1. Recycled Water Distribution System Challenges Lee Cesario, P. E. Denver Water lee.cesario@denverwater.org

2. Challenges Recycled water systems are in some ways different than potable systems. –Demand Patterns/Scheduling –Design –Construction –Operations –Regulations –Changes for the Utility

3. Distribution System Components Treatment Storage –Reservoirs/tanks, ponds Pumping –From storage and from pipe Piping –Transmission, distribution, service lines Dechlorination Valves –Control, pressure regulating, line (isolation), –Air valves, blow-offs

4. System and Potential Customers

5. Customers Potential Customers –Proximity –Combinations of customers along route –Changing circumstances Working with the Customer –Regulations Applicator Plan to Comply Notice of Authorization –Inspections –Annual Training Contract?

6. Customer Demands CustomerDemand Pattern –Golf coursecontinual (with pond) –School2-3 nights/week –Parkcontinual, at night 2-3 nights/week –Industrialcontinual or irregular Scheduling –Balance the demand over time –Less of an issue early on, critical near buildout

7. 2004 RECYCLED WATER SYSTEM WATERING SCHEDULE April 1 through October 1 CustomerPeakGeneralSunMonTueWedThurFriSat DemandSchedule GPM Bruce Randolph MS300TWTrFSa - 8 hrs per day300 Dunham Park270MWF - 8 hrs per day270 Shafer Park110TTrSu - 8 hrs per day110 Swansea Park120MTF -8 hrs per day120 Denver Zoo (3)250Every day - Midnight-6PM250 Park Hill GC340Every day - 24 hours340 City Park GC700Every day - 24 hours700 Washington Park1400Every day - 24 hours1400 City Park2100Every day - 24 hours2100 Denver Country Club700Every day - 24 hours700 Xcel Energy (3)5600Every day - 24 hours5600 Total - gpm118901120114811621166115011781139

8. Bruce Randolph Middle School

9. Swansea Park

10. City Park GC Pond

11. Shafer Park Meter Vault

12. Design Treatment Storage –Reservoirs/tanks/ponds –Location/elevation and capacity Pump Stations –Phasing of pumps –Back-up pump –PRV connections between higher-lower pump lifts –Types of pumps Horizontal split case, vertical turbine, booster Pipe –Often larger since demand is concentrated in shorter duration (6 hours at night) –Tree system rather than looped –Long distances Reliability

13. Vertical Turbine Pumps

14. Xcel’s Northwest Reservoir

15. Design Dechlorination Facility –Meters, Control Valves, Chemical Feed –Treatment Operators –Distribution Operators –Security

16. Dechlorination Facility

19. Design Recycled Water System Standards –Purple pipe, triangular covers, signs, regulations Reliability –Outages –Potable back-up? Combining Meter/Valve Vaults –One or two vaults –Cost, purpose, ownership. maintenance –Access by different work groups Meter readers, operations, customer Security

20. Bruce Randolph Middle School Meter and Valve Vault

21. Hydraulic Design Standards –Pressure-max, min, max fluctuation –Headloss –Velocity –Standard pipe diameters Headloss –Long distances may mean higher pressure fluctuations or over sized pipe Pressure Standards –5 psi less than potable? –Higher pressure with individual pressure regulating valves? Not Always Practical to Follow Potable Standards

22. Design Goal is to maximize use of the designed system thus using reduced pipe sizes. Must manage demand to avoid peaks. Excess capacity…until buildout. Cannot allow on-call usage like potable. Peak demands would be concentrated in shorter time frames and result in higher headloss, fluctuations and lower pressure.

23. Construction Winter to meet load season Existing development –Challenges New development –Opportunities Through golf courses –Restoration Directional drilling –Avoid above ground issues, maybe…

24. Operations Year around or seasonal? Start-up, Shut-down –Pumps, pipes, control valves, dechlorination Customers with varying demands Contract obligations (Xcel) Flushing –Discharge Maintaining Water Quality –Long distances

25. Operations Emergency Interconnects –Physical separation, insertable spool Pond operations –Private ponds –Balance demand, additional storage –Maintain certain water levels Inspections of Customer Systems –Periodic, Annual Private Systems –Lack of control –Lack of urgency/sensitivity/awareness

26. Regulations Standards Applicator Plan to Comply Notice of Authorization Approved uses Ponding, run-off, flushing Greater need to help the customer

27. Changes for the Utility Specialized design, construction, service Integrate into existing organization? Add specialized function/position(s)? Marketing? Feasibility for customer/utility Coordination/Contact

28. Conclusion Recycled systems present challenges different than potable systems –Customers/Demand Patterns/Scheduling –Design –Construction –Operations –Regulations –Changes for the utility

29. Questions?