THUNDER BAY — The largest engineered wetland project of its kind in Thunder Bay will soon be diverting stormwater outfalls and filter out contaminants before they enter Boulevard Lake and move on to Lake Superior.
Engineered wetlands use the natural functions of vegetation, soil, and micro-organisms to improve water quality by removing solids, organic matter, excess nutrients, pathogens, and heavy metals.
Work on the project near the south side of the lake, between the tennis courts and the children's playground, began in early summer and is now nearing completion.
It's a joint initiative of the city and the Lakehead Region Conservation Authority, supported by an Ontario government contribution of about $110,000.
A contractor dug a depression approximately 75 metres long, which will accept the runoff from three storm sewer pipes currently running from Gibson Avenue and Lyon Boulevard directly into the lake.
"We will be disconnecting the pipes before the lake, and sending that outfall into this engineered wetland which will help to filter the water as it moves through it, and have better water quality while evening out the quantity distribution over a storm as well," said Werner Schwar, supervisor of parks and open space planning for the city.
Once the level of Boulevard Lake is lowered in preparation for the winter season, two exit points will be constructed to allow the filtered water to enter the lake from the depression.
Schwar said natural vegetation including trees, shrubs and perennials – both wetland species and dry bank species – will be planted to restore the area that's been dug up.
"Experience has shown us when we did a little bit of a low-impact development beside the playground area, that there is enough existing plant material in the adjacent shoreline, so stuff like roots and seeds from that area blow in all by themselves. So we're helping it a little bit, but the idea is that what belongs there will come in on its own as well." Schwar added.
Some of the vegetation has already been planted by volunteers organized by the LRCA.
Schwar described the project as "a bit of a trial" but noted that it's just part of the whole storm water management plan for the city.
Whenever the main parking lot at Boulevard Lake is rehabilitated, he said, the city will look at similar techniques for improving the storm water runoff that now moves from the parking to the beach area.
