Presentation Outline

1. Aurora’s Prairie Waters Project – A Sustainable and Innovative Water Supply SolutionColorado State UniversitySeptember 17, 2007Mark Pifher/Aurora Water

2. Presentation Outline • Background and Need • Project Alternatives & Integrated Resource Planning • Selected Alternative • Prairie Water Project Overview • PWP Key Components • Purification Strategies • Cost Estimates

3. South Platte River Colorado River Arkansas River

4. A Water Supply Crisis for Aurora 26% of Annual Demands in Storage

5. Prairie Waters Project Provides Drought Hardening and Meets Long-Term Capacity Needs

6. Aurora Conducted Comprehensive Integrated Resource Planning • 50 potential projects • Range of individual project yields: • 2,000 to 48,000 acre-feet / year • Basins of Origin: • Colorado River • Arkansas River • South Platte River • Demand Management Included with Water Supply Forecasts

7. Integrated Resource Plan Considered Key Criteria in Evaluation of Water Supply Options • Capital/Operating Cost • Institutional/Government/Public Issues • Environmental/Permitting Issues • Sustainability • Expandability • Yield • Schedule Risk

8. Institutional Hurdles A. Federal permits/approvals (e.g., 404, section 7) B. Federal facilities (e.g., Bureau of Reclamation) C. NEPA reviews D. Local permitting (e.g., land use regulations) E. Local politics (e.g., ag to urban transfers, transbasin diversions) F. Public perception G. HB 1177 Roundtable Process

9. Regulatory Issues A. SDWA Requirements 1. MCLs 2. SWAP 3. Treatment Requirements (WQCD) 4. TDS Levels (Citizens) B. DFlows and Discharge Permits C. “New” Water Quality Standards (includes temperature and emerging contaminants)

10. Regulatory Issues D. “New” Aquatic Life Tiers E. R/O Brine Disposal F. 404 Permit and 401 certification G. ESA Issues (flows, mice, prairie dogs, eagles) H. South Platte TMDL Efforts

11. Aurora’s Prairie Waters Project

12. Aurora’s New Water Supply Project 34 miles of 60-inch pipeline 3 pumping stations North Campus (bank filtration and aquifer recharge and recovery) 50-mgd water purification facility

13. Water Quality Considerations for Prairie Waters Project (PWP) Supply Pathogens Micro-pollutants Endocrine Disrupting Compounds and Persistent Pharmaceuticals N- nitrosodimethylamine (NDMA) TDS Total Organic Carbon (TOC) Nitrate Phosphorus

14. Comparison of Quality of Aurora’s Water Supplies

15. Aurora Water Quality Goals Nitrate < 2 mg/L TDS < 400 mg/L Hardness < 150 mg/L TOC < 4 mg/L DBP concentrations no more than current supply NDMA < 10 ng/L Reduce concentration of micro-pollutants and pharmaceuticals Use a natural purification systems as initial purification step

16. Dr. Ken Carlson Dr. Gary Amy Dr. Jörg Drewes SPP’s purification systems supported by Colorado’s experts

17. Softening Challenges Taste and Odor Color TDS Nitrate Pathogens Organics Micro-Pollutants Combining the Best of Natural and Engineered Purification Steps

18. Riverbank Filtration (RBF) (10 days travel time) Aquifer Recharge & Recovery (ARR)(30 days travel time) Prairie Waters ProjectNatural Purification Systems

19. Riverbank Filtration (RBF) Field Testing Travel time – approx 10 to 15 days Water quality testing TOC, turbidity, nutrients (e.g., nitrogen, phosphate) Organic micropollutants Pharmaceutical Personal care products and other trace Endocrine Disrupters Emerging contaminants 0 m 100 m

20. Aquifer Recharge and Recovery Testing • Feedwater from RBF site • 25 Monitoring wells • 3 nested piezometer wells • 4 production wells • Water quality testing: • Bulk parameters (TOC, pH, conductivity, nitrate, ammonia) • Organic micropollutants

21. RBF and ARR are reliable sustainable/natural purification processes • Nitrate reduced to < 2 mg/L in RBF with 10 days of travel time • Many trace organics and pharmaceuticals are removed (>80%) through RBF and ARR • Phosphorus removal will require amendments to ARR to adsorb phosphorus • Some persistent organics (flame retardants) are not well removed though biodegradation • NDMA removal is significant at travel times > 20 days

22. Flow 4000 11 TOC S. Platte 10 TOC RBF water PTW1 3500 9 3000 8 7 2500 6 2000 flow (cfs) TOC concentration (mg/L) 5 1500 4 3 1000 2 500 1 0 0 1/1/2005 2/1/2005 3/1/2005 4/1/2005 5/1/2005 6/1/2005 7/1/2005 8/1/2005 9/1/2005 1/1/2006 2/1/2006 3/1/2006 4/1/2006 5/1/2006 10/1/2005 11/1/2005 12/1/2005 RBF Field Monitoring - TOC

23. 12.00 Platte PTW1 10.00 8.00 -N (mg/L) 6.00 3 NO 4.00 2.00 0.00 2/4/05 3/1/05 1/10/05 1/20/05 2/10/05 2/17/05 3/10/05 3/29/05 4/21/05 5/13/05 5/24/05 6/21/05 7/29/05 8/17/05 8/31/05 9/15/05 1/10/06 2/14/06 7/18/05 10/06/05 10/25/05 Consistent Removal of Nitrate Through Denitrification in RBF

24. RBF/ARR Combination Removal of Selected Pharmaceuticals

25. Amendments to ARR to Reduce Phosphorus

26. Prairie Waters Project Cost Estimates

27. Why is this the right project for Aurora and Colorado? • Responsible Use of Resources • Reduces the need for trans-basin diversions from Western Slope • Maximizing use of an in-basin renewable resource • Uses water rights already owned by the City of Aurora • River Water Quality Benefits • Minimizes need for a waste discharges such as brine from (RO) • Uses natural treatment systems • Environmental Benefits • Avoids the impacts to wilderness landscapes • Maintains rural open space and river corridor habitat • Protects Public Health • Improves reliability of Aurora’s purification processes • Can address changes in water quality • Exceeds current regulations and meets Aurora’s high standards • Can respond to changes in water quality • Cost Effective and Practical • Reduces cost of purification • Maximizes use of $300 million in water rights already owned by the city

28. Project Supporters: Environmentalists, Farmers, Businesses, Water Quality Experts

29. Questions?