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A5 <br /> T x U <br /> amcon <br /> 1433 North Market Boulevard-Sacramento California 95834-1943- (916)928-3300- Fax(916)928-3341 <br /> December 6, 1995 <br /> Project 0805-114 04 <br /> Mr Kyle Christie <br /> ARCO Products Company <br /> P O Box 612530 <br /> San Jose, California 95161 <br /> Re Third Quarter 1995 Status Report for ARCO Service Station No 2130, Located at <br /> 7906 North El Dorado Street, Stockton, California <br /> Dear Mr Christie <br /> At the request of ARCO Products Company (ARCO), EMCON has conducted an <br /> environmental investigation and is currently operating a remedial system at the subject site (see <br /> Figure 1) This status report includes uiformation for the third quarter of 1995 on subjective and <br /> laboratory analysis of groundwater samples collected from each monitoring well, measurements <br /> of groundwater elevations in each monitoring well, evaluation of the groundwater gradient, and <br /> performance data for the soil vapor extraction(SVE)/air sparge (AS) remediation system. <br /> i� <br /> BACKGROUND <br /> Environmental work performed at the site has included drilling 19 soil borings on site and <br /> 5 borings off site Ten vapor extraction wells (VW-1 through VW-10) were installed on <br /> site Five groundwater monitoring wells were installed on site (MW-i through MW-5), and <br /> five were installed off site (MW-6 through MW-10) One air sparge well (AS-1) and 3 air <br /> sparge monitoring points (MS-1 through MS-3) were installed on site During construction <br /> of well MW-9, cement slurry was accidentally introduced into the slotted screen The well <br /> was destroyed, and another boring was drilled near well MW-9 and converted to a <br /> monitoring well (MW-10) Well locations are shown on Figure 2 <br /> During October 1993, in association with the replacement of the underground storage <br /> tanks and product delivery lines, RESNA Industries (RESNA) of Rancho Cordova, <br /> California, observed Triangle, Inc , of Sacramento, Califoriva, excavate trenches and install <br /> horizontal piping for use during site remediation <br /> In June 1994, RESNA prepared and submitted a problem assessment report (PAR) and a final <br /> remediation plan (FRP) to the county and state regulatory agencies The reports indicated <br /> additional remedial wells were required and should include additional air sparge wells, a <br /> monitoring air sparge well., and vapor extraction wells Residual hydrocarbons were detected in <br /> soil to groundwater (approximately 60 feet below ground surface) near the existing tanks, but <br /> only relatively low concentrations were detected in soil samples collected from the other on-site <br /> borings. Gasoline hydrocarbons were not detected in the off-site soil borings Dissolved <br /> hydrocarbons have been detected in all groundwater monitoring wells Total petroleum <br /> SACV NPJOMO X08051140 4ES-95\pas l <br />