The URL can be used to link to this page

Home My WebLink About02-21-24 Board Packet 1 OTAY WATER DISTRICT SPECIAL MEETING OF THE BOARD OF DIRECTORS DISTRICT TRAINING ROOM (LOWER LEVEL PARKING LOT) 2554 SWEETWATER SPRINGS BOULEVARD SPRING VALLEY, CALIFORNIA WEDNESDAY February 21, 2024 12:00 P.M. AGENDA 1. ROLL CALL 2. PLEDGE OF ALLEGIANCE 3. APPROVAL OF AGENDA 4. PUBLIC PARTICIPATION – OPPORTUNITY FOR MEMBERS OF THE PUBLIC TO SPEAK TO THE BOARD ON ANY SUBJECT MATTER WITHIN THE BOARD’S JURIS- DICTION INCLUDING AN ITEM ON TODAY’S AGENDA 5. WORKSHOP a) RALPH W. CHAPMAN WATER RECLAMATION FACILITY’S DISINFECTION SYSTEM IMPROVEMENT PROJECT (SANTOS) b) WATER CONSERVATION GARDEN UPDATE (DIRECTOR ROBAK) RECESS TO CLOSED SESSION 6. CLOSED SESSION a) SECURITY OF PUBLIC SERVICES OR FACILITIES [GOVERNMENT CODE §54957] b) CONFERENCE WITH LABOR NEGOTIATORS [GOVERNMENT CODE §54957.6] AGENCY DESIGNATED REPRESENTATIVES: GARY CROUCHER AND JOSE LOPEZ EMPLOYEE ORGANIZATION: OTAY WATER DISTRICT EMPLOYEES’ ASSO- CIATION 2 AND ALL REPRESENTED AND UNREPRESENTED PERSONNEL, INCLUDING MANAGEMENT AND CONFIDENTIAL EMPLOYEES c) CONFERENCE WITH LEGAL COUNSEL – ANTICIPATED LITIGATION [GOV- ERNMENT CODE §54956.9] RETURN TO OPEN SESSION 7. REPORT ON ANY ACTIONS TAKEN IN CLOSED SESSION. THE BOARD MAY ALSO TAKE ACTION ON ANY ITEMS POSTED IN CLOSED SESSION. 8. ADJOURNMENT All items appearing on this agenda, whether or not expressly listed for action, may be deliberat- ed and may be subject to action by the Board. The Agenda, and any attachments containing written information, are available at the District’s website at www.otaywater.gov. Written changes to any items to be considered at the open meeting, or to any attachments, will be posted on the District’s website. Copies of the Agenda and all attachments are also available by contacting the District Secretary at (619) 670-2253. If you have any disability which would require accommodation in order to enable you to partici- pate in this meeting, please call the District Secretary at 670-2253 at least 24 hours prior to the meeting. Certification of Posting I certify that on February 16, 2024, I posted a copy of the foregoing agenda near the reg- ular meeting place of the Board of Directors of Otay Water District, said time being at least 24 hours in advance of the special meeting of the Board of Directors (Government Code Section §54954.2). Executed at Spring Valley, California on February 16, 2024. /s/ Tita Ramos-Krogman, District Secretary STAFF REPORT TYPE MEETING: Special Board MEETING DATE: February 21, 2024 SUBMITTED BY: Lito Santos Senior Civil Engineer PROJECT: R2117-001103 R2157-001103 DIV. NO.3 APPROVED BY: Beth Gentry, Engineering Manager Michael Long, Chief, Engineering Jose Martinez, General Manager SUBJECT: Ralph W. Chapman Water Reclamation Facility’s Disinfection Capital Improvement Project GENERAL MANAGER’S RECOMMENDATION: This is an informational item only. COMMITTEE ACTION: Please see Attachment A. PURPOSE: To explain the Ralph W. Chapman Water Reclamation Facility (RWCWRF) Disinfection System Improvement Project. BACKGROUND: The Board requested an explanation from staff on how ultraviolet (UV) disinfection works. AGENDA ITEM 5a 2 ANALYSIS: In 1979 the original RWCWRF was constructed and has gone through two upgrades in 1994 and 2013. The current RWCWRF is a scalping wastewater treatment plant, treating the District’s wastewater to produce and deliver tertiary recycled water to the District’s recycled water customers and treating raw sewage offsetting treatment cost for wastewater customers. Since 1994 the RWCWRF’s disinfection process occurs after the primary and secondary treatment processes, where secondary effluent is conveyed through the tertiary filter and the tertiary effluent flows into a contact basin where the disinfection process is initiated. Chlorine addition results in a chemical reaction, when introduced into the contact basin, it disinfects, kills, or inactivates harmful microorganisms. State regulations require a disinfection process that meets 99.999% (5-log) removal of bacteria. This can be done with a 90-minute contact time with chlorine disinfection at a minimum chlorine residual or through a State Board approved equivalent, such as ultraviolet (UV) disinfection. The existing disinfection system at RWCWRF uses only chlorine gas and relies upon the 3-mile-long effluent force main for meeting the plant CT (chlorine concentration times modal contact time) 90-minute requirement, necessitating effluent samples to be performed at the remote end of the pipeline location. Chlorine gas use requires extra