ARCHIVED REPORTS_XR0008796 - Laserfiche WebLink

Home Browse Search

Former Beacon Station No 12419 March 18,2002 Stockton California Problem Assessment Re ort/Corrective Action Plan under shallow gradients of approximately 0 001 to 0 01 The groundwater contour map for fourth quarter 2001 is shown on Figure 5 4.0 PREVIOUS INVESTIGATIONS Horizon and other environmental consultants have previously conducted environmental work at the site Groundwater Technologies, Inc (GTI) advanced three soil borings (SB-1 through SB-3) in March 1991, no gasoline constituents were reported in soil samples from soil borings SB-1 through SB-3 Acton, Mickelson, and van Dam, Inc (AMV) removed and replaced the UST's in October 1993, and drilled and installed three 4-inch diameter groundwater monitoring wells (MW-1, MW-2, and MW-3) in July 1994 Horizon drilled five soil borings (SB-4, S13-5, and MW-4 through MW-6) and converted three into 4-inch diameter groundwater monitoring wells (MW-4 through MW-6) in May 1996 Site plans showing soil boring and groundwater monitoring well Iocations, and tabulated soil and groundwater analytical data are contained in Appendix A Horizon performed an aquifer pumping test in May 1997 to evaluate groundwater aquifer characteristics of the shallow water-bearing zone and the potential of groundwater pumping as a remedial option Aquifer pumping test results were documented by Horizon in Results of Remedial Testing letter dated 13 August 1997 (Horizon, 1997) Test results indicate that groundwater extraction is a feasible remedial method Horizon conducted an additional subsurface investigation in September 1998 that included advancement of three soil borings (SB-6, S13-7 and SB-9) and installation of four monitoring wells (MW-7 through MW-10) Results of the additional investigation were documented by Horizon in Additional Subsurface Investigation dated 17 February 1999 The soil borings were drilled to the historical low groundwater level of approximately 85 feet bsg Soil analytical results from the soil borings indicated the presence of gasoline hydrocarbon in 419PARCAP3-02 doc 4 Project No 1419 23 HORIZON ENVIRONMENTAL INC.