expansion- Phase 1 1.3 MGD $13,000,000 $355,875
R.W. Chapman Plant Expansion- Phase 2 1.3 MGD $13,000,000 $355,875
Parallel piping 18,750 ft of 12 in piping $4,500,000 $90,000
TOTAL $30,500,000 $801,750
C.4 Ocean Desalination Options
C.4.1 Poseidon’s Carlsbad Seawater Desalination Project
A per-acre-foot unit cost of $1,300 was assumed for this option. This includes the
operational seawater treatment costs and the in-lieu exchange transportation costs.
There would be no capital costs associated with this option. Conveyance costs may be
necessary to deliver the desalinated water to the third party, but are not included for
this evaluation.
C.4.2 Southern California Partnership: Sweetwater/City of San
Diego South Bay Project
Three levels of participation were considered for this option: 20 MGD, 10 MGD, and 5
MGD. Cost estimates were developed for each of these levels and are presented in the
tables that follow.
Appendix C
Supply Option Cost Estimates
C-10 A
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Table C-17
Cost Comparison for Different Levels of Participation in the Southern California Partnership:
Sweetwater/City of San Diego South Bay Project
Level of Participation Unit Cost ($/AF) Capital Cost ($) O&M Cost ($/yr)
20 MGD $2,800 $186,164,400 $49,185,153
10 MGD $2,850 $98,509,600 $24,700,076
5 MGD $2,950 $55,307,200 $12,460,038
Table C-18
Cost Summary: Southern California Partnership: Sweetwater/City of San Diego South Bay Project (20 MGD)
unit description Capital [$] O&M [$/yr]
RO Plant 20 MGD $130,000,000 $19,042,342
Brine Disposal 20 MGD $0 $26,637,811
Conveyance
Pipeline 47,520 ft of 36 in pipe $34,214,400 $680,000
Pumping 4000 HP $21,250,000 $2,825,000
Land Acquisition 2 acres $700,000
TOTAL $186,164,400 $49,185,153
Table C-19
Cost Summary: Southern California Partnership: Sweetwater/City of San Diego South Bay Project (10 MGD)
unit description Capital [$] O&M [$/yr]
RO Plant 10 MGD $65,000,000 $9,521,171
Brine Disposal 10 MGD $0 $13,318,906
Conveyance
Pipeline 47,520 ft of 24 in pipe $22,809,600 $460,000
Pumping 8500 HP $10,000,000 $1,400,000
Land Acquisition 1 acre $700,000
TOTAL $98,509,600 $24,700,076
Table C-20
Cost Summary: Southern California Partnership: Sweetwater/City of San Diego South Bay Project (5 MGD)
unit description Capital [$] O&M [$/yr]
RO Plant 5 MGD $32,500,000 $4,760,585
Brine Disposal 5 MGD $0 $6,659,453
Conveyance
Pipeline 47,520 ft of 18 in pipe $17,107,200 $340,000
Pumping 2000 HP $5,000,000 $700,000
Land Acquisition 1 acre $700,000
TOTAL $55,307,200 $12,460,038
Appendix C
Supply Option Cost Estimates
A C-11
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C.4.3 Bi-National Partnership: Rosarito Financial Partnership
with In-lieu Colorado River Water
The unit cost of this option is $897 / AF. Total capital costs would be approximately
$36,349,000 with annual (2006) O&M costs of about $4,865,555. The capital and O&M
components of the option are presented in Table C-21 below.
Table C-21
Cost Summary: Bi-National Partnership: Rosarito Financial Partnership
with In-lieu1 Colorado River Water
unit description Capital [$] O&M [$/yr]
RO Plant 5 MGD $32,500,000 $4,760,585
Ocean Outfall 8,000 ft of 12 in outfall $3,499,000 $104,970
Land Acquisition 1 acre $350,0002
TOTAL $36,349,000 $4,865,555
1In-Lieu water deliveries are subject to SDCWA transport and wheeling charges. See Section 5. 2Assumes the cost of land in Mexico is 50% of the cost of land in the United States.
C.5 Additional Imported Water Options with Local
Treatment Agreements
Refer to Figure 5-1 for the projected imported raw water purchase rates from
SDCWA, which are discussed in the following sections.
C.5.1 Expansion of Capacity Rights from Helix Water District’s
Levy WTP
Costs for this option would include the expanded plant capacity participation
purchase at Levy WTP, and the cost for imported SDCWA purchases treated at Levy
which is equivalent to the SDCWA treated water rate. The unit cost of this option is
$744 / AF. Total capital costs would be approximately $12,300,000 with annual O&M
costs for the purchase of imported water of about $2,400,000.
Table C-22
Cost Summary: Expansion of Capacity Rights
from Helix Water District’s Levy WTP
Capital [$] O&M [$/yr]
Levy WTP Supply Participation/Purchase $12,276,911
Imported Treated Water from SDCWA $2,441,900
TOTAL $12,276,911 $2,441,900
Appendix C
Supply Option Cost Estimates
C-12 A
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C.5.2 Expansion of Capacity at City of San Diego’s Otay WTP
The unit cost of this option is $694 / AF. Total capital costs would be approximately
$49,000,000 for with annual O&M costs of about $12,000,000.
Table C-23
Cost Summary: Expansion of Capacity at City of San Diego’s Otay WTP
Capital [$] O&M [$/yr]
Otay WTP Capacity Increase $49,000,817
Imported Raw Water
Treatment at Otay WTP $2,016,248
Pumping from Otay WTP to Cent. and OM $560,069
Purchases from SDCWA $9,409,157
TOTAL $49,000,817 $11,985,474
C.5.3 Imported Water from Sweetwater Authority’s Perdue WTP
The net present value unit cost of this option is $878 / AF. Total capital costs would
be approximately $16,200,000 with annual O&M costs of about $2,700,000.
Table C-24
Cost Summary: Imported Water from Sweetwater Authority’s Perdue WTP
Capital [$] O&M [$/yr]
Pipeline from Perdue WTP to existing 36-inch
transmission main (24 in) $1,695,622
Perdue WTP pump station (3000 gpm) $2,260,830
Perdue WTP Capacity Participation/Purchase $12,276,911
Imported Raw Water
Purchases from SDCWA $1,881,831
Treatment at Perdue WTP $358,444
Conveyance (energy for pumping) $313,639
Maintenance $199,795
TOTAL $16,233,364 $2,753,709
C.5.4 Imported Water from the City of San Diego’s Alvarado
WTP
The unit cost of this option is $733 / AF. Total capital costs would be approximately
$82,400,000 with annual O&M costs including the purchase of imported water of
about $18,600,000.
Appendix C
Supply Option Cost Estimates
A C-13
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Table C-25
Cost Summary: Imported Water from the City of San Diego’s Alvarado WTP
Capital [$] O&M [$/yr]
Alvarado WTP Supply Participation/Purchase* $69,445,131
Pump Station SD17** $13,000,000
Imported Raw Water
Purchases from SDCWA $14,113,736
Treatment Fee at Alvarado WTP $3,024,372
Conveyance (energy for pumping SD17) $1,512,186
TOTAL $82,445,131 $18,650,293
* Information since the IRP analysis has indicated that there would be no participation/purchase
cost for the Alvarado imported water option. This supply option performed well regardless of the
initially assumed participation cost, and its newer lower cost would only help its performance.
