8.7.8.1 — General Requirements

(1) A leaching bed shall not be located, (a) in an area that has an average slope that exceeds one unit vertically to four units horizontally, (b) in soil or leaching bed fill having a percolation time of, (i) less than one minute, or greater than 125 minutes if constructed as a shallow buried trench, or (ii) less than one minute, or greater than 50 minutes for all other leaching beds, or (c) in or on an area that is subject to flooding that may be expected to cause damage to the leaching bed or impair the operation of the leaching bed. (2) A leaching bed shall not be covered with any material having a hydraulic conductivity less than 0.01 m/day. (3) The surface of the leaching bed shall be shaped to shed water and together with the side slopes of any raised portion, shall be protected against erosion in such a manner as to not inhibit the evaporation and transpiration of waters from the soil or leaching bed fill, and to not cause plugging of the distribution pipe. (4) No part of a leaching bed shall be sloped steeper than 1 unit vertically to 4 units horizontally. (5) A leaching bed shall be designed to be protected from compaction or any stress or pressure that may result in, (a) the impairment or destruction of any pipe in the leaching bed, or (b) the smearing of the soil or leaching bed fill.

(1) The treatment unit used in conjunction with a leaching bed constructed as a Type B dispersal bed shall provide an effluent quality that does not exceed the maximum concentrations set out opposite a Level IV treatment unit in Columns 2 and 3 of Table 8.6.2.2. (2) A Type B dispersal bed shall be, (a) rectangular in shape with the long dimension parallel to the site contours, (b) not more than 1 000 mm in depth measured from the bottom of the stone layer to the finished grade when installed in soil with a percolation time that exceeds 15 min, and (c) backfilled with leaching bed fill so as to ensure that, after the leaching bed fill settles, the surface of the leaching bed will not form any depressions. (3) The bottom of the stone layer shall be at least 600 mm above the high ground water table, rock or soil with a percolation time greater than 50 min. (4) The effluent shall be distributed over the Type B dispersal bed through a pressurized distribution system having a pressure head of not less than 600 mm when measured to the most distant point from the pump. (5) The distribution pipes shall, (a) be self-draining so as to prevent freezing of their contents, and (b) have orifices of at least 3 mm in diameter, spaced equally along the length of the pipes. (6) The stone layer containing the distribution pipes shall, (a) be comprised of washed septic stone, free of fine material, with gradation conforming to Table 8.7.3.3., (b) extend not less than 250 mm below the distribution pipe, and (c) extend not less than 50 mm above the distribution pipe. (7) The distribution pipes shall be spaced not more than 1.2 m apart with the outermost pipe spaced not more than 600 mm from the edge of the bed. (8) The pump chamber shall be sized to provide sufficient storage volume so that the effluent is evenly dosed on an hourly basis over a 24-hour period. (9) When there is more than one Type B dispersal bed in a leaching bed, the Type B dispersal beds shall be separated by at least 5 m measured from the edge of the stone layers. (10) A Type B dispersal bed shall not be located closer than the minimum horizontal distances set out in Table 8.2.1.6.B. and these distances shall be increased when required by Sentence 8.7.4.2. (11).