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�?�_ �. k ' aT �`u i 1 R S�. r -S .�, 7i.+•r .,� �.4» ,�y �• �rH _ a ;.ay,. <br /> 4 <br /> t� <br /> KEEINFEtDER <br /> -R� 2 BACKGROUND <br /> The Nomellini Construction facility is at 1.045 West Charter Way in Stockton, California <br /> �. (Plate 1). In August 1988, two 1,000-gallon fuel USTs were excavated from site southeast <br /> of the warehouse building while a 550-gallon waste oil tank was excavated from a separate <br /> site. Nomellini Construction reported that the two 1,000-gallon tanks contained regular <br /> and unleaded gasoline,but may have also held kerosene at one time. Analytical results of <br /> soil samples collected beneath the two 1,000-gallon USTs indicated that petroleum <br /> hydrocarbons and gasoline related constituents were present in the so :. Constituents were <br /> detected below levels of concern in the sample collected beneath the waste oil tank. <br /> Results of this investigation were presented in a Kleinfelder report dated September 22, <br /> 1988. Based on these results, Kleinfelder was authorized by Nomellini Construction to <br /> further assess petroleum hydrocarbon contamination in the vicinity of the UST excavations. <br /> Re-excavation Soil Assessment <br /> On November 9, 1988 additional soil was removed from the fuel tanks excavation to further <br /> assess the extent of petroleum hydrocarbon contamination. One section of the excavation <br /> _ bottom was removed from a depth of 11 to 19 feet below the ground surface. Soil samples <br /> were qualitatively screened in the field with an organic vapor detector. Organic vapor <br /> readings were detected at 408 parts per million by volume (ppmv) from a sample collected <br /> at a depth of 19 feet within the excavation and 740 ppmv from a sample collected 10 feet <br /> away from the excavation at a depth of 16 feet. Based on the positive organic vapor <br /> screening results, Nomellini Construction decided to Backfill <br /> &,11 1. <br /> W? clean iall� <br /> and further assess the extent of contamination with a soil boring program. <br /> Preliminfry Soil Boring Assessment <br /> In May 1989,Kleinfelder analyzed 15 soil samples collected from nine borings(Bl through <br /> B-9)drilled in the vicinity of the UST excavation (Plate 2). Samples were analyzed from <br /> depths of 10.5 to 26 feet. Total petroleum hydrocarbons (TPH)were detected in 10 of the <br /> 15 samples analyzed. High TPH as gasoline,benzene, toluene, ethylbenzene, and xylenes <br /> (BTEX) concentrations were detected just above and below the ground water surface in <br /> boring B-1 located adjacent to the south edge of the excavation. Similarly, high TPH <br /> concentrations were detected just above the ground water surface in B-2 approximately 20 <br /> — F18-91-62 2 <br /> Copyright 1991 Kleinfelder, Inc. e� <br />