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

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37. Construction standards: An above-ground sand-filter bed built with a gravity feed system must comply with the construction standards in subparagraphs d, e, f, g, g.1, g.2, g.3, h and h.1 of the first paragraph of section 21, and with the following standards:
(a)  the sand layer must be at least 30 cm thick and must be thoroughly settled by water spraying before installation of the pipes;
(b)  the sand filter must comply with the following:
i.  the effective diameter must be between 0.25 and 1 mm;
ii.  the uniformity coefficient must be equal to or less than 4.5;
iii.  less than 3% of the particles must have a diameter less than 80 µm; and
iv.  less than 20% of the particles must have a diameter greater than 2.5 mm;
(c)  subparagraphs a and c of the first paragraph of section 27 apply, with the necessary modifications, to an above-ground sand-filter bed;
(d)  the maximum width of a sand-filter bed or of a section of a sand-filter bed must comply with the standards in the following table, according to the permeability of the disposal site:

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Permeability of the Maximum width of the
disposal site sand-filter bed (metres)

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High permeability soil 3.1
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Permeable soil 1.9
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Low permeability soil 1.3
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(e)  a line of perforated pipes must be not longer than 18 m measured from the point of entry;
(f)  when the sand-filter bed is built on level ground, the grade of the earth backfill on each side of the sand-filter bed must be not more than 33%;
(g)  when the sand-filter bed is built on sloped ground, the grade of the earth backfill on each side of the sand-filter bed must be not more than 33%, except on the front side of the slope where it must be not more than 25% with backfill at least 6 m long;
(h)  before building the sand-filter bed, the soil on which it is built must be tilled;
(i)  the bottom of the gravel or crushed stone layer must be at least 90 cm above bedrock, impermeable soil or low permeability soil.
The above-ground sand-filter bed built with a low pressure feed system must comply with subparagraphs a, b, c, d and f to i of the first paragraph of this section, subparagraphs d, e, f, g, g.1, and g.2 of the first paragraph of section 21 and subparagraphs a and b of the second paragraph of that section.
R.R.Q., 1981, c. Q-2, r. 8, s. 37; O.C. 786-2000, s. 37; O.C. 903-2002, s. 1; O.C. 567-2008, s. 9.