Chapter 13.05
WATER SYSTEM CROSS CONTROL PROHIBITION AND BACKFLOW ASSEMBLY CONTROL
Sections:
13.05.060 Backflow prevention requirements.
13.05.080 Backflow assembly testers.
Appendix C Double Check Valve Assembly and Double Check Detector Assembly – DCVA & DCDA
Appendix D Pressure Vacuum Breaker Assembly – PVBA
Appendix E Atmospheric Vacuum Breaker – AVB
13.05.010 Purpose.
The purpose of this chapter is to provide a basis for implementing Washington State Department of Health drinking water regulations, enacted to ensure safe drinking water within the water systems that serve the public. This chapter is designed to comply with WAC 246-290-490, to protect public health, and to minimize the danger of contamination or damage to the water distribution system by the control and prevention of actual or potential cross-connections. This shall be accomplished by requiring the proper safeguarding of service lines leading to premises where cross-connections exist or are likely to occur, and by periodic inspection and regulation of backflow prevention measures isolating the customer’s plumbing system from the water distribution system. This shall also by accomplished by coordination with building inspection division that manages the Plumbing Code. (Ord. 765, 1999).
13.05.020 Scope.
This chapter applies throughout the city of Pomeroy to every premises, whether existing or under construction, and the owners and occupants thereof served by the water distribution system of the city and a condition of water service to customers outside of the city limits. It applies to all systems installed before or after its enactment. Every owner and occupant of any premises covered by this chapter is responsible for compliance with its terms and shall be strictly liable for all damage incurred as a result of failure to comply with the expressed terms and provisions contained herein. (Ord. 765, 1999).
13.05.030 References.
This chapter was prepared in accordance with WAC 246-290-490 and guidelines set forth by the “Manual of Cross-Connection Control, Ninth Edition,” (Foundation for Cross-Connection Control and Hydraulic Research, University of Southern California), and “Cross-Connection Control - Accepted Procedure and Practice”, Sixth Edition, December 1995 (American Water Works Association), and in cooperation with the Washington State Department of Health, Drinking Water Division. (Ord. 765, 1999).
13.05.040 Interpretation.
This chapter applies to connections between the public water system and the customer’s private water service (plumbing system). Nothing in this chapter is intended to, or should be interpreted as a replacement for any provisions of the plumbing code. These cross-connection provisions stand alone as the standards for connection and continuation of private water service. Water system customers building new developments may be required to install internal cross-connection fixtures under the plumbing code and be required to install a backflow preventer after the city shut-off valve and before the first branch line or point of use within the premises under the provisions of this chapter. Any interpretation of this document regarding scope, intent, degree of hazard or type of protection required, will be subject to acceptance by the city public works director or his/her designee and shall be in accordance with Washington State Department of Health drinking water regulations and guidelines. (Ord. 765, 1999).
13.05.050 Definitions.
“Air gap separation” means the unobstructed vertical physical separation through the free atmosphere between the free flowing discharge end of the potable water supply line to an open or non-pressure receiving vessel and the overflow rim of the same vessel.
“Approved air gap” means an air gap separation meeting the minimum specifications set forth by Appendix A, and approved by the cross-connection control specialist as a backflow preventer.
“Atmospheric vacuum breaker (AVB)” is a backflow preventer that contains a float check (poppet), a check seat, and an air inlet vent. When water pressure is reduced to gauge pressure of zero, the float check drops, allowing air to enter the device, preventing back siphonage. It is designed to prevent against back siphonage only.
“Auxiliary supply” means any water supply on or available to a premises in addition to the water supplied by the city public water distribution system.
“Approved backflow prevention assembly” means an RPBA, RPDA, DCVA, DCDA, PVBA, SVBA and AVB of a make, model, and size that is approved by the University of Southern California Foundation for Cross-Connection Control and Hydraulic Research (USC-FCCCHR) and by the Washington State Department of Health as a backflow prevention assembly. A backflow prevention assembly on which parts have been removed, altered, or replaced with parts other than original manufacturer parts, or an assembly that has been assembled after the factory by combining other assemblies or parts, is not considered an approved assembly.
“Approved backflow preventer” means a mechanical device or assembly designed to prevent backflow that is approved by the University of Southern California Foundation for Cross-Connection Control and Hydraulic Research (USC-FCCCHR) or the Washington State Department of Health, and meets the definition of an approved backflow preventer according to WAC 246-290-490.
“Backflow” means the flow of water or other liquids, gases, or solids from any source back into the customer’s plumbing system or the water purveyor’s water distribution system.
“Back pressure” means water pressure on the customer’s side of the service connection that is greater than the pressure provided by the water distribution system and which may cause backflow.
“Back siphonage” means backflow due to a negative or reduced pressure within the public water distribution system and/or customer’s water system.
“Certified backflow assembly tester” means an individual who is certified by the Washington State Department of Health to test backflow prevention assemblies.
“City or purveyor” means the city of Pomeroy, Washington.
“City shut-off valve” means the first working shut-off valve closest to the main as measured along the service line.
“Contaminant” means any physical, chemical, biological, or radiological substance or matter in water that may render the water non-potable, according to Washington State Department of Health regulations.
