The Ontario Building Code | Construction Requirements
8.7.5.3. Construction Requirements
(1) Sentences 8.7.4.2.(1), (2) and (4) to (11) apply to the construction of a filter bed.
(2) The lines of distribution pipe shall be evenly spaced over the surface of the filter medium to which the sanitary sewage is applied.
Note: On January 1, 2018, Sentence 8.7.5.3.(2) of Division B of the Regulation is revoked and the following substituted: (See: O. Reg. 139/17, s. 65 (1))
(2) The lines of distribution pipes or leaching chambers shall be evenly spaced over the surface of the filter medium to which the sanitary sewage is applied, with a maximum spacing between the centrelines of the distribution pipes or leaching chambers in accordance with Table 8.7.5.3.
Table 8.7.5.3.
Maximum Spacing Between Lines of Distribution pipes or Leaching Chambers
Forming Part of Sentence 8.7.5.3.(2)
| Item | Column 1 Distribution Method | Column 2 Maximum Centreline Spacing, mm |
| 1. | Distribution pipes | 1 200 |
| 2. | Type I leaching chambers | 900 |
| 3. | Type II leaching chambers | 1 000 |
(3) The filter medium shall have a minimum depth of 750 mm below the stone layer and shall be clean sand comprised of particles ranging in size between the limits of,
Note: On January 1, 2018, Sentence 8.7.5.3.(3) of Division B of the Regulation is amended by adding "or bottom of the leaching chambers" after "stone layer" in the portion before Clause (a). (See: O. Reg. 139/17, s. 65 (2))
(a) an effective size of 0.25 mm with a uniformity coefficient not less than 3.5,
(b) an effective size of 2.5 mm with a uniformity coefficient not greater than 1.5, and
(c) having a uniformity coefficient not greater than 4.5.
(4) The filter medium shall be unsaturated for its entire depth.
(5) Where there is more than one filter bed in a leaching bed, the filter beds shall be separated by at least 5 m between the distribution pipes of the filter beds.
Note: On January 1, 2018, Sentence 8.7.5.3.(5) of Division B of the Regulation is amended by adding "or leaching chambers" after "distribution pipes". (See: O. Reg. 139/17, s. 65 (3))
(6) The base of the filter medium shall extend to a thickness of at least 250 mm over an area meeting the requirements of the following formula:
where,
A = the area of contact in square metres between the base of the filter medium and the underlying soil,
Q = the total daily design sanitary sewage flow in litres, and
T = the lesser of 50 and the percolation time of the underlying soil.
(7) The stone layer required by Clause 8.7.3.3.(1)(c) shall be not less than 900 mm above the high ground water table, rock or soil with a percolation time of more than 50 minutes.
Note: On January 1, 2018, Sentence 8.7.5.3.(7) of Division B of the Regulation is amended by striking out "required by Clause 8.7.3.3.(1)(c)" and substituting "or bottom of the leaching chambers". (See: O. Reg. 139/17, s. 65 (4))
8.7.6. Shallow Buried Trench