City of Kerrville Aquifer Storage and Recovery System; A Drought Management Tool

1. Texas Innovative Water 2010 October 11-12, 2010 San Antonio, Texas City of Kerrville Aquifer Storage and Recovery System; A Drought Management Tool Stuart Barron/City of Kerrville, Texas James Dwyer, P.E. /CH2M HILL, Austin, Texas

2. Presentation Outline • ASR Concepts • Supply & Demand • Typical Applications • Regulations • Kerrville ASR • History & Phasing • Hydrogeology • Technology • Current Status

3. Water Supply and Demand • Southern and Western US • High Population and Demand Growth • Stressing Existing Water Supplies • Climate Change • Changing Precipitation Distributions • More Extreme Events • Longer Droughts • Warmer Temperatures Projected Demand Projected Supply

4. Options for Storage • Surface Reservoirs • Historical solution to enhanced availability • Regulatory, economic, political obstacles to new construction • Costs have increased • Lead times increased 10 to 20 years • Aquifer Storage and Recovery • Generally maintains quality of stored water • Can reduce required peak capacity of WTP • Reduced environmental impact • Fewer obstacles, faster, more flexible implementation • Control of stored water an issue

5. Monthly Demand Annual Average Demand ASR Recovery ASR Storage ASR Storage J F M A M J J A S O N D Months ASR Project Concept • Traditionally Annual Demand Fluctuations • Multi-year Storage for Long-Term Drought Protection • Optimization of Available Supply Injection Cycle Recovery Cycle

6. Raw Water Withdrawal Raw Water Storage Water Treatment Plant Treated Water ASR Well Treated Water Storage Typical ASR Elements

7. Texas Regulatory Considerations • Surface Water Rights • Groundwater Law • Underground Injection Control • Public Drinking Water Rules

8. Texas Surface Water Rights • Surface water belongs to the State • State grants the right to use the water • Appropriated water rights • How much • When • For what purpose

9. Texas Groundwater Law • Rule of Capture • Groundwater is the private property of the Land Owner • Texas Supreme Court 1904 • Houston & T.C. Ry Co. v. East 81 S.W.279 • Reaffirmed in Sipriano v. Great Spring Waters of America, Inc. 1 S.W. 3d 75 (Ozarka Case) • Limitations • May not pump to maliciously harm neighbor • May not use in wasteful manner • May not use in negligent manner so as to cause land to subside/settle

10. Groundwater Engineering and Science • “Because the existence, origin, movement, and course of such waters, and the causes which govern and direct their movements, are so secret, occult, and concealed that an attempt to administer any set of legal rules in respect to them would be involved in hopeless uncertainty, and would, therefore, be practically impossible.”

11. Groundwater Conservation Districts • Local Management of Groundwater Resources • climatic conditions • water use patterns • growth projections • aquifer characteristics • Comprehensive Management Plans • Associated Rules • Well spacing • Production limitations • Exporting water outside the district • Permitting and Data Collection

12. Class V Injection Wells • Texas Commission on Environmental Quality UIC • Miscellaneous group that does not fit into the other four injection well classes. • Underground Source of Drinking Water • Supplies any public water system • Contains sufficient water <10,000 mg/l TDS • Not an exempt aquifer • Generally inject non-hazardous fluids into or above an underground source of drinking water • Authorized by rule • Usually do not need permit • Must submit inventory information

13. Public Drinking Water • Texas Commission on Environmental Quality • Required offsets from potential pollution • Minimum construction standards • Plan review process

14. Project Location

15. Kerrville ASR History • Dependence on Groundwater until 1980 - Declining Trinity aquifer level • Late 1980’s - Considered Guadalupe River Water Treatment Plant expansion with off-channel reservoir • Alternative - store treated surface water from the Guadalupe River underground • Phase 1 Feasibility 1988 • Phase 2 Full-Scale Testing, ASR-1 1992 • ASR-2 Construction 2001, operational in 2002 • ASR-3 Under construction, planned completion 2011

16. Recent Kerrville Water Statistics • 80%-90% of Water from Guadalupe River • 3 permits total 5922 ac-ft/yr (1930 MG) • Balance from Trinity Aquifer Wells • 5.55 mgd (6.15 MGD with Emergency Well) • 5.2 mgd Conventional WTP Capacity • 1.0 mgd Membrane Expansion • Total Annual Raw Water Demand • approx. 1,400 MG/yr

17. Cow Creek Limestone Pre-Cretaceous Rock South Geologic Section South North North Approximate Approximate Ground Surface Ground Surface ASR-1 ASR-1 1800 Guadalupe River Guadalupe River 1600 Hosston-Sligo Upper Member of Potentiometric Surface Glen Rose Limestone 1400 Lower Member of Glen Rose Limestone Hensel Sand 1200 Hammett Shale (Confining Layer) Hosston and Sligo 1000 Formations

18. To Pump Distribution WTP Clearwell Recharge Recharge FE Line Line Recovery Recovery Monitoring Monitoring Line Line FE ASR-1 ASR-1 Wells Wells Upper Member of Injection Tubes Glen Rose Limestone 495’ 16” T&C Steel Lower Member of Casing Glen Rose Limestone Submersible Pump Hensel Sand Cow Creek Limestone Hammett Shale (Pine Island) 12” Open Hole Hosston and Sligo Formations 125’ Recovery Recharge Recovery Recharge Schematic of ASR 1

19. ASR 1 Operation • Treated water from Stadium Drive HSPS • 200 to 700 gpm through recharge tubes • Monthly backflushing during recharge to restore capacity • Recovered water disinfected at wellhead • 1000 to 600 gpm rate • Initial recovery to storm sewer • Switch to clearwell for distribution

23. FE To/From Chlorine Feed Chlorine Feed Distribution Upper Member of 13 / ” 3 8 Glen Rose Limestone T&C Casing Lower Member of Glen Rose Limestone 495’ Hensel Sand Cow Creek Limestone Hammett Shale (Pine Island) Hosston and Sligo Formations 75’ 20” Open Hole Ellenburger Ellenburger Schematic of ASR 2

24. Operation of ASR 2 • Treated water from distribution system • Up to 400 gpm (through the pump) • Monthly backflushing to restore capacity • Recovered water disinfected at wellhead • 600 gpm Rate • Initial recovery to storm sewer • Delivered directly into distribution system

32. 281 MG

33. Technical Issues • Application Feasibility • System Water Balance • Hydrogeology • Capital and Operations Costs • Integration • Test Wells • ASR Design • Well • Wellhead • Wellfield • Testing • During Construction • Post Construction • Long-Term Monitoring

34. ASR Cycle Testing • Multiple Cycles of Injection and Recovery • Evaluate Hydraulic Performance • Injection of non-native water can alter the borehole near the well • Evaluate Recovery Efficiency • Water Chemistry Interactions and Mixing • Data Collection • Flow Rate • Water Levels • Water Quality

35. Recovery Efficiency • Importance • Loss of Injected Water • Increase in Treatment Requirements • Factors • Mixing • Chemical Reactions • Regional Groundwater Gradients • Determination • Conservative Chemical Constituents • Native vs. Stored Water

36. Summary • Kerrville was one of the first communities to utilize ASR • Significant savings over surface reservoir/WTP expansion • ASR can be implemented at different scales and in phases • Currently, Kerrville has banked a large supply of treated water to protect against a long term drought • Design of ASR 3 is underway

37. Questions?