“Cross-connection” means any actual physical or potential connection between a potable water supply and any pipe, vessel, or machine containing a non-potable fluid, solid, or gas that could enter the water distribution system by backflow. A cross-connection could be any physical arrangement whereby a potable water supply is connected directly or indirectly with any non-potable or unapproved water supply system, sewer, drain, conduit, pool, storage reservoir, plumbing fixture, or any other device or location that contains, or may contain, contaminated water, liquid, gases, sewage, or other waste, or unknown or unsafe quality that may be capable of imparting contaminants to the potable water supply as a result of backflow. Bypass arrangements, jumper connections, removable sections, swivel or change-over devices, and other temporary, permanent or potential connections through which, or because of which, back flow could occur, are considered to be cross-connections
“Cross-connection control specialist” means an individual Certified by the State of Washington Department of Health and employed by the city of Pomeroy to inspect for cross-connections.
“Customer’s system” means all non-city-owned plumbing, piping, backflow prevention, and apparatuses on the customer’s side of the city shut-off valve. The meter assembly and related apparatuses installed and owned by the city are not part of the customer’s system.
“Double check detector assembly (DCDA)” is an approved assembly used for fire systems. It consists of two approved double check valve assemblies, set in parallel, equipped with a meter on the bypass line to detect a small amount of water leakage or use. This unit must be purchased as a complete assembly.
“Double check valve assembly (DCVA)” is an approved assembly consisting of two independently operating check valves, loaded to the closed position by springs or weight, and installed as a unit with, and between two resilient seated shut-off valves and having suitable connections for testing.
“Fixture isolation or in-premises isolation” means the practice of protecting the public water distribution system by installing backflow prevention assemblies at or near the point where an actual or potential cross-connection exists.
“Hazard evaluation” means an on-site review of the water source, facilities, equipment, operation, and maintenance for the purpose of evaluating potential hazards to the water distribution system.
“High health-hazard” means a hazard to the public health through the public water distribution system by poisoning or spread of disease. Examples of high health-hazards include by are not limited to:
1. Sewage
2. Industrial liquids or waste
3. Medical wastes
4. Chemicals
5. Any other contaminants (other than secondary) as defined by this chapter.
“IAPMO” means the International Association of Plumbing and Mechanical Officials.
“Large assembly” means an approved backflow prevention assembly as defined by this chapter that has a pipe diameter measuring two and one-half inches or greater.
“Low health-hazard” means a substance or condition that degrades or threatens the quality of potable water. A low health hazard does not pose a threat to the public health, but does adversely affect the aesthetic qualities of potable water for domestic use. Low health hazards may include situations involving secondary contaminants as defined in this chapter.
“Meter assembly” means the city-owned water meter and any meter setter assembly or resetter assembly that is installed and owned by the water division.
“Plumbing code” means the code adopted by the city that addresses construction, repair, replacement of plumbing fixtures and assemblies.
“Premises isolation” means the practice of protecting the public water distribution system by installing backflow prevention assemblies at or near the point where water enters the premises, effectively isolating the customer’s plumbing system from the water distribution system.
“Pressure vacuum breaker assembly (PVBA)” is an approved assembly consisting of a spring-loaded check valve loaded to the closed position independently operating air inlet valve loaded to the open position and installed as a unit with and between two resilient seated shut-off valves and with suitable connections for testing. It is designed to protect against back siphonage only.
“Reduced pressure backflow prevention assembly or reduced pressure principle backflow prevention assembly (RP or RPBA)” is an approved assembly consisting of two independently operating check valves, spring-loaded to the closed position, separated by a spring-loaded differential pressure relief valve loaded to the open position, and installed as a unit with and between two resilient seated shutoff valves and having four suitable test cocks for checking the water tightness of the check valves and the operation of the relief valve.
“Reduced pressure detector assembly (RPDA)” is an approved assembly consisting of two approved reduced pressure backflow assemblies, set in parallel, equipped with a meter on the bypass line to detect small amounts of water leakage or use. This unit must be purchased as a complete assembly.
“Safe drinking water” or “potable water” means water that has sufficiently low concentrations of microbiological, inorganic chemical, organic chemical, radiological or physical substances so that individuals drinking such water at normal levels of consumption will not be exposed to disease organisms or other substances that may produce harmful physical effects.
“Secondary contaminate” means contaminants which, at levels generally found in drinking water, do not present unreasonable risks to health, but do adversely affect taste, odor or color.
“Small assembly” means an approved backflow prevention assembly as defined by this chapter that has a pipe diameter measuring less than two and one-half inches.
“Temporary connection” means any water service installed by the city for the purpose of temporarily supplying a customer with water. Examples where temporary connections would be requested include but are not limited to:
1. Hydrant hookups for water trucks and construction purposes.
2. Public events such as amusement attractions and festivals.
“Used water” means water that has been passed beyond the city shut-off valve and out of the water distribution system.
“Water distribution system or public water distribution systems” means the city of Pomeroy water distribution system.
“Water division” means the city of Pomeroy water division.
“Water system manager” means the public works director appointed by the city of Pomeroy to manage and supervise the public water distribution system for the city. (Ord. 765, 1999).
