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F <br /> ME WN, <br /> Of <br /> fi INwz� <br /> �S.' <br /> rel;. •n .�'kdd^�6.?v�� <br />¢.nT <br /> PRELIMINARY ASSESSMENT OF <br /> SOIL AND GROUND-WATER QUALITY AT <br /> THRIFTY OIL COMPANY STATION NO. 172 <br /> 7647 PACIFIC AVENUE <br /> STOCKTON,CALIFORNIA <br /> IA INTROI)uCTION <br /> SSB Environmental Consultants, Inc., conducted a preliminary assessment of soil and ground- <br /> water quality at Thrifty Oil Company Station No. 172 located at 7647 Pacific Avenue in Stockton, <br /> California. This assessment was undertaken at the request of Thrifty Oil Company. <br /> 1.1 Purpose <br /> This investigation was designed to evaluate the presence of gasoline range hydrocarbons in sail <br /> and ground water at Thrifty Oil Company Station No. 172 in Stockton, California. <br /> 1.Y Scope of work <br /> The scope of work for this investigation included drilling four soil borings to depths ranging from <br /> 76 to 80 feet near existiag underground fuel storage tanks and fuel islands. Two-inch diameter <br /> ground-water monitoring wells were constructed in each boring. Soil samples were obtained at <br /> 5 foot intervals to a depth of 60 feet, the approximate depth to ground water. Each soil sample <br /> was field analyzed for the presence of gasoline range hydrocarbons using a photoionization <br /> detector (Model OVM 580B). Field analysis readings are recorded on the boring logs in , <br /> Appendix A. Approximately six soil samples from tach boring were submitted for laboratory <br /> analysis for benzene, toluene, ethylbenzene,xylenes (11TEX), and total petroleum hydrocarbons <br /> using a gasoline standard (TPHg). One sample from each boring was analyzed for total lead. In <br /> addition, one soil sample (5-5013-82) from boring B-2 was analyzed for gasoline range aromatic <br /> compounds and selected metals using Toxicity Characteristic Leaching Procedure (TCLP) <br /> extraction methods. <br /> A 2-inch diameter ground-water monitoring well was constructed in each boring. Thirty feet of <br /> screened casing was installed in each boring and placed approximately 15 feet into first <br /> encountered ground water. Each monitoring well was developed and purged. Ground-water <br /> samples were collected from each well and analyzed for concentrations of BTEX and TPHg, and <br /> for total and fecal coliform in wells located within 50 feet of sewer lines. <br />