Redevelopment of Former Transportation Service Facility

This 10-acre property located in Federal Way, Washington, was used as a vehicle maintenance and training facility for a school district in Washington State from 1964 to 2014. TRC was retained to perform due diligence site assessments and an asbestos survey before our Client purchased the property, and after purchase, TRC assisted in the assessment and remediation of the property and then cost-recovery.

A Phase I Environmental Site assessment identified impacts to soil and groundwater at the site resulting from releases related to the school district’s use of the property. The releases consisted of petroleum products from three underground storage tanks (USTs) that were removed in 1989, waste oil from another UST removed in 1992, automotive fluids and chemicals in a storage area in the northern portion of the property, and fluids from an oil/water separator located on the south side of the maintenance building. In addition, there was the potential for additional releases from two large commercial vehicle hoists with below ground hydraulic oil reservoirs located inside the maintenance building.

TRC conducted remedial actions in concert with our Client’s redevelopment of the property, which included demolishing all structures and removing USTs, underground hydraulic hoists, and oil/water separators. The USTs, hoists, and oil/water separators were removed and impacted soil was excavated from the four areas identified by TRC. Confirmation sample results indicate that identified impacts were removed from the property and no further remedial action for soil is required.

The remedial alternative for groundwater is monitored natural attenuation (MNA) and groundwater wells will be installed after redevelopment is complete for groundwater monitoring activities. An infiltration gallery for future groundwater remediation was installed after the excavation in case MNA is not improving groundwater quality within a reasonable restoration time frame.