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.
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