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HomeMy WebLinkAboutORD 1988-03 - Board ORDINANCE NO. 8803 OF THE TRUCKEE DONNER PUBLIC UTILITY DISTRICT ESTABLISHING CROSS-CONNECTION CONTROL REGULATIONS WHEREAS, it is the District's responsibility to protect the public potable water distribution system from contamination or pollution due to the backflow of contaminants or pollutants through the water service connection: and WHEREAS, the District intends to protect the public potable water supply from the possibility of contamination or pollution by isolating within the customer's internal distribution system or the customer's private water system such contaminants or pollutants which could backflow into the public water system; and WHEREAS , the District intends to promote the elimination or control of existing cross-connections , actual or potential, between the customer's in-plant potable water system and non-potable water system, plumbing fixtures and industrial piping systems: and WHEREAS, the District intends to provide for the maintenance of a continuing program of cross-connection control which will systematically and effectively prevent the contamination or pollution of all potable water systems; NOW, THEREFORE, BE IT ENACTED by the Board of Directors of the Truckee Donner Public Utility District that Water Rule No. 23, Control of Backflow and Cross-connection , a copy of which is attached hereto, become effective thirty days from the date of adoption of this ordinance. Further, that the Clerk of the District cause publication of this ordinance in accordance with the laws of the State of California. PASSED AND ADOPTED by the Board of Directors of the District at a meeting duly called and held within said District on the 18th day of April , 1988 by the following roll call vote: AYES: Aguera, Maass , Sutton, White and Corbett. NOES: None. ABSENT: None. TRUCKEE DONNE PUBLI I ITY ISTRICT L By J L. Corbett, President ATTEST: n Susan M. Craig, Deputy Distd6t Clerk smc/4.78 W-23-1 POLICY ITEK: CONTROL OF BACKFLOW AND CROSS-CONNECTIONS WATER RULE NO. 23 Date issued: April 18, 1988 Reference: Ordinance No. 8803 Date effective: May 18, 19R8 TRUCKEE DONNER PUBLIC UTILITY DISTRICT POLICY STATEMENT SECTION 1 CROSS-CONNECTION CONTROL - GENERAL POLICY 1.1 Purpose. The purpose of this rule is: 1 .1.1 To protect the public potable water supply of the Truckee Donner Public Utility District (hereinafter referred to as "District") from the possibility of contamination or pollution by isolating within the customer's internal distribution system(s) or the customer's private water system(s) such contaminants or pollutants which could backflow into the public water systems; and, 1 . 1 . 2. To promote the elimination or control of existing cross-connections, actual or potential , between the customer's in-plant potable water system(s) and non-potable water system(s) , plumbing fixtures and industrial piping systems; and, 1 .1.3 To provide for the maintenance of a continuing program of cross-connection control which will systematically and effectively prevent the contamination or pollution of all potable water systems. 1.2 District Responsibility. The District shall be responsible for the protection of the public potal-le water distribution system from contamination or vollution due to the backflow of contaminants or vollutants through the water service connection. If , in the iudgment of said District an approved backflow prevention assembly is required at the customer's water service connection for the safety of the water system, the District or its designated agent shall give notice in writing to said customer to install such an approved backflow prevention assembly at svecific locations on his premises. District shall not be responsible for any loss or damage directly or indirectly resulting from or caused by the prover, improver or negligent installation, operations, use , repair or maintenance of, or interfering with, any protective device by any customer or any other person. -1- /^ 1.3 Custoner Responsibility. It shall be the responsibility of each customer at his own expense to furnish, install , and keep in good working order and safe condition any and all protective devices. Once notified of the need to install a backflow prevention assembly, the customer shall immediately install such approved assembly at the customer's own expense; and failure, refusal or inability on the part of the customer to install , have tested and maintain said assembly shall constitute a ground for discontinuing water service to the premises until such requirements have been satisfactorily met. SECTION 2 DEFINITIONS 2.1 Approved. Accepted by the District as meeting an applicable specification stated or cited ' in this rule , or as suitable for the proposed use. 2.2 Auxiliary Water Supply. Any water supply on or available to the premises other than the purveyor's approved public water supply will be considered as an auxiliary water supply. These auxiliary waters may include water from another purveyor's public potable water supply or any natural source such as a well, spring, river, stream, lake , etc. or "used waters" or "industrial fluids." These waters may be contaminated or polluted or they may be obiectionabl.e and constitute an unacceptable water source over which the water purveyor does not have sanitary control. 