(a) Each pipe associated with a sludge processing unit must have a slope that ensures the flow of sludge.
(b) A pipe under a stationary structure must allow a blockage to be easily eliminated by rodding or a sewer-cleaning device.
(c) A gravity pipe must have uniform grade and alignment.
(d) The slope of a gravity discharge pipe must not be less than 3.0%.
(e) The minimum diameter for a pipe associated with sludge processing is shown in Figure: 30 TAC §217.243(e):
Attached Graphic
(f) The available head on a discharge using a gravity withdrawal pipe must be at least 4.0 feet.
(g) A gravity withdrawal pipe from a clarifier must allow for the removal of sludge.
(h) Each sludge pipe must include a means to observe the quality of the supernatant from each of the withdrawal outlets.
(i) Each individual sludge processing unit must have a dedicated means of dewatering.
(j) Pipes located inside a digestion tank must be designed for use in corrosive environments and must be sufficiently supported to prevent damage to the pipe or adjacent equipment.
(k) A sludge pipe must not contain any bends that form an acute angle with the pipe.

Source Note: The provisions of this §217.243 adopted to be effective August 28, 2008, 33 TexReg 6843; amended to be effective December 4, 2015, 40 TexReg 8254