How do you build light rail and
widen a freeway along the edge of a well-managed former municipal waste landfill?
Very carefully!
And, with plenty of cooperation among public agencies.
We’re working to do exactly that
with Sound Transit, the Washington State Department of Transportation (WSDOT)
and Seattle Public Utilities (SPU).
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| A grassy meadow covers the Midway Landfill, next to the I-5 freeway southbound lanes between Seattle and Tacoma. White pipes behind the fence are part of the system to collect landfill gas, given off by decomposing municipal solid waste below. |
The
site: a former landfill
The City of Seattle’s 60-acre Midway Landfill site adjoins the west side of I-5 in
Kent. The landfill closed in 1983. Under our oversight, and review by the U.S.
Environmental Protection Agency, SPU:
- Covered
the landfill with an engineered, multilayered waterproof cap and a top layer of
grass.
- Installed
a gas extraction system to control methane generated by material in the
landfill.
- Controlled
surface water.
- Fenced
the landfill to limit access to the site.
These protective elements have
been in place since 1992. SPU continues to monitor groundwater quality and
landfill gas at the site, under a legal agreement with us, last updated in
2006.
 |
Sound Transit will build light rail on the landfill's east side,
along I-5's southbound lanes. (Click or tap image to enlarge.) |
Transportation
projects
Two planned south King County transportation
projects will run half a mile through the eastern edge of the landfill. Sound
Transit plans to extend its Link light rail line from Angle Lake to Federal Way. WSDOT
plans to widen a stretch of I-5 as part of its SR 509 Completion Project. Preparation of the landfill for the two
projects will be combined into a single project called FWLE/SR 509 Midway. FWLE
stands for Federal Way Link Extension.
FWLE/SR 509 Midway will bring
changes to the site. We’re developing legal agreements and engineering plans
with all three parties – SPU, WSDOT and Sound Transit -- to ensure that the
site’s environmental and public health and safety measures continue to function
during and after construction.
The combined project will involve
excavating some of the landfilled municipal waste, and will affect the landfill
cap, the gas collection system, and surface water monitoring network. Because
of this, we’re requiring:
- Transfer
of excavated municipal waste to an authorized landfill.
- Restoration
of disturbed portions of the landfill cap and other infrastructure.
- Documentation
of all required work for our review and approval.
Some of the site’s land ownership
will change. Sound Transit will acquire part of a strip – for the light rail
tracks – that now belongs to WSDOT and will assume responsibility for maintaining
that portion of the landfill cap. Seattle will continue to operate surface
water controls, the gas extraction system, and the ongoing monitoring program.
Plans
and agreements available
We’re asking the public to review
and comment on four documents that will govern how the FWLE/SR 509 project will
be built, and how the site will be reconfigured:
- Consent
Decree Amendment: update to our existing legal agreement with
SPU.
- Prospective
Purchaser Consent Decree: new legal agreement between us and Sound
Transit.
- Cleanup
Action Plan Amendment: describes actions we will require to
maintain the integrity of the site’s protective elements during and after the
proposed construction.
- Public
Participation Plan:
explains how people can participate in the cleanup process.
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| Looking south across the Midway Landfill where it adjoins I-5. |
Comments
invited; public meeting planned
The comment period begins on Jan.
27 and concludes on Feb. 25, 2020. Comment online or mail comments to: Mark Adams, Site Manager;
Dept. of Ecology; 3190 160th Ave. SE; Bellevue WA, 98008-5452.
We’re also inviting the public to
a meeting and hearing. We, SPU, Sound Transit and WSDOT will give a short
presentation and answer questions about the site and the projects. There will
be time for giving oral comments.
- Tue.,
Feb. 11, 2020; 7 - 9 p.m.
- Des
Moines Elementary School, 23801 16th Ave. S.
- Interpreter services will be
available in Spanish, Korean, and Somali.
We’ll review and respond to all
comments received. We expect the new plans and agreements to be in place by
mid-2020.
By
Larry Altose, communications manager, Northwest Regional Office
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