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. Former Beacon Station 494 August 8, 1995 $tpjdnn.Cglifnmia - -- - - - . - AcsPcsmentRep= notified A well permit was obtained from the San Joaquin County Pubic Health Services, Environmental Health Division (copy in Appendix A) The Horizon Field Methods and Procedures are included in Appendix B Drillin and Soil Sam lin On June 12 and June 13, 1995, a Horizon geologist observed the drilling of four soil borings (CB-1 through CB-4) Locations of the borings were selected to attempt to evaluate and further delineate gasoline hydrocarbons in soil, and to assess if the soil vapor extraction system has removed the gasoline hydrocarbons to acceptable levels from the soil beneath the site The borings were drilled using a truck-mounted CME-75 drill ng equipped with 8-inch diameter hollow-stem augers Drilling was performed by Mitchell Drilling Environmental Corp of Rancho Cordova, California The borings were advanced to depths ranging from approximately 55 to 65 feet bgs The approximate locations of the borings identified as CB-1 through CB-4 • are shown on Figure 2 CB-1 drilled at an angle of 18 degrees from vertical terminated at a horizontal depth of approximately 58 feet at 20 feet south of the surface entry location Groundwater was not encountered in any of the borings During drilling, soil samples were collected from each boring at 5-foot intervals from the surface to the total depth of the boring Soil samples and cuttings were evaluated for the presence of petroleum hydrocarbon vapors with an orgaruc vapor meter (OVMl) Soil boring logs containing soil descriptions are included in Appendix C Upon completion of drilling with the 8-inch augers, a 2-inch inside diameter(ID) vapor well was constructed in boring CB-2 Borings CB-1, CB-3, and CB-4 were backfilled with "6-sack" cement and bentonite grout to ground surface Mr Mike Infarna of the SJPHS was onsite to wetness the grouting of the bonngs and the placement of the seal on the vapor well Sediments encountered during drilling consisted primarily of mterbedded clay, silty clay, clayey silt, silt, sandy silt, and very fine- to fine-grained sand from approximately one foot bgs to the 1494 11 RPT 3 HORIZON ENVIRONMENTAL INC I