1. © 2009 Malcolm Pirnie, Inc. All Rights Reserved An Assessment of Aquifer Storage and Recovery in Texas 66 th Annual Convention Texas Water Conservation Association March 4, 2010 Fred Blumberg Senior Associate Malcolm Pirnie, Inc.

2. Outline Introduction to ASRTWDB Priority Research ProjectCase Studies from TexasSummary

3. ASR is defined as: “…the storage of water in a suitable aquifer … during times when water is available, and recovery of the water … during times when it is needed.” -David G. Pyne, P.E. ASR Systems, LLC Gainesville, FL

4. Recharge Alternatives Include…  Basins, channels  Vadose zone wells  Injection wells

5. Native Ground Water Native Ground Water Confining Layer Buffer Zone Buffer Zone Stored Water Stored Water Target Storage Volume ASR Well

6. Over 22 ASR Applications Storage Seasonal/Peaking Long-Term Emergency Water Quality DBP Reduction Nutrient Reduction Temperature Control Reclaimed Water Storage / Reuse Defer Expansions Maintain distribution system flow / pressure Peaking Irrigation water supply Aquifer Protection Reduce drawdown Maintain springflow Pollution plume cutoff

7. Sources and Storage Zones  Water sources: Potable water Reclaimed water--treated Seasonally-available stormwater--treated Groundwater from overlying, underlying or nearby aquifers  Storage zones Fresh, brackish and saline aquifers Confined, semi-confined and unconfined aquifers Sand, clayey sand, gravel, sandstone, limestone, dolomite, basalt, conglomerates, glacial deposits Vertically “stacked” storage zones

8.  Minimal evaporation  Fewer environmental impacts  Competitive cost (capital cost ≈ $1.25/gallon/day of capacity)  Flexibility--incremental well addition ASR Advantages  Supplementation of other water supply strategies  Broad range of applications and geographic settings

9. ASR Operating Ranges  Well depths 30 to 2700 feet  Storage interval thickness 20 to 400 feet  Storage zone TDS 30 mg/l to 39,000 mg/l  Storage Volumes 100 AF to >270,000 AF  Bubble radius less than 1000 ft  Individual wells up to 8 MGD  Wellfield capacity up to 157 MGD Calleguas MWD, Thousand Oaks, California ASR Well

10. ASR Considerations/Constraints  Recharge water quality and pretreatment requirements  Water quality in receiving aquifer (e.g., TDS, Fe, Mn, pH)  Land availability and cost  Recovery efficiency  Public understanding  Legal / regulatory framework

11. ASR Development Phases  Feasibility Assessment & Conceptual Design Water supply and demand—source, reliability, variability Hydrogeology and modeling Site selection, regulations and conceptual design Target storage volume (TSV) Cost estimate Test program outline  Field Investigations & Test Program Exploratory well Baseline and cycling tests Data collection  Recharge Facilities Expansion Well spacing and design Construction and O&M

12. Operational ASR Wellfields (~ 95 in 2009)

13. TWDB Priority Water Research Topics Project  TWDB funding for topics of recognized importance  ASR Project Objectives:  Review the current state of ASR implementation  Evaluate technical and legal issues limiting broader application of ASR in Texas  Provide education on ASR and its potential applications as a water resource tool in Texas  Peer review by USBuRec

14. Study Team  Malcolm Pirnie, Inc.  ASR Systems, LLC  Edmond McCarthy, Jr., JD  Existing ASR Utilities in Texas San Antonio Water System (SAWS) El Paso Water Utilities (EPWU) City of Kerrville

15. TWDB ASR Research Project  Legal White Paper --- presenting public policy perspectives  Interviews / Site Visits with 3 Participating Utilities Kerrville SAWS EPWU  Survey of Other Utilities  Review of literature and US/global practices  Presentations and guidance for implementation

16. San Antonio Water System OBJECTIVES: Began as seasonal storage reserve; transitioned to long-term storage  3 rd largest ASR project in U.S.  29 ASR wells  Capacity: 60 mgd  Source: Groundwater from the Edwards Aquifer  Storage zone: Carrizo Aquifer  Current Volume: >70,000 AF Operation began in 2004

17. Twin Oaks ASR Facility Carrizo Aquifer  Confined aquifer  pH 5.5  Elevated Fe/Mn and hydrogen sulfide  Project includes 3 local Carrizo wells Water treatment available to remove Fe/Mn, adjust pH, and provide disinfection To date, only disinfection has been needed for recovered ASR water

18. City of Kerrville OBJECTIVES: Storage for drought management and peaking  2 nd ASR project in Texas (1995)  2 ASR wells (3 rd in development)  Capacity: 2.65 mgd  Source: Treated surface water from Guadalupe River  Storage zone: Lower Trinity Aquifer  Max Volume to Date: 2,100 AF

19. El Paso Water Utilities OBJECTIVES: Restore GW levels; store reclaimed water; improve WQ; supply peaking water  1st ASR project in Texas  4 ASR wells and 4 basins  Capacity: ~10 mgd  Source: Treated wastewater from Fred Hervey WRP  Storage zone: Hueco Bolson Aquifer

20. EPWU—Fred Hervey WRP

21. Summary ComponentEPWU (10 mgd) Kerrville (2.65 mgd) SAWS (60 mgd) Date198519952004 Source WaterTreated Wastewater Treated River Water Groundwater Storage300-835 feet Hueco Bolson 495-613 feet Lower Trinity 400-600 feet Carrizo Issues  Original well design  Customers for reclaimed water  Litigation during permitting  Lack of source water  Single pipeline  Distribution system limitations Expansion Plans Expanding FHWRP Constructing 4 th spreading basin Adding 3 rd ASR well WTP expansion in Regional Plan Part of 50-year Management Plan Evaluating TSV

22. Initial Utility Survey—Why ASR Has Not Been Pursued

23. ASR Seminar  Fall 2010  San Antonio, TX  Participants Texas Water Development Board U.S. Bureau of Reclamation Malcolm Pirnie ASR Systems

24. Questions Fred M. Blumberg Senior Associate Malcolm Pirnie, Inc. 512-370-3865 fblumberg@pirnie.com