13.05.060 Backflow prevention requirements.
All cross-connections are prohibited, whether or not they are controlled by automatic devices. Unless otherwise approved by the cross-connection control specialist, backflow preventers shall be installed on the customer side at or as near as possible to the city shut-off valve of any premises where, in the judgment of the cross-connection control specialist, the nature and extent of activity or use on the premises could present a health or system hazard in the event a backflow occurs. This requirement applies even if a cross-connection does not exist at the time the backflow prevention assembly is required to be installed. In all cases, the cross-connection control specialist shall determine the appropriate level of backflow prevention required. The customer shall be responsible for acquiring, installing, and maintaining any backflow prevention measures required by the water division to isolate the customer’s system from the water distribution system. The return of used water to the city’s water distribution system is not allowed under any circumstance. This includes but is not limited to, cases of heat exchangers designed to return water to the distribution system.
A. Premises Isolation Required. With the possible exception of cases listed under PMC 13.05.060(D) and cases where exceptions are granted under 13.05.060(B), premises isolation is required for all services where a cross-connection or a potential for a cross-connection exists, including, but not limited to:
1. Premises where the cross-connection control specialist has determined that an actual or potential cross-connection exists.
2. Premises or systems specified as requiring mandatory premises isolation by Table 1, in this section or by WAC 246-290-490.
3. Where, in the opinion of the water system manager there has been a history of repeating the same or similar backflow occurrences, cross-connections, or backflow conditions even if the cross-connection or condition has since been removed or disconnected.
4. Premises where entry is restricted so that inspections for cross-connection cannot be made with sufficient frequency or at sufficient short notice to ensure that cross-connections do not exist.
5. Premises where materials of a toxic or hazardous nature are handled such that if a backflow should occur, a serious health or system hazard may result. This includes, but is not limited to, facilities in the following table:
Table 1. Premises or Systems Required
Mandatory Premise Isolation by Means of an Approved Air Gap or Reduced Pressure Backflow Assembly.
Agricultural (farms and dairies)
Beverage bottling plants
Car washes
Chemical plants
Commercial laundries and dry cleaners
Premises where both reclaimed water and potable water are provided
Film Processing facilities
Food processing plants
Hospitals, medical centers, nursing homes, veterinary, medical and dental clinics, blood plasma centers
Premises with separate irrigation systems using the public water supply and with chemical addition1
Laboratories
Metal Plating Industries
Mortuaries
Petroleum processing or storage plants
Piers and docks
Radioactive material processing plants or nuclear reactors
Premises where access by water division personnel or backflow assembly testers is denied or restricted
Wastewater lift stations and pumping stations
Wastewater treatment plants2
Premises with an unapproved auxiliary water supply interconnected with the public water distribution system
1 For example: parks, playground, golf courses, cemeteries, estates, etc.
2 RPBAs for connections serving these premises are acceptable only when used in combination with an in-plant approved air gap; otherwise an approved air gap shall be required at the service connection.
B. Exceptions to Premises Isolation. In-premises isolation may be substituted for premises isolation requirements where mandatory premises isolation is not required by WAC 246-290-490 or Table 1 of this section, and only through written agreement with the water division when the customer has demonstrated to the satisfaction of the water system manager that premises isolation would impose a hardship on the customer and that an acceptable alternative would substantially relieve that hardship, and only if all of the following conditions are met to the satisfaction of the water system manager.
The alternative arrangement:
1. Must not pose a threat to public health;
2. Must provide at least the level of protection required by the cross-connection control specialist;
3. Must not place an undue burden on the city’s cross-connection control program or set a precedent that, if applied evenly to all customers, would have the effect of placing an undue burden on the city;
4. Must not create a potential for bypasses or other potential risks associated with future changes to the plumbing or water use on the premises;
5. Must not compromise the legal or authoritative integrity of the cross-connection program;
6. Must comply with the rest of this chapter and all other guidelines set forth by the city;
7. Must be consistent with rules and guidelines set forth by the Washington State Department of Health;
8. Must be approved by the cross-connection control specialist; and
9. Must include a written agreement providing the water division with reasonable access to conduct an initial hazard evaluation and subsequent periodic re-evaluations to determine if the backflow prevention measures are adequate to protect the public water system from health or system hazards.
C. Type of Backflow Prevention Required. The type of backflow prevention required shall be commensurate with the degree of hazard that exists as follows;
1. Air Gap. An approved air-gap separation, measured vertically above the overflow rim of the receiving vessel, shall be installed for cases in which very hazardous contaminants pose an immediate or potential risk for entering the distribution system. The substance(s) that pose a risk to the water distribution system may include but are not limited to sewage, industrial waste of a toxic nature or other contaminates that would cause a health or system hazard. Air gaps may be required in addition to other backflow prevention measures for severe health risks including, but not limited to, sewage facilities, radioactive material processing plants, and nuclear reactors. In such cases, the air gap shall be used to isolate the process(s) involving the severe health hazard, and a reduced pressure backflow assembly shall be used to isolate the facility.
2. Reduced Pressure Backflow Assembly or Reduced Pressure Detector Assembly. An approved reduced pressure backflow prevention assembly or reduced pressure detector assembly shall be installed where the substance that could backflow is a contaminant or is potentially hazardous to health. The substance(s) posing a risk to the water distribution system may include but are not limited to sewage, industrial waste of a toxic nature or other contaminants that could cause a health or system hazard.