2.3 Backflow. The reversal of the normal flow of water caused by either back pressure or back siphonage. 2.4 Back pressure. The flow of water or other liquids , mixtures or substances under pressure into the distribution pipes of a potable water supply system from any source or sources other than the intended source. 2.5 Back siphonage. 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 caused by the reduction of Pressure in the potable water supply system. 2.6 Backflow Preventer. An assembly or means designed to prevent backflow. 2.6.1 Air-gap. The unobstructed vertical distance through the free atmosphere between the lowest opening from any pipe or faucet supplying water to a tank, plumbing, fixture, or other device and the flood level rim of said vessel. An approved air-gap shall be at least double the diameter of the supply pipe , measured vertically, above the overflow rim of the vessel: and in no case less than one inch. 2.6.2 Reduced Pressure Principle Asseably. An assembly of two independently acting approved check valves together with a hviraulically operating, mechanically independent differential pressure relief valve located between the check valves and at -2- the same time below the first check valve. The unit shall include properly located test cocks and tightly closing shut-off valves at each end of the assembly. The entire assembly shall meet the design and performance specifications as determined by the USC Foundation for Cross-Connection Control and Hydraulic Research (hereinafter referred to as USCFCCCHR). The assembly shall operate to maintain the pressure in the zone between the two check valves at an acceptable level less than the pressure on the public water supply side of the assembly. At cessation of a normal flow the pressure between the two check valves shall be less than the pressure on the public water supply side of the device. In case of leakage of either of the check valves the differential relief valve shall operate to maintain the reduced pressure in the zone between the check valves by discharging to the atmosphere. When the inlet pressure is two pounds per square inch or less, the relief valve shall open to the atmosphere. To be approved these assemblies must be readily accessible for the in-line testing and maintenance and be installed in a location where no part of the assembly will be submerged. 2.6.3 Double Check Valve Assembly. An assembly of two independently operating approved check valves with tightly closing shut-off valves on each end of the check valves, plus properly located test cocks for the testing of each check valve. The entire r^ assembly shall meet the design and performance specifications as determined by a laboratory and field evaluation program resulting in an approval by the USCFCCCHR. To be approved these assemblies must be readily accessible for in-line testing and maintenance. 2.7 Contamination. Means an impairment of the quality of the potable water by sewage , industrial fluids or waste liquids , compounds or other materials to a degree which creates an actual or potential hazard to the rublic 'health through poisoning or through the spread of disease. 2.8 Cross-connection. Any physical connection or arrangement of piping or fixtures between two otherwise separate piping systems one of which contains potable water and the other non-potable water or industrial fluids of questionable safety, through which , or because of which, backflow may occur into the potable water system. This would include any temporary connections, such as hoses, swing connections, removable sections, four way plug valves, spools , dummy section of pipe , swivel or change-over devices or sliding multi-port tube. 2.9 Cross-connections - Controlled. A connection between a potable water system and a non-potable water system with an approved backflow prevention assembly properly installed and maintained so that it will continuously afford the protection commensurate with the degree of hazard. 2.10 Cross-connection Control. The installation of an approved backflow prevention assembly at the water service connection to any customer's premises. 2.11 Customer. The owner or operator of a private water system having a service from the District. 2.12 District. The Truckee Donner Public Utility District. 2.13 Hazard, degree of. The term if derived from an evaluation of the Potential risk to public health and the adverse effect of the hazard upon the potable water system. 2.13.1 Hazard - health. Any condition, device, or practice in the water supply systPm and its operation which could create , or in the Judgment of the District , may create a danger to the health and well-being of the water customer. 2.13.2 Hazard - plumbing. A olum'-,ing type cross-connection in a consumer's potable water system that has not been properly protected by an approved air-gap or approved backflow prevention assembly. 