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Northwest City Becomes Model For Improving Water Quality

City of Bellingham, Washington

Stormwater Treatment

Owner:

City of Bellingham

Installation:

.

Technical Description:

The Stormwater Management StormFilter

The City of Bellingham, Wash., is wedged between Puget Sound and Lake Whatcom, on the eastern side of the city. The lake provides drinking water and recreation, including boating, swimming, and fishing. The city found that many of the existing stormwater systems around Lake Whatcom did not meet current design standards, and turned to a novel mix of treatment methods.

The Challenge

Bellingham’s watershed planners understood that pollution from urban areas is the most complex and difficult kind to control. They were particularly concerned with the Lake Whatcom watershed directly east of Bellingham that covered 37,000 acres. Bellingham is among the leading communities in conforming to Washington State’s Department of Ecology (Ecology) treatment and water quality standards. Ecology strictly regulates pollutants discharging into surface and ground waters. Ecology has one of the nation’s most rigorous limits, monitoring requirements and management practices.

Bellingham has experienced significant growth, and during the past several years, construction and development have changed drainage patterns. Rainfall from impervious surfaces runs quickly and directly into area streams. The City’s busiest park, Bloedel-Donovan Park, was also the site of the largest parking lot in the watershed. Stormwater containing automotive runoff, contaminated boat bilgewater and animal waste from the paved three acre posed a serious water quality concern. Without treatment, rain washed the pollutants down the gently sloping surface directly into Lake Whatcom.

The Solution

Given current and future population growth, the city proactively took critical steps to develop water management strategies that ensure economic vitality while protecting water resources. During improvements to Bloedel-Donovan Park, the City installed a mixed treatment system to address 99% of the parking lot surface, which serves hundreds of vehicles every day.

The APWA award-winning project used a stormwater filtration system, the Stormwater Management StormFilter ®, to remove suspended solids, metals, phosphorus and oils attached to solids. The project also used natural systems. Rain gardens filter pollutant-carrying water though sand, soil and plants. A sand filter and two infiltration galleries were also part of the mixed solution.

The city’s Storm and Surface Water Utility plus a small grant from Puget Sound Action Team funded the project. The mix of proprietary and nonproprietary solutions used at Bloedel-Donovan Park made the project more affordable.

“This project was a team effort to control pollution going into Lake Whatcom by improving the largest single parking lot in the watershed,” said Kirk Christensen, Stormwater Engineering Manager for Whatcom County.

The City uses a mix of systems and seeks the most cost-effective solution. Because the StormFilter is approved by Ecology, it’s easier to design into projects. In January 2005, the StormFilter received a General Use Level Designation (GULD) for basic treatment from Ecology. It was the first and only stand-alone proprietary technology approved by the state for basic treatment.

The system meets the basic treatment goals with influent particle size distribution ranging from silt to silt loam, when individual cartridges perform at a flow rate of 7.5 gpm (specific flow rate of 1 gpm/ft2) using ZPG™ media. ZPG is a blend of zeolite, perlite and granular activated carbon.

The StormFilter has been used in more than 80 sites in Bellingham for both public and private stormwater systems.

One of these, a roundabout at Kellogg Road and Cordata Parkway includes a six-by-nine foot vault to filter stormwater running into a fish bearing stream. For retrofit projects, Contech engineers customized the vaults to fit tight spaces under sidewalks or sloped to match the area’s landscape, and was even used at the Port of Bellingham marina. As the city’s APWA award shows, StormFilters can be used with other stormwater technologies to create a holistic system.

The city reviews its projects annually to determine if public construction work should include retrofits of stormwater systems. This allows Bellingham public works to include retrofits when resurfacing roads, coordinate with private developers on subdivisions, and even replace water mains. “Stormwater mitigation is a high priority for all public works projects,” said Brian Dempsey, project engineer in Bellingham’s public works department. “We’re always looking at ways to improve stormwater runoff quality in affordable ways. It makes projects more costeffective when we plan ahead yearly.”

Technical Description:

The Stormwater Management StormFilter

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