3. Double Check Valve Assembly or Double Check Detector Assembly. An approved double check valve assembly or double check detector assembly shall be installed only where the substance that could backflow is not a contaminant. In situations involving secondary contaminates, or where a potential for backpressure exists, a double check valve assembly shall be required at a minimum.
4. Pressure Vacuum Breaker Assembly. An approved pressure vacuum breaker assembly shall be installed for in-premises isolation only for the purpose of preventing backflow through back siphonage and only where all of the following conditions are true:
a. Where the substance that could backflow is not a contaminant and there is no high health hazard posed by the system;
b. Where there is no possibility of flooding of the assembly; and
c. Where there is no possibility of back pressure in the downstream piping.
5. Atmospheric Vacuum Breaker. An atmospheric vacuum breaker shall be installed for in-premises isolation only for the purpose of preventing backflow through back siphonage and only where all of the following conditions are true:
a. The substance that could backflow is not a contaminant;
b. There is no possibility of flooding of the atmospheric vacuum breaker;
c. There is no possibility of back pressure in the downstream piping;
d. Where there are no shut off valves located downstream of the atmospheric vacuum breaker; and
e. Where the atmospheric vacuum breaker is not subject to pressure for more than twelve hours in a twenty-four hour period.
D. Requirements for Specific Types of Services. The following specific types of services must comply with the following requirements. The cross-connection control specialist shall determine the level of backflow prevention required and whether or not premises isolation shall be required.
1. Temporary Water Service. Temporary connections shall have backflow prevention in the form of a reduced pressure backflow assembly unless otherwise approved by the cross-connection control specialist and/or water superintendent. The required assembly may, at the customer’s request, be provided by the city and a charge be assessed to the customer for the use of the assembly. In cases where the customer required temporary service for a period of time exceeding six months, the customer shall provide the required backflow assembly, which shall be inspected and tested by the cross-connection control specialist. In all cases, water service shall be provided only after the following requirements are met:
a. Completion by the customer of an event application with development services and/or the parks department as required. (Note: customers requesting temporary services for the sole purpose of construction may be exempt for the requirement);
b. Completion by the customer of a temporary water service application with the water division and approval by the water distribution system manager; and
c. The assembly is tested and installation approved by the cross-connection control specialist.
2. Fire Systems. Fire systems that are not metered shall have backflow prevention in the form of an approved model of the detector type that includes a monitoring meter or detection system to detect unauthorized use or leakage within the system. The type of backflow preventer shall be appropriate to the degree of hazard as follows:
a. High Health Hazard. Systems that use or are designated to use unapproved auxiliary water supplies, chemical additives, or that contain any other cross-connection shall require a reduced pressure backflow assembly for metered services, or a reduced pressure detector assembly for non-metered services.
b. Low Health Hazard. Systems that are designed for and use only potable water from the public distribution system, and that have been evaluated by the cross-connection control specialist as low health hazard shall be required to have at a minimum, backflow prevention in the form of a double check valve assembly for metered services, or a double check detector assembly for non-metered services. Residential flow-through fire systems and combination fire systems using potable water do not require backflow prevention provided no cross-connections exist within the fire system or plumbing connection to the fire system, and the construction is of potable water piping and materials.
3. Water Trucks and Mobile Equipment. All trucks and mobile equipment that employ water reservoirs filled with water directly from the water distribution system shall have backflow prevention in the form of a reduced pressure backflow assembly or an approved air gap, unless otherwise approved by the cross-connection control specialist or water superintendent. The cross-connection control specialist or water superintendent shall determine the type and arrangement of the measures based on the degree of health or system hazard associated with existing or potential uses of equipment.
4. Heat Exchangers and Solar Potable Hot Water Systems. Any installation of a heat exchange or solar potable hot water system shall require inspection and approval by the cross-connection control specialist before being placed into service. In no case shall any heat exchanger or solar potable hot water system return used water to the city’s distribution system. All heat exchangers and solar potable hot water systems shall require backflow prevention in the form of a reduced pressure backflow assembly or approved air gap unless the device meets all of the following conditions (in which case a double check valve assembly shall be required at a minimum):
a. The heat exchanger or solar potable hot water heater is IAPMO certified;
b. There is no non-potable fluid or transfer medium used and the probability is very low in the opinion of the cross-connection control specialist that such substances will be added in the future; and
c. The heat exchanger type is double walled with leak detection.
5. Irrigation. All irrigation and lawn irrigation systems that are supplied by city water shall have backflow prevention that is commensurate with the degree of hazard that exists as follows:
a. A pressure vacuum breaker assembly shall be required as a minimum for all new irrigation systems.
b. Atmospheric vacuum breakers installed on irrigation systems before April 1, 1999, may remain in service provided the backflow preventer meets minimum installation requirements as defined in this chapter and is inspected and approved by the cross-connection control specialist as appropriate to the degree of hazard. Upon replacement or repair of atmospheric vacuum breakers used for irrigation systems, the backflow preventer shall be replaced by an approved pressure vacuum breaker assembly at a minimum.
c. A double check valve assembly shall be required as a minimum for irrigation systems subjected to backpressure, elevated piping, or flooding or that use or are equipped to use any winterizing process where the irrigation system is pressurized or blown out.
d. A reduced pressure backflow assembly or approved air gap shall be required for any irrigation system that contains pumps or injectors, or when the addition of chemicals is used, or when any of the following conditions exist:
i. Where an unapproved auxiliary supply is available or likely to be used;
ii. Where there is additional hazard(s) posed by bacteriological or chemical contaminants; or
iii. Where the cross-connection control specialist determines there is a high health or system hazard or a possibility of changes being made to the irrigation system that could result in a high health or system hazard.
