§ 98-413. Installation guidelines, requirements, standards, and specifications.

(a)

General to ensure proper operation and accessibility of all backflow prevention assemblies, the following national guideline requirements shall apply to the installation of these assemblies.

(1)

Backflow prevention assemblies shall be installed in accordance with the current TNRCC Rule and these regulations. The assembly installer must obtain the required plumbing permits and have the installation inspected by a representative of the regulatory authority.

(2)

At those facilities where the regulatory authority requires a backflow prevention assembly to be installed at the point of delivery of the water supply. Such installation of the assembly must be before any branch in the line and on private property located just inside the boundary between the city right of way and the landowner's property. The regulatory authority may specify other areas for installation of the assembly. Assemblies that must be installed or are located on city rights-of-way are the responsibilities of the business or entity that the water line is serving.

(3)

The assembly must be protected from freezing and other severe weather conditions.

(4)

All backflow prevention assemblies shall be of a type and model approved by the regulatory authority.

(5)

All vertical installations of backflow assemblies must have prior approval by the regulatory authority.

(6)

Assemblies installed more than five feet above floor level, must have a suitable platform for use by testing or maintenance personnel.

(7)

Bypass lines are prohibited. Pipe fittings which could be used for connecting a bypass line must not be installed.

(8)

Premises, where an uninterrupted water supply is critical, should be provided with two assemblies installed in parallel. They should be sized in such a manner that either assembly will provide the maximum flow required.

(9)

Lines should be thoroughly flushed prior to installation. A strainer with blowout tapping may be required ahead of the assembly.

(10)

All facilities that require continuous, uninterrupted water service and are required to have a backflow assembly, must make provisions for the parallel installation of assemblies of the same type; so that testing, repair, and maintenance can be performed.

(11)

The property owner assumes all responsibility for any damages resulting from installation, operation, and/or maintenance of a backflow assembly. The owner shall be responsible for keeping all backflow prevention assembly vaults reasonably free of silt and debris.

(12)

Upon completion of installation, the regulatory authority shall be notified and all assemblies must be inspected and tested. All assemblies must be registered with the regulatory authority and shall provide the date of installation, manufacturer, model, type, size, serial number of the backflow assembly, and initial test report.

(b)

Reduced pressure principle backflow prevention assembly (RP) may be utilized at premises where a substance is handled that would be hazardous to health if introduced into the potable water system. The RP is normally used in locations where an air gap is impractical. The RP is effective against both backsiphonage and backpressure.

(1)

RPs must be sized to provide an adequate supply of water and pressure for the premises being served. Flow characteristics are not standard. Consult manufacturer's specifications for specific performance data.

(2)

The assembly must be readily accessible for testing and maintenance and must be located in an area where water damage to building or furnishing would not occur from relief valve discharge. The property owner assumes all responsibility for any damage caused by water discharge from an RP assembly. An approved air gap shall be located at the relief valve orifice of RP assemblies.

(3)

No part of a reduced pressure principle backflow prevention assembly shall be submerged in water or installed in a location subject to flooding. RPs are typically installed above grade in well drained areas, but may be installed below grade (ground level) if a boresight drain to daylight, is provided. The drain shall be of adequate capacity to carry the full rated flow of the assembly and shall be screened on both ends.

(4)

Enclosures shall be designed for ready access and sized to allow for the minimum clearances established below. Removable protective enclosures are typically installed on the smaller assemblies. Daylight drain ports must be provided to accommodate full pressure discharge from the assembly.

(5)

Assemblies two inches and smaller shall have at least six-inch clearance on both sides and on top of the assembly, and 12 inches below and behind the assembly. All assemblies larger than two inches shall have a minimum of 12 inches on the back side, 24 inches on the test cock side, and the relief valve opening shall be at least 12 inches plus nominal size of assembly above the floor or highest possible water level. Headroom of six feet zero inches is required in vaults without a fully removable top. A minimum access opening of 30 inches is required on all vault lids.

(6)

All RP assemblies must be tested in accordance with this article. Tests are the responsibility of the assembly owner. The owner must notify the regulatory authority upon installation of any backflow prevention assembly.

(7)

Variances from these specifications will be evaluated on a case-by-case basis. Any deviations must have prior written approval by regulatory authority.

(c)

Reduced pressure principle detector backflow prevention assembly (RPDA) may be utilized in all installations requiring a reduced pressure principle backflow prevention assembly and detector metering.