2.13.3 Hazard - pollutional. An actual or potential threat to the physical properties of the water system or to the potability of the Public or the customer's potable water system but whicti+ would constitute a nuisance or be aesthetically objectionable or could cause damage to the system or its appurtenances, but would not be dangerous to health. 2.13.4 Hazard - system. An actual or potential threat of severe damage to the physical properties of the public potable water system or the consumer's potable water system or of a pollution or contamination which would have a protracted affect on the quality of the potable water in the system. 2.14 Industrial Fluids System. Any system containing a fluid or solution which may be chemically, biologically or otherwise contaminated or polluted in a form or concentration such as would constitute a health, system, pollutional or plumbing hazard if introduced into an approved water supply. This may include , but not be limited to: polluted or contaminated waters; all types of process waters and "used waters" originating from the public potable water system which may have deteriorated in sanitary quality; chemicals in fluid form; elating acids and alkalises, circulating cooling waters connected to an open cooling tower and/or cooling towers that are chemically or biologically treated or stabilized with toxic substances; contaminated natural eaters such as from wells, springs , streams , rivers, irrigation canals or systems, etc.; oils , gases, glycerine, paraffins, caustic and acid solutions and. other 'liquid and gaseous fluids used in industrial or other purposes or for fire-fighting purposes. 2.15 Pollution. Means the presence of any foreign substance (organic, inorganic, or biological) in water which tends to degrade its quality so as to constitute a hazard or impair the usefulness or quality of the water to a degree which does not create an actual hazard to the ')ublic health but which does adversely and unreasonably affect such waters for domestic use. 2.16 hater - potable. Any water which, according to recognized standards , -4- is safe for human consumption. 2.17 Water - non-potable. Water which is not safe for human consumption or which is of questionable potability. 2.18 Water - service connection. The terminal end of a service connection from the public potable water system; i.e. , where the water purveyor loses jurisdiction and sanitary control over the water at its point of delivery to the customer's water system. If a meter is installed at the end of the service connection, then the service connection shall mean the downstream end of the meter. There should be no unprotected takeoffs from the service line ahead of any meter or any backflow prevention assembly located at the point of delivery to the customer's water system. Service connection shall also include water service connection from a fire hydrant and all other temporary or emergency water service connections From the public potable water system. 2.19 Water Supervisor. The customer or a person on the premises appointed by the customer charged with the responsibility of maintaining the customer's water system(s) on the property free from cross-connections and other sanitary defects during installation, operation and maintenance of the customer's pipelines and equipment. A certified backflow prevention asseml-+ly tester may not act as a water supervisor unless he is a full-time employee of the customer having the day-to-day responsibility for the installation and use of pipelines and equipment on the premises and for avo{dance of cross-connections. 2.20 Water - used. Any water supplied by a water purveyor from a public Potable water system to a customer's water system after it has passed through the point of delivery and is no longer under the sanitary control of the water purveyor. SECTION 3 REQUIREMENTS 3.1 Water system 3.1.1 The water system shall be considered as made up of two parts: The utility system and the customer system. 3.1.2 Utility system shall consist of the source facilities and the distribution system; and shall include all those facilities of the water system under the complete control of the utility, up to the point where the customer's system begins. 3.1.3 The source shall include all components of the facilities utilized in the production, treatment, storage, and delivery of water to the distribution system. 3.1.4 The distribution system shall include the network of conduits used for the delivery of water from the source to the customer's system. 3.1.5 The customer' s system shall include those parts of the facilities beyond the termination of the utility distribution -5- system which are utilized in conveying utility-delivered domestic water to points of use. 3.2 Policy 3.2.1 No water service connection to any premises shall be installed or maintained by the District unless the water supply is protected as required by State laws and regulations and this Dolicv/rule. Service of water to any premises shall be discontinued by the District if a backflow prevention assembly required by this policy is not installed, tested and maintained , or if it is found that a backflow prevention assembly has been removed , by-Dassed, or if an unprotected cross-connection exists on the premises. Service will not Se restored until such conditions or defects are corrected. 