meydenbauer creek sewer replacement and bank stabilization

MEYDENBAUER CREEK SEWER
REPLACEMENT AND BANK STABILIZATION
StreambankStabilizationProject
Bellevue, Washington: Summer 2009
Problem
Project
Background
Solution
Flashy storm events have caused repeated flooding of this urban creek leading
to erosion of the streambank, settling of storm sewers and increased
sedimentation buildup in Lake Washington. With the increased sediment
discharge into Lake Washington a permanent resolution was needed to protect
migrating Salmon.
Meydenbauer Creek is a key drainage way for stormwater runoff from downtown
Bellevue that discharges into Meydenbauer Bay on Lake Washington. With
increased urban development and the addition of impermeable surfaces
downtown, stormwater discharge into Meydenbauer Creek has increased
flooding and caused stream bank erosion. Adjacent streets, storm sewers and
culverts have settled and been damaged as a result. During storm events, the
creek becomes flashy with the final two bends in the creek experiencing severe
st
erosion. The resulting streambank washouts have caused settling on 101
st
Street, failure of the stormwater culverts under 101 and sedimentation buildup in
the bay.
An Envirolok ™ Vegetated Bag Wall system was designed as a structural
solution to the riparian erosion at the last 90 degree bend in the creek before
entering the bay. This 120’ section of the creek was restored using the
engineered bag wall and was planted with native riparian zone plants. The top of
the wall was protected using a straw/coir fiber mat and was planted with native
grass plants. The entire wall was hydroseeded using a native seed and flower
mix for immediate additional protection.
Permits
Engineering
Consultants
Environmental
Review
Permits were obtained through the City of Bellevue Utilities Department
and issued by the Army Corp of Engineers, Seattle District NWP 13 and
NWP 33.
PBS Engineering and Environmental, Seattle WA
J.E. Jacobs Engineering
Protecting fish during construction, encapsulating stream flows during
the low water season, working in very limited right of way and daily
removal of all construction equipment and materials from a single traffic
lane closed only 10 hours a day all presented significant obstacles during
construction. The work was completed in four working days with limited
disruption to the neighborhood and without effecting any of the adjacent
sewer work being done simultaneously.
The project was partially re-engineered on site to address potential
severe flash points with additional wall at locations added. The work was
completed on schedule without disruption to other trades with the
resulting final product professionally delivered.
Agency reaction
According to City of Bellevue Utility Construction Inspector on the project
Chris Brookes “The results speak for themselves”.
Project Fact Sheet
Contractor Installer:
Certified Installer:
Sunmark Environmental Services
18032 NE Airport Way
Portland OR 97230
Sunmark Environmental Services, LLC
th
2255 NE 194 Ave
Portland OR 97230