** The City of SD estimated the cost of SD17 to be $20M. However, they have been issued grant
funding. Assume OWD would contribute $8M (per Jim Peasley).
C.6 Imported Raw Water from SDCWA Pipeline No. 3
for Irrigation
The unit cost of this option is $590/AF. Total capital costs would be approximately
$2,400,000 with annual O&M costs including the purchase of imported water of about
$1,500,000.
Table C-26
Cost Summary: Imported Raw Water from SDCWA Pipeline No. 3 for Irrigation
Capital [$] O&M [$/yr]
Modifications to Flow Balancing Structure: Pipelines No. 3 & 4 $812,500
Modifications to San Diego 5 Take off structure $812,500
Tie-in to Pipeline No. 3 $812,500
Imported Raw Water Purchases from SDCWA $1,176,145
Min Flow Requirement to Lower Otay Reservoir $299,901
TOTAL $2,437,500 $1,476,045
C.7 Imported Treated Water from SDCWA Pipeline No. 4
There are no capital costs for this option, since all the necessary infrastructure is
already in place. The projected purchase rates of imported treated water from the
SDCWA are discussed at the beginning of this section, and shown in Figure 5-1.
C.8 Water Transfers and Water Banking
See discussion in Section C.8.
Appendix D
Portfolio Summary and Performance
Central
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
Chapman WRP
#11
Helix WTP
SD
C
W
A
P
L
#
4
(
F
i
l
t
e
r
e
d
)
Reservoirs
2.8 m g d (p u mp e d t o C en t r a l )#10
#12
#13
SD
C
W
A
P
L
#
3
(
R
a
w
)
City of SD
Otay WTP
SDCWA 1st Aqueduct (Raw )
New Supply Options:
1. Middle Sweetwater Conjunctive Use
2. Lower Sweetwater Brackish GW Demin
3. Santee/El Monte Conjunctive Use
4. Santee/El Monte Brackish GW Demin
5. San Diego Formation Brackish GW Demin
6. Expansion of Chapman WRP
7. North District Recycled Water Concept
8. Imported Raw Water from Pipeline No. 3 for Irrigation
9. Otay Mountain Well for Recycled Use
10. Conservation
11. Sweetwater/City of San Diego South Bay Ocean
Desalination Project
Water Quality A Portfolio Schematic
Existing (in model) Potable Facilities
Existing (in model) Raw/Recycled Facilities
Proposed Facilities
Expanded Use of Existing Facilities
Santee/ El Monte
Basin
3
3
4
Uses LMSE
2
2
2
2
1.1 m
gd7
San Vicente
Reservoir
8
6
Middle Sweetwater
Basin
Imported Raw
Water for
Recharge
Lower Sweetwater
Basin
RO Plant2
4Demin Plant
Uses LMSE
5
San Diego
Formation
Demin
Plant
Well
9
10
10
10
1
Desal Plant
11
Central
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
#11
Helix WTP
SD
C
W
A
P
L
#
4
(
F
i
l
t
e
r
e
d
)
Reservoirs
#10
#12
#13
SD
C
W
A
P
L
#
3
(
R
a
w
)
City of SD
Otay WTP
SDCWA 1st Aqueduct (Raw )
New Supply Options:
1. Santee/ El Monte Brackish GW Demineralization
2. Lower Sweetwater Brackish GW Demineralization
3. San Diego Formation Brackish GW Demineralization
4. Southern California Partnership: Sweetwater/City of
San Diego’s South Bay Ocean Desal Project
Water Quality B Portfolio Schematic
Existing (in model) Potable Facilities
Existing (in model) Raw/Recycled Facilities
Proposed Facilities
Expanded Use of Existing Facilities
Lower Sweetwater
Basin
RO Plant
2
San Diego
Formation
Demin
Plant
3
Chapman WRP
Desal Plant
4
Santee/ El Monte
Basin 1Demin Plant
Uses LMSE
Central
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
#11
Helix WTP
SD
C
W
A
P
L
#
4
(
F
i
l
t
e
r
e
d
)
Reservoirs
#10
#12
#13
SD
C
W
A
P
L
#
3
(
R
a
w
)
City of SD
Otay WTP
Assume sufficient
capacity for 18+
mgd
SDCWA 1st Aqueduct (Raw )
New Supply Options:
1. Imported water from Pipeline No. 3 for Irrigation
2. Chula Vista Stripping Plant
3. Additional Effluent Purchases from South Bay WRP
4. North District Recycled Water Concept
5. Middle Sweetwater Conjunctive Use
6. Santee/El Monte Brackish GW Demineralization
7. Poseidon Desal Plant (In-lieu)
8. Transfers: Central Valley GW and Land Fallowing
9. Conservation
Reliability A Portfolio Schematic
Existing (in model) Potable Facilities
Existing (in model) Raw/Recycled Facilities
Proposed Facilities
Expanded Use of Existing Facilities
Stripping Plant 2
Santee/ El Monte
Basin
6
7
7
7
7
9
9
9
9
3
1.1 m
gd4
Use LMSE
Middle Sweetwater
Basin
Imported Raw
Water for
Recharge
5
San Vicente
Reservoir
6
1
Chapman WRP
8
8
Central
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
#11
Helix WTP
SD
C
W
A
P
L
#
4
(
F
i
l
t
e
r
e
d
)
Reservoirs
#10
#12
#13
SD
C
W
A
P
L
#
3
(
R
a
w
)
City of SD
Otay WTP
SDCWA 1st Aqueduct (Raw )
New Supply Options:
1. Middle Sweetwater Conjunctive Use
2. Lower Sweetwater Brackish GW Demineralization
3. Santee/El Monte Conjunctive Use
4. Santee/El Monte Brackish GW Demineralization
5. San Diego Formation Brackish GW Demineralization
6. Southern California Partnership: Sweetwater/ City of
San Diego South Bay Ocean Desal Project
7. Bi-national Partnership: Rosarito Joint Facility in lieu
Colorado River water
8. Conservation
Reliability B Portfolio Schematic
Existing (in model) Potable Facilities
Existing (in model) Raw/Recycled Facilities
Proposed Facilities
Expanded Use of Existing Facilities
Santee/ El Monte
Basin 4Demin Plant
8
8
8
1 .1 m g d (p u m p e d )
Use LMSE
Middle Sweetwater
Basin
Imported Raw
Water for
Recharge
1
Lower Sweetwater
Basin
RO Plant
2
San Diego
Formation
Demin
Plant
5
Chapman WRP
Desal Plant
6
3
Use LMSE
San Vicente
Reservoir
3
5
7
7
7
7
Central
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
Chapman WRP
#11
Helix WTP
SD
C
W
A
P
L
#
4
(
F
i
l
t
e
r
e
d
)
Reservoirs
1 .1 mg d
#10
#12
#13
SD
C
W
A
P
L
#
3
(
R
a
w
)
Temporary Pump Station
•Summer: 10 – 21 mgd
•Winter 21 mgd
Permanent Pump Station: will be 30
mgd
City of SD
Otay WTP
Assume sufficient
capacity for 18+
mgd
SDCWA 1st Aqueduct (Raw )
New Supply Options:
1. Santee/El Monte Conjunctive Use
2. Additional Effluent Purchases from South Bay WRP
3. North District Recycled Water Concept
4. Transfers: Central Valley GW and Land Fallowing
Affordability Portfolio Schematic
Existing (in model) Potable Facilities
Existing (in model) Raw/Recycled Facilities
Proposed Facilities
Expanded Use of Existing Facilities
Santee/ El Monte
Basin
1
2
1.1 m
gd3
Use LMSE
San Vicente
Reservoir
1
4
4
Central
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
#11
Helix WTP
SD
C
W
A
P
L
