Section 445A.6724 - Cross-connections and backflow: Installation of double check valve assemblyExcept as otherwise authorized by the Division or the appropriate district board of health, if a double check valve assembly is installed on a service connection:
1. The double check valve assembly must be installed: (a) In a horizontal and level position, except that the double check valve assembly may be installed in a vertical position if the assembly has been:(1) Specifically designed for operation in that position; and(2) Tested and certified to be suitable for operation in that position by an approved backflow testing laboratory.(b) As closely as practicable to the service connection, on the opposite side of the service connection from the public water system.(c) Above ground and, to the extent possible, not less than 12 inches nor more than 36 inches above the finished grade, as measured from the bottom of the assembly.(d) In such a manner as to be readily accessible for maintenance and testing.2. There must be no type of outlet, tee, tap, take-off or connection to or from the service line between the service connection and the double check valve assembly.3. Expansion tanks or pressure relief valves must be provided as appropriate for the potential threat of water hammer and thermal expansion.4. The double check valve assembly may, if above-grade installation is impracticable and the Division or the appropriate district board of health approves of the installation, be installed in a below-grade vault in such a manner that: (a) The top of the double check valve assembly is not more than 8 inches below grade.(b) There is: (1) At least 12 inches of clearance between the bottom of the vault and the bottom of the double check valve assembly;(2) At least 24 inches of clearance between the side of the vault and the side of the double check valve assembly with test cocks; and(3) At least 12 inches of clearance between the side of the vault and the other sides of the double check valve assembly.(c) To the extent warranted by climatic conditions, the double check valve assembly is protected from freezing.(d) The vault has adequate drainage to prevent the accumulation of water, which drains to daylight, to free-draining soil or to a sufficient amount of gravel placed under the vault to provide for free drainage and prevent the accumulation of water under the vault. A vault that does not have an integrated bottom must be placed on a layer of gravel which is not less than 3 inches deep.(e) The vault is protected from vandalism.(f) The vault is not located in an area subject to vehicular traffic.5. The double check valve assembly may be installed indoors if:(a) The installation complies with subsections 1 to 4, inclusive; and(b) The double check valve assembly has a clearance of:(1) At least 12 inches on top;(2) At least 24 inches on the side with test cocks; and(3) At least 12 inches on the other sides.Nev. Admin. Code § 445A.6724
Added to NAC by Bd. of Health, eff. 2-20-97; A by Environmental Comm'n by R194-08, 10-27-2009