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r r I i� FOOTHILL ENOINEER NCY 1 PH gC KM 365-93Bl FAX C;KM PADDY CREEK LANE U001. 6 -1 96240 163 Mr. Harland Knoll May 5, 1997 San Joaquin County Public Health Services Environmental Health Division P O Box 388 Stockton, CA 95201 Subject Report of Site Investigation Findings-400 N. El Dorado Street Stockton CA Owner. Ms Sara Wasserman Dear I& Knoll: The following is a report of the site investigation of the sods under the sand filled underground storage tanks located on the above stated site REPORT OF SITE IlWESTIGATION Investigation Procedure Ms.Wasserman,owner of the property located at 400 N El Dorado Street,has retained J'un Thorpe . Oil and Foothill Engineering to investigate the existing soil under three underground storage tanks on the above stated property The investigation was performed on April 18, 1997 with a slant boring under the tanks The three tanks that are the subject of this investigation were originally closed in place by filling with sand. The vent and fill covers for each tank are still in place in the concrete sidewalk The two large gasoline tanks are located to the north and south of a small tank(See attached drawing of the tank location). The tank location under the sidewalk required that soil samples be extracted by slant Push Bore Four slant Push Bores were used to extract samples from under the tanks (See attached sketch). Eads bore would terminate at approximately 18'below the surface and directly under the tank Three or four samples were taken from each of the push bores at bore lengths of IV, 15', 20', and 25' Samples were extracted using a standard split spoon sampler with a brass sample tube liner Each soil tube was capped with a layer of foil secured by plastic caps, sealed with duct tape, labeled for identification, and stored on ice for transport to the laboratory Soil samples were transported under a chain of custody to a Sherwood Labs for analysis. Samples were analyzed per EPA Methods 8020 (BTEX), (MTBE), 5030/8015(M)TPH-Gasoline and TEPH as required A selected sample from under the waste oil tank was tested for heavy metals No soil samples were extracted below the water table and no water samples were taken from the site Results of Soil Sample Analysis The slant bore samples under the southern most tank were contaminated with gasoline ( See Recap of Soil Analysis Results attached) The PBI @ 20' sample was extracted from under the center of south tank and has an analysis of 16200 mg/Kg of TPH The PB2 @ 20' sample was extracted from