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1 CONFIRMATION SOIL SAMPLING REPORT VINTAGE CAR WASH, INC PACIFIC AVENUE CAR WASH STOCKTON, CALIFORNIA ' 1.0 INTRODUCTION On October 10, October 29 and November 4, 1991, TreaTek Inc (TreaTek) conducted confirmation soil sampling of the fuel distribution network area soils at the Pacific Avenue Car Wash site located ' at the intersection of Pacific Avenue and Bianchi Road in Stockton, California (Figure 1) The purpose of this sampling was to determine whether petroleum hydrocarbon compounds associated with the fuel distribution network were present within the vadose zone sods The following sections ' provide a discussion of the field sampling activities conducted at the site as well as a description of the soil conditions encountered during sampling and a discussion of the sample analytical results The final section of this report provides conclusions and recommendations for the site based on the observed site conditions and the analytical and field data 2.0 FIELD SAMPLING ACTIVITIES ' On October 10, 1991, TreaTek initiated subsurface sampling activities at the Pacific Avenue Car Wash site The initial activities involved the coring through both the concrete and asphalt covering the area above the fuel distribution network Nine holes were cored The location of these nine ' holes and the subsequent TreaTek location identification numbers are shown on Figure 2 The first location sampled was location RGN1 This location is situated approximately four feet north of the west end of the regular leaded gasoline storage tank A four inch diameter stainless steel hand auger was used to advance the borehole to a depth of five feet beneath the ground surface (bgs) At the five foot depth, a sample collection tube driver lined with a clean two inch diameter, 1 six inch long, stainless steel tube, was used to collect a soil sample for field screening The field screening method utilized an organic vapor analyzer (OVA) Once field screened, the sample was sealed with aluminum foil and plastic end caps and secured with elastic tape The sample was then labeled and stored on ice The borehole was then advanced to ten feet bgs, at which another sample was collected, screened and stored The borehole was finally advanced to the maximum depth of 15 feet bgs At the 15 foot depth, another soil sample was collected and screened Since no sample from the borehole exhibited detectable OVA readings, the 15 foot sample from location RGN1 was sealed, labeled and stored on ice for laboratory analysis The other soil samples from this borehole were discarded The OVA field screening results for the samples from this and the other boreholes are presented on Table 1 ' Following the collection of sample RGN1, the auger and tube driver were thoroughly decontaminated utilizing a potable water/laboratory reagent soap mixture wash followed by a potable water rinse and a deionized water final rinse This process was repeated between each borehole location sampled T ne next location sampled was location RGN2 This location is north of the east end of the regular gasoline storage tank Field screening samples were collected at depths of five feet and 9 feet bgs At the nine foot depth, the hand auger could not be advanced further due to a below grade obstruction None of the samples collected from this location were analyzed The final location sampled on October 10, 1991 was location RGS1 Only a five foot depth field screening sample was collected before field activities were halted