6. Tall Buildings. Buildings that contain plumbing that meets or exceeds thirty feet in elevation above the main where the service line taps the main shall be required to have at a minimum, backflow prevention in the form of a double check valve assembly. Buildings with plumbing systems that employ booster pumps shall also be required to have a minimum premises isolation in the form of a double check valve assembly.
E. Previously Installed Assemblies. Backflow prevention assemblies that were approved at the time they were installed but are not on the current list of approved assemblies, shall be permitted to remain in service provided they meet the following conditions to the satisfaction of the cross-connection control specialist:
1. The assembly is properly maintained and tested annually;
2. The assembly is commensurate with the degree of hazard as determined by the cross-connection control specialist; and
3. The assembly performs satisfactorily as determined by the cross-connection control specialist.
When assemblies of this type are moved, or in the opinion of the cross-connection control specialist require more than minimum maintenance, they shall be replaced by assemblies that are on the list of approved assemblies by the Washington State Department of Heath.
F. Installation Requirements for Backflow Preventers. All backflow preventers required under this chapter shall be of a type and model approved by the Washington State Department of Health and the city of Pomeroy. In addition, the installation of each backflow preventer is subject to inspection and approval by the cross-connection control specialist. All backflow preventers for premises isolation shall be installed on the customer’s side of the city shut-off valve and before any quick-connect fittings or other fixtures that may allow any substance to enter or exit the service line, unless otherwise approved by the water system manager. Backflow preventers used for premises isolation shall be located downstream from the city shut-off valve as close as possible to the meter. The distance between the meter and the backflow preventer must meet the approval of the cross-connection control specialist. If the backflow preventer for premises isolation is installed inside the building, the backflow preventer shall be located no more than ten feet downstream of the point at which the line enters the building (as measured along the pipe from the inside surface of the outside wall where the pipe enters the building). Any alternative to the preceding requirement shall be at the discretion of the cross-connection control specialist. For all backflow preventers installed at or near the meter, a distance of at least five times the backflow preventer’s pipe diameter shall be provided between the meter and the backflow assembly. The backflow assembly shall be placed before the first branch line or point of use and shall be easily accessible for inspecting, testing, repair, and replacement. Backflow preventers shall not be installed in city-owned enclosures, boxes, vaults, or other city facilities without the express written permission of the water system manager. Existing backflow prevention assemblies installed within city-owned enclosures, boxes, or vaults shall be moved outside upon replacement. All backflow preventer enclosures shall meet the current ASSE 1060 standard at the time of installation. In addition, every installation, including all enclosures, pits, or vaults shall be designed to provide adequate room and access for testing and repair of the backflow preventer. Parallel assemblies shall be separated by a minimum clearance of eighteen inches unless otherwise approved by the cross-connection control specialist. Additional specifications may be made by the cross-connection control specialist for ensuring adequate access and proper operation of all assemblies. Parallel assemblies or large assemblies require unique specifications to each installation and the installer should contact the cross-connection control specialist for details before finalizing plans. All backflow preventers shall be installed no higher than five feet from the floor or ground to the top of the assembly to permit reasonable access by the inspector or repair person. An alternative, the backflow preventer may be installed at a distance of five feet or less above a platform designed for access to the backflow preventer. Unless the backflow preventer installation is otherwise evaluated and approved by the cross-connection control specialist, it shall only be installed in the orientation for which it is designed. Any other orientation may interfere with the proper operation and testing of the backflow preventer.
1. Air Gap. Air gaps must be properly designed and operated such that there are no obstructions surrounding the gap and so that there is no possibility of any splashing from the receiving vessel to the supply pipe. For the required minimum specifications, see Appendix A.
2. Reduced Pressure Backflow Assembly and Reduced Pressure Detector Assembly. Minimum dimension specifications for installation of a reduced pressure backflow assembly or reduced pressure detector assembly are given by the city guideline for installation (RPBA & RPDA) attached as Appendix B. Reduced pressure backflow assemblies (RPBA) and reduced pressure detector assemblies (RPDA) shall be installed a minimum of twelve inches above grade. An approved air gap must be maintained directly below the differential pressure relief valve. No RPBA and RPDA may be installed in such a way that it may be exposed to gases or submersion by water or any other material. No RPBA or RPDA may be installed in a below-ground pit without prior approval by the water system manager. Sufficient drainage must be provided to allow complete drainage in the event the differential pressure relief valve discharges at maximum capacity.
3. Double Check Valve Assembly and Double Check Detector Assembly. Minimum specifications for installation of a double check valve assembly or a double check detector assembly are given by the guidelines for installation (DCVA & DCDA) attached as Appendix C. A double check valve assembly (DCVA) or double check detector assembly (DCDA) may be installed in a pit below ground. In such cases, the installation must be designed to prevent flooding of the pit and a twelve inch-deep gravel drainfield must be provided below the assembly. In addition, plugs must be installed in the test cocks to reduce the risk of ground water being siphoned through a leaking test cock. The assembly must be installed with test cocks facing up or to one side for testing.
