Technical Requirements for a Natural Landfill Site Permit:
Specified Risk Material Confinement
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- Base: Non-engineered landfills may be based over natural geological materials that have a hydraulic conductivity of not more that 1 x 10-8 m/s (1 x 10-6 cm/s). If the area in which the landfill is located typically receives an average of less than 1000 mm total annual precipitation, the layer of natural geological material must be at least 2.0 m thick. If the area receives an average of more than 1000 mm total annual precipitation, the layer of natural geological material must be at least 4.0 m thick.
Groundwater Protection: There must be a minimum of 1.5 m between the level of the bottom of the waste cell and any groundwater. Contact the provincial authority that is responsible for water and other natural resources for the location of aquifers.
The landfill is constructed to operate as a hydraulic trap. The water table and groundwater on all sides of the landfill cell must not be less than 1.0 m higher than the height of the leachate in the cell. Wells to monitor the water table and the leachate levels are mandatory. Data from the wells must be collected at least twice a year. If the water table were to decrease to less than 1.0 m above the leachate level within the cell bottom, it would be necessary to pump out all leachate in the cell. The maximum leachate level at the bottom of the cell, above the liner, must be no more than 30 cm. Alternatively, the groundwater may be lowered (by pumping) to obtain the 1.5 m separation from the bottom of the cell to the groundwater as above.
- Surface Water Management: The landfill must have a surface water management system that diverts surface and stormwater from the disposal area, controls runoff discharge from the landfill, and controls erosion, sedimentation, and flooding.
- Landfill Cap: The final cover of any part of a cell or landfill must consist of a barrier layer of at least 60 cm of compacted natural or amended soil, or a geomembrane and a soil layer of reduced thickness with a hydraulic conductivity of 1 x 10-8 m/s (1 x 10-6 cm/s). Additional layers of substrates and final topography, including a minimum of 15 cm of topsoil, must be installed to minimize infiltration and erosion, and to prevent pooling of water in accordance with local environmental standards and requirements (i.e. soil graded at a slope between 3%–5% with vegetation or an armoured surface). If the cap is not mounded to prevent pooling or ponding, or otherwise designed to prevent rain from intruding and forming leachate, then the saturated hydraulic conductivity of the cap must be no more than 1 x 10-9 m/s (1 x 10-7 cm/s), and must be at least 60 cm thick.
- For background information and general landfill site requirements, refer to the Canadian Food Inspection Agency Policy: Permits for Landfill Sites Receiving Specified Risk Material.
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