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- <br /> - <br /> November 18, 1991 <br /> ARCO Station No. 2130, Stockton, California <br /> ` o Develop, purge, and sample the ground-water monitoring wells. Water <br /> samples will be placed in iced storage and maintained at 4 degrees centigrade <br /> for transport to the analytical laboratory. <br /> o Submit soil samples to a laboratory approved by ARCO for analysis of total <br /> petroleum hydrocarbons as gasoline (TPHg) and benzene, toluene, <br /> ethylbenzene,and total xylene isomers(BTEX)using modified Environmental <br /> Protection Agency (EPA) Method 8015 and EPA Method 8020 respectively. <br /> The soil sample collected just above the saturated zone and the sample having <br /> the highest PID reading will be submitted. If the soil sample from just above <br /> the saturated zone has the highest PID reading, the soil sample having the <br /> next highest reading on the PID will be submitted for chemical analyses. <br /> Additional soil samples may be submitted to evaluate the upper and I.Dwer <br /> boundary of hydrocarbons, <br /> o Submit the soil sample from the borings having the highest reading on the <br /> PID for total lead using EPA Method 7421. If total lead is detected,we will <br /> discuss with ARCO the submittal of additional soil samples to delineate total <br /> lead in soil. <br /> o Submit -,vater samples to a laboratory approved by ARCO for analysis of <br /> TPHg and BTEX. <br /> o Contract a licensed surveyor to survey the wells with respect to mean sea <br /> level. <br /> o Evaluate the groundwater gradient beneath the site. <br /> o Collect samples of the drill cuttings and submit the samples to an ARCO- <br /> approved laboratory for analysis of TPHg, BTEX, and total lead using above <br /> methods. The tentative location for the stockpiled soil is shown on Plate 2. <br /> Drill cuttings from the proposed onsite borings w1il be placed on plastic and <br /> covered with plastic. Results of these analyses will be used to evaluate <br /> disposal options for the soil. We will apprise ARCO of these options. <br /> In addition to the subsurface investigation, we will conduct a vapor extraction test at this <br /> -Results of the vapor-extraction-test-will be used to evaluate the feasibility of vapor T <br /> extraction as a soil remediation alternative and to determine the number and placement of <br /> 3=3-aw 3 <br />