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Limited Phase II Environmental Site Assessment January 11,2007 Page 2 2006, when Wal-Mart closed the store. The oil change facility consists of a large subsurface bay that extends to an approximate depth of 8 feet below ground surface (bgs). The facility was formerly equipped with four 350-gallon above-ground storage tanks (ASTs) containing motor oil and one 500-gallon use oil AST. These tanks have been removed, and were formerly located within the oil change pit. A sump and associated submersible pump is located within the floor of the oil change pit, in the northwest corner of the oil change facility. The sump collected oil and rinse water from floor washing (AEI, 2006). The location of the sump is shown on Figure 2. GEOLOGY AND HYDROGEOLOGY The site is located at an approximate elevation of 26 feet above mean sea level, with the local topography sloping gently towards the southwest. The United States Geological Survey (USGS) has identified the area surrounding the site to be underlain by the Stockton Clay, a poorly drained soil with moderate water holding capacity. These soils were formed in alluvial deposits derived from a mix source of parent rocks. The nearest natural surface water is the Calaveras Rivers, located approximately 0.95 miles to the south-southeast of the property. The Mokelumne Aqueduct is located approximately 900 feet northwest of the site. AEI reports that groundwater is anticipated to be approximately 63 feet bgs. Based on regional topography, the direction of groundwater flow beneath the site has been inferred to be towards the southwest. PROPOSED SCOPE OF WORK To evaluate the subsurface conditions adjacent to the sump, SECOR proposes to drill one soil boring to a maximum depth of 25 feet bgs. The soil boring will be drilled using direct push drilling equipment. The soil boring location is shown on Figure 2. Health & Safety Plan and Site Specific Permitting Prior to drilling, SECOR will prepare a site-specific health and safety plan (HASP) in accordance with 29 CFR 1910.120 to address potential hazards at the site during the proposed field activities. The HASP will be reviewed, signed, and adhered to by all on-site personnel. Additionally, SECOR has completed and attached the San Joaquin County Environmental Health Department (SJCEHD) soil boring permit and fees, the Master File Record and fee, and the Licensed Contractor Declaration (Attachment A). Utility Location An important safety consideration in situating the proposed soil boring is proximity to utilities. SECOR has endeavored to place the proposed soil boring as strategically as possible while maintaining a safe distance from known hazards and other obstructions. Prior to drilling, SECOR will contact Underground Service Alert (USA) to notify local utilities of the planned work. SECOR will also contact a private utility locator to search for other utilities that may or may not be marked. Prior to drilling with mechanized equipment, SECOR personnel will perform a health and safety tail-gate meeting to discuss safety issues related to potential subsurface utilities that may exist at the site. P:/CEC/Stockton/Stockton Limited Phase II ESA Work Plan DRAFT 01.10.07 SECOR