3.2.2 The customer's system should be open for insaection at all reasonable times to authorized representatives of the District and County Health Departments to determine whether cross-connections or other structural or sanitary hazards, including violations of these regulations, exist. When such a condition becomes known, the District shall deny or immediately discontinue service to the premises by providing for a physical break in the service line until the customer has corrected the condition in conformance with State, County and District regulations relating to plumbing and water service. 3.2.3 An approved backflow prevention assembly shall also be installed on each service line to a customer's water system at or near the Property line or immediately inside the building being served; hut, in all cases , before the first branch line leading off the service line wherever the following conditions exist: 3.2.3.a In the case of Premises having an auxiliary water supply which is not or may not be of safe bacteriological or chemical quality and which is not acceptable as an additional source by the District , the public water system shall be Protected against backflow from the premises by installing an approved backflow prevention assembly in the service line appropriate to the decree of hazard. 3.2.3.b In the case of premises on which any industrial fluids or any other objectionable substance is handled in such a fashion es to create an actual or Potential hazard to the public water system, the public system shall be protected against backflow from the premises by installing an approved backflow Prevention assembly In the service line appropriate to the degree of �... hazard. 3.2.3.c In the case of premises having (1) internal cross-connection that cannot be permanently corrected or controlled , or (2) intricate plumbing and piping arrangements or where entry to all portions of the -6- premises is not readily accessible for inspection purposes , making it impracticable or impossible to ascertain whether or not dangerous tross-connect ions exist , the public water system shall be protected against backflow from the premises by installing an approved backflow prevention assembly in the service line. 3.2.4 The type of protective assembly required under subsections 3.2.3.e , b, and c shall depend upon the degree of hazard which exists as follows: 3.2.4.a In the case of any premises where there is an auxiliary water supply as stated in subsection 3.2.3.a of this section and it is not subject to any of the following rules, the public water system shall be protected by an approved air-gap separation or an approved reduced pressure Principle backflow prevention assembly. 3.2.4.b In the case of any premises where there is water or substance that would be objectionable but not hazardous to health, if introduced into the public water system, the public water system shall he protected by an approved double check valve assembly. 3.2.4.c In the case of any premises where there is any material dangerous to health which is handled in such a fashion as to create an actual or potential hazard to the public water system, the public water system shall be protected by an approved air-gap separation or an approved reduced pressure principle backflow prevention assembly. Examples of premises where these conditions will exist include sewage treatment plants , sewage pumping stations, chemical manufacturing plants , hospitals , mortuaries and plating plants. 3.2.4.d In t*ie case of any premises where there are It unconcrolled" cross-connections , either actual or potential, the public water system shall be protected by an approved air-flap separation or an approved reduced pressure principle backflow prevention assembly at the service connection. 3.2.4.e In the case of any premises where , because of security requirements or other prohibitions or restrictions, it is impossible or impractical to make a complete in-plant cross-connection survey, the public water system shall be protected against backflow from the premises by either an approved air-gap separation or an approved reduced pressure principle backflow prevention assembly �. on each service to the premises. 3.2.5 Any backflow prevention assembly required herein shall be a model and size approved by the District. The term "approved backflow prevention assembly" shall mean an assembly that has been manufactured in full conformance with the standards -7- established by the American Water Works Association entitled: AWWA C506-84 Standards for Reduced Pressure Principle and Double Check Valve Bsckflow Prevention Devices; and have met completely the laboratory and field performance specifications of the Foundation for Cross-Connection Control and Hydraulic Research of the University of Southern California. The following testing laboratory has been qua'tfied by the District to test and certify backflow nreventers: Foundation for Cross-Connection Control and Hydraulic Research, University of Southern California, University Park, Los Angeles, California 90089-0231. 