111. A landfill site must have at least 5 water table observation wells.
Each well must be drilled to at least 1 m into the bedrock or into an impermeable layer of unconsolidated deposits, have a minimum diameter of 5 cm and have a strainer over the entire width of the most permeable water-saturated layer.
At least 1 reference well must be situated upstream from the landfill site in relation to the direction of flow of the water table. The other observation wells must be located so as to intercept the potential diffusion and contamination zone; one of the wells must be situated at a distance of 300 m from the site, unless the landfill site is impermeable.