31.1. Construction standards: A gravity feed seepage bed built under a non-watertight secondary treatment system must comply with subparagraph h.1 of the first paragraph of section 21 and with the following requirements:
(a) the secondary treatment system must be able to cover and uniformly distribute water over the entire absorption area required by section 28;
(b) the maximum length of every section of a seepage bed must not exceed the maximum length of the secondary treatment distribution system. The maximum length must be provided in the manufacturer’s manuals and have been certified by an engineer who is a member of the Ordre des ingénieurs du Québec;
(c) if the base of the non-watertight secondary treatment system is less than the area referred to in the table in section 28, without the absorption area exceeding the base of the treatment system by more than 60 cm, a minimum 15 cm layer of gravel or crushed stone complying with subparagraph f of the first paragraph of section 21 must be spread over the entire seepage surface. If the seepage bed is built in sections, this requirement applies with the necessary modifications; and
(d) the bottom of the non-watertight secondary treatment system or the layer of gravel or crushed stone referred to in paragraph c of section 31.1 must be at least 60 cm above bedrock, impermeable soil, low permeability soil or underground water.