Case Study: Filtration System Maximizes Valuable Land Space While Meeting Stormwater Requirements
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Progress Ridge, a 110-acre mixed-use development, is designed around a reclaimed rock quarry on the border between the cities of Beaverton and Tigard, Ore. The quarry is now an 11-acre lake surrounded by 746 high-density residential units, a commercial town center and 43 acres of parkland.
Beaverton requires on-site detention of stormwater runoff to control the volume of runoff sent to downstream channels. This protects channels from scouring and reduces potential flooding. Under EPA permit regulations, a specific level of water quality is required before discharging runoff into downstream waterways.
The Challenge In a development like Progress Ridge, engineers typically meet stormwater requirements with large aboveground detention ponds. Because of the development's size, a detention pond would displace 200 to 300 residential units.
Site engineers considered detention facilities with corresponding water quality at different locations, or installing individual water quality manholes to provide settling before directing runoff to a larger on-site collection facility. While both offered flow control and water quality improvement, each would reduce the amount of developable land.
Polygon Northwest, a Vancouver, Washington engineering firm, proposed installing underground filtration systems manufactured by Stormwater Management, Inc. to meet detention and water quality requirements and maximized land use.
"We decided that this development might not happen if we didn't find a way to accommodate some form of stormwater management that didn't include above-ground detention using valuable land on the site," said Gary Brentano, operations director for the City of Beaverton. "You hit a point where a developer can't generate enough return on investment to make the investment to begin with. That's in part what led us to consider the StormFilter."
Click here to download the entire case study in pdf format.
Source: Stormwater360