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f <br /> Emcon <br /> 1433 North Market Boulevard • Sacramento California 95834-1943 • (916)928-3300• Fox(916)928-3341 <br /> 1s� <br /> January 24, 1996 <br /> Project 0805-140 02 <br /> Mr Kyle Christie <br /> ARCO Products Company <br /> P O. Box 612530 <br /> San Jose, California 95161 <br /> Re Fourth Quarter 1995 Status Report for ARCO Service Station No 0548, Located at <br /> 1612 Hammer Lane, Stockton, California <br /> Dear Mr Chnsue. <br /> At the request of ARCO Products Company (ARCO), EMCON is conducting an <br /> environmental investigation at the subject site (see Figure 1) We"have prepared this status <br /> report on the work conducted during the fourth quarter 1995, which included rrrasunng <br /> depths to groundwater, collecting groundwater samples from the wells for subjective' and <br /> laboratory analyses, and calculating the groundwater gradient and d,kbctbn of groundwater <br /> flow beneath the site <br /> BACKGROUND <br /> From December 1990 through November 1993, RESNA Industries (RESNA [formerly <br /> Applied GeoSystems]) observed the drilling of 21 borings (B-1 through B-21) and the <br /> installation of five on-site groundwater monitoring wells (MW-1 through MW-5), one off- <br /> site groundwater monitoring well (MW-6), and four vapor extraction wells (VW-1 <br /> through VW-4) (RESNA, June 26, 1992, Report No. 30004-4, RESNA, June 21, 1993, <br /> Report No. 30004-8, and RESNA, May 11, 1994, Report No 30004-8). The locations of <br /> soil borings, wells, and other site features are , presented on Figure 2. Residual <br /> hydrocarbons were analytically identified in soil samples collected from the borings near <br /> the tank cavity Low concentrations of hydrocarbons were detected in soil samples <br /> collected from borings near the dispenser islands. <br /> During drilling of soil boring B-18, a product line was accidentally fractured and product <br /> leaked into adjacent soil. RESNA collected a soil twVlp from 6 feet below the product ' <br /> lute (S-6-PL1), gasoline hydrocarbons were detected in this sample. RESNA installed one <br /> vapor extraction well (VW-4) near the product release. Total petroleum"hydrocarbons as <br /> gasoline (TPHG), and benzene, toluene, ethylbenzene, and total xylenes (BTEX) were <br /> below laboratory detection limits in soil collected at 11 feet, 26 feet, and 46 feet below <br /> ground surface. <br /> RESNA began monitoring the groundwatgr,, in wills MW.1 through MW-4 on <br /> October 30, 1991 (RESNA, June 26, 1991, Report No. 30004-4) Wells MW-5 and <br /> sAG%NVJaA0M30514W 2DS.%Nvpt i <br />