Technical Requirements for an Engineered Landfill Site Permit:
Specified Risk Material Confinement
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- Liner and associated leachate containment system: The liner for an engineered landfill and the associated leachate containment systems must have a hydraulic conductivity of not more that 1 x 10-9 m/s (1 x 10-7 cm/s) and have a thickness of at least 80 cm. An equivalent combination that provides a breakthrough time of at least 25 years is also acceptable. The liner may be constructed of natural clay, engineered clay-compacted soil, rock, geomembranes (industry-approved plastic sheeting or high density polyethylene), or a combination thereof. The bottom slopes of the liner must be at least 2% on controlling slopes and 0.5% on the remaining slopes. More complex liner systems may incorporate further protective layers, such as sand or gravel and Geotextile mats.
- Groundwater protection: The height of the groundwater must be maintained at a minimum of 50 cm below the lowest point of the liner throughout all seasonal variations. Groundwater-lowering systems may provide for positive drainage of the groundwater away from the landfill area.
- Surface water management: The landfill must have a surface water management system that diverts surface and stormwater from the disposal area, handles runoff discharge from the landfill, and controls erosion, sedimentation, and flooding. This system must be hydraulically separate from the site's leachate management system.
- Leachate control system: The landfill must have a leachate collection network, or equivalent, that is hydraulically separate from the landfill's stormwater system. This system must function year-round, offer adequate storage capacity, and be accessible for inspection and monitoring of flow.
- 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 mounted 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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