Cleanup of the Former NSD Transportation Facility

This site was located in the northern portion of Bothell downtown, in the area formerly occupied by the Northshore School District’s (NSD) Transportation Facility and Bus Maintenance Shop. The site had contamination in soils and groundwater from leaking hydraulic hoists in the maintenance shop, as well as from underground fuel storage tanks in the active fueling area located in the bus barn, and abandoned fuel tanks possibly located in the parking area.

Cleanup work consisted of excavating petroleum-contaminated soils and transporting them for disposal at a licensed facility that handles hazardous materials. The excavations were then treated with slurry to remediate the remnant soils and groundwater, followed by backfill with clean material. Groundwater at the sites was then monitored quarterly, by sampling newly installed monitoring wells for a one-year period following the cleanup.

Contract plans and technical specifications were developed in order for a contractor to perform the cleanup work. This work was completed in two steps:
  • Building demolition – to allow for access to the contaminated soils located beneath the building foundations.
  • Cleanup work – removal of underground storage tanks, hydraulic hoists and all associated underground piping; followed by excavation and disposal of contaminated soils.