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E-meon Associates 1433 North Market Boulevard • Sacramento C:"iforn,a 95834-1943 • (916)928-3300 • Fax(916)928-3341 November 14, 1994 ' Project 0805-140.01 V Mr Kyle Christie 1 ' ARCO Products Company 1 P O Box 5811 San Mateo, Califorrua 94402 ' Re Third Quarter 1994 Status Report for ARCO Service Station aon No 0548 at 1612 Hattirrner Lane, Stockton, California ' Dear Mr Christie: ' At the request of ARCO Products Company (ARCO), EMCON Associates (EMCON) is conducting an environmental investigation at the subject site(see Figure 1) We have prepared this status report on ' the work conducted during the third quarter 1994 BACKGROUND From December 1990 through November 1993, RESNA Industries ([RESNA) formerly Applied Geosystems) observed the drilling of twenty one borings (B-1 through B-21) and the installation of five on-site groundwater monitoring wells (MW-1 through MW-5), one off-site groundwater monitoring well(MW-6), and four vapor extraction wells (RESNA,June 26, 1992, Report 300044, and RESNA, ' June 21, 1993, Report 300048, and RESNA. May 11, 1994 Report 30004-8) The locations of soil borings, wells, and other site features are presented in Figure 2 Residual hydrocarbons were analytically identified in soil samples collected from the borings near the tank cavity Low ' concentrations of hsxdrocarbons were detected in soil samples collected from borings near the dispenser islands IDuring drilling of soil boring B-18, a product line was accidentally fractured and product leaked into adjacent soil RESNA collected a soil sample from 6 feet below the product line (S-6-PLI), gasoline hydrocarbons were detected in this sample. RESNA began monitoring the groundwater in wells MW-1 through MW-4 on October 30, 1991, I (RESNA, June 26, 1991, Report 30004-4) Well MW-5 was added to the monitoring program in March 1993 Dissolved hydrocarbons have been detected in monitoring wells MW 1 and MW-5 since monitoring began. ' In March 1992, EA Engineering, Science, Technology (EA) observed removal of the ori water separator/clarifier (EA Engineering, Science and Technology, August 1992, Report 80633 01). EA collected one sod sample from beneath the former oil-water separator and one sample from the concrete. Analytical results from the soil samples indicated that oil grease (quantified as total od and grease [TOG]) was present. Concentration of volatile organic compounds, seen-volatile organic compounds, and polychlorinated biphenyls were below detection limits. Total metals were also below detection hrrnts wuh the exception of arsenic and barium which were detected at concentrations of 0 0051 and 0 12 parts per million, respectively(see Attachment A). ISAC/PjG0g0M051400.1 AS-944c 5