Every drop of rain that falls on the Halton Waste Management Site must be dealt with properly. Here are some examples of how this is done by design.
Rain that falls within the open, uncapped areas of the landfill stays inside the landfill footprint and is collected within the leachate collection system. Leachate is formed when moisture from rain, snow melt or from within the waste itself sinks through the buried waste and arrives at the landfill liner at the bottom. There it makes its way into perforated piping that allow the leachate to flow by gravity to a common storage point where it can be pumped off site for treatment. By design, leachate is kept separate from the surrounding environment at all times.
Rain that falls on the outer slopes of the landfill, which has a clay cap, topsoil and vegetation in place, will find its way to surface water ditches and storm water containment ponds built around the site. When rain lands on the yard waste compost facility it will flow by gravity to a surface drainage pond that is used for irrigation of the shredded yard waste while it is composting.
The roofs of the largest site buildings are used as collection surfaces for our grey water system. Rain water is funneled into a 150,000 litre holding tank. From there, the grey water is used to water plants, clean machinery, flush soiled surfaces, and spray upon site roads for dust control when the weather is very dry. The grey water system conserves potable water for drinking and other sanitary uses.
The grey water storage tank also serves as a fire fighting water supply, so the grey water tank is kept “topped up” by automatic pumping from the nearest surface water storage pond.
The landfill gas collection system extracts moist gas from the landfill’s interior using a vacuum system. Since the gas has a humidity level above 90%, a lot of liquid condenses out of the gas as it travels along the sealed pipe network. This liquid is referred to as “condensate” and is another form of leachate. It is separated from the gas either by gravity, turbulence or cooling and is collected either for redistribution into the larger leachate collection system of the landfill or, when concentrated, shipped off site for processing. The condensate is kept separate from the surrounding environment.
A 100-year flood water retention pond is in place at the north side of the site. As the name implies, this level of flooding would not be expected very often (once in a hundred years on average). The inclusion of this large pond is part of the overall site drainage plan. Its purpose is to hold massive amounts of flood water that would have normally flowed southwards across the original site property from the farm fields and other properties north of the site. Large land developments are required to implement storm water retention ponds, and the Halton Waste Management Site is no exception.
As you can see, every drop of rain must be taken seriously. The number one reason for being so careful about water management is to prevent contamination of the environment. From ground water, to surrounding streams and waterways – it’s all part of an enduring water cycle. Protecting our shared water resources is a priority shared by the Halton Waste Management Site. It all starts with a drop of rain.