By Greg Glass
Public Participation Grant. The Edmonds Citizens’ Awareness Committee (ECAC) was notified by Ecology earlier this year that it was awarded a two-year Public Participation Grant for 2011-2013. However, as a result of the ongoing state budget woes continued funding for this next two-year period has been withdrawn by Ecology. ECAC is considering other options for funding its role in supporting good cleanup decisions and community education for the UNOCAL Edmonds site. ECAC has been working on this site since 1995; it now appears that final cleanup will not occur until 2014 or 2015. Suggestions for funding sources are welcome!
Ground Water Monitoring Results, 3rd Quarter 2011. An additional round of ground water samples was collected in September. Chevron reported the results of that sampling round in its November monthly progress report to Ecology. As outlined in the proposal for continued ground water monitoring, the September 2011 sampling round included only the 21 perimeter (point-of-compliance) wells. The next sampling round will occur in December and will include both perimeter and interior wells.
LNAPLs were reported at MW-510 (near the former slops pond), and also at two newly installed piezometers near MW-510 to the southwest and southeast. No ground water sample was collected for analysis at MW-510 because LNAPLs were present. Of the remaining 20 wells that were sampled, only one – MW-129R near the SE corner of DB-1 – had a high total TPH concentration. The September 2011 TPH level at MW-129R was 2,955 ug/L. This was the second highest concentration over the last 3 years of ground water monitoring. The lack of any downward trend in TPH continues to suggest that there is an ongoing TPH source near MW-129R.
Overall the TPH concentrations in the other 19 perimeter wells were very low in September; MW-129R is notable as an exception to this overall pattern. The second highest reported TPH level was only 330 ug/L at MW-518 on the western property boundary. None of these other 19 wells exceeded the ground water TPH cleanup levels for the site. In some cases the decline in TPH concentrations from the previous rounds was dramatic. At well LM-2, for example, TPH declined from a range of 2,345 to 3,925 ug/L over the last 3 rounds (October 2010 to June 2011) to not detected in September 2011. As has been noted before, some wells have shown a distinct “up-and-down” pattern over time in TPH concentrations. With 14 rounds of sampling over three years, it is possible to start to look at how TPH concentrations vary with ground water elevations, which in the Northwest reflect a typical seasonal variation, with lowest water levels in early Fall (e.g., during the last sampling round in September) after typically dry summers. A scatterplot of ground water elevations (X-axis) versus well LM-2 total TPH concentrations (Y-axis) is provided below to illustrate this relationship. It is apparent that for this well TPH levels are high when ground water elevations are high, and low when ground water elevations are low. (A similar relationship is shown at well MW-104, but not at all wells). The not-detected result for the last sampling round at LM-2 in September 2011 occurred in combination with one of the lowest water levels seen in that well. It will be interesting to see whether TPH concentrations rebound to higher levels in continued sampling rounds, as water levels rise. Any (annual) seasonality trends would be combined with any long-term (multi-year) trends in the record of TPH concentrations over time. Therefore, a seasonality trend could be “stable” over periods of years or could be repeated at lower and lower levels if there is an overall declining trend in TPH. This difference could reflect either “steady-state” conditions (ongoing source) or “recovery” conditions (diminishing or absent source). The take-home message: a single round of low, even extremely low, TPH concentrations is not definitive, especially where seasonal trends have been evident over previous rounds.
2011 Site Investigation Completion Report. In Summer 2011 Chevron’s consultant, ARCADIS, completed several additional site investigations to provide information needed for the Feasibility Study leading to selection of final cleanup actions. ARCADIS submitted a report on these additional site investigations to Ecology on December 9, 2011. That report presents the results of the following types of studies: 1) a study of tidal influences on Lower Yard ground water, including the influence of the widespread soil excavation and backfill activities during Interim Actions; 2) hydraulic conductivity studies of site ground water; 3) an LNAPL baildown test to investigate LNAPL mobility at MW-510; and 4) field observations and soil testing results from a program of borings near well MW-510 and DB-2.
The ground water investigation results will inform the development and evaluation of cleanup alternatives in the Feasibility Study for addressing continued ground water contamination in excess of site cleanup levels.
The borings near well MW-510 and DB-2 revealed areas of elevated soil TPH, with 8 borings having at least one soil sample above 10,000 ppm (mg/kg) total TPH and a maximum of over 220,000 ppm TPH. LNAPLs were also observed during field activities at some locations and confirmed by subsequent monitoring of installed piezometers near MW-510.
Draft Feasibility Study Work Plan. Chevron submitted a Draft FS Work Plan to Ecology on September 21, 2011. That report proposed a number of additional site investigations to support the Feasibility Study evaluations of cleanup alternatives, but did not actually address the FS process or schedule. ECAC met with Ecology and Washington State Department of Transportation representatives at Ecology’s Northwest Regional Office on October 28th to discuss this FS Work Plan and site status. David South, Ecology’s site manager, asked for comments on remaining site issues and then proposed that agency and stakeholder comments on the Draft FS Work Plan await review of the forthcoming Site Investigation report (see above). Ecology has scheduled a meeting for January 20, 2012 to continue development of a final FS Work Plan by Chevron. After the October 28th Ecology meeting with stakeholders, Chevron submitted a preliminary proposed schedule for completion of the FS process, which will formally become part of the Final FS Work Plan.
Feel free to visit: email@example.com