ARCHIVED REPORTS XR0000294 - Laserfiche WebLink

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In March 1993, an EHD review of the data available to date suggested that the horizontal and the vertical extent of soil contamination may not have been adequately defined On November 18, 1993, the EHD issued a letter requiring an additional investigation to evaluate the extent of contamination in soil and groundwater The remainder of this report focuses on the work completed to respond to this request 1.2 Scope of Work i The scope of the field investigation was originally proposed by WESTON in a Work Plan dated February 8, 1994. Review and comment by the EHD lead to series of letter modifications to the work plan The modified work plan included the completion of four soil bonngs and collection of two Hydropunch groundwater samples In addition, monitor wells MW-2 and MW- 3 were abandoned, and a file review completed to evaluate the local groundwater gradient per an additional request of EHD Four modifications to the proposed field investigation activities were necessary because of field conditions The northern soil boring (S133) was moved approximately 20 feet further east northeast than planned because the proposed location was inaccessible to the drill ng and because of the location of underground utilities Because this new location was closer to the location of ' the former UST, the hydropunch groundwater sample was collected from the bottom of this boring rather than from beneath the dry monitor well MW-3 The groundwater sample (from S133) was collected through the augers because the Hydropunch was dry Similarly, because the southern soil boring (SB4) was adjacent to the location of dry monitor well MW-2, a hydropunch groundwater sample was collected from the bottom of the southern boring (S134) rather than from beneath MW-2 None of these changes compromised the objectives of the site investigation 2.0 SUMMARY OF FIELD ACTIVITIES WESTON conducted the field investigation between July 5 and July 7, 1994 Three soil samples were collected in brass sleeves from each of four soil borings located as shown on Figure 2 and submitted for analysis of total petroleum hydrocarbons as gasoline (TPH-G) and benzene, toluene, ethylbenzene and xylene (BTEX) Two groundwater samples were collected using a HydropunchO groundwater sampling tool, which was pushed through the bottom of soil borings S133 and S134 (see Figure 2) The groundwater samples were also analyzed for TPH-G and BTEX compounds All samples were ' delivered with chain-of-custody documentation to WESTON's analytical laboratory in Stockton, California At the conclusion of sampling, the borings were grouted from the bottom to the top with a 5% bentonite/cement mixture The existing dry monitor wells (MW-2 and MW-3) were also abandoned by grouting from the bottom to the top using the 5% bentonite/cement mixture A detailed discussion of field procedures is presented in Appendix A Soil boring lithologic logs are presented in Appendix B 9rMRPTSvVCMVC01 WP 4 asrt9rr