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2320 EI OoraO ,Stockton.Caldornm , q <br /> Previous reports on this site, submitted by Aegis, include: J <br /> 1 3 1991 <br /> LNVIRJNMENTRZ <br /> Report DateERM/T/SERV!ES�TH <br /> Pre-Tank Replacement Site Assessment Work Plan December 1989 <br /> Pre-Tank Replacement Site Assessment Results Report April 1990 <br /> Tank Closure Report September 1990 <br /> Letter Work Plan Marco 1991 <br /> Two additional soil borings were requested by the SJCPHS after reviewing both the Tank <br /> Closure Report and a leachate potential calculation performed on the basis of soil sample <br /> analytical results following over-excavation of the dispenser islands. A letter from the <br /> SJCPHS, dated December 27, 1990, requested additional subsurface investigation in the <br /> location of the southeast and southwest dispenser islands. Figure 2 shows the locations <br /> of the dispenser islands, and previous soil samples and soil borings (SB-1 and SB-2). <br /> SOIL BORINGS <br /> Two soil borings were drilled with a trailer mounted, hollow-stem auger drill rig. This rig <br /> is equipped with a 10-foot mast, and drilled underneath the station canopy. Soil boring <br /> SB-1 was drilled to a total depth of 19 feet below grade and soil boring SB-2 was drilled <br /> to a total d6,,)th of 16 feet below grade. <br /> The two borings were sampled while drilling, every 2-1/2 feet, to 10 feet below grade <br /> according to the Aegis standard operating procedures included in Attachment A. Af,er <br /> 10 feet, the borings were sampled at 5-foot intervals. The samples were analyzed for <br /> benzene,toluene,ethylbenzene and total xylenes (BTEX), ethylene dibromide(EDB),total <br /> petroleum hydrocarbons (fPH), as gasoline, and total lead. The soil samples were <br /> screened for the presence of petroleum hydrocarbons with a portable photoionization <br /> detector. <br /> The soils beneath the canopy consist of clayey silt overlying a silty sand. Soil boring logs <br /> are included in Attachment B. <br /> SUMMARY <br /> Two soil samples from each soil boring were submitted to a state-certified laboratory. The <br /> samples were analyzed for BTEX, EDB, TPH and total lead. The analytical results are <br /> summarized in Table 1, and laboratory reports and chain-of-custody forms are included <br /> in Attachment C. <br /> 09-0 90.LTF -2- <br />