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I _oil <br /> rork Plan September 5, 1990 <br /> ARCO Station 548, Stockton, California AGS 30004-1 <br /> Drilling ProcedureL <br /> r; <br /> Before drilling,we will acquire a permit from the SJPHS for drilling a maximum of four soil <br /> borings in the area of the gasoline tank cavity. Applied GeoSystems will contact . <br /> Underground Service Alert at least 48 hours before drilling to delineate public utility tines <br /> at the site. Before drilling, each borehole will be hand-augered 3 to 5 feet below grade. <br /> The soil borings will be drilled using a truckmounted rig equipped with 8-inch-diameter, <br /> continuous-flight, hollow-stem augers. The drilling will be performedunder the guidance <br /> ® of a field geologist, and the earth materials will be logged as drilled by the Unified Soil <br /> Classification System. <br /> We will drill the first borirg approximately 2-1/2 feet from the Edge of the tank area,near <br /> the fll ends of the product tanks, to 30 feet below grade, ground water, or auger refusal, <br /> 4® whichever is encountered first. A photoionization detector (PID)will be used to evaluate <br /> soil samples for gasoline hydrocarbons. Field instruments such as the PID are useful for <br /> indicating relative levels of gasoline hydrocarbon vapors but do not detect the concentrations <br /> of gasoline hydrocarbons present with the precision of laboratory analyses. If the PID <br /> reading of the soil sample collected at 30 feet be,ow grade is greater than 50 parts per <br /> million by volume(ppmv),we will drill until:(1)two consecutive samples collected at 5-foot <br /> ApO&VI ed Geosystems . - <br />