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NO- <br /> Addendum . <br /> y, <br /> to Wurk Plan May 24, 1991 <br /> z ARCO Station No. 760,Lodi. California AGS 38048-6W <br /> To investigate the feasibility of using vapor extraction to remediate hydrocarbons in soil <br /> below the site,we will install three vapor-extraction wells (shown on Plate P-2) and <br /> conduct a vapc.r-e ztraL—.an test using the wells. Our procedures for well installation and <br /> conducting a vapor-extraction test are discussed under Feld Methods: <br /> We will conduct the following tasks during the additional work: <br /> o Update the site safety plan to include the use of propane for the vapor- <br /> extraction test. <br /> o Obtain a drilling permit from the San Joaquin County Public Health <br /> Services, Environmental Health Division. <br /> o Contact Underground Service Aleft at least 48 hours before drilling to <br /> identify public utility lines at the site. <br /> o Obssrve drilling of three 10-inch-diameter soil borings. <br /> o Collect relatively undisturbed soil samples frar7 each boring at 5-foot <br /> intervals or other appropriate intervals from the ground surface to the total <br /> boring depth and classify the samples according to the Unified Soil <br /> Classification System.. <br /> o Install thi--e 4-inch-diameter vapor-extraction wells in the borings. <br /> o Submit.selected soil samples to a laboratory approved by ARCO for <br /> analysis of total petroleum hydrocarbons as gasoline (TP,-ig) and benzene, <br /> toluene, ethflbenzene, and total xylene isomers (BTEX). <br /> o Copect four discrete soil samples from the drill cuttings to be composited <br /> into one sample and analyze for TPHg and BTEX. We will apprise ARCO <br /> +3 <br /> of disposal options after receiving laboratory analyses. <br /> o Transport a portable vapor-extraction system to th- site. <br /> o Operate the vapor-extraction systern as required to obtain vapor samples <br /> and vacuum pressure: and now rate information. <br /> llmma <br />