MTCA RI/FS and Interim Action

Former Naval Shipyard – Tacoma, WA

Port industrial yard

CRETE completed the MTCA RI/FS in March 2016 under an Agreed Order. Investigation data was collected to allow future cost recovery from PLPs that performed shipbuilding and dismantling. The site is located at the end of the Blair-Hylebos peninsula in the Tacoma tide flats and is an aggregation of multiple smaller sites that are primarily driven by TPH impacts.

In reviewing work by previous consultants, CRETE was able to identify and correct several errors. CRETE was able to identify USTs that were previously mislocated. Work included execution of a tidal study to evaluate attenuation as groundwater migrates to a tidally-influenced water body, a detailed evaluation of TPH chromatograms to help identify likely sources, and a review of indoor air sampling data. Review of chromatograms identified sources of contamination for which cost recovery will be pursued. A review of air data determined that Port contamination was not responsible for any indoor air exceedances.

CRETE also prepared a UST Decommissioning Interim Action Work Plan. CRETE supported the Port in overseeing this work in Fall 2015 and incorporated the results of this work into the RI/FS report. CRETE is continuing to work on the Cleanup Action Plan and will support Consent Decree negotiations and perform the remedial design. Cleanup work is expected to be performed in 2018.

Work PerformedEBC drilling

  • Regulatory negotiations – MTCA
  • Upland RI/FS
  • Permitting – UST decommissioning
  • UST interim action
  • Indoor air evaluation
  • TPH fingerprinting

Value Added

  • Accurately mapped and located abandoned USTs that could not be located previously
  • Performed TPH fingerprinting to identify contaminant sources for cost recovery
  • Evaluated sub-slab, indoor, and ambient air quality to demonstrated client impacts were not a source of indoor air impacts
  • Negotiated use of groundwater sample preparation and analytical techniques to address sample interference and potential false positive results
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