City of Davis Conversion of Well #11 from Potable to Irrigation Supply, Challenges and Benefits. Tim Williams, Kennedy/Jenks Consultants Oct 21, 2014

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1 City of Davis Conversion of Well #11 from Potable to Irrigation Supply, Challenges and Benefits Tim Williams, Kennedy/Jenks Consultants Oct 21, 2014

2 City of Davis Background Provides water, wastewater, and stormwater utilities Population 65,000 and 16,672 metered connections 177 miles of 6 through 16- inch water mains Currently 21 Wells, 3 storage 8.3 MG, 2 booster pump stations Transitioning to conjunctive use water system 10.2 MGD surface water and 10.5 MGD deep well water by 2016

3 City is Known for Biketown USA, UC Davis Aggies and Open Space Parks & Greenbelts

4 Drivers to Convert Potable Water Well to Irrigation Well CURRENT OBJECTIVES: Reduce 40 MGD peak demands on Public Water Supply Replace 1.8 MGD surface water supply wheeling to UC Davis Reduce $$ impacts to General Fund Use less expensive water for irrigating large landscaped areas Reduce $$ impacts to Davis Joint Unified School District (DJUSD) Use less expensive water for irrigating large landscaped areas

5 1 st Opportunity 28 Ac. Community Park & DJUSD Athletic Fields with Well #11 Well 11

6 Keys to a Successful Project Determine Well #11 Feasibility to Convert to Irrigation Well Confirm Irrigation Demands by Zone Confirm Irrigation Distribution System Adequate Determine if DJUSD in or out Select Pump Capacity & Head to Cover Demand / Pressure Ranges Conduct X-Connection Survey

7 Well #11 Remaining Useful Life

8 Determine Feasibility to Convert to Irrigation Well Risk Analysis Drilled in 1961, rotary depth, ¼ wall thickness Capacity 1,350 gpm with 100 HP motor (rebuilt 2008) Water quality typical for intermediate wells Hardness 517 mg/l 740 mg/l 20 mg/l 26 ug/l 920 mg/l 9 ug/l

9 Determine Feasibility to Convert to Irrigation Well Risk Analysis Sand producer (Not Detected to 13.2 ppm after 2 hrs) AWWA A100 5 ppm after 2 hrs High specific capacity 51 gpm/ft drawdown Cleaned and Rehabbed Well in 2005 swaged liner repair and installed screen liner repair Pump test % efficiency Estimate Remaining Useful 10 to 15 years City decision - worth the risk

10 Estimate Irrigation Demands No Meters Insert Figure of Irrig Zones

11 Irrigation Demands by Zone Zone # Name No. of Sprinkler Heads Flow/Unit (gpm) 1 Green Belt Demand (gpm) 2 Com Park NW PS 12 to to ND Elem - City 9 to to Com Park SE PS 14 to to Little League Park 11 to to Davis HS ND Elem - DJUSD 9 to to 172 Total 87 to 108 1,383 to 1,679

12 Irrig Water Demand > Well Capacity Prioritize Zone Preference by: 1. Compare Well and Irrigation Water Distribution System Upgrades: Well control modifications Add 13,000 gallon hydro tank Reuse irrigation booster Add irrigation/potable water pipelines 2. DJUSD Willingness to Participate

13 Irrigation Water Dist Improvements

14 Prioritized Combined Irrigation Zones to 1,004 gpm

15 Prioritized Combined Irrigation Zones 692 to 926 gpm

16 Prioritized Combined Irrigation Zones to 1,209 gpm

17 DJUSD In or Out DJUSD guarded yes Cost Sharing to be negotiated Reduce cost: City crews install irrigation/potable water distribution mains City conduct x-connection survey City crews eliminate cross connections

18 Cost of Well #11 & Irrig System Improvements Improvement Quantity Cost Estimate Well Controls & Hydro Tank 6 & 8 Irrigation Pipelines ¾ to 6 Potable Pipelines 1 LS $90K 2,600 LF $215K 3,000 LF $120K Misc Improvements 1 LS $21K Total $446K

19 Developed X-Connection Survey Protocol Confirm tie-in of potable water facilities to existing Community Park water distribution system Determine best approach to separating the two recommend new potable water mains Reuse existing Community Park water distribution as irrigation pipelines Maintain potable water connection(s) as back up for irrigation supply

20 Next Steps Confirm & Design Improvements Existing well pump with hydro tank meets range of demands and pressures Sizing of irrigation water mains to deliver demand at desired pressure Finalize negotiations with DJUSD Construct improvements

21 Any Questions Tim Williams, P.E. Project Manager Kennedy/Jenks Consultants (916)