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Environmental Clean-up Project

Seattle City Light purchased the Greyhound Bus Maintenance Facility in 2009 with the intention of using the property for the Denny Substation. Prior to purchasing the property, the utility conducted a Phase I-II Environmental Assessment to determine environmental conditions and to evaluate the costs and potential risks associated with purchase.

The environmental assessment found soil and groundwater contamination from gasoline, diesel, and waste oil products due to historical leakage from underground storage tanks. Some of these materials were found as deep as 35 feet below ground surface within areas of the property. Seattle City Light developed a voluntary clean-up plan to remediate the site to meet Model Toxics Control Act (MTCA) "Level A" clean-up standards as applied in close proximity to residences (see WAC-173-340-704 - Use of Method A). The clean-up plan includes removal of all contaminated soil on the property that has been identified as exceeding these standards.

Seattle City Light published a SEPA Environmental Checklist and a Determination of Non-Significance in September 2011. The checklist contains additional information about the history of the site, the clean-up plan and construction work required to complete the clean-up. The utility has obtained permits required for this remedial construction including wastewater discharge, land use, demolition, grading, shoring, and street improvements.

Seattle City Light contracted with Glacier Environmental to implement the clean-up plan, which is being conducted in two phases. The first phase began in late August 2012 and consists of the following actions:
  • Abate and properly dispose of hazardous materials inside the building (asbestos and lead containing materials and mercury and PCBs in light fixtures)
  • Salvage items with historic significance or architectural value (such as signage, windows, and doors)
  • Demolish the building and recycle or dispose of all demolition debris offsite
  • Remove four previously decommissioned underground storage tanks (Partially complete - resuming April 2013)
  • Decommission and remove one underground storage tank (April 2013)
  • Backfill maintenance pits, install erosion controls, and secure the site over rainy months
  • Continue operation of an existing interim on-site treatment system to remove and dispose of contaminated groundwater
Phase 2 of the environmental clean-up began April 1st and is scheduled for completion in October 2013. Here’s what to expect during construction:
  • Fence a larger site including adjacent parking lots, and a portion of Pontius Avenue for construction staging
  • Excavate, stockpile, separate and remove contaminated soils for proper disposal off-site
  • Install a shoring wall around two-thirds of the site to safely support soil excavation work
  • Use clean fill and clean excavated material to backfill excavated areas
  • Install a storm water detention system
  • Bring the site to a final grade and cover with crushed rock
  • Restore sidewalks and areas of the street right of way affected by construction
  • Utility relocations on John Street and Pontius Avenue requiring brief electrical and water service disruption for some customers
  • Partial closure of the Alley behind the Colwell Building
  • Sidewalk closure on the east side of Minor Avenue between Denny Way and John Street
  • Parking restrictions and sidewalk and lane closures on John Street between Pontius Avenue and Yale Avenue and along Pontius for the duration of the street closure.
  • Construction noise typical to the use of heavy equipment
  • Additional truck traffic on John Street, Denny Way, Fairview Avenue, Mercer and Westlake. Click here to view a map of the general truck routes
  • Work hours will typically be between 7 am and 3:30 pm on weekdays, but could extend to 7 pm
  • Pontius Avenue will be closed between Denny Way and just short of John Street, allowing continued access to the Brewster Apartment Building east entrance
  • Should interruption of electric service be required, expect at least 10 days advance notice
  • Should interruption of water service be required, residential customers should expect 2 days notice and business customers should expect 5 days notice.
For additional information about the site clean-up project, contact Allison Crowley, Seattle City Light Environmental Engineer / Site Manager at (206) 684-3167 or or Tyson Lin, Community Relations and Promotions at (206) 684-3026 or