- (a) Force mains shall be sized to yield a cleansing velocity of 3 feet per second or greater at design pumping rate.
- (b) Force mains shall be 4 inches or larger in nominal diameter except when used in conjunction with grinder pumps and necessary to achieve adequate cleansing velocity at design pumping rate.
- (c) To prevent air locking, force mains shall be provided with an automatic air relief valve at each high point, installed within a manhole structure that meets the design requirements of Env-Wq 704.12 through Env-Wq 704.17.
- (d) Force mains shall enter the gravity sewer system at the flow line of the receiving manhole.
(e) Force mains shall be provided with a drainage blow-off at each low point that:
- (1) Has a properly valved connection for a vacuum truck or other suitable containment device; and
- (2) Is installed within a manhole structure that meets the design requirements of Env-Wq 704.12 through Env-Wq 704.17, with sufficient space for handling the displaced waste without danger of pollution or health hazard.
- (f) Force mains pipe joints shall include mechanical joint restraint or thrust blocks made from inorganic, corrosion-resistant material at all bends, elbows, tees, and junctions. Heat fused high density polyethylene joints do not require mechanical restraint or thrust blocking.
- (g) Force mains shall be designed to withstand instantaneous hydrostatic pressures of at least 2.5 times the design total dynamic head or at least 100 psi, whichever is greater.
Source. (See Revision Note at chapter heading for Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14; ss by #14258, eff 7-1-25, EXPIRES: 7-1-35