Interim Actions
In June 2010, Ecology and the City collaboratively executed amendments to the Agreed Orders to include Interim Actions. Under WAC 173-340-430, an interim action is a remedial action that is technically necessary to reduce a threat to human health or the environment by eliminating or substantially reducing one or more pathways for exposure to a hazardous substance, that corrects a problem that may become substantially worse or cost substantially more to address if the remedial action is delayed, or that is needed to provide for completion of a site hazard assessment, remedial investigation/feasibility study or design of a cleanup action. An interim action is a partial cleanup that could eventually qualify as a final cleanup under MTCA.
Four of the sites were cleaned up during the Crossroads roadway construction in 2010, 2013, and 2017. Cleanup consisted of excavating contaminated soils and transporting them for disposal at a licensed facility that handles hazardous materials. The excavations were treated with slurry and oxygenated pellets to remediate the remnant soils and groundwater, followed by backfill with clean material. Due to the type of contaminant at the Ultra Cleaners site, a different treatment approach consisting of bioremediation was implemented at this location. Groundwater at the sites was then monitored quarterly by sampling newly installed monitoring wells for a one year period following the cleanup.