4. Pressure Vacuum Breaker Assemblies. Pressure vacuum breaker assemblies shall be used only where there is no possibility of back pressure, and may be used only as in-premises isolation. Minimum dimension specifications for installation of a pressure vacuum breaker assembly are given by the guidelines for installation (PVBA) attached as Appendix D. Pressure vacuum breaker assemblies shall only be installed in a vertical configuration a minimum of twelve inches above the highest fixture or point of downstream piping or water usage and in such a manner that drainage will preclude back pressure. The pressure vacuum breaker assembly shall be installed vertically with test cocks and control valves accessibly located for connection of test equipment.
5. Atmospheric Vacuum Breaker. Atmospheric vacuum breakers shall be used only where there is no possibility of back pressure. Minimum dimension specifications for installation of an atmospheric vacuum breaker are given by the guidelines for installation (AVB) attached as Appendix E. Atmospheric vacuum breakers shall only be installed in a vertical configuration a minimum of six inches above the highest fixture or point of downstream piping or water usage and in such a manner that drainage will preclude back pressure. Downstream shut off valves of any kind are not allowed. (Ord. 765, 1999).
13.05.070 Enforcement.
Any necessary actions to be taken to enforce the rules of this chapter shall be at the direction of the city of Pomeroy public works director or his/her designee.
A. Hazard Evaluation. The degree of hazard and corresponding risk to the water distribution system shall be determined by the cross-connection control specialist. This determination shall be made based on hazard evaluation made by the cross-connection control specialist, and on any other relevant information obtained by the water division. The hazard evaluation shall be performed by a walk-through evaluation of the premises and evaluation of blueprints and other documents pertaining to the plumbing of the building, and by the nature of the use of water in the building. In a case where the customer is unable or unwilling to comply with the walk-through evaluation, the customer’s system shall be considered a high-health or system hazard in accordance with WAC 246-290-490 and the customer shall be required to install a reduced pressure backflow assembly or approved air gap or both for premise isolation. The choice of backflow prevention shall be determined by the cross-connection control specialist.
B. Customer’s Duty of Inspection. Customer systems shall be open for hazard evaluation at all reasonable times to the cross-connection control specialist to determine whether cross-connections or other sanitary hazards exist including violations of these regulations, and for the purpose of observing testing, repair, relocation or installation practices. Failure to provide such access shall result in the requirement to install a reduced pressure backflow assembly or an approved air gap for premises isolation. The city will notify the customer of the results of the hazard evaluation, listing the corrective actions to be taken. A time period of thirty days shall be given to the customer to complete all corrective actions required, including installation of appropriate means of backflow prevention. An extension of this time may be granted by the city public works director or his/her designees under extenuating circumstances.
C. Alterations to Backflow Preventers. Any changes made to plumbing or configuration of backflow assemblies installed or covered under the requirements of this chapter shall be subject to prior approval by the cross-connection control specialist. In addition, after service is shut off for repairs or changes, the service shall be restored only after the finished work has been approved, tested, and passed by a backflow assembly tester registered with the city.
D. Inspection and Testing. Inspections by the cross-connection control specialist of the customer’s plumbing or water distribution system(s) or backflow prevention equipment shall be made under any of the following conditions:
1. Immediately following any backflow incident in the customer’s facility;
2. Immediately following any backflow incident in the vicinity of the customer’s facility as deemed necessary by the cross-connection control specialist or other water division personnel;
3. Immediately following re-installation or relocation of backflow prevention equipment or replumbing of air gaps;
4. Upon the completion of a new installation of a backflow preventer or replacement of an existing backflow preventer;
5. Periodically as scheduled by the water division; and
6. At any reasonable time deemed necessary by the city public works director or his/her designee(s) to evaluate a potential immediate high health or system hazard.
The customer shall notify the cross-connection control specialist or water superintendent immediately when any of the preceding conditions exist. For new service, re-installation, relocation, or repairs (with the exception of regular minor repairs and maintenance), water service to the customer’s facility shall be provided only after backflow prevention measures are inspected, tested (if applicable), and approved by the cross-connection control specialist. It will be the customer’s responsibility to have the backflow preventer tested on installation and tested and maintained on an annual basis or more frequently if required by the cross-connection control specialist. Requirements for more frequent testing and inspection will only be required for situations in which the cross-connection control specialist has determined more frequent testing is necessary to ensure the safety and quality of the water in the public water distribution system. Any costs or inconveniences associated with the maintenance, inspection, and testing of backflow prevention measures shall be the responsibility of the customer. As a courtesy, the water division will notify the customer at least thirty days before the required test is due. If the test has not been performed and satisfactory results submitted by the end of the day on which the results are due, the city shall terminate water service to the affected customer until the subject assembly performs and tests satisfactorily. An additional time period may be granted by the city public works director or his/her designee under extenuating circumstances. The assembly owner is required to contact a backflow assembly tester who is registered with the city as a backflow assembly tester and who can perform the test in the necessary time period. A list of registered backflow assembly testers will be provided by the cross-connection control specialist.
