City of Davis Introduction of Surface Water Community Meeting May 5, 2016
WDCWA Project Overview Agenda Water Treatment Process City of Davis Preparation for surface water introduction Construction of transmission main Surface water delivery Water quality How to report concerns Q&A 2
Issues/Concerns 100% Dependent on groundwater Aging water infrastructure Degrading groundwater water quality Increasingly stringent drinking water regulations Increasingly restrictive wastewater discharge regulations Example: Nitrates Example: Hexavalent Chromium Example: Selenium, Salinity 3
Well Shutdowns Woodland Davis Well shut downs Active wells Under Construction 4
Governing Board: 2 council members from each city Non-voting representative from UC Davis and Yolo County FORMED September 15, 2009 JPA Funded Davis and Woodland UC Davis a Contracting Agency User fees in each city; cost sharing based on capacity allocation 5
Project Goals & Objectives Quantity & Quality Regulations Environmental Diversify Sustainable GW Conservation Improve water supply quantity and quality Comply with drinking water & wastewater discharge regulatory requirements Provide environmental benefits and minimize impacts Diversify supply portfolio to improve supply reliability Allow sustainable groundwater pumping integrated with ASR wells Integrate water conservation elements 6
ASR Wells Raw Water Transmission 4.5 miles Local Transmission Treatment Facility 30 mgd Intake/Pumping 400 cfs Water Transmission 9.9 miles Local Transmission 7
Water Supplies ASR/ Supplemental Supplies (primarily Woodland) Municipal Groundwater (Davis: Deep aquifer wells; Woodland: Emergency GW use only) Purchased Water (available Apr Oct; subject to Shasta critical years) Agency Water Right (subject to Term 91 curtailments) 8
9 Source Water 5 15% 85 95% 9
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CLEARWELLS IN-PLANT PUMP STATION FINISHED WATER PUMP STATION OZONATION SAND BALLASTED CLARIFICATI ON FLASH MIX GRANULAR MEDIA FILTERS BACKWASH EQUALIZATION BASINS GRAVITY THICKENERS DRYING BEDS OPERATIONS BUILDING MAINTENANCE BUILDING CHEMICAL BUILDING 12 12
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Overall Process Flow Diagram (PFD) 1 14
City of Davis Surface Water Delivery and Operational Start-up
Outline Preparation for surface water introduction Construction of transmission main Surface water delivery Water quality How to report concerns
Preparation for Surface Water Introduction Studied other cities that converted to surface water Anti-corrosion ph control Zinc orthophosphate Water distribution system flushing Water quality testing
Preparation for Surface Water Introduction Water Distribution System Flushing
Preparation for Surface Water Introduction Water Distribution System Flushing
Preparation for Surface Water Introduction Water Quality Testing ph Hardness Alkalinity Turbidity Color Free Chlorine Het. bacteria plate count Lead Manganese Total chromium Zinc orthophosphate Aluminum Asbestos
Construction Sequence Timing
Timing of Surface Water Delivery
Surface Water Delivery Initiate delivery - June 2016 Initial flow of 3 MGD Increase by 1 MGD every few days during water plant acceptance testing Maximum delivery of 6 MGD through August 2016 Surface water fully integrated by December 2016
Water Quality Water Quality Parameter Existing Groundwater Finished Water (Bryte Bend) Deep Aquifer Wells Magnesium (mg/l) 60 6.4 7-20 Total Hardness as CaCO3 306 (17.5 grains) 56 (3.5 grains) 66-130 (4-7.5 grains) Sodium (mg/l) 84 11 82-100 Chloride (mg/l) 53 6.8 21-30 Sulfate (mg/l) 74 5.1 34-45 Total Dissolved Solids (mg/l) 539 89 310-360 Specific Conductance (EC) 914 59 510-610 Lead (mg/l) < 0.0061 < 0.0005 < 0.0005 Alkalinity (mg/l as CaCO3) 358 60 200-240 Boron (mg/l) < 0.9 < 0.7 0.6-0.9
Water Quality Hardness Water softener use Lead Hexavalent chromium Turbidity and/or discolored water Special concerns Medical concerns Aquatic species
Water Softeners Typical water hardness below 7 grains Personal preference for level of hardness Suggest bypassing for short period of time to assess need Lower grain setting on softener to appropriate level Individual determination to use water softener or not
How to Report Water Quality Concerns Do not report water quality concerns via City website During normal business hours (8-5 M-F) - call Public Works at 757-5686 After normal business hours contact Davis PD at 747-5400 For general questions email PWWeb@cityofdavis.org