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  • Writer's pictureThe Low Down

Imprudent to build on a wetland, ravine

When you arrive in winter at that snowy glade on Ridge Road, you know you’ve made it to the top. It’s all downhill — not just for you, but for all the winter snow and summer rainfall that accumulates there.

At the western end of that glade is the tributary that replenishes Kingsmere Lake. The creek drops 80 metres over the next kilometre through a V-shaped ravine. Over time, gravel and fines were carried down the ravine and settled where the incline levels out. That layer of gravel and fines eventually became deep, and plants grew upon the alluvial deposits.

If you fill up a jar with gravel and sand and slowly pour water into it, it holds a surprising amount of water. Similarly, the creek draining towards Kingsmere Lake saturates the alluvium, creating the wetland. When there is heavy rainfall and snowmelt, the wetland absorbs the brunt of the deluge.

Building on a floodplain or wetland is imprudent. Building at the bottom of a ravine particularly so. Readers of the frontpage article “Chelsea allows construction of home in wetland” (July 26 edition) might perceive that the wetland was small, stagnant even. The reality is the house is situated within an active wetland/floodplain. And it floods. Residents are familiar with how much water and cobble can be thrown down that ravine. In the past 20 years, flooding from the creek has blown out an old concrete dam and submerged Kingsmere Road.

That a building permit was issued allowing construction was a surprise to residents. For one, there was the bylaw limiting the number of houses that could be built on a non-municipal road. There was also the wetland bylaw and the lot was, well, mostly wetland. And the property was prone to flooding.

Deep pockets enabled legal arguments to bypass the municipal bylaw. Once that barrier was overcome, a consultant’s report characterized the wetland as smaller than it appeared, clearing the way for a new home and septic system. [There was] a report inaccessible to the public and adjacent residents, including homeowners, who rely on the creek for well water. Finally, grandfathering allowed the structure to be 15 meters from the wetland instead of 30.

Chelsea’s present council deserves praise for now requiring a 30-metre setback from any wetland, regardless of size.

Chelsea’s new master plan recognizes that climate change is a significant challenge, and supporting ecological resilience, including maintaining wetlands, is important not only to biodiversity conservation, but also to infrastructure. We can all attest to increased precipitation events. The recent flash flooding and destruction of infrastructure through New England, eastern Quebec and the Maritimes were anticipated by climate science. Those hilly regions, like ours, saw major roads ripped apart by normally placid streams.

How will the degradation of this wetland play out? How might a flash flood impact that property, well water, Kingsmere Road, and Kingsmere Lake? Climate science suggests we may soon be faced with assessing the costs.

Andrew Henry is resident of Chelsea.

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