BPU Study Session O t b October 18, Utilities Department

Transcription

1 Basic ASR Wells 101 BPU Study Session O t b October 18, 2012 Utilities Department

2 Today s Presentation 1. What is ASR 2. What are the benefits of an ASR program 3. Implementing a feasibility study 4. Case study

3 ASR is the Use of a Specially Designed Well To Inject and Extract Potable Water From A Target Aquifer The same well is used for injection & extraction Treated, potable water is the source water for injection Source water can be taken anywhere in the distribution system

4 How can ASR be Utilized? Groundwater banking Seasonal storage of excess waters Drought or emergency reserves Establish or preserve water rights Increase safe yield of basin Offset peaking demands Stabilize water quality Optimize transmission network capacity Increase basin storage capacity Offset adverse affects from climate change

5 Implementing a Feasibility/ Pilot Demonstration Study natural environment. As such, each ASR is an engineered adaptation to the project is constrained by the unique character of its environmental setting, including the source water quality, local geology, and aquifer geochemical characteristics.

6 Implementing a Feasibility Study Determine needs and goals of program Evaluate local hydrogeology, source water quality, and system hydraulics from historical records Identify and fill-in data gaps Evaluate existing facilities for candidate pilot demonstration testing

7 Implementing a Pilot Demonstration Study Complete Planning & Permitting for pilot demonstration testing Perform pilot demonstration testing Evaluate data and plan full scale/permanent ASR program OR perform additional studies Permitting of full scale program

8 ASR Technical Feasibility is Affected by Three Main Factors Aquifer Characteristics Transmissivity Specific Capacity Hydraulic Conductivity Storativityti it Basin Freeboard Depth to Water, Confining Layers Geochemistry Saturation, Stability, Gas Evolution, Leaching, Redox, Bioactivity, Ion Exchange

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10 Pilot Testing Alternatives Testing can be performed on most any wells, subject to piping, i well casing, pump capacity, and back-flushing capabilities However Pilot testing of existing facilities may present limitations on test program results Single-aquifer wells with nearby monitoring wells (< 100ft.) are most desirable

11 Pilot Testing vs Data Quality Short term (1-3 week) results: Aquifer response Well plugging rate Initial water quality issues (Ppt, IX, Gasses) Intermediate (3-6 month) results: Migration and dispersion factors Long-term plugging response/restoration Intermediate water quality issues (Redox, Bio, DBP s*)

12 Pilot Testing vs Data Quality Long term (1-3 year) results: Regional aquifer response Drift, migration, and capture Well performance decline and rehabilitation restoration Full water quality interaction, dilution/mixing, geochemical stabilization ti

13 Importance of Geochemistry Rigorous Geochemical Analyses needed for CEQA, RWQCB, and Public support Geochemical issues include: Adverse g geochemical reactions DBP degradation Ion Exchange Redox shifts Bioactivity Leaching potential

14 Importance of Aquifer Monitoring Well Plugging Rates Can Vary Significantly Well Plugging Can Increase Exponentially

15 Application of Monitoring Determine Normal vs Abnormal Plugging Rates Establish Backflushing and Rehab Triggers Monitor Restorative Performance from O&M Activities Once Lost Well Performance Once Lost, Well Performance Can t Always Be Restored

16 Determination of Well Plugging Rates 20 Injection Plugging Analysis 30 pth to Water, feet De 40 'Plugging' Drawup Theoretical Drawup Elapsed Time, minutes

17 Time Series Water Quality During Well Back Flushing

18 Time Series of City Water Main Flushing Prior to Well Injection 150 min. 120 min. 90 min. 60 min. 30 min.

19 Cost Implications Conventional vs. ASR Wells Well Cost Only 4 MGD Well, S.C. = 40 gpm/ft, 600 ft. TD

20 Case Study - MPWMD Bad News State Board orders CAW to terminate take of 10,750 AFY from Carmel River Determination made that winter diversions are OK (subject to minimum flow req s) eqs) Good News Feasibility study identifies nearby Seaside Basin has freeboard of over 20, AF Tsm aquifer has 370 swl and sc >50 gpm/ft

21 MPWMD ASR Project 1999: Shallow pilot test results for injection and geochemistry favorable 2001: Deep 18 demonstration well injection rates of 1500 gpm and production rate of 3,000 gpm confirmed : Long-term testing

22 2008: Second deep well constructed (2,000 gpm / 4,000 gpm yield) 2010: Third ASR well constructed performance testing in progress

23 Water Resources on the Monterey Peninsula

24 CARMEL RIVER CONDITIONS

25 Monterey Peninsula ASR Concept

26 (1982)

27 SEASIDE BASIN CONDITIONS

28 ASR Proof-of-Concept 1996

29 Shallow Pilot Scale Project 1998

30 ASR Concept Planning Success Joint Agency approved funding for full-scale Demonstration Well in 2000 Site acquired for $1000 from US Army Plan called for siting well adjacent to groundwater basin depression

31 Hydrogeologic Success Demonstrated Well Yield» 1,500 gpm injection» 2,500 gpm extraction water quality maintained during aquifer storage

32 Hydrogeologic Success well backflushing program effectively controls plugging

33 Hydrogeologic Success Well performance maintained throughout 6-month injection season via engineered backflushing operational schedule and instrumentation.

34 Questions s and Discussion BPU Study Session O t b October 18, 2012 Utilities Department