3.2.6 It shall be the duty of the customer at any premises where backflow prevention assemblies are installed to have certified inspections and operational tests made at least once per year. In those instances where the District deems the hazard to be great enough certified inspections may be required at more frequent intervals. These inspections and tests shall be at the expense of the customer and shall be performed by a tester certified by the American Water Works Association , California-Nevada Section. It shall be the duty of the District to see that these tests are made in a timely manner. The customer shall notify the District in advance when the tests are to be undertaken so that an official representative may witness the tests if so desired. T1,ese assemblies shall be repaired , overhauled or replaced at the expense of the customer whenever said assemblies are found to be defective. Records of such tests, repairs and overhaul. shall be kept and made available to the District. 3.2.7 All presently installed backflow prevention assemblies which do not meet the requirements of this section but were approved devices for the purposes described herein at the time of installation and which have been -,iroperl.y maintained, shall, except for the inspection and maintenance requirements under subsection 3.2.6, be excluded from the requirements of these rules so long ac the District is assured that they will satisfactorily protect the utility system. Whenever the existing device is moved from the present location or requires more than minimum maintenance or when the District finds that the maintenance constitutes a hazard to health, the unit shall be reDlPced by an approved backflow prevention assembly meeting the requirements of this section. smc/d6.33 -8- Control of Backflow and Cross Connections GUIDELINES AND STANDARDS: GENERAL REQUIREMENTS District Responsibilities It is the responsibility of the Truckee Donner Public Utility District to evaluate the hazards beyond the service connection in a customer' s water system to determine whether pollutants or contaminants are or may be handled on the customer' s premises in such a manner as to possibly permit contamination of the public water system. When a hazard or potential hazard to the public water system is found or suspected, the customer shall be required to install an approved backflow prevention assembly at each public water service connection to the premises in accordance with District Water Rule No. 23. Customer Responsibilities I. Customer is required to furnish and install in a manner approved by the District, and keep in good working order and safe condition, any and all backflow prevention assemblies. Device shall be owned by the customer. 2 . Customer to provide that any backflow prevention assembly be tested by a certified backflow prevention assembly tester at the time of installation and annually thereafter, or more often as the District may require. 3. Customer to provide that any defective backflow prevention assembly be repaired or replaced. 4. Customer shall not bypass or render inoperative any backflow prevention assembly. If a backflow prevention assembly is temporarily removed for repair or other reason, the customer shall provide that an approved backflow prevention assembly be installed and tested by a certified backflow prevention assembly tester at the time of installation. 5. Customer to maintain adequate heat source to backflow prevention assembly housings in order to prevent cold weather from affecting the operation of the assembly. Protective Devices Required ,ram The protection required to prevent backflow into the public wter system shall be commensurate with the degree of hazard that exists on the customer' s premises. The types of backflow prevention assemblies that may be required include: Double Check Valve Assembly: DC Reduced Pressure Principle Assembly: RP Air Gap Separation: AG The minimum types of backflow protection required at specific facilities are identified below. Those facilities or situations which are not listed shall be evaluated on a case by case basis and the appropriate type of protection shall be as determined by the District. 