#
4
(
F
i
l
t
e
r
e
d
)
Reservoirs
#10
#12
#13
SD
C
W
A
P
L
#
3
(
R
a
w
)
City of SD
Otay WTP
SDCWA 1st Aqueduct (Raw )
Existing (in model) Potable Facilities
Existing (in model) Raw/Recycled Facilities
Proposed Facilities
Expanded Use of Existing Facilities
Baseline Portfolio Schematic
Supply Option:
1. Imported Water from Pipeline No. 4 (Treated)
1
1
1
1
Chapman WRP
Central
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
Chapman WRP
#11
Helix WTP
SD
C
W
A
P
L
#
4
(
F
i
l
t
e
r
e
d
)
Reservoirs
3.9 mg d (pu mp e d)#10
#12
#13
SD
C
W
A
P
L
#
3
(
R
a
w
)
City of SD
Otay WTP
SDCWA 1st Aqueduct (Raw )
New Supply Options:
1. Spring Valley Stripping Plant
2. Imported Water from Pipeline No. 3 (Raw)
3. Expansion of Chapman WRP
4. Santee/El Monte Brackish GW Demineralization
5. Southern California Partnership: Sweetwater Authority/City of
San Diego’s South Bay Ocean Desal Project
6. Transfers: North of Delta Banking, Central Valley GW and
Land Fallowing
7. Conservation
8. Sweetwater Authority’s Perdue WTP
9. Agreement with City of San Diego to treat raw CWA water at
Alvarado WTP
10. Middle Sweetwater Conjunctive Use
11. Lower Sweetwater Brackish GW Demineralization
12. San Diego Formation Brackish GW Demineralization
Diversity A Portfolio Schematic
Existing (in model) Potable Facilities
Existing (in model) Raw/Recycled Facilities
Proposed Facilities
Expanded Use of Existing Facilities
Stripping Plant
12
Santee/ El Monte
Basin
4
Demin Plant
4
6,9
6,9
6,9
6,9
6
7
7
7
Middle Sweetwater
Basin
Lower Sweetwater
Basin
RO PlantSan Diego
Formation
Demin Plant
12
Perdue WTP8
10
10
1111
Imported Raw
Water for
Recharge
Use LMSE
3
Desal Plant
5
Central
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
Chapman WRP
#11
Helix WTP
SD
C
W
A
P
L
#
4
(
F
i
l
t
e
r
e
d
)
Reservoirs
2 .8 mg d (p u m pe d t o C e nt r a l)#10
#12
#13
SD
C
W
A
P
L
#
3
(
R
a
w
)
City of SD
Otay WTP
Assume sufficient
capacity for 18+
mgd
SDCWA 1st Aqueduct (Raw )
New Supply Options:
1. Chula Vista Stripping Plant
2. Helix’s Levy WTP
3. Bi-national Ocean Desal Partnership: Colorado River
Water (in-lieu)
4. Transfers: Central Valley GW
5. Conservation
6. City of San Diego’s Otay WTP
7. Additional Effluent Purchases from South Bay WRP
8. North District Recycled Water Concept
9. Expansion of Chapman WRP and Sewer Collection
System
Diversity B Portfolio Schematic
Existing (in model) Potable Facilities
Existing (in model) Raw/Recycled Facilities
Proposed Facilities
Expanded Use of Existing Facilities
Stripping Plant
1
3,4
3,4
3,4
3,4
3,4,6
5
5
5
2
7
1.1 m
gd8
9
U s e L M S E
3,4
Central
Otay
Mesa
North
Lower
Otay
Reservoir
City of SD
SBWRP
Chapman WRP
#11
Helix WTP
SD
C
W
A
P
L
#
4
(
F
i
l
t
e
r
e
d
)
Reservoirs
1.1 mg d (pu mp e d)#10
#12
#13
SD
C
W
A
P
L
#
3
(
R
a
w
)
City of SD
Otay WTP
Assume sufficient
capacity for 18+
mgd
SDCWA 1st Aqueduct (Raw )
New Supply Options:
1. Imported Water from Pipeline No. 3 (Raw)
2. Helix’s Levy WTP
3. Sweetwater’s Perdue WTP
4. Middle Sweetwater Conjunctive Use
5. Otay Mountain Well for Recycled Use
6. Southern California Partnership: Sweetwater/City
of SD’s South Bay project
7. Agreement with City of San Diego to treat raw
CWA water at Alvarado WTP
Flexibility Portfolio Schematic
Existing (in model) Potable Facilities
Existing (in model) Raw/Recycled Facilities
Proposed Facilities
Expanded Use of Existing Facilities
Stripping Plant11
7
7
7
7
2
Perdue WTP3
U s e L M S E
Middle Sweetwater
Basin
4
Imported Raw
Water for
Recharge
Well5
Desal Plant6
4
Otay WD IRP
January 8, 2007
Water Quality A: DBP Portfolio
This portfolio was developed with the objective of improving water quality by
minimizing the potential for disinfection by-products (DBP’s). The supply options
included in this portfolio include:
I. Existing Supply Source Annual Yield (2010)
Ia. Potable
Imported Water from Pipeline No. 4 (treated) 136,000 AFY (capacity)
City of San Diego, Otay WTP 10,100 AFY
Helix’s Levy WTP 13,400 AFY
Ib. Recycled
OWD’s Chapman WRP 1,200 AFY
City of San Diego, South Bay WRP 6,700 AFY
II. New Supply Options in Portfolio Annual Yield
IIa. Potable
Middle Sweetwater Groundwater Conjunctive Use 5,000 AFY in dry years
Lower Sweetwater Brackish Groundwater Desalination 1,500 AFY
Santee/El Monte Combined Conjunctive Use – Brackish
Groundwater Desalination
4,250 AFY plus additional
5,000 AFY in dry years
San Diego Formation Brackish Groundwater Desalination 2,125 AFY
Sweetwater/City of San Diego’s South Bay Ocean
Desalination Project
5,600 AFY
Additional Conservation 5,390 AFY (2030 savings)
IIb. Recycled
North District Recycled Water Concept 1,230 AFY
Imported Raw CWA Water from Pipeline No. 3 for Irrigation 2,800 AFY (over 6 months)
Expansion of Chapman WRP and Sewer Collection System 3,140 AFY
Otay Mountain Well for Recycled Use 1,370 AFY
2030 Imported Shortage Supply Mix
0
2,000
4,000
6,000
8,000
10,000
12,000
Ja
n
u
a
r
y
Fe
b
r
u
a
r
y
Ma
r
c
h
Ap
r
i
l
Ma
y
Ju
n
e
Ju
l
y
Au
g
u
s
t
Se
p
t
e
m
b
e
r
Oc
t
o
b
e
r
No
v
e
m
b
e
r
De
c
e
m
b
e
r
AF
M
Total Monthly Deficit
Total Treated Imported CWA Supply
Total Otay WTP supply with Imported Raw
Helix's Levy WTP Supply
Sweetwater/City of SD South Bay Ocean Desal
Otay Mtn Well Supply
San Diego Formation Supply to Central
Santee El Monte Brackish GW Desal Supply to North
Santee El Montee CU Supply to North
Middle Sweetwater Supply to North
Lower Sweetwater Supply to Central
Total Conservation
Pipeline #3 Supply to Central for Irr
Total SBWRP Flow Purchases for Demands
Chapman WRP Supply to North District
Total Chapman Supply to Central and OM
Otay WD IRP
January 8, 2007
Water Quality A: DBP Portfolio
Objective/Sub-objective Performance
Measure
Score
Objective 1 -Meet or Exceed Water Quality Standards and Guidelines
1a) Meet current and future drinking water standards All portfolios will
comply 3.0
1b) Address compatibility of new sources with current imported supply Compatibility Score 4.1
1c) Meet TDS goals for recycled water, potable water and Basin Plan Potable TDS - (mg/L) 426
Non-potable TDS
(mg/L) 968
1d) Minimize potential issues due to disinfection method DBP Score 4.5
Objective 2 – Achieve Reliability
