Exploring the role of stormwater ponds (column)

London Community News

You’ve probably seen one, you might even have one in your neighbourhood — those little lakes (well, actually, large ponds might be a better description) in the centre of a subdivision. But have you ever given a thought to what they do? And ‘they’ have a name, too — stormwater management ponds, which accurately describes their primary function on the urban landscape. It’s a secondary function, however, which tends to get a neighbourhood’s attention, usually in a good way, although sometimes not. Take the stormwater management pond in the Hyde Park area just north of Gainsborough, a community eyesore since it was dug out almost a decade ago. It’s functional, but esthetically more akin to a treeless barren than the Forest City. Berta Krichker is the city’s manager of the stormwater management unit. And as you might expect with a title like that, stormwater management ponds come under the jurisdiction of her department. She’s heard the complaints, and is in on-going discussions with developers in the area to get the problem fixed. And that was one of the problems with stormwater management ponds — they were constructed by developers and the transition from eyesore to environmental eye-candy was often dependent on the speed with which a subdivision filled in. Since 2009 the city has been in charge of construction to ensure they get completed more quickly and to the city’s specifications to which the developer agrees when a subdivision site plan is approved. It takes serious money, though. A single SMP — that’s what they get called around City Hall — can cost upwards of $3 million. But when complete and grown out, they provide an attractive green space in a neighbourhood that supports a menagerie of flora and fauna. Many become the focus of trail networks that encourage biking and cycling. As a result, home builders often can charge higher prices for properties adjacent to these ponds. Home building, in fact, is directly linked to SMPs, Ms. Krichker explains. The creation of new subdivisions is the reason they are needed and built into the cost of each home sold is a development charge of around $20,000, a portion of which goes to paying for the ponds. That’s because SMPs provide an important service beyond just looking good. Their primary function is to emulate nature’s watersheds which slowly and gently trail rainfall from the highlands to the river. When the city pushes outward, though, the natural watershed is disrupted. Trees get cut down; what once were open fields get covered with rooftops and asphalt; runoff water is pushed into catch-basins and a labyrinth of underground pipes. Instead of trickling when it rains, the water now gushes and can, if not controlled, overflow the capacity of the man-made system causing floods. So since 1993, out in the suburbs, the storm drain system first flows into these ponds which, by filling up and slowly releasing water over hours instead of minutes, act as a sort of brake. “It’s common sense,” Ms. Krichker says. “We’ve disrupted Mother Nature. To fix the problem we’ve got to mimic her by building something that works like the original system.” So for that reason London now has 80 ponds, each draining upwards of 40 city blocks. Call them Mother Nature’s little helpers. Philip McLeod is a longtime London journalist who writes a regular blog on civic affairs. Email phil@philipmcleod.ca.