25.An engineered landfill must have a system capable of collecting leachate and conveying it towards a treatment or discharge site. The collection system must incorporate the following components:
(1) a drainage layer placed across the base and sideslopes of the disposal areas over the soil liner or the geomembrane, as the case may be, and which, to a minimum depth of 50 cm,
— consists of materials having less than 5% by weight of particles 0.08 mm or finer in diameter;
— has a constant minimum hydraulic conductivity of 1 x 10-2 cm/s.
The drainage layer must not impair the integrity of the underlying geomembrane, if any;
(2) a network of drainage pipes and collectors embedded within the drainage layer on the bottom of the disposal areas. The pipes must
— have a smooth interior and a minimum diameter of 150 mm;
— have no synthetic filter sock;
— have a minimum slope of 0.5%;
— have cleanout ports.
Despite the foregoing, if, pursuant to section 21, an engineered landfill has an impermeable sideslope liner system, the leachate may be collected and removed by means of another system if the system ensures compliance with the requirements of section 27.
If any portion of the collection system used to convey the leachate to the treatment site is situated outside the landfill disposal areas, the pipes in that portion must be leakproof.