The project has undergone a SEPA environmental review as well as a site clean-up in preparation
for site construction.
Seattle City Light completed the Final Environmental Impact Statement (EIS) in January 2015. Review and
download the Draft EIS
and Final EIS
The Final EIS expands on the Draft EIS. Together, these documents compose the "Denny Substation Project EIS"
and should be read in tandem for a full understanding of the project's likely environmental impacts and
The Final EIS volume includes:
- additional analysis on several topics (noise and land use, for example),
- a summary of probable adverse impacts for all project components,
- responses to public and agency comments on the Draft EIS, and
- a list of commitments and actions that City Light now proposes to avoid, minimize,
or otherwise mitigate environmental impacts where possible.
While three transmission line route alternatives were studied in the EIS, a preferred
alternative was not identified. Please see the Program
to view the transmission routes.
The completion of the environmental clean-up at the Denny Substation site in early 2014 marked an important
milestone for the project. The soil and groundwater at the former Greyhound Bus Maintenance Facility were
contaminated with gasoline, diesel and waste oil, and needed to be cleaned up prior to development of the
property. The site clean-up efforts involved demolishing the maintenance facility, removing underground
storage tanks, removing contaminated soils, installing a stormwater detention system and backfilling the site
with clean dirt.