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LER - RYAN 1 c. <br /> 6ETT- <br /> N <br /> SUBSURFACE INVESTIGATION REPORT <br /> for <br /> Tosco (Former BP)Service Station No. 11195 <br /> 16500 South Interstate 5 <br /> Lathrop, California <br /> Report No.140193.11-2 <br /> 1.0 INTRODUCTION <br /> This report summarizes the results of the recent subsurface investigation performed by Gettler-Ryan Inc. (GR) <br /> at the subject site. The work was performed at the request of Tosco Corporation (Tosco), a subsidiary of <br /> Phillips 66.Company, in order to evaluate the degree and extent of petroleum hydrocarbon-impacted <br /> groundwater downgradient of the site. This scope of work was proposed in GR's report number 140193.11-1, <br /> titled Work Plan For Limited Subsurface Investigation dated October 15, 2001, and approved by the San <br /> Joaquin County Public Health Services,Environmental Health Division (PHS-EHD), in a letter to Tosco dated <br /> November 8, 2001. The scope of work included: preparing a site-specific safety plan; obtaining the required <br /> drilling permits; advancing five off-site GeoprobesOO; collecting and submitting selected soil and all grab <br /> f'vr groundwater samples for chemical analysis; and preparing a report summarizing the findings of the <br /> investigation. <br /> 2.0 SITE DESCRIPTION <br /> 2.1 General <br /> The subject site is situated immediately east of the Louise Avenue off-ramp of Interstate 5 at the southwest corner <br /> of East Louise Avenue and Harlan Road in Lathrop,California(Figure 1). Current station facilities include two <br /> 12,000-gallon double-wall gasoline USTs,two dispenser islands,related product lines,one canopy,and a station <br /> building.. Former station facilities removed during the construction activities performed in December 1998 and <br /> January 1999 included one 10,000-gallon,one 8,000-gallon,and one 6,000-gallon single-wall fiberglass gasoline <br /> USTs, two dispenser islands,related product lines,and two canopies. Six on-site groundwater monitoring wells <br /> (MW-1 through MW-6)and five off-site groundwater monitoring wells(MW-8 through MW-12)are present at j <br /> and around the site. In addition, one 6-inch diameter,temporary groundwater extraction conductor casing(CC- f <br /> WS)was installed in the former UST pit prior to backfilling. Locations of the pertinent site features are shown <br /> on Figure 2. <br /> 2.2 Geology and Hydrogeology <br /> l <br /> The site is situated on generally flat topography at an elevation of approximately 10 feet above sea level. The <br /> San Joaquin River is approximately 1.1 miles southwest of the site and Weatherbee Lake is approximately 2.7 { <br /> miles south of the site. <br /> f <br /> 140193:11-2 F <br /> 6747 Sierra Court , Suite J Dublin , California 94568 ( 925) 551 - 7555 <br />