2a) Meet demands under average hydrology conditions Average Annual
Deficit (AFY) 251
2b) Meet demands under drought imported shortage conditions Cumulative Deficit
(AF/ all shortage
years)
9,036
2c) Minimize impacts under emergency conditions Shortage during a
three month
emergency - AF
20,101
Objective 3 – Maintain Affordability
3a) Minimize impacts to an average single-family customer NPV Unit costs --
$/AF 1,465
3b) Manage Capital Costs NPV Capital costs -- $ 266,585,000
Objective 4 – Increase Flexibility
4a) Increase Number of Take Points and Alternative Flow Routes Total Number of Take
Points 12
Objective 5 – Increase Diversity
5a) Maximize number of sources Total number of
contracts 12
5b) Reduce contribution of largest source 2030 contribution of
the largest source to
total supply - %
54
Objective 6 – Address Environmental and Institutional Constraints
6a) Minimize environmental permitting requirements Permitting Score 3.3
6b) Minimize institutional coordination and implementation requirements
(local/State/Federal/International)
Institutional
Coordination Score 3.7
6c) Maximize customer acceptance Customer Acceptance
Score 4.2
6d) Minimize regulatory constraints Regulatory
Constraints Score 3.8
6e) Minimize technology uncertainty Technology
Uncertainty Score 4.0
Otay WD IRP
January 8, 2007
Water Quality B: TDS Portfolio
This portfolio was developed with the objective of improving water quality by
minimizing the potential for Total Dissolved Solids (TDS). The supply options included
in this portfolio include:
I. Existing Supply Source Annual Yield (2010)
Ia. Potable
Imported Water from Pipeline No. 4 (treated) 136,000 AFY (capacity)
City of San Diego, Otay WTP 10,100 AFY
Helix’s Levy WTP 13,400 AFY
Ib. Recycled
OWD’s Chapman WRP 1,200 AFY
City of San Diego, South Bay WRP 6,700 AFY
II. New Supply Options in Portfolio Annual Yield
IIa. Potable
Lower Sweetwater Brackish Groundwater Desalination 1,500 AFY
Santee/ El Monte Brackish Groundwater Desalination 4,250 AFY
San Diego Formation Brackish Groundwater Desalination 2,125 AFY
Sweetwater/City of SD’s South Bay Ocean Desal project 11,200 AFY
IIb. Recycled
None
2030 Imported Shortage Supply Mix
0
2,000
4,000
6,000
8,000
10,000
12,000
Ja
n
u
a
r
y
Fe
b
r
u
a
r
y
Ma
r
c
h
Ap
r
i
l
Ma
y
Ju
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Ju
l
y
Au
g
u
s
t
Se
p
t
e
m
b
e
r
Oc
t
o
b
e
r
No
v
e
m
b
e
r
De
c
e
m
b
e
r
AF
M
Total Monthly Deficit
Total Treated Imported CWA Supply
Total Otay WTP supply with Imported Raw
Helix's Levy WTP Supply
Sweetwater/City of SD South Bay OceanDesal
San Diego Formation Supply to Central
Santee El Monte Brackish GW Desal Supply
to North
Lower Sweetwater Supply to Central
Total SBWRP Flow Purchases for Demands
Total Chapman Supply to Central and OM
Otay WD IRP
January 8, 2007
Water Quality B: TDS Portfolio
Objective/Sub-objective Performance
Measure
Score
Objective 1 -Meet or Exceed Water Quality Standards and Guidelines
1a) Meet current and future drinking water standards All portfolios will
comply 3.0
1b) Address compatibility of new sources with current imported supply Compatibility Score 4.2
1c) Meet TDS goals for recycled water, potable water and Basin Plan Potable TDS - (mg/L) 406
Non-potable TDS
(mg/L) 990
1d) Minimize potential issues due to disinfection method DBP Score 3.8
Objective 2 – Achieve Reliability
2a) Meet demands under average hydrology conditions Average Annual
Deficit (AFY) 455
2b) Meet demands under drought imported shortage conditions Cumulative Deficit
(AF/ all shortage
years)
21,862
2c) Minimize impacts under emergency conditions Shortage during a
three month
emergency - AF
24,367
Objective 3 – Maintain Affordability
3a) Minimize impacts to an average single-family customer NPV Unit costs --
$/AF 1,562
3b) Manage Capital Costs NPV Capital costs -- $ 163,975,000
Objective 4 – Increase Flexibility
4a) Increase Number of Take Points and Alternative Flow Routes Total Number of Take
Points 9
Objective 5 – Increase Diversity
5a) Maximize number of sources Total number of
contracts 9
5b) Reduce contribution of largest source 2030 contribution of
the largest source to
total supply - %
70
Objective 6 – Address Environmental and Institutional Constraints
6a) Minimize environmental permitting requirements Permitting Score 3.0
6b) Minimize institutional coordination and implementation requirements
(local/State/Federal/International)
Institutional
Coordination Score 3.6
6c) Maximize customer acceptance Customer Acceptance
Score 4.6
6d) Minimize regulatory constraints Regulatory
Constraints Score 4.0
6e) Minimize technology uncertainty Technology
Uncertainty Score 4.5
Otay WD IRP
January 8, 2007
Reliability A: Drought Portfolio
This portfolio was developed with the objective of increasing reliability under drought
conditions involving imported water shortages. The supply options included in this
portfolio include:
I. Existing Supply Source Annual Yield (2010)
Ia. Potable
Imported Water from Pipeline No. 4 (treated) 136,000 AFY (capacity)
City of San Diego, Otay WTP 10,100 AFY
Helix’s Levy WTP 13,400 AFY
Ib. Recycled
OWD’s Chapman WRP 1,200 AFY
City of San Diego, South Bay WRP 6,700 AFY
II. New Supply Options in Portfolio Annual Yield
IIa. Potable
Middle Sweetwater Groundwater Conjunctive Use 5,000 AFY in dry years
Santee/El Monte Groundwater Conjunctive Use 5,000 AFY in dry years
Poseidon Ocean Desalination (in-lieu) 11,200 AFY
Additional Conservation 5,390 AFY (2030 savings)
Transfers : Central Valley Groundwater 7,500 AFY
Transfers : Land Fallowing 7,500 AFY
IIb. Recycled
Imported Raw CWA water from Pipeline No. 3 for Irrigation 2,800 AFY (over 6 months)
Chula Vista Stripping Plant 5,600 AFY
South Bay WRP (Additional Purchase Only) 4,480 AFY
North District Recycled Water Concept 1,230 AFY
2030 Imported Shortage Supply Mix
0
2,000
4,000
6,000
8,000
10,000
12,000
Ja
n
u
a
r
y
Fe
b
r
u
a
r
y
Ma
r
c
h
Ap
r
i
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Ma
y
Ju
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Ju
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y
Au
g
u
s
t
Se
p
t
e
m
b
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Oc
