Where I’m from (Vancouver, BC), we don’t get much snow and even when we do, it goes away fairly quickly. But with Edmonton’s longer, colder winters, there’s much more snow and it can take quite a while for it to melt. That means the City has to find a place to put all of the snow after it’s plowed off the streets.
Many years ago, the City used to dump snow removed from roads directly into the river but this raised environmental concerns due to the amount of salt and sediments entering the North Saskatchewan River. For that reason, snow storage facilities were built around Edmonton during the 1980s.
How snow storage facilities work is by storing the snow in piles, letting it melt, and diverting melt water into the storage pond where sediments and contaminants can settle, be removed and safely disposed of. Then the cleaned melt water is diverted to the storm drain where it runs off into an adjacent storage pond.
Snow removal and storage is costly but it is necessary to preserve our water quality.
Kennedale was established in 1984 and was built specifically for snow removed from downtown. Unlike the newer facilities, the Kennedale site has a packed clay surface to mound snow on. The storage pond is lined with a material called HDPE (high density polyethylene) to protect the pond sides from erosion, and lets the sediment settle while pumping out the water. In order to melt the snow pile, equipment is used to break down the mass.
The current issue at the Kennedale site is that clay is being pushed into the pond from equipment use. Any area that is not covered with concrete tends to erode due to flowing water with sediments, which acts like an abrasive stream. The excessive sediments are accumulating in the pond and removing them is a challenge. For this reason, newer snow storage facilities use hard surfaces on which to store and break down the snow mounds.
Horse Hills snow storage site, located on the north east quadrant of the City, is the newer of the two facilities we visited. Here, the surface is made out of a hard, roller packed concrete. A wetland treatment pond was considered in the original design; however, it was revealed that birds may cause a threat to military planes and other equipment at the adjacent military base. Audio bird deterrents have been installed and fences are used to keep out other wildlife.
The melt water at this site travels at a very slow rate to allow more sediment to remain on the pad. Once a critical level of water is reached in the first pond, the water can overflow into the second pond. Lastly, the melted water at Horse Hills flows through a long pipe that runs to the City’s storm water system.
According to our guide, the melt water ponds are tested weekly and groundwater testing is done, too. This ensures that the total suspended solids (TSS), salt concentrations, and many other parameters, are monitored to ensure the water leaving the site is not contaminating our waterways, thus preventing pollution to the natural environment.
It was great to see how the site operates, by minimizing contaminants getting into the watershed. It is also neat to see how this plays a part in the City’s environmental strategy, The Way We Green, and how this adds to what the City is doing to work towards environmental sustainability.