1. City of Black Hawk Water HammerSeptember 2002 Arber Water Hammer Travis Meyer, P.E. Richard P. Arber Associates

2. City of Black Hawk Water HammerSeptember 2002 Arber INTRODUCTION Background Water Hammer Modeling System Improvements Results Conclusions

3. City of Black Hawk Water HammerSeptember 2002 Arber City of Black Hawk Distribution System 1 2 3 4 5 Pressure Reducing Station Pump Station Dory Hill Tank Mesa Tank

4. City of Black Hawk Water HammerSeptember 2002 Arber Distribution System Profile Grade Hydraulic Grade Pressure Reducing Station Dory Hill Tank (8375 ft) Mesa Tank (8775 ft) 1 2 3 140 psi 120/40 160/70 3 4 5 140/90 140/65 70 Pump Station Pump Suction Line

5. City of Black Hawk Water HammerSeptember 2002 Arber Problem

6. City of Black Hawk Water HammerSeptember 2002 Arber Water Hammer - Causes Sudden Velocity Change –fire hydrant –fire sprinkler system –pumps Vapor Cavity Formation –pressure down surge at a low pressure dead end Equipment Malfunction –fire hydrants, valves, PRVs

7. City of Black Hawk Water HammerSeptember 2002 Arber SURGE 5 MODEL SUDDEN VALVE CLOSURE 2,000 GPM TO 0 GPM IN 3 SECONDS

8. City of Black Hawk Water HammerSeptember 2002 Arber SURGE 5 MODEL SUDDEN VALVE OPENING 0 GPM TO 2,000 GPM IN 3 SECONDS

9. City of Black Hawk Water HammerSeptember 2002 Arber SURGE 5 MODEL SUDDEN VALVE OPENING 0 GPM TO 2,000 GPM IN 3 SECONDS PUMP SUCTION ISOLATED

10. City of Black Hawk Water HammerSeptember 2002 Arber Water Hammer Modeling Conclusions Sudden Large Demand Changes Can Initiate a Water Hammer Event Vapor Cavity Formation and Collapse Can Occur in the Pump Suction Line Unable to Model PRV Behavior During Water Hammer –Cause of Extended Hammers?

11. City of Black Hawk Water HammerSeptember 2002 Arber Water Hammer - Solutions Sudden Velocity Changes –Pressure Relief Valves –Surge Tanks –Surge Anticipation Valves –Standpipe Vapor Cavity Formation –Eliminate Low Pressure Dead Ends –Connect System High Points to Open Tanks

12. City of Black Hawk Water HammerSeptember 2002 Arber Recommended Improvements Reconfigure Pump Suction to Eliminate Possibility of Vapor Cavity Formation and Collapse Install Pressure Relief Valves in Pressure Zones 3 and 4 Reconfigure Existing, Unused 12” Pipe as a Standpipe Optimize PRV Settings Lower System Pressures Require Surge Tanks for New Construction with Fire Service

13. City of Black Hawk Water HammerSeptember 2002 Arber System Improvements 1 2 3 4 5 6 Pressure Reducing Station with Pressure Relief Valve Pump Station Standpipe

14. City of Black Hawk Water HammerSeptember 2002 Arber System Improvements Grade Hydraulic Grade Pressure Reducing Station Dory Hill Tank (8375 ft) Mesa Tank (8775 ft) 1 2 3 120/40 160/70 3 4 5 140/90 140/65 70 Pump Station Pump Suction Line

15. City of Black Hawk Water HammerSeptember 2002 Arber Initial Implementation of Improvements Isolated Pump Suction Line Installed Temporary Pressure Relief Valves Put Locks on Fire Hydrants Lowered System Pressures Where Possible (Zone 4)

16. City of Black Hawk Water HammerSeptember 2002 Arber Initial Implementation

17. City of Black Hawk Water HammerSeptember 2002 Arber Initial Implementation

18. City of Black Hawk Water HammerSeptember 2002 Arber Water Hammer Test Fire Dept Indicated That One Fire Hydrant Always Seemed to Cause Water Hammer Initiated a Water Hammer Event on Purpose Monitored System Pressures and PRV Behavior During Water Hammer

19. City of Black Hawk Water HammerSeptember 2002 Arber Water Hammer Test

20. City of Black Hawk Water HammerSeptember 2002 Arber Water Hammer Test Conclusions Damaged Stem Extension on Fire Hydrant –City Subsequently Inspected All Fire Hydrants for Damage Pressure Regulating Valves –Appeared to Operate Smoothly During Water Hammer

21. City of Black Hawk Water HammerSeptember 2002 Arber Final Implementation of Improvements Pump Suction Line Reconfigured Standpipe On-Line Two New PRV Stations with Pressure Relief Valves On-Line System Pressures Lowered to Final Levels

22. City of Black Hawk Water HammerSeptember 2002 Arber Another Water Hammer

23. City of Black Hawk Water HammerSeptember 2002 Arber Probable Cause Contractor Started Work Approximately Same Time as Water Hammer –May Have Filled Water Truck from Fire Hydrant Pressure Regulating Valve –Corrosion Buildup on Stem Guide Caused Valve to Stick and Operate Unevenly

24. City of Black Hawk Water HammerSeptember 2002 Arber Another Water Hammer

25. City of Black Hawk Water HammerSeptember 2002 Arber Final Adjustments - PRV Stations Pressure Zone Primary Supply 100 psi Secondary Supply 95 psi Emergency Supply 90 psi Pressure Zone 100 psi

26. City of Black Hawk Water HammerSeptember 2002 Arber Success!!??

27. City of Black Hawk Water HammerSeptember 2002 Arber Conclusions To Avoid Water Hammer –Eliminate Potential for Vapor Cavity Formation (Low Pressure Dead-End Lines) –Maintain Fire Hydrants, System Valves, Fire Protection Systems, Pressure Regulating Valves for Proper Operation –Try Alternate PRV Strategy for Multiple PRV Pressure Zones

28. City of Black Hawk Water HammerSeptember 2002 Arber Conclusions To Protect System and Customers –Install Pressure Relief Valves –Install Standpipes –Require Surge Tanks on Fire Service Taps –Lower System Pressure

29. City of Black Hawk Water HammerSeptember 2002 Arber Proud Papa Jeffrey - Born 9/10/02