t
o
b
e
r
No
v
e
m
b
e
r
De
c
e
m
b
e
r
AF
M
Total Monthly Deficit
Total Treated Imported CWA Supply
Total Otay WTP supply with Imported Raw
Helix's Levy WTP Supply
Total Transfers Supply
Total Poseidon Desal Supply
Santee El Montee CU Supply to North
Middle Sweetwater Supply to North
Total Conservation
Pipeline #3 Supply to Central for Irr
Chapman WRP Supply to North District
Total CVSP Supply
Total SBWRP Flow Purchases for
Demands
Otay WD IRP
January 8, 2007
Reliability A: Drought Portfolio
Objective/Sub-objective Performance
Measure
Score
Objective 1 -Meet or Exceed Water Quality Standards and Guidelines
1a) Meet current and future drinking water standards All portfolios will
comply 3.0
1b) Address compatibility of new sources with current imported supply Compatibility Score 4.3
1c) Meet TDS goals for recycled water, potable water and Basin Plan Potable TDS - (mg/L) 490
Non-potable TDS
(mg/L) 990
1d) Minimize potential issues due to disinfection method DBP Score 3.7
Objective 2 – Achieve Reliability
2a) Meet demands under average hydrology conditions Average Annual
Deficit (AFY) 0
2b) Meet demands under drought imported shortage conditions Cumulative Deficit
(AF/ all shortage
years)
0
2c) Minimize impacts under emergency conditions Shortage during a
three month
emergency - AF
23,813
Objective 3 – Maintain Affordability
3a) Minimize impacts to an average single-family customer NPV Unit costs --
$/AF
1,197
3b) Manage Capital Costs NPV Capital costs -- $
131,906,000
Objective 4 – Increase Flexibility
4a) Increase Number of Take Points and Alternative Flow Routes Total Number of Take
Points 9
Objective 5 – Increase Diversity
5a) Maximize number of sources Total number of
contracts 12
5b) Reduce contribution of largest source 2030 contribution of
the largest source to
total supply - %
34
Objective 6 – Address Environmental and Institutional Constraints
6a) Minimize environmental permitting requirements Permitting Score 3.9
6b) Minimize institutional coordination and implementation requirements
(local/State/Federal/International)
Institutional
Coordination Score 3.2
6c) Maximize customer acceptance Customer Acceptance
Score 4.6
6d) Minimize regulatory constraints Regulatory
Constraints Score 4.1
6e) Minimize technology uncertainty Technology
Uncertainty Score 4.4
Otay WD IRP
January 8, 2007
Reliability B: Seismic Portfolio
This portfolio was developed with the objective of increasing reliability under seismic
conditions. The assumed seismic condition involves an interruption of imported water
supply caused by SDCWA Pipelines No.3 and No. 4 being offline. The supply options
included in this portfolio include:
I. Existing Supply Source Annual Yield (2010)
Ia. Potable
Imported Water from Pipeline No. 4 (treated) 136,000 AFY (capacity)
City of San Diego, Otay WTP 10,100 AFY
Helix’s Levy WTP 13,400 AFY
Ib. Recycled
OWD’s Chapman WRP 1,200 AFY
City of San Diego, South Bay WRP 6,700 AFY
II. New Supply Options in Portfolio Annual Yield
IIa. Potable
Middle Sweetwater Groundwater Conjunctive Use 5,000 AFY in dry years
Lower Sweetwater Brackish Groundwater Desalination 1,500 AFY
Santee/El Monte Combined Conjunctive Use – Brackish
Groundwater Desalination
4,250 AFY plus additional
5,000 AFY in dry years
San Diego Formation Brackish Groundwater Desalination 2,125 AFY
Bi-national Ocean Desalination Partnership: Colorado
River Water (in-lieu)
5,600 AFY
Sweetwater/City of SD’s South Bay Ocean Desal project 22,400 AFY
Additional Conservation 5,390 AFY (2030 savings)
IIb. Recycled
None
2030 Imported Shortage Supply Mix
0
2,000
4,000
6,000
8,000
10,000
12,000
Ja
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a
r
y
Fe
b
r
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a
r
y
Ma
r
c
h
Ap
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i
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Ma
y
Ju
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Ju
l
y
Au
g
u
s
t
Se
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m
b
e
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Oc
t
o
b
e
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No
v
e
m
b
e
r
De
c
e
m
b
e
r
AF
M
Total Monthly Deficit
Total Treated Imported CWA Supply
Total Otay WTP supply with Imported Raw
Helix's Levy WTP Supply
Sweetwater/City of SD South Bay Ocean
Desal
CR in lieu Rosarito Desal Supply
San Diego Formation Supply to Central
Santee El Monte Brackish GW Desal Supplyto North
Santee El Montee CU Supply to North
Middle Sweetwater Supply to North
Lower Sweetwater Supply to Central
Total Conservation
Total SBWRP Flow Purchases for Demands
Total Chapman Supply to Central and OM
Otay WD IRP
January 8, 2007
Reliability B: Seismic Portfolio
Objective/Sub-objective Performance
Measure
Score
Objective 1 -Meet or Exceed Water Quality Standards and Guidelines
1a) Meet current and future drinking water standards All portfolios will
comply 3.0
1b) Address compatibility of new sources with current imported supply Compatibility Score 3.4
1c) Meet TDS goals for recycled water, potable water and Basin Plan Potable TDS - (mg/L) 388
Non-potable TDS
(mg/L) 990
1d) Minimize potential issues due to disinfection method DBP Score 4.8
Objective 2 – Achieve Reliability
2a) Meet demands under average hydrology conditions Average Annual
Deficit (AFY) 118
2b) Meet demands under drought imported shortage conditions Cumulative Deficit
(AF/ all shortage years)
2,833
2c) Minimize impacts under emergency conditions Shortage during a
three month
emergency - AF
16,242
Objective 3 – Maintain Affordability
3a) Minimize impacts to an average single-family customer NPV Unit costs --
$/AF 1,940
3b) Manage Capital Costs NPV Capital costs -- $ 380,065,000
Objective 4 – Increase Flexibility
4a) Increase Number of Take Points and Alternative Flow Routes Total Number of Take
Points 10
Objective 5 – Increase Diversity
5a) Maximize number of sources Total number of
contracts 11
5b) Reduce contribution of largest source 2030 contribution of
the largest source to
total supply - %
34
Objective 6 – Address Environmental and Institutional Constraints
