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Two city engineers are asking the province to stop the proposed 700-hectare Kanata West development in the watershed of the flood-prone Carp River.
Darlene Conway and Ted Cooper have filed formal requests — known as “Part II Order Requests” — with Environment Minister John Wilkinson, asking him to reject the city’s environmental assessments of the Kanata West Development and the Carp River Restoration Plan. They filed the requests as private citizens.
“Based upon experience gained from over 20 years of professional engineering practice, it is my opinion that the Carp River Restoration Plan … is fundamentally flawed in its proposed design and implementation. This is by virtue of its failure to meet the requirements and criteria of virtually every policy, guideline, and standard practice developed over the last 30 years in this province to guide the management of stormwater and floodplains,” Conway wrote.
In 2008, she discovered a serious flaw in the city’s modelling of water flow in the Carp River, which put the development on hold for two years while the current environmental assessments were completed.
Don Herweyer, a program manager in the city’s planning department, said experts from the Mississippi Valley Conservation Authority, the ministries of the environment and of transportation and the consulting company Greenland International had all reviewed the city’s environmental assessments.
“The city certainly does not agree (with Conway). We feel we’ve gone above and beyond the call in terms of due diligence,” Herweyer said.
The Carp River Restoration Plan is a $6-million project to give the river a more natural shape, increase its capacity to hold water during heavy rains and melts and improve the flow so stormwater moves downstream faster. It involves changing the river to create a narrow main channel, as well as several ponds and pools, in the section beginning at Hazeldean Road and ending 500 metres south of Richardson Side Road. The plan — whose cost will be split among the city, the Kanata West developers and other landowners — also involves planting vegetation along the riverbank, and making the channel more meandering.
The restoration plan, along with other stormwater management measures, is meant to improve drainage, allowing construction of the massive development that will fill the fields around Scotiabank Place with 7,200 homes as well as office and retail buildings. The construction will extend onto 28 hectares of the Carp River floodplain.
Herweyer said that, after the river was reconfigured, the area would no longer be part of the floodplain. However, Cooper, who has long fought the city’s development plans in the Carp River watershed, says the plan won’t stop the flooding problems. Those problems hit the headlines last summer when 800 homes in Kanata and Stittsville flooded in a torrential rainstorm on July 24.
If the city’s calculations about post-development waterflow in the Carp River are right, Cooper said, they actually show that peak water flows downstream will increase by up to 60 per cent during a 100-year storm, similar to the one last July.
Cooper also said he believed the new course of the waterway with its naturalized plantings of vegetation along the banks would slow the flow more than the city predicted. That would mean water will back up and pool in the southern reaches of the Carp, including the new Kanata West development, exacerbating flooding problems.
“In order to get their approval (from the Ministry of the Environment), they want to show they won’t have any impacts in Kanata West, but they will,” Cooper said. “If you don’t anticipate the proper flood levels, you could end up with basement flooding in Kanata West.”
Herweyer said he disagreed with how Cooper and Conway interpreted the model.
“We definitely disagree and would not be creating something set up to fail,” he said.
Herweyer added that the city was monitoring the Carp River and would adjust the model based on the data. He expects a fully calibrated model to be finished by next year. In the meantime, any new development in the watershed must have stormwater systems in place to ensure that no new runoff is added to the river.
The environment minister can:
n deny the requests and allow the development to go ahead;
n place conditions on the development;
n order the city to conduct new environmental assessments; or refer the matter to mediation.
A decision is not expected before late this year or early 2011.
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