(1)

RPDAs shall comply with the installation requirements applicable for reduced pressure principle backflow assemblies (RP).

(2)

The line-size RP assembly and the bypass RP assembly must each be tested. A separate test report for each assembly must be completed by the certified tester.

(d)

Double check valve backflow prevention assembly (DC) may be utilized at premises where a substance is handled that would be objectionable but not hazardous to health if introduced into the potable water system.

(1)

DCs must be sized to provide an adequate supply of water and pressure for premises being served. Consult manufacturer's specifications for specific performance data.

(2)

Premises, where an uninterrupted water supply is critical, should be provided with two assemblies installed in parallel. Assemblies should be sized in such a manner that either assembly will provide the minimum water requirements while the two together will provide the maximum flow required.

(3)

The assembly shall be readily accessible with adequate room for testing and maintenance. DCs may be installed below grade, providing all test cocks are fitted with brass pipe plugs. All vaults shall be well drained, constructed of suitable materials, and sized to allow for the minimum clearances established below.

(4)

Assemblies two inches and smaller shall have at least six-inch clearance below and on both sides of the assembly, and if located in a vault, the bottom of the assembly shall be not more than 24 inches below grade. All assemblies larger than two inches shall have a minimum clearance of 12 inches on the back side, 24 inches on the test cock side, and 12 inches below the assembly. Headroom of six feet zero inches is required in vaults without a fully removable top. A minimum access opening of 30 inches is required on all vault lids. "Y" pattern double check valve assemblies shall be installed so that the checks are horizontal and the test cocks face upward. These clearance standards apply to all assemblies installed in vaults, enclosures, and meter boxes.

(5)

Vertical installations of DCs are allowed only on sizes up to and including four inches that meet the following requirements:

a.

Internally spring-loaded check valves;

b.

Flow is upward through assembly;

c.

Manufacturer states their assembly can be used in a vertical position; and

d.

Approved by director.

(6)

All DCs must be tested in accordance with this article. Tests are the responsibility of the assembly owner. The owner must notify the regulatory authority upon installation of any backflow prevention assembly.

(7)

Variances from these specifications will be evaluated on a case-by-case basis. Any deviations must have prior written approval regulatory authority.

(e)

Double check detector backflow prevention assembly (DCDA) may be utilized in all installations requiring a double check valve assembly and detector metering.

(1)

DCDAs shall comply with the installation requirements applicable for double check valve assemblies (DCs).

(2)

The line-size DC assembly and the bypass DC assembly must each be tested. A separate test report for each assembly must be completed by the certified tester.

(f)

Pressure vacuum breaker backflow prevention assembly (PVB) may be utilized at point-of-use protection only and where a substance is handled that would be objectionable but not hazardous to health if introduced into the potable water system. PVBs protect against backsiphonage only and shall not be installed where there is potential for backpressure.

(1)

Assembly shall be installed a minimum of 12 inches above highest downstream piping.

(2)

PVBs shall not be installed in an area subject to flooding or where damage would occur from water discharge.

(3)

The assembly shall be readily accessible for testing and maintenance, with a minimum clearance of 12 inches all around the assembly.

(4)

All PVBs must be tested in compliance with this article. Tests are the responsibility of the assembly owner. The owner must notify the regulatory authority upon installation of any backflow prevention assembly.

(5)

Variances from these specifications will be evaluated on a case by case basis. Any deviations must have prior written approval of the regulatory authority.

(g)

Spill resistant pressure vacuum breaker backflow prevention assembly (SVB) may be utilized in all installations requiring a pressure vacuum breaker.

(1)

SVBs shall comply with the installation requirements applicable for pressure vacuum breaker backflow prevention assemblies.

(h)

Atmospheric vacuum breaker (AVB) AVBs provide minimal protection and are approved for very low hazard application only. AVBs protect against backsiphonage only and are prohibited where there is potential for backpressure.

(1)

The assembly shall be installed a minimum of six inches above the highest use outlet or overflow level downstream from assembly.

(2)

Shut-off valves downstream from the assembly are prohibited.

(3)

AVBs are allowed for only those applications where there is less than 12 hours per day continuous use.

(4)

AVBs cannot be installed below grade.

(5)

AVBs cannot be used around toxic or poisonous fumes.

(6)

AVBs shall not be installed in an area subject to flooding or where damage may occur from water discharge.

(7)

AVBs are allowed for point-of-use protection only.

(Ord. No. O-98-057-11, § 1, 1-11-99)