6a) Minimize environmental permitting requirements Permitting Score 2.2
6b) Minimize institutional coordination and implementation requirements
(local/State/Federal/International)
Institutional
Coordination Score 3.1
6c) Maximize customer acceptance Customer Acceptance
Score 3.9
6d) Minimize regulatory constraints Regulatory
Constraints Score 2.9
6e) Minimize technology uncertainty Technology
Uncertainty Score 3.8
Otay WD IRP
January 8, 2007
Affordability Portfolio
This portfolio was developed with the lowest cost options based on their dollar per acre-
foot unit cost. The supply options included in this portfolio include:
I. Existing Supply Source Annual Yield (2010)
Ia. Potable
Imported Water from Pipeline No. 4 (treated) 136,000 AFY (capacity)
City of San Diego, Otay WTP 10,100 AFY
Helix’s Levy WTP 13,400 AFY
Ib. Recycled
OWD’s Chapman WRP 1,200 AFY
City of San Diego, South Bay WRP 6,700 AFY
II. New Supply Options in Portfolio Annual Yield
IIa. Potable
Santee/ El Monte Groundwater Conjunctive Use 5,000 AFY in dry years
Transfers : Central Valley Groundwater 15,000 AFY
Transfers : Land Fallowing 15,000 AFY
IIb. Recycled
South Bay WRP (Additional Purchase Only) 4,480 AFY
North District Recycled Water Concept 1,230 AFY
2030 Imported Shortage Supply Mix
0
2,000
4,000
6,000
8,000
10,000
12,000
Ja
n
u
a
r
y
Fe
b
r
u
a
r
y
Ma
r
c
h
Ap
r
i
l
Ma
y
Ju
n
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Ju
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y
Au
g
u
s
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p
t
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m
b
e
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Oc
t
o
b
e
r
No
v
e
m
b
e
r
De
c
e
m
b
e
r
AF
M
Total Monthly Deficit
Total Treated Imported CWA
Supply
Total Otay WTP supply withImported Raw
Helix's Levy WTP Supply
Total Transfers Supply
Santee El Montee CU Supply to
North
Chapman WRP Supply to NorthDistrict
Total SBWRP Flow Purchases for
Demands
Otay WD IRP
January 8, 2007
Affordability Portfolio
Objective/Sub-objective Performance
Measure
Score
Objective 1 -Meet or Exceed Water Quality Standards and Guidelines
1a) Meet current and future drinking water standards All portfolios will
comply 3.0
1b) Address compatibility of new sources with current imported supply Compatibility Score 4.9
1c) Meet TDS goals for recycled water, potable water and Basin Plan Potable TDS - (mg/L) 492
Non-potable TDS
(mg/L) 990
1d) Minimize potential issues due to disinfection method DBP Score 3.2
Objective 2 – Achieve Reliability
2a) Meet demands under average hydrology conditions Average Annual
Deficit (AFY) 68
2b) Meet demands under drought imported shortage conditions Cumulative Deficit
(AF/ all shortage
years)
2,983
2c) Minimize impacts under emergency conditions Shortage during a
three month
emergency - AF
26,887
Objective 3 – Maintain Affordability
3a) Minimize impacts to an average single-family customer NPV Unit costs --
$/AF 1,087
3b) Manage Capital Costs NPV Capital costs -- $ 52,092,000
Objective 4 – Increase Flexibility
4a) Increase Number of Take Points and Alternative Flow Routes Total Number of Take
Points 6
Objective 5 – Increase Diversity
5a) Maximize number of sources Total number of
contracts 8
5b) Reduce contribution of largest source 2030 contribution of
the largest source to
total supply - %
47
Objective 6 – Address Environmental and Institutional Constraints
6a) Minimize environmental permitting requirements Permitting Score 3.7
6b) Minimize institutional coordination and implementation requirements
(local/State/Federal/International)
Institutional
Coordination Score 3.3
6c) Maximize customer acceptance Customer Acceptance
Score 4.9
6d) Minimize regulatory constraints Regulatory
Constraints Score 4.8
6e) Minimize technology uncertainty Technology
Uncertainty Score 4.8
Otay WD IRP
January 8, 2007
Baseline Portfolio
This portfolio represents the ‘No Action’ condition, and utilizes all of the District’s
existing (or already planned) supply sources. The supply options included in this
portfolio include:
I. Existing Supply Source Annual Yield (2010)
Ia. Potable
Imported Water from Pipeline No. 4 (treated) 136,000 AFY (capacity)
City of San Diego, Otay WTP 10,100 AFY
Helix’s Levy WTP 13,400 AFY
Ib. Recycled
OWD’s Chapman WRP 1,200 AFY
City of San Diego, South Bay WRP 6,700 AFY
II. New Supply Options in Portfolio Annual Yield
IIa. Potable
None
IIb. Recycled
None
2030 Imported Shortage Supply Mix
0
2,000
4,000
6,000
8,000
10,000
12,000
Ja
n
u
a
r
y
Fe
b
r
u
a
r
y
Ma
r
c
h
Ap
r
i
l
Ma
y
Ju
n
e
Ju
l
y
Au
g
u
s
t
Se
p
t
e
m
b
e
r
Oc
t
o
b
e
r
No
v
e
m
b
e
r
De
c
e
m
b
e
r
AF
M
Total Monthly Deficit
Total Treated Imported CWA
Supply
Total Otay WTP supply with
Imported Raw
Helix's Levy WTP Supply
Total SBWRP Flow Purchases forDemands
Total Chapman Supply to Central
and OM
Otay WD IRP
January 8, 2007
Baseline Portfolio
Objective/Sub-objective Performance
Measure
Score
Objective 1 -Meet or Exceed Water Quality Standards and Guidelines
1a) Meet current and future drinking water standards All portfolios will
comply 3.0
1b) Address compatibility of new sources with current imported supply Compatibility Score 5.0
1c) Meet TDS goals for recycled water, potable water and Basin Plan Potable TDS - (mg/L) 492
Non-potable TDS
(mg/L) 990
1d) Minimize potential issues due to disinfection method DBP Score 3.0
Objective 2 – Achieve Reliability
2a) Meet demands under average hydrology conditions Average Annual
Deficit (AFY)
1,066
2b) Meet demands under drought imported shortage conditions Cumulative Deficit
(AF/ all shortage
years)
110,864
2c) Minimize impacts under emergency conditions Shortage during a
three month
emergency - AF
29,137
Objective 3 – Maintain Affordability
3a) Minimize impacts to an average single-family customer NPV Unit costs --
$/AF 952
3b) Manage Capital Costs NPV Capital costs -- $ 0
Objective 4 – Increase Flexibility
4a) Increase Number of Take Points and Alternative Flow Routes Total Number of Take
Points 5
Objective 5 – Increase Diversity
5a) Maximize number of sources Total number of
contracts 5
5b) Reduce contribution of largest source 2030 contribution of
the largest source to
