A sanitary landfill is a large land area where solid waste is disposed of in a manner that helps to protect human health and the environment (SWANA 1991).Â Sanitary landfillingÂ is an engineering method for the disposal of municipal solid waste. It includes the spreading of sorted garbage (solid waste) in layers,Â the waste isÂ compactedÂ before being covered with soil (SWANA 1991).Â Additional considerations for a sanitary landfill also includes:
- Proper siting (layout) and design of facilities, operational procedures and methods to ensure the protection of human health and the environment;
- monitoring of surface waters,, groundwater, anÂ liquid waste from s the compacted garbage (also known as leachate) and the venting ofÂ landfill gases during the time the facility is open and operational and also when it is decommissioned and closed;
Site selection is important for the siting of these facilities.Â In the case of the Mile 24 Regional Sanitary Landfill, site selection was included in the EIA process.
The Mile 24 Regional Sanitary Landfill was designed, constructed and supervised in accordance withÂ internationally accepted standards for municipal solid waste landfills. The landfill has the following features:
- Â A composite bottom liner: to keep all liquids within the landfill and prevent the contamination of water sources e.g. surface and ground water. The composite bottom liner is comprised of a the following:
- Geomembrane â€“Â aÂ synthetic material (thick plastic) which is placed on top of the compacted native clay.
- A leachate (contaminated water) collections system which is comprised of a river gravel drainage layer and a network of perforated pipes are placed on top of two layers of another synthetic material known as geotextile.
- Leachate or liquid waste collection and treatment system:Â this system is comprised of the lechate collection pipes, a submersible pump that automatically discharges leachate into Â the first of a series of treatment ponds.
- Treatment Ponds: Three ponds ( anaerobic, maturation and facultative)Â lined with geomembrane receive the leachate where it undergoes natural treatment.
TheÂ leachate once treated and testedÂ is discharged into the sedimentation area and eventually offsite by way of the storm water system.Â Prior to the discharge of leachate off site it must meet effluent standards established by the Department of the Environment.
Additionally the landfill facility is equipped with an administrative building, a weigh scale and scale house, mechanic workshop, monitoring wells and a hazardous waste cell.
The Hazardous Waste Cell is to be used for the safe disposal of hazardous waste (prior approval required from the Operator). This cell has two composite bottom liners to prevent the percolation of leachate or contaminated water to groundwater. Each of these liners consists of, from the bottom up: a compacted clay, geomembrane, one layer of geotextile, round river gravel drainage layer and submersible pump.