E. Termination of Service. The city may refuse to furnish water and discontinue service to any premises where plumbing facilities, appliances, or equipment using water are dangerous or unsafe or not in conformity with this chapter or with the rules and regulations of the Washington State Department of Health regarding water distribution systems. All cross-connections posing an immediate and high health or system hazard as determined by the water division may, at the direction of the city Director of public works or his/her designee, result in the service to the affected area being immediately terminated without notice.
F. Failure to Comply/Tampering. It is unlawful for any persons, firm, or corporation to destroy, circumvent, tamper with, or otherwise interfere with the performance of any installed approved backflow preventer or arrangement that is required by this chapter or by written notice by the cross-connection control specialist. Any such actions shall be considered grounds for termination of service or additional backflow prevention requirements as determined by the city water superintendent or his/her designee. In addition, the person(s) responsible for such actions may be held liable for any damages resulting from such actions, including, but not limited to loss of life or property, personal injury, or property damage.
13.05.080 Backflow assembly testers.
All backflow assembly testers who wish to perform backflow assembly tests for customers of the city water division must be certified to test backflow assemblies in Washington State and must notify the cross-connection control specialist in writing with a copy of the tester’s certification and proof of calibration of test equipment. Upon written approval by the water division, the tester may perform tests in the city and will be placed on the backflow assembly tester list for the city. Test reports submitted by non-registered testers will not be accepted. Test reports shall be on a form approved by the cross-connection control specialist. Computer generated reports are also acceptable. The city reserves the right to remove from the list or reject the application of any backflow assembly tester who:
A. Provides altered or false reports;
B. Purposefully interferes with the city’s ability to protect the water distribution system through the proper maintenance and testing of backflow equipment;
C. Violates this chapter; or
D. Repeatedly provides improper or untimely reports. (Ord. 765, 1999).
13.05.090 Liability.
The city of Pomeroy will not be held liable for any and all water pressure loss, flow loss, head loss, friction loss, or other costs of damages associated with the use and operation of backflow assemblies including, but not limited to, interruption of service. For continuous service, it is recommended that at least two assemblies be installed in parallel to prevent total flow loss due to testing and repairs. In cases where the customer has successfully obtained approval from the water system manager for an exception to premises isolation, the city shut-off valve shall continue to be the beginning of the customer’s system and the customer shall retain the associated responsibilities and liabilities described in this chapter. In all cases the customer shall indemnify and hold harmless the city for all contamination of the customer’s system or the city’s water distribution system that results from an unprotected or inadequately protected cross-connection within the customer’s premises. Under no circumstances shall the city’s grant of any exemption from premises isolation be construed to mean that the city assumes responsibility or liability for any cross-connection incident on the customer’s premises. This indemnification shall pertain to all backflow conditions that may arise from the city’s suspension of water supply, water main breaks, or reduction of water pressure.
13.05.100 Appendices.
Appendix A: Approved Air Gap
Definition: An approved air gap is a vertical physical separation between the free flowing discharge end of a potable water supply pipeline and the overflow rim of an open or non-pressure receiving vessel. The minimum vertical clearance separation is given by Table A.1.
|
Effective diameter of supply pipe opening “D” |
Air Gap |
If walls, ribs or obstructions are within 3 times D from the AG, the AG must be at least: |
If intersecting walls are within 4 times D from the AG the AG must be at least: |
|---|---|---|---|
|
Not greater than 1/2” |
1" |
1" |
2" |
|
Not greater than 3/4” |
1" |
2 1/4” |
3" |
|
Not greater than 1" |
2" |
3" |
4" |
|
1 inch and greater |
2 x D |
3 x D |
4 x D |
|
D= inside diameter of supply pipe |
|||
Figure A-1. Minimum Clearances for Approved Air Gap
Other Considerations:
1 An obstruction around or near an air gap may restrict the flow of air into the outlet pipe during a backsiphonage condition and reduce the effectiveness of the air gap. When the air flow is restricted, such as the case of an air gap located near a wall, the air gap separation must be increased as indicated by Table A.1.
2 If the supply line is cut at an angle, the separation is measured from the bottom of the angular cut as shown in figure A-1.
3 Any manufactured air gap fitting must meet the dimension criteria of an approved air gap shown in Table A.1.
4 Hoses are not allowed as part of an approved air gap.
5 Air gaps must be installed above grade, unless otherwise approved by the cross-connection control specialist.
6 Adequate access and clearances for inspection, testing, and repairs must be provided. If you have any questions, call the cross-connection control specialist
Note: Some material courtesy of the Pacific Northwest Section of the American Water Works Association
Appendix B: Reduced Pressure Principle Backflow Assembly
and Reduced Pressure Detector Assembly – RPBA & RPDA
Reduced Pressure Principle Backflow Assembly and Reduced Pressure Detector Assembly: An RPBA or RPDA must never be exposed to gases or submersion by water or any other material. In addition, these assemblies must be installed one hundred twenty-three inches above grade, and not in a below-ground pit unless approved by the water system manager.
Figure B-1.
Minimum Clearances for small RPBA or RPDA Installation (above grade enclosure)
Other Considerations:
1 Large (2 1/2 inches and greater pipe diameter) RPBA and RPDA specifications are handled on a per case basis. Contact the cross-connection control specialist for details.
