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1 <br /> February 14, 1992 <br /> ARCO Service Station No 2130, Stockton, California <br /> 1 <br /> Excavation of Former Tank Cavity and Product Lines <br /> A geologist from RESNA will be onsite to observe excavation of the soil from the former <br /> tank cavity Immediately following the removal of the existing underground-storage tanks, <br /> the tank cavity will be excavated approximately 2 feet below the former tanks <br /> (approximately 12 feet below grade) During excavation, the geologist will use a PID to <br /> characterize the relative levels of hydrocarbons in the soil and note any subjective evidence <br /> of hydrocarbons such as obvious product odor and discoloration We will collect soil <br /> samples within 2 feet of base of the former product lines at 20-foot intervals Soil samples <br /> will be submitted to a State-licensed laboratory and analyzed for appropriate compounds <br /> according to the S3CPHS-EHD guidelines Details of our sampling procedures are in <br /> Appendix A <br /> • Estimate of_Excavated Soil <br /> We estimate 920 cubic yards of soil may be excavated from the existing tank cavity and <br /> product-line trenches The estimate of the volume of soil is based on (1) the dimensions <br /> of the existing tank cavity (75 feet by 30 feet by 12 feet) and the volume occupied by the <br /> existing tanks (3,170 cubic feet) and (2) the anticipated dimensions of the trenches excavated <br /> during the removal of the product and vapor piping (170 feet by 2 feet by 3 feet) The <br /> actual volume will vary depending on the final depths of the excavations <br /> Excavated soil will be stockpiled onsite The stockpiled soil will be placed on and covered <br /> with plastic sheeting to restrict vapor emissions and control dust Soil samples will be <br /> collected from the stockpiles, composited, and analyzed for hydrocarbons to evaluate <br /> whether the soil can be classified as nonhazardous <br /> 30003-4W 9 <br />