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Home My WebLink About04.a. Receive Wet Weather UpdatesPage 1 of 7 Item 4.a. F.1-448�411C-S 0 December 11, 2023 TO: ENGINEERING AND OPERATIONS COMMITTEE FROM: PAUL SEITZ, COLLECTION SYSTEM OPERATIONS DIVISION MANAGER GREG NORBY, DEPUTY GENERAL MANAGER - OPERATIONS REVIEWED BY: ROGER S. BAILEY, GENERAL MANAGER SUBJECT: RECEIVE WET WEATHER UPDATES The attached presentation will provide an update regarding the wet weather operations and strategy review. Strategic Plan re -In GOAL TWO: Environmental Stewardship Strategy 1 - Achieve compliance in all regulations GOAL SIX: Infrastructure Reliability Strategy 1 - Manage assets optimally GOAL SEVEN: Innovation and Agility Strategy 3 - Be Adaptable, resilient, and responsive ATTACHMENTS: 1. Presentation December 11, 2023 EOPS Regular Committee Meeting Agenda Packet - Page 19 of 27 Page 2 of 7 Wet Weather Operations & Strategy Review Engineering & Operations Committee December 11, 2023 Greg Norby Deputy General Manager - Engineering & Operations Table of Contents December 2022 - January 2023 Storms: Event Recap and Lessons Learned 2. Overflow Basins - Volume Estimation 3. Wet Weather Flow Modeling and Collection System Upgrades 4. Wet Weather Capacity Projects in 10-Year Capital Improvement Plan (CIP) 5. Pending & Future Initiatives to Adapt to a Changing Regional Hydrology 0 r December 11, 2023 EOPS Regular Committee Meeting Agenda Packet - Page 20 of 27 1 Page 3 of 7 December 2022 - January 2023 Storms: Event Recap 10-20 inches of rain, 6 main storms over 3 weeks. Wettest 3 weeks in the Bay Area since 1862. Statewide $30 billion in damages, 20 deaths. No observed Collection System overflows. No National Pollutant Discharge Elimination System permit violations. Treatment and storage nearly maxed out. Central San performed well under historic conditions, a credit to decades of planning and investment. MMA December 2022 - January 2023 Storms: Lessons Learned Importance of preventative maintenance for operational reliability during peak events. Ensure emergency equipment is ready to be deployed. Allocate additional on -call staffing. Improve systems for monitoring and transferring of flow between wet weather basins and returning to treatment. Plan for high grit load handling. Importance of integrating capacity improvements with Capital Projects planning. Past performance is no guarantee of future results, hydrologic conditions are changing. December 11, 2023 EOPS Regular Committee Meeting Agenda Packet - Page 21 of 27 2 Page 4 of 7 Overflow Basins - Volume Estimation* Prior estimate was approximately 172 million gallons (MG) total capacity with 6 inches freeboard. New topographic survey in 2022 to verify volume. New estimate is 163 MG with 6 inches freeboard or 127 MG with 2 feet freeboard. Freeboard of 2 feet recommended for design criteria under a 20-year storm. With ultraviolet (UV) upgrades and localized low spots improved, basins may be able to handle a 20-year storm. *All volumes are exclusive of Basin A South, which is not used due to concerns with contaminated soils under the engineered soils cover. Wet Weather Flow Modeling and Collection System Upgrades Central San invested in major update to hydraulics/hydrology model in 2015-2017. Conducted wet weather flow monitoring for inflow and infiltration (I&I) characterization. Assessed trunk lines and local pipes for adequate capacity. Developed updated service criteria of 20-year storm for relief - sewers. Identified areas of improvement to meet higher flow capacity: 6.5 miles of pipe replacement ranging from 12 inches to 24 inches. 1�21 Broken into 20 projects: 3 complete, 1 in design, and 16 pending. December 11, 2023 EOPS Regular Committee Meeting Agenda Packet - Page 22 of 27 3 Page 5 of 7 Wet Weather Capacity Projects in 10-Year CIP Current Projects: UV Disinfection Replacement and Hydraulic Improvements - treatment of up to 140 million gallons a day (MGD), primary and disinfection. Estimated investment of $70 million (M). Walnut Creek/Grayson Creek Levee Rehab - protect basins and treatment plant from flooding. Estimated investment of over $4 M (estimate being updated). Wet Weather Basin Improvements - several improvements identified over three phases. Estimated investment of $6 M. Wet Weather Capacity Project Fiscal Year 2024-25 Phase 1 of the Wet Weather Basin Improvements: 1A— Monitoring Cameras and Level Instrumentation 1B — Dichlorination Building Demolition 1C— Basin B and C Gate Structure 1D — Basin C and D Low Spot 1E — Basin D Cleaning 1F — Control Structure A and B Improvements 1G — Drainback Mechanical Screen 1H — Basin A North Improvements 1.1 — Earthen Channel Geomembrane Liner December 11, 2023 EOPS Regular Committee Meeting Agenda Packet - Page 23 of 27 4 Page 6 of 7 Wet Weather Capacity Projects in 10-Year CIP Future Projects, Phase 2 and 3: Basin Flow Management starting in Fiscal Year 2029-30. Estimated investment of $15.5 M. Includes drainback pumping, raw diversion pipeline, and improved grading and basin drainage. wine sw rrwwNP � IwYAtR NFNY�� ewP uEf yrP Nai[ Lehi m IUMSA mr 1r 4-M. 01P� tlMPfM1 1Pl!_ I� nN. x. _ww,.f pv wQ t.. N'KN1 - NRi.io NutNuoNP1[ule�� 4 s �Cr-6e fCSMCP v �� r�anssv['e�ua� nezarroec uH El. HMY'4 NNMI iieslWN f_ PMIN'V MrNP lie s NePf i rvn N[Yt N Ip NaNIKIO N^J �neuC[rM5 Y9 PF[CYiRI®�IJW. �PEfI xi[m�lb� 4bIPP iP[+ ..: L' M1W n£14S YC KL dOEfID Pending & Future Initiatives to Adapt to a Changing Regional Hydrology Storm intensities estimated to increase up to 30%+ based on "downscaled" global climate modeling for Bay Area. Building bigger pipes, pumps, and plants is not sustainable. Advanced Quantitative Precipitation Information radar network near full deployment, 6-hour high accuracy local forecast for Central San service area. Bay Area Clean Water Agencies cooperative pilot in early discussion. Flow monitoring network deployment for I&I and wet weather flow monitoring. Build off findings from 2015-17 monitoring/modeling to target wet weather loading hot spots. I&I reduction through lateral program and gravity sewer repair and replacement. Artificial intelligence/machine learning for real time forecasting and operations decision support. Refine treatment/storage operational strategies to optimize capacity as major plant investments (UV, secondary clarifiers, etc.) are made. December 11, 2023 EOPS Regular Committee Meeting Agenda Packet - Page 24 of 27 5 Page 7 of 7 Questions andDiscussion 0OW December 11, 2023 EOPS Regular Committee Meeting Agenda Packet - Page 25 of 27 6