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Jim,
I have reviewed the document entitled: NW Pipe Company Remedial Investigation and Source Control Evaluation, January 2014, by CH2M-Hill. I apologize that my comments are not more in keeping with how the document was structured but the issues of concern to me were covered in multiple document areas. My review comments focused on groundwater geochemistry and hydrogeology follow:
General Comments:
This report is an end product document compiling many years of data and the results of many individual research projects performed to address DEQ questions and meet RI and SCE expectations. As such, I reviewed the document for its reasonableness of the conclusions drawn and recommendations to DEQ that the site is ready to receive an NFA determination.
What made review difficult was that details on many individual environmental investigation area efforts, their affected media, and the supporting data set do necessarily not lead to a clean conclusion. But, I think that overall, the weight of evidence while not perfect, indicates that the RP has completed the job. I look forward to hearing what your team has to say about the other site concerns.
Specific Comments:
SE Corner of site (Environmental investigation areas 1 and 13)
I spoke with Ken Schump this week about the cVOC sources in the SE portion of the site. He told me that the site historically used a 600-gallon tank on an above-ground stand to store waste oil (and presumably chlorinated solvents). The tank was located at the location of GP1. Source removal of 170 CY of stained soil at this location constituted removal action. Despite this soil removal work, PCE and breakdown products affected groundwater in this area. Schump also spoke about anecdotal evidence that a railroad car on the siding east of the NWP site was observed dripping liquid (PCE?) onto the ground by a former NWP employee.
Figure 5-7 I added PCE concentration contours to Figure 5-7. The contour pattern does not fit the pattern anticipated by the release mechanism described by Schump. Groundwater flow direction is calculated to be to the south at a low gradient. The classic elongated groundwater plume shape is not apparent in the PCE contours adding to uncertainty about the nature and extent of the cVOC plume in this area.
Section 6.2.12.3 DEQ asked for data on whether unconfined groundwater meets drinking water MCLs where it exits the southern margin of the NWP property. This determination is best made using data from MW-3 and MW-4 located at the south end of the property. The author did not answer DEQ’s question. I reviewed the data and found that these wells exceeded MCLs for cVOCs. Chlorinated VOC concentrations have been decreasing in these wells and reductive dechlorination appears to be proceeding apace. Recommendation: Use of unconfined groundwater in the SE portion of the site should be prohibited as a condition of the future NFA. Offsite neighbors should be notified of offsite trespass. Offsite neighbors should be notified of offsite trespass of NWP contaminants.
Environmental concern area #2
MW-7, MW-8, MW-9 have been sampled in 2013. Fate and transport modeling (BIOSCREEN) indicates that offsite trespass of PAHs in GW from this area, is limited to a point well short of the Willamette River. The modeling work appears to be adequately conservative. Various trials were made to best represent actual conditions. (Note, I was not able to locate or review actual groundwater data from these three wells. I only reviewed the modeling information provided in Appendix C). I recommend that we approve the RI work for this area and that no further action is needed. The Willamette River shoreline is about 200 feet away from the NWP property line. Recommendation: Use of unconfined groundwater in the vicinity of MW-7, MW-8, & MW-9 should be prohibited as a condition of the future NFA. Offsite neighbors should be notified of offsite trespass of NWP contaminants.
Source Control Evaluation
Groundwater data from MW-3 and MW-4 located at the south end of the property indicates that Metals far exceed JSCS MCLs for manganese. Groundwater from MW-3 exceeded the Manganese SLV by 32X using 2005 data (Table 5-2). Groundwater from MW-3 exceeded the Manganese SLV by 36X. Other metal concentrations, especially arsenic, would be of interest to DEQ but apparently were not analyzed. The reductive chlorination conditions apparently active in this area appear to be mobilizing manganese and likely other metals into near-surface groundwater.
Offsite neighbors should be notified of offsite trespass of contaminants in groundwater as part of DEQ’s Source Control Decision.
Areas of trespass include:
• South of Environmental concern areas #1 & #13: cVOCs, Manganese, other metals?
• West of environmental concern area #2: PAHs, Metals?
Note: The entire property is hardscaped strongly limiting downward infiltration of surface water to the water table. This adds confidence to my recommendation to approve this document.
Sincerely,
Ken Thiessen