Cross Connections

1. Cross Connections September 29-30, 2011 Drinking Water Program Sustained Compliance Workshop Lee Johnson, P.E. lee.johnson@alaska.gov 907-451-2179

2. Objectives • What is a Cross Connection? • How are they regulated? • What is a Back Flow Preventer? • Types of Preventers • Examples of Cross Connections

3. What is a Cross Connection? • Defined in 18 AAC 80.1990(a)(36) • Basically it is an ACTUAL or POTENTIAL physical connection or arrangement between otherwise separate piping systems containing potable water and any contaminant, whereby water may flow between the two systems.

4. Backflow – TwoTypes Back Pressure: Pressure of nonpotable fluid is greater than pressure of potable water. Back Siphonage: Negative pressure in potable water piping causes nonpotable fluid to be siphoned into potable water line.

5. High or Low Hazard • Low Hazard - will not have an immediate effect on health, but could have an impact on the potable water. • High Hazard - will cause an immediate toxic effect or cause immediate and severe illness.

6. Cross Connections Are Prohibited 18 AAC 80.025(a) A person may not construct, install, or use a cross connection in a public water system, or allow a water system that contains a cross-connection to connect to a public water system.

7. 18 AAC 80.025(b) If the department determines that a facility has the potential to contaminate public water system through backflow, the owner or operator of the public water system shall install, maintain, and test on the service line to and at other locations in that facility, a backflow prevention device that conforms to ANSI/AWWA Standards C510-97, Double Check Valve Backflow prevention Assembly, or C511-97, Reduced-Pressure Principle Backflow Prevention Assembly, adopted by reference in 18 AAC 80.010(b).

8. 18 AAC 80.025(b) continued The owner or operator of the public water system may delegate the installation, maintenance, and testing of the backflow prevention device to the owner or operator of the facility that poses the risk. This delegation does not relieve the owner or operator of the public water system of the responsibility to install, maintain, and test the backflow prevention device.

9. Statutes & Codes • Alaska Statutes: • Article 8 Section 18.60.705 • Portions of Uniform Plumbing Code – 2009 adopted by reference, 18 AAC 80.010(c) • UPC Chapter 6 • Section 603 pertains to Cross Connections • Table 6-2 Backflow Prevention Devices, Assemblies, and Methods

10. Service Connections and Premise Plumbing • Drinking water program regulates water systems – Sources , treatment, and distribution systems, not service connections. • There is risk within a building from cross connections even if distribution system is protected. Plumbing Code • What about cross connections within your facility? • Need to protect potable taps from nonpotable use taps within water plant.

11. Plan Review & Sanitary Survey • During engineering plan reviews we look for Cross Connections within the public water system, the treatment plant, and the water distribution system. • BUT…….. For existing systems the sanitary survey process is the only other opportunity for staff or inspectors to look for and ask questions about facilities connected to the distribution system? • Also – Systems and plants are often modified through routine maintenance resulting in new cross connections or elimination of backflow prevention.

12. Owners, Operators, and Surveyors Should Consider: Types of facilities connected to drinking water distribution system (Actual or Potential Hazards?): • Health Clinics • Hospitals • Schools • Water and Wastewater Treatment plants • Mortuaries • Other

13. Others? • What other potential or actual cross connections can you name?

16. Direct vs Indirect

17. Devices and Assemblies • Device -- cannot be tested • Assembly -- has two isolation valves and has test cocks for proper testing of the backflow prevention assembly

18. Backflow Prevention • Air Gap 2 Pipe Diameters or 1 inch minimum • RPZReduced Pressure Zone Assembly • DCDouble Check Valve Assembly • PVBPressure Vacuum Breaker • AVBAtmospheric Vacuum Breaker

19. Backflow Prevention • Prevents Backsiphonage LOW & HIGH HAZARD • Proper Air Gap • Atmospheric Vacuum Breaker • Pressure Vacuum Breaker • Reduced Pressure Zone BFP • Double Check Valve (low hazard only) • Prevents Backpressure LOW HAZARD • Proper Air Gap • Double Check Valve HIGH HAZARD • Proper Air Gap • Reduced Pressure Zone BFP

20. Insert New table 6-2

21. Protection Air Gap Flow condition Non flow condition Atmospheric Vacuum Breaker

22. EXAMPLE AIR GAPS

23. POTABLE SUPPLY FLOAT NONPOTABLE APPLICATION PUMP Tank Air Gap

24. Hose Bibb Vacuum Breaker

25. Pressure Vacuum Breaker TEST PORTS NORMAL FLOW

26. Double Check Valve

27. Reduced Pressure Zone Backflow Prevention Assembly (RPZ) TEST PORTS #2 CHECK VALVE PRESSURE DIFFERENTIAL RELIEF VALVE #1 CHECK VALVE FLOW DIRECTION #1 GATE VALVE #2 GATE VALVE #2 CHECK VALVE High hazard condition

28. RPZ

29. RPZ

30. RPZ – Proper Installation?

31. RPZ

32. Proper Installation?

33. Priming of raw water pumps with finished water. Air relief valves piped directly to a drain. •Cooling water for an emergency generator submerged in a drain or returned to the potable supply. Pumping Station Cross-connections AIR VACUUM RELEASE GATE VALVE SILENT CHECK FLOOR DRAIN

35. Treatment Bypass Piping

36. Emergency Bypass

37. Emergency Bypass Installed

38. Filter Bypass Piping Bypass Piping

39. Disinfection Bypass Piping

40. Water Meter as Cross Connection?

41. Submerged Inlet

42. Surface Wash Arms

43. Surface Wash Arm – Pressure Filter

44. Backwash Waste Lines

45. Softener Backwash Waste Line

46. Air Gap

47. UV and Cross Connections?

48. Treatment Plant Lab Sink

49. Distribution System • Direct connections to sewers for flushing either the water main or sewer.

50. Distribution Issues