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.
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.
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
®, 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.”
The Stormwater Management StormFilter