By Greg Glass
Starting the Feasibility Study. Chevron submitted a Draft Year 2 Ground Water Monitoring Report to Ecology on January 25, 2011. After compiling review comments from Ecology, WSDOT, and ECAC, David South, Ecology’s site manager, convened a stakeholder meeting on May 25, 2011 to discuss that draft report and related matters.
After the stakeholder meeting, Ecology issued a formal determination that the Lower Yard Interim Actions did not constitute a final site cleanup, based on continued exceedances of cleanup levels at multiple Point of Compliance ground water monitoring wells. That letter (see separate posting under Additional Info on the left of the blog) dated May 27, 2011 started a 90 day period for Chevron to prepare and submit a work plan for a Feasibility Study (FS) that will identify and evaluate various alternatives to achieve final site cleanup. The Draft FS Work Plan is thus due by August 26, 2011. David South forecast that reviews of the FS Work Plan would not be completed until December 2011, indicating that a revised Final Work Plan would be ready around February 2012. Allowing for completion of Draft and Final Feasibility Study Reports, selection of a cleanup alternative and preparation of a Cleanup Action Plan by Ecology, and required design studies, it now appears likely that further physical cleanup actions in the Lower Yard will not occur before 2014.
Chevron’s Year 2 Ground Water Monitoring report included a proposal to continue ground water monitoring activities at the site. Quarterly sampling of the POC wells, and bi-annual sampling of interior wells, was proposed. Sampling of POC wells for the first quarter of 2011 occurred in March (see summary below); second quarter sampling of both POC and interior wells will occur in June. ECAC considers it critically important to continue ground water monitoring so that trends in TPH contamination can be effectively evaluated. Several comments on the proposal for continued ground water monitoring are still being discussed with Ecology and Chevron.
It was clear at the completion of the two years of post-Interim Action ground water monitoring that Lower Yard cleanup was not complete. Before the formal initiation of the FS process, Chevron prepared a Draft Aquifer Testing Work Plan, submitted to Ecology on November 19, 2010. The Final Work Plan was submitted on January 25, 2011 and field work for tidal influence and aquifer testing was completed in May. The extensive Lower Yard excavations and backfilling changed the characteristics of soils throughout much of the Lower Yard. The FS evaluations of ground water cleanup options will require an updating of aquifer properties; this aquifer testing program is a first example of identifying and filling data gaps for completing the FS. Full evaluations of the data collected in this field program will occur within the FS.
Petroleum product (LNAPL) has been consistently found at one monitoring well, MW-510. Chevron will submit a plan to Ecology by June 30, 2011 to further investigate the extent of NAPLs in this area near the former slops pond. Except in unusual circumstances, NAPLs must be removed for site cleanup to be considered complete. Field work to carry out the NAPLs Work Plan investigations is expected to occur in August 2011. Final NAPLs cleanup actions are expected to be part of the FS evaluations.
Ground Water Monitoring Results, 1st Quarter 2011. Chevron’s May 12, 2011 monthly progress report to Ecology included a summary of the results of ground water monitoring that occurred in March (first quarter 2011 sampling). Under Chevron’s proposed scope for continued ground water monitoring, samples were collected and analyzed in Q1 2011 only for the 21 Point of Compliance (property boundary) wells.
Product (LNAPL) was still found at well MW-510 in the vicinity of the former slops pond location; therefore, no ground water sample was collected for analysis at that well.
The total TPH concentrations at the Point of Compliance (POC) perimeter wells continue to show multiple exceedances of default cleanup levels at locations spread across most of the Lower Yard property boundary. LM-2 at the northern corner of Detention Basin 1 had the highest total TPH concentration (3,925 ug/L) among sampled wells in the last round of the two-year post-Interim Action monitoring program, in October 2010. It still had the highest concentration among wells sampled in March 2011, at 2,625 ug/L. Chevron collected an additional sample at LM-2 in December 2010 to check the high value reported in October 2010; the December total TPH of 2,405 ug/L confirmed the general trend toward higher concentrations in recent sampling rounds. MW-129R, near the southeast corner of DB-1, had 2,275 ug/L total TPH; it has exceeded 2,000 ug/L for 9 of the last 10 sampling rounds. Wells MW-135 and MW-136, at 695 and 643 ug/L total TPH, had substantially decreased concentrations from previous rounds and reflected the greatest reductions. Along the western boundary, MW-104 at 1,214 ug/L showed a substantial increase from the last 3 rounds, and continued an “up-and-down” (seasonal?) pattern. MW-147 at 1,524 ug/L continued a pattern of frequent higher concentrations at that location, except for lower mid-summer values (seasonality?). Additional years of monitoring will be required to confirm any seasonal patterns in ground water TPH concentrations.
As part of its review of Chevron’s Year 2 Ground water Monitoring report, ECAC prepared tables summarizing the TPH results for two years of ground water monitoring. That summary is provided below and gives results by sampling date and by well over 11 rounds of sampling. Ecology will meet with ARCADIS, Chevron’s consultant, in late June 2011 to make final revisions to the Year 2 Ground Water Monitoring report in response to reviewer comments, as discussed at the May 25th stakeholder meeting. That report will become primarily a data report rather than an evaluation and interpretation report.
Feel free to contact: HYPERLINK "mailto:email@example.com" firstname.lastname@example.org
|UNOCAL Edmonds Former Bulk Fuel Terminal|
|Summary of Ground Water Monitoring Results|
|Round 1 through Round 11 (Oct 2008 - Oct 2010)|
|TPH Exceedances of Default Ground Water Cleanup Levels:|
|Summary by Sampling Round|
|POC Wells [n=21]|
|Oct 2009||11||715||2,720||MW-147 (a)|
|Jan 2010||8||845||3,105||MW-104 (a)|
|Apr 2010||7||908||2,015||MW-129R (a)|
|Jul 2010||8||592||2,275||MW-129R (a)|
|Oct 2010||7||924||3,925||LM-2 (a)|
|Interior Wells [n=19]|
|Apr 2009||6||534 ||1,503||MW-502|
|June 2009||5||512 ||1,175||MW-143|
|Aug 2009||3||539 ||847 ||MW-514|
|Oct 2009||4||534 ||1,013||MW-507|
|Apr 2010||4||646||1,565 [1,875]||MW-143|
|(a)||LNAPLs detected at MW-510, no sample collected for|
|||A second TPH concentration in brackets is for a field|