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Emcon Associates _ <br /> 1433 North Market Bou -vara • Sacramento.Calif.•ner: t <br /> 4Rhp,Q�B y 16) 28-3300 Fax(916)928-3341 <br /> 00 <br /> ]CSV 15 PM 4: 52 <br /> November 14, 1994 <br /> Project 0805-152.01 <br /> Mr. Kyle Christie <br /> ARCO Products Company <br /> P.O. Box 5811 <br /> San Mateo, California 94402 <br /> Re: Status Report, Third Quarter 1994, ARCO Service Station 6100, 25775 South Patterson <br /> Pass Road, Tracy, California <br /> Dear Mr. Christie: <br /> At the request of ARCO Products Company (ARCO), EMCON Associates (EMCON) is presenting <br /> this status report for work conducted during the third quarter 1994 at the subject site. The location of <br /> the site is shown on the Site Vicinity Map (see Figure 1), and the configuration of the site is shown on <br /> the Generalized Site Plan (see Figure 2). <br /> PREVIOUS WORK <br /> In June 1990, RESNA Industries (RESNA [formerly Applied GeoSystems]) observed dolling of five <br /> soil borings (B-1 through B-5) at the site (Applied GeoSystems, July 16, 1990, Report 30041-1). <br /> Gasoline hydrocarbons were detected in soil samples collected from the borings. <br /> Roux Associates (Roux) conducted an investigation from November 1990 to February 1991 in <br /> conjunction with the removal of five underground storage tanks and associated product delivery lutes <br /> (Roux, May 29, 1991, Report AR06776W). Soil containing residual hydrocarbon within the tank <br /> cavity was excavated to 15 to 25 feet below ground surface (bgs). Soil samples collected from the <br /> limits of the enlarged tank cavity contained concentrations of total petroleum hydrocarbons as gasoline <br /> up to 7,400 parts per million. Four new tanks were installed in the new tank cavity. <br /> In October and November 1991 and June 1992, RESNA observed drilling of 20 soil borings (B-6 <br /> through B-25) and construction of 15 vapor extraction wells. Residual gasoline hydrocarbons were <br /> detected in soil beneath the dispenser islands, between the underground gasoline storage tanks and the <br /> dispenser islands, along the north and west side of the former gasoline tank cavity, and near the <br /> southeast corner of the site (RESNA, January 31, 1992, Report 30041-2, and November 12, 1992, <br /> Report 30041-3). The lateral extent of residual gasoline hydrocarbons in soil was delineated at the site, <br /> except for the area near the southeast comer of the site. Although trace to low concentrations of <br /> gasoline hydrocarbons were detected below 70 feet bgs, the vertical extent of residual gasoline <br /> 1 <br /> SACIS AC�PJMMM8051520.I AM-94/Ifc3 <br />