Laserfiche WebLink
,y .J <br /> _IQ4 <br /> Emcon <br /> 1433 North Market Boulevard • Sacramento California 958341943 • (916)928-3300• Fax(916)928-3341 <br /> January 24, 1996 <br /> Project 0805-152.02 <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 6100, Located at <br /> 25775 South Patterson Pass Road, Tracy, California <br /> Dear Mr Christie <br /> At the request of ARCO Products Company (ARCO), EMCON is presenting this status <br /> report for work conducted during the fourth quarter 1995 at ARCO Service Station <br /> No 6100, located at 25775 South Patterson Pass Road, Tracy, California. The site <br /> location is shown on Figure 1, and the site configuration is shown on Figure 2. <br /> ,• <br /> PREVIOUS WORK <br /> In June 1990, at the request of ARCO, RESNA, Industries (RESNA (formerly Apphed <br /> GeoSystems]) observed the drilling of five sod borings (B-1 through B-5) at the site <br /> (Applied GeoSystems, July 16, 1990, Report No. 30041) Gasoline hydrocarbons were <br /> detected in the soil samples collected from the borings <br /> Roux Associates (Roux) conducted an investigation from November 1990 to February <br /> 1991 in conjunction with the removal of five underground storage tanks (USTs) and <br /> associated product delivery lines (Roux, May 29, 1991, Report No. AR06776W) The <br /> presence of hydrocarbons in the soil within the tank cavity necessitated the excavation of <br /> the cavity to depths ranging from 15 to 25 feet below ground surface (bgs) Soil samples <br /> collected from the limits of the overexcavated tank cavity contained concentrations of total <br /> petroleum hydrocarbons as gasoline (TPHG) up to 7,400 parts per million (ppm). Four <br /> new tanks were installed in the new tank cavity. <br /> In October and November 1991 and June 1992, RESNA observed the drilling of 20 soil <br /> borings (B-6 through B-25) and the construction of 15 vapor extraction wells. Residual <br /> gasoline hydrocarbons were detected in the soil beneath the dispenser islands, between the <br /> gasoline USTs and the dispenser islands, along the north and west sides of the former <br /> gasoline tank activity, and near the southeast corner of the site (RESNA, January 31, 1992, <br /> . Report No. 30041-2, and November 12, 1992, Report No 30041-3) The lateral extent of <br /> residual gasoline hydrocarbons in the soil was delineated at the site, except for the area <br /> near the southeast corner of the site. Although trace to low concentrations of gasoline <br /> hydrocarbons were detected below 70 feet bgs, the vertical extent of residual gasoline <br /> sA4 NvJ0=0"8051520.2DS-%-"s 2 <br />