Workshop developed by RCAP/AWWA and funded by the USEPA System Operations: Cross Connections Instructors please mention that this is the second of two modules focused on distribution system operations. This module focuses on main breaks and cross connections, and describes how these events can compromise water quality in the distribution system. Workshop developed by RCAP/AWWA and funded by the USEPA Developed by American Water Works Association with funds from the U.S. Environmental Protection Agency, Published 2015

Cross Connections Cross Connection― any direct interconnection between a public water system and a non-public water system or other source which may result in the contamination of the drinking water provided by the public water system…. MS Primary Drinking Water Regulation

Cross Connections The contaminants can be drawn or pushed back into the water distribution system during a backflow event A dynamic problem since plumbing systems are constantly being installed, altered and extended

Cross Connections “over 100,000 new cross-connections are formed each day” (AWWARF, 2000)

Can you find the Cross Connection? Cross Connections Can you find the Cross Connection?

Cross Connections “the greatest contributing factor to waterborne disease outbreaks in the U.S.” (AWWARF, 2000)

Cross Connections: A Backflow Danger Backflow: The flow of water or other liquids, mixtures or substances into the distribution pipes of a potable water supply from any source other than its intended source. Two causes of backflow Backsiphonage Backpressure 9

What Causes Backflow? Backsiphonage A reversal of the normal direction of flow in the line due to a negative or reduced pressure in the supply line. Non-potable fluids (contaminants) can be sucked into the distribution system Low pressure can be caused by line break, fire fighting, pump failure, flushing and others 10

Cross Connections: Backsiphonage Maryland A herbicide entered the distribution system Cross connection between the herbicide holding tank and the potable water supply line USEPA, Cross-Connection Control Manual 12

Cross Connections: Backsiphonage Pennsylvania Low pressure in the supply line due to a line break Chlordane and heptachlor entered the distribution system through a cross connection (a hose immersed in a chemical tank) USEPA, Cross-Connection Control Manual 13

What Causes Backflow? Backpressure: Pressure downstream becomes greater than the supply pressure causing a reversal of the normal flow When a potable water system is connected to equipment or a facility working under a higher pressure, forcing non-potable water into the potable system 14

Cross Connections: Backpressure Private well attached to home Home attached to public water system

Cross Connection Program Cross Connections Prohibited ….. unless a backflow prevention assembly is installed between the public water system and the source of contamination Cross Connection Control Program All public water supplies shall adopt and enforce a cross connection control policy or ordinance Backflow prevention assemblies must be tested by Certified Testers at least annually Records must be maintained for 5 years

Cross Connection Control Devices Air Gap Maximum protection Must be twice the diameter of water supply outlet USEPA, Cross-Connection Control Manual 18

Cross Connection Control Devices Reduced Pressure Zone Backflow Preventer Used in high hazard conditions Can be used under constant pressure Common installations include carwashes, dry cleaners, funeral homes, hospitals, sewage facilities USEPA, Cross-Connection Control Manual 19

Cross Connection Control Devices Double Check Valve Protects against backsiphonage & backpressure Can be used under constant pressure Common installations include fire sprinkler systems & multi-story buildings USEPA, Cross-Connection Control Manual 20

Cross Connection Control Devices Atmospheric Vacuum Breaker Protects against backsiphonage only Not designed to protect against back pressure conditions Commonly used on plumbing fixtures and hose bibs USEPA, Cross-Connection Control Manual 21

What to do in case of a backflow event? Stop the pressure differential that caused backflow of contamination, if possible Identify and remove the cross connection Contact MSDH If harmful contaminants are suspected, provide immediate notice to the affected customers Develop and carryout a plan for systematic flushing of the system Continue to sample within and outside the suspected contaminated area 22

What is wrong with this picture? High Service Pump Discharge Line Ask the class to identify the cross connection before sharing the answer: Hose with no hose bib or vacuum breaker The open ended garden hose is connected to the high service pump discharge. When the high service pumps are off and there is no pressure in the pipe, if there is flooding on the floor, or if the end of the hose is connected to a tank or bucket, water can flow through the hose into the pump discharge line as there are no breakers. This will result in cross connection and contamination.

Online Resources USEPA Cross-Connection Control Manual http://www.epa.gov/safewater/crossconnectioncontrol/pdfs/crossconnection.pdf USEPA Cross-Connection Control: A Best Practices Guide http://www.epa.gov/safewater/smallsystems/pdfs/guide_smallsystems_crossconnectioncontrol.pdf ASSE Series 5000, USC's FCCC & HR's "Manual of Cross-Connection Control", or UFL's TREEO's "Backflow Prevention – Theory and Practice" 24

Questions?

Thank You! Alexander Brandon Jim Miller State Coordinator 601-506-6305 Jim Miller Section Manager 256-310-3646 Dinah Foreman Regional Trainer 256-483-8611