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f � t October 13, 1992 Working To Restore Nature BP Oil Facility No. 11193, Stockton, California it SOIL BORINGS / SAMPLING AND ANALYSES / MONITORING WELL I INSTALLATION our..soiLboring� ill bedrilled using a truck-mounted drill rig equipped with 8-inch-diameter hollow stem augers. Soil borings will be drilled-adjacent to two corners of the existing fuel tank cavity and near the dispenser islands. The locations of the borings are shown on the Generalized Site Plan (Plate 2). tSoil-borings'willxbe drilled`to a p imately 45 fe`ei below grade or to �ppro`xunately f0 feet below the fust-encountered ground water if-ground-water is encountered %within 45'feet below grade:;Soil borings will'b6-drillR-3'to'5-feet,into any—confining layer encountered Beneath the-uppermost`water-bearing zone. If a confining layer is encountered,the boring will be terminated and backfilled with bentonite to the top of the confining layer before installing a ground water monitoring well. The hollow stem augers will be steam cleaned between each boring, and all sampling equipment will be properly cleaned between sample S intervals. We expect the drilling to be conducted over a one to two day period. Soil samples will be collected at five-foot depth intervals,just above fust encountered ground water(if present), and at notable changes in sediment composition utilizing an 18-inch California-modified, split-spoon sampler equipped with 2-inch-diameter brass sample sleeves. Samples ' will be collected by advancing the-auger-to a point just above the sampling depth and driving the sampler into the soil. The sampler mill be driven 18 inches with a standard 140-pound hammer repeatedly dropped 30 inches.. .The number of blows required to drive the sampler each successive 6-inch interval will be counted and recorded.to'give an indication of soil consistency. Each soil sample will be screened for-volatile compounds utilizing a photoionization detector (PID). Drilling will be performed under the:observation,of a RESNA,geologist, and�the earth materials in the borings will identified using manual andvisual methods, and classified as drilling .progresses according to the Unified :Soil Classification,System. This work will be performed under the supervision of a-California registered-geologist. One sample from every sampling interval will be sealed-with aluminum foil,capped, taped,labeled, and.placed on ice in an insulated container. Soil generatedthrough drilling.will be stored on plastic sheeting pending characterization for disposal. Soil will be disposed by a contractor selected by BP Oil and contacted by RESNA. I i Soil samples selected for analyses from each of the four soil borings will generally be the sample producing the highest reading on the PID andthe sample from directly above fust encountered ground water. If ground water is not encountered, `the soil sample producing the second highest PID reading will also be analyzed in a laboratory. The`RESNA-project manager may select other + appropriate samples from the borings utilizing the previously noted.field screening techniques. Selected samples will be ;analyzed by a State-certified laboratory for total petroleum hydrocarbons as gasoline (TPHg) using U.S.:Environmental Protection Agency (EPA) Method 8015 (modified),'for benzene, toluene, ethylbenzene and,total xylenes (BTEX) using EPA Method 8020. Analytical methods and detection limits will conform to guidelines specified in - the latest edition of the Tri-Regional Recommendations of the California Regional Water Quality Control Board. I _ I I 17051.01w 2 t