By Charles (Pony) Ellingson
New Technical Consultant. With the retirement of Greg Glass, ECAC hired me to consult on technical matters at the cleanup site, update the blog, and provide written reports. Thanks to Greg and ECAC for providing such a good foundation for continuing this work! See the November 2012 update for a brief bio, and to www.pgwg.com for a company website.
New Public Participation Grant. ECAC received notice from the Washington State Department of Ecology that ECAC is to receive an additional grant to continue review of project reports and to inform the public between July 2013 and June 2015. The tasks required in the grant scope are similar to past work and include:
- Progress reporting
- A final project report in 2015
- Technical review of project documents
- Blog posts
- Educational tools
- Attend technical meetings
The primary focus of ECAC’s technical work for this new grant will be to review the Feasibility Study Reports, including a groundwater model that will be used to test the feasibility of further cleanup actions. After Ecology’s acceptance of the Feasibility Study (final report to Ecology about April 2014), a Cleanup Action Plan will be drafted by Chevron for Ecology’s review. Ultimately, Ecology must approve the Cleanup Action Plan and adopt it as an Ecology document that directs Chevron to take any further cleanup and monitoring actions that are required. A public-review draft Cleanup Action Plan should be available in November 2014. We will review the Cleanup Action Plan and provide a summary in this blog.
Final Conceptual Site Model Report. Chevron submitted this report dated June 7, 2013 after consideration of ECAC and Ecology comments on a draft report. This report describes the soils, water, contamination and environmental and human exposure conditions that form the basis for cleanup level calculations. This a good report to review for a broad view of the cleanup project. It is available on Ecology’s website, as are most significant documents (https://fortress.wa.gov/ecy/gsp/CleanupSiteDocuments.aspx?csid=5180).
Final Cleanup Levels and Remediation Levels Report. Chevron submitted this final report to Ecology with a date of September 17, 2013. ECAC and Ecology commented on the draft report, primarily focusing on the need for better substantiation of the soil cleanup level proposed to protect groundwater from contamination (see May 2013 blog entry). In the final report, Chevron did not propose a specific soil TPH cleanup level, and instead proposed to use groundwater monitoring data to empirically demonstrate that whatever soil contamination still exists must be below the soil contamination level that is sufficient to prevent groundwater contamination. Ecology has accepted that approach.
Feasibility Study. The Feasibility Study is required by Ecology as a basis for selecting the final remedy for the site. It recognizes the extensive removal of contaminated soil and groundwater that were performed as “interim actions”. The first step of the Feasibility Study is to identify the technologies that are applicable to the site. A draft Technology Screening Report was submitted to Ecology dated September 3, 2013 and ECAC submitted comments on it. Technologies proposed for the next phase of analysis are limited to Environmental Covenants, Monitored Natural Attenuation, additional excavation, and pumping and treating contaminated groundwater.
A groundwater model is being developed by Chevron to assist in evaluating final remedies for the Feasibility Study. The model will simulate the movement of water under the site and into the creek and sound, under a variety of conditions stipulated by the modeler. ECAC participated in a meeting regarding the model on May 8, 2013, but a model report promised in September 2013 has not yet been submitted. ECAC will review and comment on the expected model report.
A final Feasibility Study Report is due to Ecology in April 2014.
Groundwater Monitoring Results 2nd Quarter 2013. The perimeter Point of Compliance (POC) wells and the interior wells were sampled in June of 2013. Chevron reported the results to Ecology an August quarterly report.
Of the 50 wells sampled, TPH was detected in 11 wells. The locations of the detections are consistent with contamination that is known to remain in soils. Recently installed interior well MW-525, near the WSDOT storm drain line, appears to have the highest remaining TPH concentration. Two duplicate samples collected in June 2013 had 5,564 and 5,984 ug/L total TPH.
Of the 23 POC wells, 22 had TPH concentrations below their respective cleanup levels. Only monitoring well MW-510 contained a concentration of TPH (1,620 μg/L) in excess of its respective cleanup level. POC wells that had shown exceedances long after completion of the Lower Yard Interim Actions, including LM-2, MW-129R, MW-135, and MW-136 among others, have now had four or more consecutive quarterly sampling rounds without an exceedance of cleanup levels. The trends in ground water TPH thus continue to be encouraging.
Vapor Intrusion Pathway Analysis. Field work is currently underway to evaluate risks posed to occupants of possible future buildings on the site from migration of soil vapors. Based on my recommendation, ECAC has not expended resources reviewing this work. The work plan for this investigation is at the Ecology website noted above.
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This product was funded through a grant from Washington State Department of Ecology. While these materials were reviewed for grant consistency, this does not necessarily constitute endorsement by the Department.