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Stephen Donell - 3 - 31 January 2014 General Comments 1. The number of non-detect sampling results in this Report was unexpected, as they do not correspond to previous investigation results. Due to the recent construction of the sampled wells, it is possible that equilibrium conditions were not established prior to sample collection. Therefore, another round of groundwater sampling is needed to evaluate the nature and extent of Site contamination. 2. All future reports, data, and correspondence need to be uploaded to Geo Tracker, followed by hard-copy submittal to the Regional Water Board Office in Rancho Cordova. The Phase I and II Reports, Site Assessment Work Plan and Appendix F for the Site Assessment Report must be uploaded in GeoTracker. Future submittals should be complete with all appendices included to facilitate Regional Water Board review. Larger appendices, such as analytical data, may be submitted on compact disc in future report submittals. Specific Comments 1. Current and historical sampling show elevated TPH and VOCs typical of former USTs at four concrete patch locations. Two exterior locations were designated as former UST sites during an April 2012 investigation. The other two patches are located inside the warehouse interior. Each concrete patch needs to be addressed as follows: a. Exterior South Patch Soil staining impacts were noted in photo logs found in Appendix E of the April 2012 Limited Phase II Environmental Site Assessment Report (Phase 11 Report). The Phase II Report did not note the presence of fill material or depth to the bottom of the excavation. A clean soil sample from SB-106 taken at 5-ft depth does not correspond to the observed staining in the photo log. The stained soil needs to be sampled and analyzed for Site constituents of concern, including TPH, VOCs, and nitrates. The contaminated soil will need to be removed and confirmation samples taken to document clean soil margins. b. Exterior East Patch Soil staining impacts from this former UST were also noted in Appendix E of the Phase II Report. Boring SB-1005 was advanced directly through the concrete patch, however, no soil samples were analyzed from this boring. Groundwater did not contain volatile organic compounds (VOCs) at SB-1005, but a soil sample from adjacent boring SV-5 contained 705 mg/kg of TPH at 2-ft depth. The contaminated soil will need to be removed and confirmation samples taken to document clean soil margins. c. Interior South Patch Photoionization detector (PID) readings in the Report boring logs showed increasing PID readings in TW-2 from approximately 5 to 12-ft bgs. Although the sample from 12 feet had the highest PID reading, only the 5-ft bgs and 25-ft bgs samples were selected for further analysis. TPH was detected at 2,980 mg/kg at 5-ft depth. March 2012 sampling results collected at 2-ft depth from sampling point SV-25, located at the north-western corner of the patch, detected approximately 46,000 mg/kg TPH. The contaminated soil will need to be removed and confirmation samples taken to document clean soil margins.