NAC445A.67135. Distribution system: Release and blowoff valves.

     1. Air and vacuum valves, air release valves or hydrants must be installed at high points in water mains where air tends to accumulate.

     2. Suitably sized blowoff valves must be provided in appropriate locations at low points in water mains with diameters of 20 inches or more. Blowoff valves must have air gaps and must not discharge directly into sewer lines.

     3. Except as otherwise provided in subsection 4, the openings of any vents in a valve required pursuant to this section must:

     (a) Be located at least 1 foot above the grade of the ground surface; and

     (b) Have a discharge pipe that is screened, elbowed and faced downward in such a manner as to protect the pipe from traffic and other disturbances. The screen must not be susceptible to damage by corrosion and must have not less than 22 nor more than 24 mesh per inch.

     4. If compliance with subsection 3 is impracticable, the Division or the appropriate district board of health may, on a case-by-case basis, authorize below-grade openings in vents. If so authorized:

     (a) The openings must be located in subsurface chambers or pits which are adequately drained and are not subject to flooding; and

     (b) The drains from the chambers or pits must have air gaps and must not be connected directly to any sewer lines.

     (Added to NAC by Bd. of Health, eff. 2-20-97; A by Environmental Comm’n by R194-08, 10-27-2009)