safety practices, results in high chlorine residual at the treatment plant, creates a highly corrosive environment, causes the effluent pumps to be repaired and replaced more frequently, and has greatly increased chemical costs over the past several years. Ultraviolet (UV) disinfection is a physical reaction to radiation which transfers electromagnetic energy from a special lamp to an organism’s genetic material or DNA/RNA. When UV radiation penetrates the cell wall of an organism, it destroys the cell’s ability to reproduce. Contact time for a UV disinfection is typically 20 to 30 seconds. UV disinfection does not have a residual byproduct like chlorine, which saves on chemical cost. The new disinfection system will utilize UV disinfection as the primary treatment and sodium hypochlorite, a liquid chlorine, as the post supplemental disinfection. Post sodium hypochlorite will maintain a residual for disinfection and provide a disinfection redundancy in the distribution system. Having both UV disinfection as the primary and sodium hypochlorite as post disinfection is common for plants that have converted to a UV disinfection system. The use 3 of ultraviolet (UV) equipment as the primary disinfectant with a shorter contact time will move the sampling location to the plant as opposed to after the 3-mile-long force main location currently used. Studies have determined the most cost-effective method for improving the disinfection system at the RWCWRF is to convert to a UV process with post sodium hypochlorite treatment. The project will result in reduced chlorine levels in the effluent pump station and force main that is anticipated to extend the life of the pumps, piping, valves, and appurtenances. Lower the chemical cost at RWCWRF and in the distribution system. Removal of the chlorine gas at the plant will eliminate the hazardous material, its transport, associated training, and other administrative work related to it. FISCAL IMPACT: Joe Beachem, Chief Financial Officer None. GRANTS/LOANS: Information only. Not applicable. STRATEGIC GOAL: This Project supports the District’s Mission statement, “To provide exceptional water and wastewater service to its customers, and to manage District resources in a transparent and fiscally responsible manner” and the General Manager’s Vision, "To be a model water agency by providing stellar service, achieving measurable results, and continuously improving operational practices." LEGAL IMPACT: None. LS/BG:jf https://otaywater365.sharepoint.com/sites/engcip/Shared Documents/R2117 RWCWRF Contact Basin Expansion Project/Staff Reports/2024-0221 UV Disinfection (Info)/02-21-24 Staff Report R2117-R2157_LS_BS.docx Attachments: Attachment A – Committee Action Attachment B – Presentation ATTACHMENT A SUBJECT/PROJECT: R2117-001103 R2157-001103 Ralph W. Chapman Water Reclamation Facility’s Disinfection System Improvement Project Special Board Meeting - Retreat/Workshop This is an informational item only. This staff report was reviewed at a meeting held on February 21, 2024. Ralph W. Chapman Water Reclamation Facility(RWCWRF) Disinfection Capital Improvement Project Ultraviolet Disinfection (UV) CIPs R2117 & R2157 ATTACHMENT B Existing Treatment Process Aerial Existing Treatment Process -Profile Chlorine Advantages: •Most common disinfection •Residual can prolong disinfection •Well established technology Disadvantages: •Rising cost •Residual at low concentration is toxic to aquatic life and requires dechlorination. •Highly corrosive •Requires a 90-minute contact time Existing Chlorine Gas •Relies on 3-mile effluent force main to meet 90-minute contact time •High dosage and residual in contact basin creates corrosive environment for effluent pumps •Increased cost of chlorine gas $37,000 in 2021 to $79,000 in 2024 New: UV Disinfection Disadvantages: •Organisms can sometimes repair and reverse the destructive effects of UV through a repair mechanism •Additional maintenance to control fouling Advantages: •Physical process, eliminating need to generate, handle, and transport toxic material •No residual •20-30 Second contact time •Requires less space •Most cost-effective alternative for the District •Proven technology – used at San Diego South Bay Treatment Plant, Olivenhain Municipal Water District Disinfection Improvement Project Proposed Improvements •Install new UV system within the existing contact basin •Replace chlorination from gas to liquid (Sodium Hypochlorite) for post treatment Advantages: •Shorter contact time •Sampling will be moved back to the treatment plant •Most cost-effective solution Questions? AGENDA ITEM 5b