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Southwestern Landfill Environmental Assessment

Landfill Design

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The figure below is a model of the proposed Southwestern Landfill site that shows how key safety features and added environmental protections work independently, and together to protect the surrounding environment. 

In this diagram, key Design and Mitigation components of the landfill are indicated with a black arrow and a title. To learn more about these key features, please read the corresponding title and descriptions below.


Landfill Design Diagram


Berms & Trees

To minimize visual impacts around the site, screening berms (or mounds) and trees are often used. They also help minimize noise.

Bird Control

Trained Bird Control staff use falconry, pyrotechnics and other forms of deterrents to prevent birds from visiting the landfill.

Groundwater Collection System

An underdrain (former quarry sump) or groundwater collection system is used to draw groundwater in towards the site from the surrounding area to allow the construction and operation of landfill. 

The groundwater collection system or underdrain also acts as a contingency plan in the unlikely event there was an issue with the landfill liner. By collecting groundwater underneath the landfill, groundwater flows towards the landfill where it can be collected at a single point where it can be treated if needed.

Groundwater Monitoring Wells

Groundwater monitoring wells are located around the landfill site to monitor the groundwater conditions and confirm that the liner system is functioning properly. The wells provide important information like groundwater flow direction and quality. 

All of the information that is collected is put into a monitoring report that is provided to Ministry of Environment, Conservation and Parks every year. 

Landfill Cap

Once landfilling is complete, an engineered landfill cap is used to cover the waste. The cap, which typically consisted of a specific type of soil also includes a topsoil layer so vegetation can be grown for aesthetics and to reduce erosion. 

Landfill Gas Collection

Gas produced by the landfill will be collected using a landfill gas collection system. The collection system consists of a series of wells drilled into the waste that are connected by pipes. The pipes are connected to a landfill gas plant which places a vacuum on the system and draws the gas out of the landfill. By collecting landfill gas, odours are controlled. Landfill gas can also be used as a renewable fuel source to generate electricity or power nearby businesses. 

Landfill Gas-to-Energy Plant

Landfill gas, which is produced from the decomposition of organic matter in the waste, is approximately 50% methane. The bio-methane can be used as a fuel in nearby industries (i.e. lime kilns) or to produce renewable electricity or natural gas. By collecting and controlling methane emissions, a landfill gas-to-energy facility can significantly reduce Greenhouse Gas (GHG) emissions. 

Landfill Liner

The landfill liner is designed to be fully protective of the environment and meets the strict requirements of Ontario’s environmental regulations. At approximately 12 feet (3.5 metres) thick, it includes multiple layers of engineered clay and geomembranes that serve two important purposes: 

  1. To provide a barrier between the waste inside the landfill and the outside environment, including groundwater. 
  2. To collect leachate so it can be removed from the landfill and treated.

Leachate Collection System

Precipitation that falls onto active areas of the landfill or any water that has come into contact with waste is contained by the landfill liner system.  This liquid, commonly called leachate, is then collected by a series of pipes and removed from the landfill so it can be treated.  It must meet the strict provincial water quality standards before it can be released back into the environment.

Leachate Treatment Plan

Leachate, which is any water that has come into contact with waste, is removed from the landfill by the Leachate Collection System and pumped to the Leachate Treatment Facility. 

The Leachate Treatment Facility operates much like a municipal wastewater treatment facility to treat and clean the water. Treated water must meet strict provincial water quality standards before it can be released back into the environment.

Scalehouse & Inspection Station

Upon arriving at the site, trucks must report to a Scalehouse and inspection station to confirm that they are approved to enter. At the Southwestern Landfill, all trucks must be pre-approved before arriving to the site. Once they have arrived, the Scalehouse attendants check paperwork and can visually inspect the waste to make sure it permitted to be received at the site.

Storm Water Management Ponds

Stormwater, or precipitation that falls on parts of the site that are either capped or in areas where it has not come into contact with waste will be collected in stormwater management ponds. These ponds help settle any silt that might be in the water and act as a storage area to minimize risk of any flooding of creeks or rivers off-site.  As an added precaution, water is tested before it is slowly released to nearby watercourses.


In Ontario, a solid non-hazardous landfill, like the proposed Southwestern Landfill, is not permitted to receive wastes that are liquid or hazardous. Some examples of solid, non-hazardous waste include packaging from retails stores/malls, general waste from office buildings and schools, waste from construction and demolition projects and curbside waste from residential areas to name a few.