1. Aircraft and missile plants RP 2. Automotive plants RP 3. Autopsy facilities RP 4. Auxiliary water system a. with no known cross-connections DC b. with known or suspected cross-connections RP 5. Beverage bottling plants RP 6. Boilers - Steam generating facilities RP ,,•, 7. Breweries RP S. Buildings: a. Hotels , apartments , public and private build- ings or other structures, where sewage pumps and/or sewage ejectors have been installed RP b. Any commercial structure in which the speci- fic business activity cannot be ascertained RP C. Multi-storied buildings that use booster pumps or elevated storage tanks to distribute pot- able water within the premises DC d. Any building that exceeds 40 ' in height as measured from the service connection to the highest water outlet DC 9. Canneries , packing houses and reduction plants RP 10. Chemical Plants - any premises, served from a public water supply where there is a facility re- quiring the use of water in the industrial process of manufacturing, storing, compounding or process- ing chemicals. This will include facilities where chemicals are used as additives to the water supply or in the processing of products RP 11. Chemically Contaminated Water Systems - any pre- mises where chemicals are used as additives to the water supply, or where the water supply is used for transmission or distribution with chemicals, or where chemicals are used with water in the com- pounding or processing of products RP 12. Cold storage plants RP 13. Convalescent homes RP 14. Dental clinics RP 15. Dry cleaning facilities RP 16. Dye works RP 17. Electronics industry RP 18. Film processing or film manufacturing facilities RP 19. Fire Protection Systems that are supplied from a public water system: (a) Low-Hazard Fire Protection Systems: ( 1) Premises where the fire system is direct- ly supplied from the public water system and there is an unapproved auxiliary water supply on or to the premises (not interconnected) DC (b) High-Hazard Fire Protection Systems: ( 1) Premises where the fire system is supplied from the public water system and where ele- vated storage tanks or fire pumps which take suction from private reservoirs or tanks are used, or where an outside connection is re- quired by the F.P.D. and where water from un- approved sources or fire suppression chemicals can be entered into the fire sprinkler system. DC (2) Premises where the fire protection system is supplied from a public water system and in- terconnected with an unapproved auxiliary water supply RP (3) Premised where the fire protection system is supplied from a public water system and con- tains any hazardous substance RP 20. Hair styling RP 21. Hospitals RP 22. Ice Manufacturing Plants RP 23. Irrigation Systems: (a) Premises or locations where facilities have been installed for pumping, injecting or spreading fertilizers, pesticides or other hazardous sub- stances RP (b) Premises or locations having a separate ser- vice connection for irrigation purposes RP 24. Laboratories - Including, but not limited to, teaching institutions , biological and analytical facilities RP 25. Laundries (Commercial) RP 26. Medical Buildings and Clinics RP �^ 27 . Metal Manufacturing, Cleaning, Processing or Fabri- cating Plants RP 28. Morgues RP 29. Mortuaries RP 30. Multi-Storied Buildings : See Buildings 31. Multiple Services: Includes two or more inter- connected services provided by one or more water purveyors to a single consumer complex. (A) Minimum backflow protection required at each service connection DC (B) If any one of the interconnected services re- quires an RP device, each service requires RP 32. Nursing Homes RP 33. Oil/Gas Production, Storage or Transmission premi- ses RP 34. Paper and Paper Products Manufacturing Plants RP 35. Plastic Manufacturing, Extruding and Injection Molding ( See Chemical Plants) RP 36. Plating Plants RP 37. Portable Spray or Cleaning Equipment which can be connected to a public water system AG 38. Radioactive Materials or Substances - Plants or Facilities that process, handle or store radioac- tive materials or substances RP 39. Reclaimed Water Distribution Systems: (a) Premises whjere the public water system is used to supplement the reclaimed water system AG (b) Premises where reclaimed water is used and there is no interconnection •with the potable water system RP 40. Restricted, Classified or Other Closed Facilities RP 41. Rubber Manufacturing Plants - Natural or Synthetic RP 42. Sand and Gravel Plants RP 43. Sanitariums RP 44. Sewerage Systems - Sewerage or surface water pumps for priming, cleaning flushing or unclogging pur- poses , direct injection chlorination, sump ejec- tors RP 45. Schools , Colleges and Universities RP ( if actual or potential health hazard exists on the premises) 46. Solar Heating Systems - Direct and Auxiliary: (a) For solar collector systems in which a corro- sion inhibitor may be used and where there is a direct make-up connection to the public water sys- tem RP (b) Service connection protection is not required for "once through" solar heating systems including, but not limited to, domestic hot water systems. 47. Tank Trucks RP 48. Vehicle Washing Facilities RP 49. Veterinary Clinics RP Installation Requirements for Backflow Prevention Assemblies Customers with services which require backflow protection assemblies shall purchase approved devices and pay all costs associated with installation of the appropriate size and type of device. New installations shall be installed under private contract or by District staff, at the customer ' s expense. Exisitng facilities determined to need backflow protection will be retrofitted with the appropriate device under private contract or by District staff , at the customer' s expense. All new installa- tions shall be completed and tested prior to obtaining a certi- ficate of occupancy. A. Air-Gap Separation (AG) : 1. An air-gap separation shall be located on the water customer' s side of , and as close to, the service con- nection as is practicable. 