total supply - %
91
Objective 6 – Address Environmental and Institutional Constraints
6a) Minimize environmental permitting requirements Permitting Score 4.0
6b) Minimize institutional coordination and implementation requirements
(local/State/Federal/International)
Institutional
Coordination Score 4.0
6c) Maximize customer acceptance Customer Acceptance
Score 5.0
6d) Minimize regulatory constraints Regulatory
Constraints Score 5.0
6e) Minimize technology uncertainty Technology
Uncertainty Score 5.0
Otay WD IRP
January 8, 2007
Diversity A Portfolio
This portfolio was developed with the objective of increasing the diversity of supply
sources. The supply options included in this portfolio include:
I. Existing Supply Source Annual Yield (2010)
Ia. Potable
Imported Water from Pipeline No. 4 (treated) 136,000 AFY (capacity)
City of San Diego, Otay WTP 10,100 AFY
Helix’s Levy WTP 13,400 AFY
Ib. Recycled
OWD’s Chapman WRP 1,200 AFY
City of San Diego, South Bay WRP 6,700 AFY
II. New Supply Options in Portfolio Annual Yield
IIa. Potable
Middle Sweetwater Groundwater Conjunctive Use 5,000 AFY in dry years
Lower Sweetwater Brackish Groundwater Desalination 1,500 AFY
Santee/El Monte Brackish Groundwater Desalination 4,250 AFY
San Diego Formation Brackish Groundwater Desalination 2,125 AFY
Sweetwater/City of San Diego’s South Bay Ocean Desal project 5,600 AFY
Conservation 5,390 AFY (2030 savings)
Transfers : North of Delta Banking 5,000 AFY
Transfers : Central Valley Groundwater 5,000 AFY
Transfers : Land Fallowing 5,000 AFY
Sweetwater Authority’s Perdue WTP 4,480 AFY
SD17 Agreement with City of San Diego to treat raw CWA water
at Alvarado WTP
33,600 AFY
IIb. Recycled
Imported Raw CWA Water from Pipeline No. 3 for Irrigation 2,800 AFY (over 6 mo)
Spring Valley Stripping Plant 5,600 AFY
Expansion of Chapman WRP and Sewer Collection System 3,140 AFY
2030 Imported Shortage Supply Mix
0
2,000
4,000
6,000
8,000
10,000
12,000
Ja
n
u
a
r
y
Fe
b
r
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a
r
y
Ma
r
c
h
Ap
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i
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Ma
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Ju
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Ju
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Au
g
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b
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Oc
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o
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No
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b
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De
c
e
m
b
e
r
AF
M
Total Monthly Deficit
Total Treated Imported CWA Supply
Total Alvarado Supply
Total Otay WTP supply with Imported Raw
Helix's Levy WTP Supply
Sweetwater Authorities Perdue WTP Supply
Total Transfers Supply
Sweetwater/City of SD South Bay Ocean Desal
San Diego Formation Supply to Central
Santee El Monte Brackish GW Desal Supply toNorth
Middle Sweetwater Supply to North
Lower Sweetwater Supply to Central
Total Conservation
Total SVSP Supply
Total SBWRP Flow Purchases for Demands
Total Chapman Supply to Central and OM
Otay WD IRP
January 8, 2007
Diversity A Portfolio
Objective/Sub-objective Performance
Measure
Score
Objective 1 -Meet or Exceed Water Quality Standards and Guidelines
1a) Meet current and future drinking water standards All portfolios will
comply 3.0
1b) Address compatibility of new sources with current imported supply Compatibility Score 4.6
1c) Meet TDS goals for recycled water, potable water and Basin Plan Potable TDS - (mg/L) 483
Non-potable TDS
(mg/L) 990
1d) Minimize potential issues due to disinfection method DBP Score 3.7
Objective 2 – Achieve Reliability
2a) Meet demands under average hydrology conditions Average Annual
Deficit (AFY) 0
2b) Meet demands under drought imported shortage conditions Cumulative Deficit
(AF/ all shortage
years)
0
2c) Minimize impacts under emergency conditions Shortage during a
three month
emergency - AF
21,921
Objective 3 – Maintain Affordability
3a) Minimize impacts to an average single-family customer NPV Unit costs --
$/AF 1,440
3b) Manage Capital Costs NPV Capital costs -- $ 380,707,000
Objective 4 – Increase Flexibility
4a) Increase Number of Take Points and Alternative Flow Routes Total Number of Take
Points 13
Objective 5 – Increase Diversity
5a) Maximize number of sources Total number of
contracts 17
5b) Reduce contribution of largest source 2030 contribution of
the largest source to
total supply - %
38
Objective 6 – Address Environmental and Institutional Constraints
6a) Minimize environmental permitting requirements Permitting Score 3.5
6b) Minimize institutional coordination and implementation requirements
(local/State/Federal/International)
Institutional Coordination Score 3.7
6c) Maximize customer acceptance Customer Acceptance
Score 4.6
6d) Minimize regulatory constraints Regulatory
Constraints Score 3.9
6e) Minimize technology uncertainty Technology
Uncertainty Score 4.5
Otay WD IRP
January 8, 2007
Diversity B Portfolio
This portfolio was developed with the objective of increasing the diversity of supply
sources and expanded use of existing (or already planned) sources. The supply options
included in this portfolio include:
I. Existing Supply Source Annual Yield (2010)
Ia. Potable
Imported Water from Pipeline No. 4 (treated) 136,000 AFY (capacity)
City of San Diego, Otay WTP 10,100 AFY
Helix’s Levy WTP 13,400 AFY
Ib. Recycled
OWD’s Chapman WRP 1,200 AFY
City of San Diego, South Bay WRP 6,700 AFY
II. New Supply Options in Portfolio Annual Yield
IIa. Potable
Helix’s Levy WTP 4,480 AFY
City of San Diego’s Otay WTP 22,400 AFY
Bi-national Ocean Desalination Partnership: Colorado
River Water (in-lieu)
5,600 AFY
Conservation 5,390 AFY (2030 savings)
Transfers : Central Valley Groundwater 5,000 AFY
IIb. Recycled
Chula Vista Stripping Plant 5,600 AFY
South Bay WRP (Additional Purchase Only) 4,480 AFY
North District Recycled Water Concept 1,230 AFY
Expansion of Chapman WRP and Sewer Collection System 3,140 AFY
2030 Imported Shortage Supply Mix
0
2,000
4,000
6,000
8,000
