August 24, 2007

CULTEC

An artist's concept demonstrates the operation of the storm water retention system used at the Guelph Wal-Mart parking lot to help maintain the city's aquifer and avoid overloading municipal storm drains.

Environment

Storm water system designed for zero impact

Guelph Wal-Mart preserves city's sensitive aquifer

PETER KENTER

correspondent

GUELPH

The flagship store of the new Guelph SmartCentres plaza development project is a big Wal-Mart — with a big parking lot.

The city of Guelph welcomed the business but had concerns about the volume and quantity of its groundwater, used to replenish most of the area’s drinking water.

The area’s storm water management system is also operating at full capacity.

To allay concerns about the environmental impact of the new building, located at the intersection of Highway 6 and Highway 7, the project’s developers agreed that the shopping centre would neither add to the area’s storm water burden, nor rob the Speed River aquifer of precious groundwater.

The solution: an underground storm water retention/detention system supplied by CULTEC.

The Guelph SmartCentres system consists of a series of eight dome-shaped chambers nestled in a bed of granular material.

The domes feature open bottoms and perforated side walls to allow water infiltration.

Water is collected from the parking lot through traditional catch basins and passes through a series of nine filters.

The filters remove oil, debris, silt, road salt, and other particles from the storm water before it enters the storage tanks and is slowly returned to the aquifer.

A separate rooftop storm water storage system completes the development’s commitment to the city.

“The system was installed prior to the construction of the Wal-Mart in 2005,” says Prakash David, director of Land Development for SmartCentres.

“Currently, Wal-Mart is the flagship store in the development, but our plan is to add more units as the shopping centre expands.”

CULTEC

Construction workers install a stormwater retention system in the gravel bed underneath the future parking lot of a Guelph, ON Wal-Mart.

David says the system comes with a “seven figure” price tag, but adds that such accommodations are par for the course in suiting new developments to local conditions. “Sure it’s very expensive,” he says.

“But each development site is different and we do our best to address the sustainability requirements of each community.”

The units were installed over a period of several days by project sub-contractor Terra-Alta Construction Ltd. of Cambridge, ON.

“We were told that this was one of the largest systems of its kind in Canada so we were privileged to work on it,” says company president Joe Monteiro.

The entire area was first excavated and the units were installed under the direction of CULTEC consultants.

“The closest thing I could compare it to is weeping tile with headers and pipes running out into the soil,” says Monteiro.

“We completed the installation up to the buildings and the plumbers took over from there. That area already had a naturally-occurring granular bed, so the ground conditions were working with us.”

While some storm water management systems require additional adjustment after installation, engineering reports conducted by SmartCentres show that storm water is infiltrating into the aquifer at the same rate as it did before the development.

“It places no additional burden on the storm water system,” says David.

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