Cross Connection Control

Cross ConnectionsSeptember 29-30, 2011Drinking Water ProgramSustained Compliance Workshop

Lee Johnson, P.E.lee.johnson@alaska.gov907-451-2179

1ObjectivesWhat is a Cross Connection?How are they regulated?What is a Back Flow Preventer?Types of PreventersExamples of Cross Connections

2What 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.

3Backflow Two TypesBack 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.

4High or Low HazardLow 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.5Cross Connections Are Prohibited18 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.618 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). 718 AAC 80.025(b) continuedThe 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.8Statutes & CodesAlaska 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 ConnectionsTable 6-2 Backflow Prevention Devices, Assemblies, and Methods9Service Connections and Premise PlumbingDrinking 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 CodeWhat about cross connections within your facility?Need to protect potable taps from nonpotable use taps within water plant.

10Plan Review & Sanitary SurveyDuring 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.11Owners, Operators, and Surveyors Should Consider:Types of facilities connected to drinking waterdistribution system (Actual or Potential Hazards?):Health ClinicsHospitalsSchoolsWater and Wastewater Treatment plantsMortuariesOther12Others?What other potential or actual cross connections can you name?

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15Direct vs Indirect

16Devices and AssembliesDevice -- cannot be tested

Assembly -- has two isolation valves and has test cocks for proper testing of the backflow prevention assembly17Backflow PreventionAir Gap2 Pipe Diameters or 1 inch minimumRPZReduced Pressure Zone AssemblyDCDouble Check Valve AssemblyPVBPressure Vacuum Breaker AVBAtmospheric Vacuum Breaker

18Backflow PreventionPrevents Backsiphonage LOW & HIGH HAZARDProper Air GapAtmospheric Vacuum BreakerPressure Vacuum BreakerReduced Pressure Zone BFPDouble Check Valve (low hazard only)Prevents BackpressureLOW HAZARDProper Air GapDouble Check Valve

HIGH HAZARDProper Air GapReduced Pressure Zone BFP19Insert New table 6-2

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Air GapFlow conditionNon flow conditionAtmospheric Vacuum BreakerProtection21

EXAMPLE AIR GAPS22

TankAir GapPOTABLESUPPLYPUMPFLOATNONPOTABLEAPPLICATION23

Hose Bibb Vacuum Breaker24

Pressure Vacuum BreakerTEST PORTSNORMAL FLOW25

Double Check Valve26

FLOW DIRECTION#1 GATE VALVE#2 CHECK VALVEReduced Pressure Zone Backflow Prevention Assembly (RPZ)TEST PORTSPRESSUREDIFFERENTIALRELIEF VALVE#2 CHECK VALVE#1 CHECK VALVE#2 GATE VALVEHigh hazard condition27RPZ

28RPZ

29RPZ Proper Installation?

30RPZ

31Proper Installation?

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Pumping Station Cross-connections

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.GATE VALVEFLOOR DRAINAIR VACUUM RELEASESILENT CHECK33

34Treatment Bypass Piping

35Emergency Bypass

36Emergency Bypass Installed

37Filter Bypass Piping

Bypass Piping38Disinfection Bypass Piping

39Water Meter as Cross Connection?

40Submerged Inlet

41Surface Wash Arms

42Surface Wash Arm Pressure Filter

43Backwash Waste Lines

44Softener Backwash Waste Line

45Air Gap

46UV and Cross Connections?

47Treatment Plant Lab Sink

48Distribution System Direct connections to sewers for flushing either the water main or sewer.

49Distribution Issues

50RESOURCES Alaska Drinking Water Regulations 18AAC 80.025 American Water Works Association Recommended Practice for Backflow Prevention and Cross Connection Control M14 EPAs Cross Connection Control Manual Uniform Plumbing CodeChapter 6 Kenneth Kerry Water Distribution System O&M Manual USC Foundation for Cross-Connection Control and Hydraulic ResearchLots of internet resources

51Questions?52