8.7.3.3.

(1) Except for shallow buried trenches, the distribution pipe used in the construction of a leaching bed shall be,

(a) of not less than 3 in. trade size for gravity flow systems, or 1 in. trade size for pressurized systems,

(b) installed with a uniform downward slope from the inlet with a drop of not less than 30 mm and not more than 50 mm for each 10 m of distribution pipe, and

(c) installed within a layer of stone conforming to Sentence (5).

(2) Prior to backfilling, the stone layer required in Clause (1)(c) shall be protected in such a manner so as to prevent soil, or leaching bed fill from entering the stone by completely covering with,

(a) untreated building paper, or

(b) a permeable geo-textile fabric.

(3) Every pressurized distribution pipe shall be self-draining so as to prevent freezing of its contents.

(4) Every pressurized distribution pipe shall have orifices of at least 3 mm in diameter, spaced equally along the length of the pipe.

(5) The layer of stone required by Clause (1)(c) shall,

(a) be comprised of washed septic stone, free of fine material, with gradation conforming to Table 8.7.3.3.A.,

(b) be not less than 500 mm in width,

(c) extend not less than 150 mm below the distribution pipe, and

(d) extend not less than 50 mm above the distribution pipe.