By Greg Glass
Chevron completed Phase I of the Lower Yard Interim Action cleanup by April 2008. A full report on those Phase I activities is being prepared and will be made available by the end of the year. The work remaining for Phase II includes some minor areas of soil excavations and cleanup of contaminated sediments in a portion of Willow Creek along the western property boundary. The planning and permitting for Phase II activities have been completed and as of the week of July 21st mobilization to start Phase II cleanup activities has begun.
After the Phase II cleanup is completed in Fall 2008, additional ground water monitoring wells will be installed and periodic ground water sampling and analysis will be performed to establish whether ground water cleanup standards have been met and how any remaining ground water contamination is diminishing over time.
The Phase I soil excavations were more extensive than originally planned, based on field observations during the cleanup. Even with such extensive excavations, the question was still posed whether there were any remaining data gaps that warranted additional investigation, with the goal of assuring the effectiveness of the Interim Actions at completion. Doing additional investigations now allows any remaining areas of contamination to be included as part of Phase II cleanup actions.
On behalf of Chevron, ARCADIS prepared a report on potential data gaps, titled “Evaluation of Lower Yard Phase I Data and Work Plan for Additional Site Investigation, UNOCAL Edmonds Bulk Fuel Terminal, Lower Yard (May 30, 2008)”. ARCADIS proposed a number of additional soil borings in three areas: 1) the far southwest corner of the Lower Yard, near the former railroad trestle; 2) adjacent to the Washington State Department of Transportation storm drain line in the central Lower Yard; and 3) near the southeast corner of Detention Basin 1, where a ground water monitoring well had historically shown evidence of floating petroleum product and no soil excavations were done.
I reviewed the ARCADIS report and also reviewed the cumulative data sets from site investigations to date as well as the history of site operations as presented in an earlier report by UNOCAL’s consultant EMCON Northwest, Inc. (Background History Report, February 15, 1994). I agreed with ARCADIS’ proposed additional investigations, but identified three additional areas as potential data gaps where historic site operations suggested possible releases of contamination. Those three areas were: 1) the “apron” off the eastern end of Detention Basin 1; 2) the footprint of the former asphalt warehouse south of Detention Basin 1; and 3) the former “slops pond” between the asphalt plant and Detention Basin 1, along the northwestern property boundary, on top of which lined Detention Basin 2 had been built. On behalf of ECAC, I submitted my recommendations for additional investigations to Ecology (see memorandum of June 11, 2008: ECAC Comments on May 30, 2008 Work Plan for Additional Site Investigation).
After receiving my review comments, Ecology met with ARCADIS to review the data gaps issues. Additional borings were added to the original ARCADIS proposal to address my first two identified areas. Locations near the former “slops pond” were already targeted for minor soil excavations during Phase II cleanup actions; depending on how extensive those excavations become, additional investigations were identified as a contingent part of Phase II field activities.
Except for the contingent “slops pond” borings, ARCADIS has completed the additional data gaps investigations prior to starting the Phase II cleanup. Duane Uusitalo and I made site visits on two days to observe some of the additional borings and soil sampling. A full report of results is not yet available. Based on discussions with ARCADIS, the added borings at the location of the former asphalt warehouse showed Total Petroleum Hydrocarbon (TPH) contamination above the criterion for soil excavation. The temporary water treatment plant was located on part of the former asphalt warehouse footprint where I identified potential data gaps; the just-completed borings showing soil contamination were placed just off the edge of the treatment plant pad. ARCADIS will be relocating the water treatment plant at the start of Phase II so that additional investigations and soil excavations, as appropriate, can be completed in this area.
Phase II cleanup activities should start up within a few weeks. Duane Uusitalo and I will be making periodic site visits to observe cleanup activities, and I will post updates as new information becomes available.
Feel free to contact me via e-mail ( HYPERLINK "mailto:gglassenviro@comcast.net" gglassenviro@comcast.net) if you have comments or questions.
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