Location: 1945 SE Water Ave.

Facility location: Interior parking lot landscaping for both lots.

Type of facility: Vegetated swales

Date of installation: 1990, modified in 1996

Impervious area managed: 174,000

Size of facility:  Ten swales covering 13,980 ft² total. (2,330 linear feet of swale at 6 feet wide)

Cost: saved about $78,000 in construction costs by using swales in place of a traditional stormwater management system such as drywells.

 

When OMSI was developing its new location on the banks of the Willamette River, staff from Environmental Services approached OMSI asking them to redesign their parking lot to treat stormwater. This was achieved by converting traditional landscaped parking lot islands to vegetated swales. To gain additional area for the swales, the lot was the first in the city to use smaller parking stalls. The smaller stalls are 8 ½ ft wide and 16 ft long. Car bumpers overhang the curb stops. OMSI received special permitting approval from the city for this parking lot design. BES staff provided significant levels of support for this project because there were no policies or codes addressing onsite stormwater management design at the time.

In 1996 BES performed a water quality audit to test the performance of the swales.  It is estimated that they capture 50% of total suspended solids, and observations show that they absorb most of the rainwater they capture.

Owner: OMSI

Architect: Zimmer Gunsul Frasca Partnership

Landscape Architect: Murase Associates

Project Support: Environmental Services