See Polrep # 2 for Site Description for this Phase II Removal Action.
Since the product recovery wells were installed in December 2006, ERRS monitored and recovered free product from the site, under EPA OSC direction, until October 2008. During periodic visits to the site, ERRS recorded groundwater levels, the amount of any free product present in the wells, and emptied the recovered free product out of passive recovery skimmers into a 55-gallon drum stored on site.
When product monitoring began in December 2006, product levels in the recovery wells were typically less than 0.05 feet thick. Through May and June 2007, as average groundwater levels began to fall, the amount of free product present in the wells increased. The highest product levels were observed in the summer of 2007 (approximately July through September), with product levels as high as 0.38 feet. During this time, free product was routinely observed in as many as five of the six product recovery wells. The rate of product recovery also increased, and the cumulative amount of free product recovered approached 20 liters. Beginning in the fall of 2007, free product levels were lower and rarely exceeded 0.05 feet. The rate of product recovery also slowed during this time, with only about an additional 1 liter of free product recovered between the fall of 2007 and the fall of 2008. Monitoring and product recovery was discontinued after the last monitoring session performed on October 18, 2008. A total of 21 liters of free product was recovered from the recovery wells.
Monitoring and sampling of groundwater from site monitoring wells and neighboring domestic wells has been performed at the site on a periodic basis (almost quarterly). The groundwater quality monitoring program was conducted under 104(b) authorities as an ongoing removal assessment. A PCP groundwater plume was discovered early on during Phase I removal assessment and the extent of contamination confirmed in the follow-up Phase II removal assessment with the installation of a set of monitoring wells. Additional monitoring wells were installed during the Phase 2 Removal Action. Eleven domestic drinking water wells were added to the groundwater monitoring program for sampling in January 2006 and most of these wells have been sampled regularly with a few exceptions.
Drinking water well DW-05, is located west of and adjacent to the CPPI property and directly downgradient of the PCP groundwater plume. Previously, PCP was not detected in DW-05 with the exception of two detections at very low levels (less than the Maximum Contaminant Level of 1 ug/liter) in two of the seven last sampling rounds. In the March 2009 sampling round, PCP was detected at 2.1 ug/liter, above the MCL. EPA has reported the PCP in groundwater sample results to all of the well owners after analytical results were received and validated. The two detections in DW-05 were reported to the well owner who indicated to EPA that he was bringing in potable water for drinking and cooking. The EPA verified with the well owner that he was continuing to bring in potable water for drinking and cooking now that there was an exceedance of the MCL.
Another round of groundwater samples was collected from select on-site monitoring wells and domestic wells (including DW-05) in early August 2009. Preliminary analytical results for duplicate field samples collected from DW-05 indicate that PCP concentrations (0.67 and 0.71 ug/liter) are below the MCL.
With the distribution of this POLREP the Phase 2 Removal Action is considered complete at the Colville Post and Poles, Inc. Site. At this time, it has not been determined if or when there will be further monitoring and sampling of the PCP plume in a groundwater quality monitoring program. Should DW-05 PCP levels exceed the MCL in the future, an alternative water supply should be considered for short and long-term drinking/cooking water needs. It is not clear if that action would be taken by the RP, the Washington State Department of Ecology (Ecology), or EPA. Should EPA be requested to evaluate the need for and provide an alternative water supply, it will be considered a new removal action.
Currently, EPA is in final discussions with the RP and Ecology regarding Post-Removal Site Control. Institutional controls on land use, groundwater use, and site operations are expected to be addressed with an Environmental Covenant being negotiated as part of a cost recovery settlement with EPA. EPA and Ecology will have the right to enforce the Environmental Covenant, however because EPA's removal action is complete, as documented in this POLREP, Ecology will provide oversight for this site.
None
Finalize Environmental Covenant and commence Post-Removal Site Control activities.
Not applicable.
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