10,000
12,000
Ja
n
u
a
r
y
Fe
b
r
u
a
r
y
Ma
r
c
h
Ap
r
i
l
Ma
y
Ju
n
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Ju
l
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Au
g
u
s
t
Se
p
t
e
m
b
e
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Oc
t
o
b
e
r
No
v
e
m
b
e
r
De
c
e
m
b
e
r
AF
M
Total Monthly Deficit
Total Treated Imported CWASupply
Total Otay WTP supply with
Imported Raw
Helix's Levy WTP Supply
Total Transfers Supply
CR in lieu Rosarito Desal Supply
Total Conservation
Chapman WRP Supply to NorthDistrict
Total CVSP Supply
Total SBWRP Flow Purchases forDemands
Total Chapman Supply to Central
and OM
Otay WD IRP
January 8, 2007
Diversity B Portfolio
Objective/Sub-objective Performance
Measure
Score
Objective 1 -Meet or Exceed Water Quality Standards and Guidelines
1a) Meet current and future drinking water standards All portfolios will
comply 3.0
1b) Address compatibility of new sources with current imported supply Compatibility Score 4.8
1c) Meet TDS goals for recycled water, potable water and Basin Plan Potable TDS - (mg/L) 492
Non-potable TDS
(mg/L) 990
1d) Minimize potential issues due to disinfection method DBP Score 3.3
Objective 2 – Achieve Reliability
2a) Meet demands under average hydrology conditions Average Annual
Deficit (AFY) 113
2b) Meet demands under drought imported shortage conditions Cumulative Deficit
(AF/ all shortage
years)
908
2c) Minimize impacts under emergency conditions Shortage during a
three month
emergency - AF
27,790
Objective 3 – Maintain Affordability
3a) Minimize impacts to an average single-family customer NPV Unit costs --
$/AF 1,019
3b) Manage Capital Costs NPV Capital costs -- $ 150,341,000
Objective 4 – Increase Flexibility
4a) Increase Number of Take Points and Alternative Flow Routes Total Number of Take
Points 6
Objective 5 – Increase Diversity
5a) Maximize number of sources Total number of
contracts 8
5b) Reduce contribution of largest source 2030 contribution of
the largest source to
total supply - %
59
Objective 6 – Address Environmental and Institutional Constraints
6a) Minimize environmental permitting requirements Permitting Score 3.9
6b) Minimize institutional coordination and implementation requirements
(local/State/Federal/International)
Institutional
Coordination Score 3.8
6c) Maximize customer acceptance Customer Acceptance
Score 4.6
6d) Minimize regulatory constraints Regulatory
Constraints Score 4.6
6e) Minimize technology uncertainty Technology
Uncertainty Score 4.8
Otay WD IRP
January 8, 2007
Flexibility Portfolio
This portfolio was developed with the objective of increasing the District’s operational
flexibility by increasing the number of take points into the system. The supply options
included in this portfolio include:
I. Existing Supply Source Annual Yield (2010)
Ia. Potable
Imported Water from Pipeline No. 4 (treated) 136,000 AFY (capacity)
City of San Diego, Otay WTP 10,100 AFY
Helix’s Levy WTP 13,400 AFY
Ib. Recycled
OWD’s Chapman WRP 1,200 AFY
City of San Diego, South Bay WRP 6,700 AFY
II. New Supply Options in Portfolio Annual Yield
IIa. Potable
Helix’s Levy WTP 4,480 AFY
Sweetwater Authority’s Perdue WTP 4,480 AFY
SD17 Agreement with City of San Diego to treat raw CWA
water at Alvarado WTP
33,600 AFY
Middle Sweetwater Groundwater Conjunctive Use 5,000 AFY in dry years
Sweetwater/City of SD’s South Bay Ocean Desal project 5,600 AFY
IIb. Recycled
Imported Water from Pipeline No. 3 (raw) for Irrigation 2,800 AFY (over 6 mo)
Otay Mountain Well for Recycled Use 1,370 AFY
2030 Imported Shortage Supply Mix
0
2,000
4,000
6,000
8,000
10,000
12,000
Ja
n
u
a
r
y
Fe
b
r
u
a
r
y
Ma
r
c
h
Ap
r
i
l
Ma
y
Ju
n
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Ju
l
y
Au
g
u
s
t
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p
t
e
m
b
e
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Oc
t
o
b
e
r
No
v
e
m
b
e
r
De
c
e
m
b
e
r
AF
M
Total Monthly Deficit
Total Treated Imported CWA
Supply
Total Alvarado Supply
Total Otay WTP supply withImported Raw
Helix's Levy WTP Supply
Sweetwater Authorities PerdueWTP Supply
Sweetwater/City of SD South Bay
Ocean Desal
Otay Mtn Well Supply
Middle Sweetwater Supply to
North
Pipeline #3 Supply to Central for
Irr
Total SBWRP Flow Purchases for
Demands
Total Chapman Supply to Central
and OM
Otay WD IRP
January 8, 2007
Flexibility Portfolio
Objective/Sub-objective Performance
Measure
Score
Objective 1 -Meet or Exceed Water Quality Standards and Guidelines
1a) Meet current and future drinking water standards All portfolios will
comply 3.0
1b) Address compatibility of new sources with current imported supply Compatibility Score 4.6
1c) Meet TDS goals for recycled water, potable water and Basin Plan Potable TDS - (mg/L) 484
Non-potable TDS
(mg/L) 912
1d) Minimize potential issues due to disinfection method DBP Score 3.5
Objective 2 – Achieve Reliability
2a) Meet demands under average hydrology conditions Average Annual
Deficit (AFY) 1
2b) Meet demands under drought imported shortage conditions Cumulative Deficit
(AF/ all shortage
years)
18
2c) Minimize impacts under emergency conditions Shortage during a
three month
emergency - AF
24,894
Objective 3 – Maintain Affordability
3a) Minimize impacts to an average single-family customer NPV Unit costs --
$/AF 1,329
3b) Manage Capital Costs NPV Capital costs -- $ 245,265,000
Objective 4 – Increase Flexibility
4a) Increase Number of Take Points and Alternative Flow Routes Total Number of Take
Points 10
Objective 5 – Increase Diversity
5a) Maximize number of sources Total number of
contracts 11
5b) Reduce contribution of largest source 2030 contribution of
the largest source to
total supply - %
78
Objective 6 – Address Environmental and Institutional Constraints
6a) Minimize environmental permitting requirements Permitting Score 3.6
6b) Minimize institutional coordination and implementation requirements
(local/State/Federal/International)
Institutional
Coordination Score 3.8
6c) Maximize customer acceptance Customer Acceptance
Score 4.8
6d) Minimize regulatory constraints Regulatory
Constraints Score 3.8
6e) Minimize technology uncertainty Technology
Uncertainty Score 4.7