1. Colorado Springs’ ASR Program Presented by Cortney Brand Western Water Workshop, Gunnison, CO July 28, 2005

2. Outline  Colorado Springs’ Water System  Long-Term Water Supply Plan  Denver Basin Aquifers  Benefits of ASR  ASR Operational Concept  Feasibility Investigation  Long-Term Testing  Next Steps Rampart Reservoir

3. Colorado Springs’ Water System  Serve water to approx. 410,000 people  97% surface water (primarily snowmelt)  3% alluvial and bedrock groundwater  Extensive network of diversions, tunnels, reservoirs, pipelines and canals  Can deliver 110,000 AF/yr from 200 miles away  Current demands of 80-90 KAF/yr, projected to be 180 KAF/yr by 2040  includes existing and planned DSM programs

4. 2 3 5 4 1 6 S. Platte R. Arkansas R. Continental Divide Supply Systems 1.Local (1800’s – present) 2.Blue R./S. Platte (50’s) 3.Homestake (60’s) 4.Fry-Ark (60’s) 5.Twin Lakes (70’s) 6.Colorado Canal - Exchange (80’s) Colorado Springs Blue River Pipeline Homestake Pipeline FVA Pipeline

5. Long-Term Water Supply Plan  New major delivery system – Southern Delivery System (SDS)  43-mile, 66-inch pipeline from Arkansas River  Delivery capacity of 78 MGD  Online by around 2011-12  Bridge gap by:  Local water system improvements  Nonpotable water development & distribution  Groundwater development & ASR

6. Denver Basin Aquifers  Extensive sedimentary bedrock aquifer system  Non-renewable  Underlies ~7,000 mi 2 area (40% of Colorado Springs)  Relatively low transmissivities and well yields  Colorado Springs has 15 Denver Basin wells  Delivery capacity of 3,600 AF/yr  Used for supplemental potable supply and irrigation (parks, etc.) Colorado Springs Denver Basin

7. Why Pursue ASR?  Unique (for Front Range) combination of surface and groundwater supplies and infrastructure  Additional water storage capacity  Leverage investment in groundwater supply infrastructure  Use off-peak capacity in treatment plants and pipelines  Bank water for future dry years  Improve sustainability of Denver Basin groundwater  Diversify water supply portfolio (risk mitigation)

8. Inject into aquifers ASR Operational Concept October – April (Inject/Store) Proactively Deliver from Reservoir Storage (make space to capture spills) Treat Pipe to wells

9. ASR Operational Concept May – September (recover) Recover Water Disinfect Deliver to Tanks

10. ASR Feasibility Investigation  Conducted Fall of ’04  Injection/recovery testing at two wells  Water sampling & analysis  Geochemical modeling  ASR water availability analysis  Used supply system Operations & Yield model to quantify “spills”  Conceptual plan for implementing ASR

11. ASR Testing Results  Arapahoe Well  Injection rate of 500 gpm (pumping rate of 600+ gpm)  No water quality concerns  Denver Well  Injection rate of 75 gpm (pumping rate of 75+ gpm)  Potential recovered water quality concerns  Need pH adjustment Northgate Tank Site

12. ASR Water Availability Short-term goal (5 yrs) Ultimate goal (10 yrs)

13. Long-Term Testing  Started in July – complete in December  Objectives  Determine sustainable, long-term injection rates  Verify water quality  Determine backwash frequencies  Arapahoe Well 500 gpm 3 months injection 2+ months recovery  Denver Well 50-75 gpm pH adjustment 2 injection/recovery cycles

14. Next Steps “Crawl, Walk, Run” 1.Evaluate long-term testing results 2.Operate Northgate ASR facility in 2006  Will recovered water need to be re-treated?  Can we maintain injection rates?  Is the system easy to operate?  Develop and implement water accounting practices 3.Retrofit additional wells 4.Work toward goal of 2-3 KAF/yr capacity by 2010

15. Questions?