SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

Specific Comments Comment 1 Page 3-5, Section 3.2, Determination of Removal Scope, Site SA The EE/CA should explain the significance of excavating to 10 mg/kg polychlorinated biphenyls (PCBs) and at least 10 inches of soil in the swale. Excavating to 10 mg/kg PCBs does not address the metal concentrations which need to be removed. Furthermore, soil in the Swale has not been tested for total petroleum hydrocarbons (TPH) and volatile organic compounds (VOCs), and the ground water beneath the sivale has not been tested at all. The EE/CA should explain why 170 cubic yards (cy) of soil can be excavated in the swale but only 20 cy can be excavated in the vicinity of the former drain line. The EE/CA does not state whether or not contaminated soils, if found ne_rt to sump, will be excavated after removal of the sump contents. Response: The EE/CA cites Title 40 of the Code of Federal Regulations Section 761.130 as a contaminant-specific applicable or relevant and appropriate requirement (ARAR) for PCBs. This regulation requires excavation of a minimum of 10 inches of soil at PCB spill locations, and also that PCB concentrations in soil do not exceed 10 mg/kg after the excavation is complete. The EE/CA states (in lines 1 and 5 of paragraph 2, page 3-5) that the recommended action is interim and that final cleanbp of the swale (if necessary) will be integrated with the response (if necessary) to Site 5D (line 6, paragraph 2, page 3-5). Because there are no contaminant-specific ARARs for metals and because background levels for metals are not available, the proposed action is limited to removing surficial soils. However, soil containing potentially elevated metals concentrations will be removed with the PCB-containing soil, thus the action also addresses the metals on an interim basis. The scope of the EE/CA with regard to the Swale at Site 5A includes an interim action to remove spilled PCBs and control high levels of metals (page 3-5). The presence of TPH in the swale soil will not significantly affect the ultimate disposition of Swale soils as a result of the presence or PCBs and metals. For this reason, TPH was not chosen as an analyte during the additional investigation. Because the surficial soils (0 to 0.5 foot) were sampled from the swale, it was not practical to analyze for VOCs; VOCs would not persist in the surface soil because of their tendency to evaporate and photo-degrade. Thus, samples for VOC analysis were not collected. Groundwater is monitored in well W-24, approximately 65 feet southwest of the swale. If additional monitoring wells are needed at Site 5A, they will be installed during the future remedial investigation (RI). The volume of soil (170 cy) is estimated by multiplying the swale length and width by the 10-inch excavation depth. The 20 cy estimate is based on the observed data from under the drainline (Tables 2-5 and 2-6), experience EEC.IRESPSTA:044-3321RERE I:11/15/95 1106wn 2