The Centre is committed to “Walking Lightly on the Environment.” This simply means that we manage our waste materials in an environmentally friendly manner and work to conserve our valuable landfill space. But even with our recycling and composting programs some material must go in the garbage.
Material is received at the active area of the landfill. All loads are inspected to make sure they do not contain recyclable, compostable, construction/demolition materials, hazardous or electronic waste and/or tires. If loads do contain these materials and to encourage people to sort their garbage properly a higher tipping fee is applied.
To conserve space, material is compacted using heavy equipment designed especially for working in the landfill. The landfill compactor has 4 wheels that weigh four tonnes each! These wheels have large teeth that work like giant rolling pins; crushing and compacting the garbage to conserve landfill space. The landfill is covered daily with clean, ground up shingles, wood waste and/or soil to minimize blowing litter and odours.
Leachate Treatment Facility
Leachate is created when rainwater percolates through the garbage and drains out of the landfill, eventually mixing with ground and surface water. Leachate can contain high concentrations of nitrogen, iron, heavy metals and other chemicals such as pesticides and solvents. Making sure that materials such as hazardous waste, drywall and even food waste are kept out of the landfill helps to lower the toxicity of the leachate. If left untreated, leachate can have a detrimental impact to the environment.
At the Ottawa Valley Waste Recovery Centre’s landfill site, an engineered wetland treats the ground and surface water that may have come into contact with landfill leachate. Engineered and natural wetlands are used to clean polluted waters through a variety of physical, chemical and biological processes. These wetlands can remove nutrients, metals and other pollutants from the wastewater before it is put back into the natural environment.
The Leachate Treatment Facility collects all leachate impacted ground and surface water though a series a pipes and transfers the liquid to a pumping station. From the pumping station the leachate is moved to the equalization pond and then into an underground recirculation tank. The equalization pond has a capacity of 1 million litres and the recirculation tank can hold 525,000 litres! From the recirculation tank the leachate is intermittently dosed into the engineered wetland which consists of 4 treatment cells with filter mediums (sand, gravel, wood chips) and some vegetation.
Landfill Gas Collection System
Inside the landfill, buried organic waste decomposes under anaerobic (without oxygen) conditions and produces landfill gas. Landfill gas is approximately 50% methane which is a potent greenhouse gas with a global warming potential 21 times that of carbon dioxide. Removing methane gas from the landfill both reduces odours and cuts down the emission of ozone depleting methane into the atmosphere. At the OVWRC, methane gas is collected and flared, reducing its global warming potential by 95%. Flaring methane gas also destroys most of its harmful components which can cause nuisance odours, stress on vegetation, smog, and a risk of fire, explosion and asphyxiation.
OVWRC’s Landfill Gas Collection System
Over 3 kilometers of piping were installed within the buried waste at the landfill site. The pipes are connected to well heads which allow Centre staff to monitor gas concentration. These pipes allow the gas to flow, under vacuum, from the landfill interior to the enclosed flaring system. Based on the relatively small size of the landfill, methane gas available for combustion is in the range of 180 cfm (cubic feet per minute) to 300 cfm. Larger sites generating electricity from landfill gas would be operating on flows over 1300 cfm. Due to the potential presence of landfill gas, smoking on OVWRC property is prohibited.
The Centre’s Environmental Compliance Approval (ECA) issued by the Ontario Ministry of Environment (MOE) dictates the operating and monitoring requirements of all facilities and areas at the Centre. OVWRC received their final landfill expansion approval from the MOE in 2010. The current ECA outlines the allowable landfill capacity. The total waste disposed of at the site will not exceed a volume of 2,650,000 cubic meters. At the current (2010) fill rate, the landfill will actually reach capacity in 27 years. Reducing waste going to landfill through recycling, reuse, and other waste diversion programs is a priority for the Ottawa Valley Waste Management Board and Centre staff. When the Centre received the ECA Amendment in 2010, a requirement was to install a Leachate Treatment System and a Landfill Gas Collection System.