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Stantec UST and Line Removal Report ARCO Service Station No. 6080 March 15, 2011 1.0 INTRODUCTION AND SITE BACKGROUND On behalf of Atlantic Richfield Company, a BP Affiliated Company, Stantec Consulting Corporation (Stantec) is submitting this report to document the results of soil sampling activities conducted during the excavation and removal of underground storage tanks (UST), fuel dispensers, product lines, and associated piping at the above referenced site. Gettler-Ryan, Inc. (Gettler Ryan) of Dublin, California was contracted to remove and replace the fueling system. The environmental investigation during the excavation and removal activities was overseen by San Joaquin County Environmental Health Department (SJCEHD). This report includes a brief discussion of site settings and results of the soil sampling activities. The site is located at 85 East Louise Avenue in Lathrop, California (Figure 1). The site is bound by Louise Avenue to the south, South Harlan Road to the east, Interstate 5 to the west, and a vacant property to the north. The site is currently operating as a gasoline station with an AM/PM mini mart, one 10,000-gallon, one 12,000-gallon, and one 20,000-gallon fiberglass USTs with associated piping and two dispenser islands. According to the United State Geologic Survey (USGS) Map dated 1999, the site is at an elevation of approximately 15 feet above mean sea level (MSL) on flat terrain. The nearest open body of water is an irrigation canal located approximately 1,500 feet west of the site flowing from south to north. SJCEHD formerly provided cleanup oversight for the site under the local oversight program case number 0712. Site investigation and cleanup began in 1999 when petroleum hydrocarbon impacts were discovered in the subsurface of the site during the dispenser and product line upgrade activities, which continued until 2007. In 2007, SJCEHD approved a no-further action request for the site and confirmed that the site environmental investigation and cleanup was completed. 2.0 2010 FUEL SYSTEM UPGRADE SAMPLING ACTIVITIES 2.1 SITE-SPECIFIC HEALTH AND SAFETY PLAN Stantec prepared a site-specific Health and Safety Plan for sampling activities at the site, as required by the Occupational Health and Safety Administration (OSHA) Standard "Hazardous Waste Operations and Emergency Response" guidelines (29 CFR 1910.120). The document was reviewed and signed by Stantec personnel and subcontractors performing work at the site. 2.2 UST EXCAVATION DE-WATERING Because groundwater at the site is approximately 12 feet below ground surface, it was necessary to de-water the shallow subsurface to facilitate the removal of the USTs, former fuel lines, fuel dispensers, and other associated equipment. In December 2010 during the UST excavation activities, the UST excavation pit was de-watered by Gettler-Ryan using the tank-pit well as a collection point. The generated groundwater was temporarily stored in a 20,000 gallon 6080 UST and Line Removal Report.doc 1