2 An RPBA or PRDA must be installed only in a horizontal position unless the assembly has been designed and approved for vertical installation. In addition, the assembly should be installed upright so that the differential pressure relief valve discharges downward as designed.
3 Fluctuating supply pressure may cause nuisance dripping or spitting at the relief valve and potential fouling of the number one check valve. Installing a single soft seated spring loaded check valve immediately upstream of the RPBA or RPDA will usually correct this problem by holding the supply pressure constant during fluctuating conditions.
4 Freeze protection measures must be taken for outdoor installations. Do not stuff insulation around any RPBA or RPDA as it may interfere with the performance of the differential pressure relief valve.
5 All manufactured enclosures for RPBAs or RPDAs must meet ASSE 1060 standards as required by PMC 13.05.060(E).
6 Adequate access and clearances for inspection, testing, and repairs must be provided. If you have any questions, call the cross-connection control specialist.
Note: Some material courtesy of the Pacific Northwest Section of the American Water Works Association
Appendix C: Double Check Valve Assembly and Double Check Detector Assembly – DCVA & DCDA
Double Check Valve Assembly and Double Check Detector Assembly: DCVAs and DCDAs are designed to prevent backflow for low to zero health hazards only. They prevent backflow through backpressure and backsiphonage like the RPBA and RPDA by do not have the additional relief valve feature.
Figure C-1. Minimum Clearances for small DCVA and DCDA Installation
Other Considerations:
1 A DCVA or DCDA must be installed only in an upright, horizontal with the test cocks facing up or to one side as designed unless the assembly has been approved for vertical installation or other configurations as given by the manufacturer. All installations are subject to the approval of the cross-connection control specialist.
2 The installed assembly must be easily accessible for testing, inspection, and repair purposes. Submersion by soil, water or other liquids or solids is not acceptable except on an occasional and temporary basis unless specifically approved for such conditions by the cross-connection control specialist. Such conditions must not interfere with the regular testing and repair of the assembly.
3 These assemblies may be installed in a pit, vault, or enclosure if the pit, vault, or enclosure meets the minimum clearances specified by Figure 1 and plugs are installed in the test cocks to prevent fouling and reduce the risk of groundwater being siphoned through a leaking test cock.
4 Sufficient drainage must be provided in installations in below-ground pits. A minimum twelve-inch in gravel base must be provided for below-ground installations.
5 A minimum lateral clearance must be maintained around the backflow preventer to provide adequate room for attaching test hoses and for repair and removal. For small assemblies, the minimum clearance shall be 8 inches. For large assemblies, the minimum clearance shall be eighteen inches unless specified otherwise by the cross-connection control specialist.
6 Adequate access and clearances for inspection, testing, and repairs must be provided. If you have any questions, call the cross-connection control specialist.
Note: Some material courtesy of the Pacific Northwest Section of the American Water Works Association
Appendix D: Pressure Vacuum Breaker Assembly – PVBA
Pressure Vacuum Breaker Assembly: The PVBA is designed to prevent backflow for low to non-health hazards only. It prevents backflow form backsiphonage only and is most commonly used for lawn irrigation systems.
Figure D-1. Pressure Vacuum Breaker Assembly
(Lawn irrigation system that drains for winterization)
Other Considerations:
1 PVBAs must be installed at least twelve inches above the highest downstream piping or point of use.
2 As with all backflow assemblies, the PVBA must be installed no more than five feet above the standing or walking surface. If necessary to install at a higher level due to sprinklers installed on a hill, a platform from which tests and repairs may be made should be installed or a double check valve assembly must be installed instead.
3 PVBAs must never be subjected to backpressure.
4 Winterizing with compressed air or gas is not allowed. If it is necessary to do so, a DCVA or RPBA must be used instead.
5 Adequate access and clearances for inspection, testing, and repairs must be provided. If you have any questions, call the cross-connection control specialist.
Note: Some material courtesy of the Pacific Northwest Section of the American Water Works Association
Appendix E: Atmospheric Vacuum Breaker – AVB
Atmospheric Vacuum Breaker: The AVB is designed to prevent backflow for low to non-health hazards only. It prevents backflow from backsiphonage only and is most commonly used as backflow prevention on hose bibs and faucets. AVBs may not be used for premises isolation.
Figure E-1. Installation of Atmospheric Vacuum Breaker
Other Considerations:
1 AVBs must be installed at least 6 inches above the highest downstream piping or point of use.
2 An AVB may only be installed for applications where the AVB will be operating under pressure for no more than twelve hours in a day.
3 As with all backflow assemblies, the AVB must be installed no more than five feet above the standing or walking surface. If necessary to install at a higher level, a platform from which tests and repairs may be made must be installed or a double check valve assembly must be installed instead.
4 AVBs should never be subjected to backpressure.
5 Winterizing with compressed air or gas is not allowed. If it necessary to do so a DCVA or RPBA must be used instead.
6 Manual or automatic shutoff valves are not allowed downstream of an AVB.
7 Adequate access and clearances for inspection, testing, and repairs must be provided.
8 If you have any questions, call the cross-connection control specialist.
Note: Some material courtesy of the Pacific Northwest Section of the American Water Works Association
(Ord. 765, 1999).