A controversial plan to include Lacombe Lake as part of a stormwater project drew about 100 people to a Blackfalds open house on Wednesday night.
Those opposed to Blackfalds’ Northwest Stormwater Management Plan fear it will pollute the small lake despite the town’s best intentions to ensure stormwater entering the lake is clean.
The town insists the Stantec-designed stormwater system has been designed to go above and beyond provincial water and flood standards, uses natural drainage patterns and is the best alternative for channelling stormwater from a new development area in northwest Blackfalds.
Anita Alexander, who has been a vocal opponent of the town’s plans, said nothing she heard at the meeting convinced her that the lake’s health would not be put at risk by the stormwater proposal.
“The contamination risks are certainly not addressed to my satisfaction,” said Alexander, whose family has owned property on the lake for 90 years.
“(I have) just as many concerns and I think that everybody that walked out the door probably has just as many concerns, if not more than they did when the came in.”
Besides contamination, she is worried about the impact flooding could have on the lake and what warm stormwater will do to the lake’s ecosystem.
Martine Francis, from stormwater plan designer Stantec, said in a presentation that the system takes a “treatment chain approach” that uses a series of stormwater ponds, natural wetlands and constructed wetlands to clean runoff before it reaches Lacombe Lake.
Most stormwater will never reach the lake, but will evaporate or be absorbed into the ground. More than 25 mm of rain must fall in a day before the system discharges into the lake Stantec engineering consultants have estimated. The system has also been designed so that it would take a one-in-500-year storm event to cause overland flooding.
As well, those developing in northwest Blackfalds will be required to put down 25 to 30 cm of topsoil to soak up water.
Alexander’s husband, Richard Thom, was among those skeptical that the stormwater system will work as well as promised.
“I don’t really have a lot of faith that all these best management practices will actually occur,” he said, questioning why a pristine lake will be risked.
Lacombe Lake property owner Bill Hill said the lake is fed by groundwater and creating a surface connection through a stormwater system creates a risk of invasive species.
“It only takes one goldfish with eggs,” he said.
Blackfalds Mayor Richard Poole stands by the system, saying only clarified water will ever reach Lacombe Lake and the amount would be minimal.
“A monitoring system is very important to our plan,” he said.
The town also said during the meeting a land management plan will be in place to ensure developers meet topsoil requirements and other standards.
Information gathered at the open house will now be forwarded to Alberta Environment and Parks, which must approve the stormwater plan.