Q-2, r. 22 - Regulation respecting waste water disposal systems for isolated dwellings

Section 87.25.4 Disposition versions

2020-12-03

87.25.4. Construction standards: A leaching field installed in the conditions described in section 87.25.2 must be built with a low pressure feed system,

(a)  applying a maximum hydraulic loading rate to the soil at the disposal site that does not exceed the rates in the following table based on the hydraulic conductivity or percolation time and the soil characteristics at the disposal site:

Hydraulic conductivity (cm/s)	Percolation time (min/cm)	Maximum hydraulic loading rate L/(m2.d)
4X10-3 to 4 X10-4	4 to 15	33
4X10-4 to 2 X10-4	15 to 25	24
2X10-4 to 6 X10-5	25 to 45	12

Soil characteristics at disposal site			Maximum hydraulic loading rate L/(m2.d)
Textural class	Structure
	Type	Grade
Silt loam	Prismatic, blocky or granular	Moderate or strong	33
		Weak	24
Silt, clay loam or silty clay loam	Prismatic, blocky or granular	Moderate or strong	24
		Weak	12
Sandy clay, silty clay or clay	Prismatic, blocky or granular	Moderate or strong	12

(b)  applying a maximum linear hydraulic loading rate to the soil at the disposal site that does not exceed the rate in the following table based on the soil characteristics and grade at the disposal site as well as the thickness of the soil at the disposal site above the level of bedrock, underground water or any layer of impermeable soil available under the leaching field’s seepage surface:

Soil characteristics at disposal site			Linear hydraulic loading rate L/(m.d)
Textural class	Structure		Grade at disposal site
	Type	Grade	< 5 %		≥ 5 % < 10 %		≥ 10 % < 30 %
			Thickness of disposal site (cm)		Thickness of disposal site (cm)		Thickness of disposal site (cm)
			30-60	60-120	30-60	60-120	30-60	60-120
Silt loam	Prismatic, blocky or granular	Moderate or strong	37	41	43	50	47	53
		Weak	34	37	37	41	43	50
Silt, clay loam or silty clay loam	Prismatic, blocky or granular	Moderate or strong	36	42	37	41	43	50
		Weak	31	37	34	40	36	42
Sandy clay, silty clay or clay	Prismatic, blocky or granular	Moderate or strong	31	37	34	40	36	42

If the leaching field consists of trenches, it must meet the standards in subparagraphs b, c, d, e, f, g, g.1 and g.2 and subparagraph i of subparagraph i of the first paragraph of section 21 and in subparagraphs a and b of the second paragraph of that section, those in sections 23 to 25 and those in the third paragraph of section 87.22, with the necessary modifications.

If the leaching field consists of a seepage bed, it must meet the standards in subparagraphs d, e, f, g, g.1 and g.2 of the first paragraph of section 21 and in subparagraphs a and b of the second paragraph of that section, those in sections 24 and 25, those in subparagraphs a and c and in subparagraph i of subparagraph b of the first paragraph of section 27 and those in the fourth paragraph of section 87.24, with the necessary modifications.

O.C. 1156-2020, s. 67.