October 29, 2007

TOM BARTSIOKAS

Christine Doody-Hamilton, Seneca College professor, showcases the permeability of the pavement test site.

Environment

Permeable pavement test site shows promising results

DAN O’REILLY

CORRESPONDENT

Masonry is a critical component in a special three-year research project at Seneca College’s King campus that is testing the efficiency of porous pavement in allowing rainwater to drain through, thereby recharging the groundwater table and reducing storm water runoff.

The project’s test site is a 360-spot parking lot divided into three 8.8-metre-wide by 32-metre-long sections. Two years ago, the asphalt paving of one of those sections was ripped up and replaced with interlocking bricks.

A high ridge on the interlocking bricks allows storm water to flow naturally in the Granular A material underneath instead of storm water pipes, as is the case with the two control sections.

“We’ve had a 95-per-cent reduction rate (in storm water),” says Seneca College professor Christine Doody-Hamilton of the results that have been collected since a test centre was opened last year.

That’s based on a comparative analysis of the storm water that flows into storm drains from the asphalt sections. Two computer-operated well sensors are powered by three voltaic cells and a wind turbine, which measures the amount of storm water runoff.

Data is collected and analyzed by the Toronto Region Conservation Authority, which is leading the project in partnership with the college and with the support of several corporate sponsors such as Unilock, Wal-Mart and the Cement Association of Canada.

Officially known as the Performance Evaluation of Permeable Pavement and a Bioretention Swale, it’s one of only a few porous pavement research studies under way in Ontario.

“We’re looking at ways to reduce runoff, both in terms of the quantity and quality,” says Doody-Hamilton, a faculty member of the college’s School of Civil Engineering Technology within the Centre for the Built Environment.

Urban development in the form of buildings and paved parking lots diminishes the amount of rainwater flowing naturally into the ground and is the source of major environmental problems, including flooding, erosion of streams, breaks and contaminated swimming areas. A major source of contamination is the oil, grease, tire, brake and clutch linings wear and other sediment particles that are directed from parking lots into storm drains, she says.

“The potential environmental benefits of implementing this technology in our urban centres are significant.”

Builders and developers could also realize substantial savings if the need for extensive and expensive storm drain networks is reduced, she says.

An interim report on the performance of the porous pavement was published earlier this year by the conservation authority. After it completes its research next year, Seneca College will continue long-term monitoring of the test site and use it as a teaching tool for its civil engineering students, says Doody-Hamilton.

Another porous pavement project is currently under way at the Inniskillin Winery in Niagara-on-the-Lake. A tour of the site will be conducted Nov. 22 by Unilock. For information, contact 1-800-Unilock or ruthbecker@unilock.com.

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