Weighing Station

Any vehicle arriving at the landfill site must first stop at the weighing station so that an attendant can register the weight of its waste load.

 

The site is divided into four sections

A. Unloading Area for Small Vehicles

B. Recyclable Materials Area

C. Landfill Area

D. Construction Materials Landfill Area

 

A. Unloading Area for Small Vehicles

This unloading area allows individuals to securely dispose of small quantities of wastes without having to go right up to the cell with their vehicle.

 

B. Recyclable Materials Area

This salvage area is used to store large materials until they are reused or sent for recycling (household appliances, refrigerators, metal, tires, wood). Freon coolants found inside refrigerators are harmful to the ozone layer, which is why they are removed from each appliance before it is sent for metal recovery. A specialized firm extracts the gases that are later reused.

 

C. Landfill Area

Wastes are emptied in a landfill cell. The landfill cell is designed to prevent the leachate (contaminated water) from penetrating into the ground and contaminating watercourses. It is composed of 4 layers of compacted clay, 15 cm each, to ensure its impermeability. Two synthetic liners are added, namely a HDPE liner of sixty-thousandth of an inch (around 1.5 mm) and another one of eighty-thousandth of an inch (around 2 mm) (primary liner). A geogrid is placed between the HDPE membranes to determine if the primary liner is leaking. A geotextile covers the cell and a drainage system is then installed to collect the leachate. A 45-cm layer of gravel is then placed on top of the drainage system. The cell is now ready to receive the wastes.

A cell is 60 meters wide by 200 meters long. It is designed to receive 100,000 tonnes of waste. One cell costs approximately one million dollars. The major steps of cell construction are:

• Clay Compacting
• Installation of Connecting Leachate Collection Pipe
• Installation of HDPE Membrane
• Preparation of Membrane for Welding
• Welding of the Membrane to the Landfill Cell Components
• Welding and Membrane Quality Control
• lnstallation of Geogrid
• Installation of Leachate Collection Pipe and Layer of Gravel

The wastes emptied into the cell are not burned. They are compacted with a compactor so they take up the least possible space in the cell. With this practice, approximately 800 kg of wastes can be stored in each cubic meter. Wastes are covered with a layer of soil in order to eliminate problems with vermin, rodents, and fire hazards and also to reduce the scattering of wastes by the wind.

 

Leachate Treatment System

Leachate is a liquid that forms when melting snow or rain percolates through waste. The exact composition of leachate varies depending on the type of waste contained in the cell. The Montagne-de-la-Croix regional sanitary landfill comprises a leachate treatment system. Leachate that emerges from landfill cells is directed into the different leachate treatment stages where it is transformed in a liquid that has been treated and is safe for the environment.

 

Aeration Lagoon

As a first step, leachate emerging from the landfill cell is directed to the aeration lagoon where the primary treatment of the contaminated liquid takes place. The aerators provide oxygen to bacteria that destroy microorganisms.

 

Retention Lagoon

Then, the treated leachate is directed into the retention lagoon equipped with surface aerators that maintain the level of oxygen in the water. It acts as a temporary storage facility in order to control the flow of leachate into the rest of the system.

 

Sand Filters

Leachate passes through the sand filters in order to extract all heavy metals it could contain, and to eliminate suspended solids and purify the water.

Sampling is done when leachate emerges from the sand filters. Leachate that has been treated must meet the standards of the Canadian Council of Ministers of the Environment (CCME) before it can be released. The release conditions are that the environmental standards are met and that the flow of water in the stream (holding facility) is adequate.

If leachate meets all these requirements, it is then released in the sedimentation pond. If not, it is redirected to the primary or secondary treatment lagoons (aeration or retention lagoon) to continue the treatment process.

 

Sedimentation Pond

The sedimentation pond collects the treated leachate discharge water as well as the site surface water. These waters are released in the Big Spring Brook near the landfill site. Discharge is done either in the spring or fall, when the stream water level is higher. The treated leachate must meet the environmental standards before being released.

Tests are conducted internally each month in order to verify the effectiveness of the water treatment system and ensure that there is no contamination (surface water and phreatic water). Every three months, the same tests are conducted by external consultants. In addition to these series of tests, testing is carried out inside monitoring wells for an in depth evaluation of phreatic water. Piezometer tests are also conducted to verify water accumulation in the landfill cell in order to ensure that the leachate flows properly.

 

D. Construction Materials Landfill Area

This zone is reserved for collecting construction materials. These materials are inert, therefore they do not produce leachate. They are: concrete, wood, insulating materials, and plasterboard.