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a <br /> INTRODUCTION <br /> The following report presents the findings of a soil and groundwater investigation <br /> performed by Pacific Environmental Group, Inc. (PACIFIC) at UNOCAL Bulk Plant <br /> No.0788 located at 8203 East 11th Street in Tracy, California (Photos 1 &2 and <br /> Figure 1). Three groundwater monitoring wells were installed on October 24 and 25, <br /> 1990, to evaluate the extent of petroleum hydrocarbons in the soil and groundwater in <br /> the vicinity of a subsurface 5,000-gallon transmission fluid tank recently removed from <br /> the site. This report presents site background information, a regional geologic and <br /> hydrologic overview, sample collection and analytical procedures, findings, and <br /> recommendations. <br /> Background <br /> on and <br /> The above referenced site is an operating bulk plant with o19,500in thewestern <br /> - two 20,000-gallon above ground hydrocarbon storage tanks located <br /> portion of the property (Figure 2). The 19,500-gallon tanks contain diesel and super <br /> lar <br /> unleaded gasoline, and the e and <br /> 20,000-gallotanks c�he em ranks were ins <br /> nstalled inaded �1918 to <br /> unleaded gas <br /> =nP. According to site personnel, <br /> replace the tanks originally installed during construction of the facility. <br /> A partially buried 5,000-gallon tank was removed from the southwestern portion of the <br /> site on December l3, 1989. The prmafy use of this tank was for:transmission fluid <br /> storage;but it has also been used to contain heating 0 in.the past. .Details of the exca- <br /> vation of this tank are described in a PACIFIC etter to west ern ends of the tanks xc©� <br /> 1990. Soil samples were collected from the eastern <br /> vation at a depth of 8 feet below ground surface during:tank removai.actiivides Ceon <br /> fled laboratory analysis of these samples indicated the presence of 17 parts Per.milli.an <br /> (ppffif diesel, 12 pQm toluene,and 4.9 ppm ethylbenzene in the eastern.end'of the exca= <br /> vation. The transmission fluid tank resided on an underground concrete pad,which was <br /> not.ren-�oved:aur g exca�iation. Groundwater was"abserved)n the exMvati0l' a <br /> depth of.6 fleet beluw surface during December 1989 tank removal activity. <br /> 1 February 13,1991 <br /> 3100101/REPORT <br />