2. All piping from the service connection to the receiving tank shall be above grade and visible unless otherwise approved by the District. 3. There must be no outlet, tee, tap, take-off or connection of any sort, to or from the supply pipe line, between the service connection and the air-gap separation. B. Reduced Pressure Principle Assembly (RP) : I . RP to be installed above ground on the water custo- mer' s side of, and as close to, the service connection as is practicable, unless otherwise approved by the Disrict. 2. RP to be installed a minimum of twelve inches( 12" ) above finished grade and not more than thirty-six( 36" ) above finished grade as measured from the bottom of the assembly, and shall be readily accessible for maintenance and testing as depicted in Figure , page 3. There shall be no outlet , tee, tap, take-off or con- nection of any sort , to or from the supply pipe line, between the service connection and the backflow preven- tion assembly. 4. RP shall be installed such that no part of the assembly will be submerged during normal operating and !" weather conditions. 5. RP shall be housed in a heated structure such that it will be kept from freezing and with adequate drainage. If a separate housing is not practicable, the device must be installed within the structure being served, in such a manner that it is readily accessible for inspection and testing. Care should be taken to place the device in an area which will not be adversely af- fected when the relief port opens during a backflow con- dition. It is the customers responsibility to provide drainage capable of removing maximum flow discharged through the device according to manufacturers specifications. In all cases the location of the device must be approved by the District. C. Double Check Valve Assembly (DC) : 1. DC to be installed aboveground on the water cus- tomer' s side of , and as close to, the service connec- tion as is practicable, unless otherwise approved by the �.-. District. 2. DC to be installed as minimum of twelve inches ( 12" ) above finished grade and not more than thirty-six ( 36" ) above finished grade as measured from the bottom of the assembly, and shall be readily accessible for maintenance and testing as depicted in Figure , page . 3. There must be no outlet, tee , tap, take-off or con- nection of any sort, to or from the supply pipe line, be- tween the service connection and the backflow prevention assembly. 4. DC shall be housed in a heated structure such that it will be kept free from freezing and have adequate drain- age for testing purposes. If a separate housing is not practicable, the device must be installed within the structure being served, in such a manner that it is read- ily accessible for inspection and testing. Care should be taken to place the device in an area which will not be adversely affected during testing. It is the customer' s responsibility to provide drainage capable of removing maximum flow discharged through the device according to manufacturers specifications. In all cases, the location of the device must be approved by the District. Testing and Maintenance The District will ensure that as a minimum each backflow prevention assembly is tested annually to assure proper operation. In instances where a hazard is deemed great enough, testing may be required at more frequent intervals. The customer shall bear all - - - -, costs of device testing. The cost of any maintenance required as a result of inspections or testing is the. responsibility of the customer. Maintenance work shall be performed by private contract. Records of inspections, testing or repairs shall be kept by the District and made available to the health department. The District will notify the customer when tests are required and supply the necessary test forms and instructions. These forms will be completed by the certified backflow-prevention tester and returned to the District by the date indicated. Test procedures shall be those recommended by the Foundation for Cross-Connection Control and Hydraulic Research, University of Southern California. Results of Non-Compliance If following an inspection and/or testing a device is found to be in non-compliance, the customer shall be notified and given fifteen (15) days to correct the deficiency after which time the ,00- inspection will be repeated. The District shall cause discontinuance of-water service if a backflow prevention device has failed to be tested properly or properly maintained or installed as required by District Rule 23 and Guidelines and Standards. Notification of intent to terminate water service shall be commensurate with the hazard to public health and may be delivered to the tenant, owner, or both as the situation requires. DB/st dl. 18 f"`