Colorado Springs’ ASR Program

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

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. Colorado Springs Denver Basin Aquifers • Extensive sedimentary bedrock aquifer system • Non-renewable • Underlies ~7,000 mi2 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.) 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. Treat Pipe to wells ASR Operational Concept October – April (Inject/Store) Proactively Deliver from Reservoir Storage (make space to capture spills) Inject into aquifers

9. ASR Operational Concept May –September (recover) Disinfect Recover Water 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” • Evaluate long-term testing results • 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 • Retrofit additional wells • Work toward goal of 2-3 KAF/yr capacity by 2010

15. Questions?