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i <br /> r <br /> Un <br /> 1! 1.117P€ lft <br /> October 4, 2002 <br /> t <br /> Mr. Jeffrey Wong t){ t � tti�. 5450.41 <br /> Senior Environmental Health Specialist °�i `i lti ! , , t 06.0 <br /> San Joaquin County Environmental Health Department <br /> 304 East Weber Avenue f , ` t A�U �{ <br /> Third Floor Alyl <br /> Stockton, CA 95202 <br /> Re: Site Investigation Report <br /> ARCO Service Station#5450 > 43 <br /> 1617 West Fremont Street <br /> Stockton,California <br /> Dear Mr.Wong: <br /> URS Corporation Americas (URS), on behalf of Atlantic Richfield Company (ARCO) is pleased to <br /> present this report documenting the additional site investigation activities conducted at the ARCO <br /> service station located at 1617 West Fremont Street (near the intersection of West Fremont Street and <br /> North Pershing Avenue) in Stockton, California (site) (Figure 1). This investigation was conducted to <br /> comply with the request by the San Joaquin County Environmental Health Department (SJCEHD) to <br /> install three groundwater monitoring wells and to conduct a conduit survey (see letter in Attachment 1). <br /> The site investigation was performed as described in the Workplan for Monitoring Well Installation, <br /> dated July 5, 2002. The workplan was approved by SJCEHD as indicated in the letter dated July 30, <br /> 2002(Attachment 1). <br /> SITE BACKGROUND <br /> The site is an operating gasoline service station and AM/PM Mini-Mart. Currently, site facilities <br /> include three gasoline underground storage tanks (USTs), and associated product lines and dispensers. <br /> On October 5, 1995, Brown and Caldwell (BC) performed oversight and soil sampling during facility <br /> product piping upgrades. Fourteen soil samples were collected 18 inches beneath the product piping <br /> trenches. Laboratory analysis reported maximum concentrations of gasoline-range total petroleum <br /> hydrocarbons (TPHg), benzene, toluene, ethylbenzene, and total xylenes(BTEX) of 360,000 milligrams <br /> per kilogram (mg/kg), 5,600 mg/kg, 2,400 mg/kg, 6,700 mg/kg, and 39,000 mg/kg, respectively, near <br /> the southwestern dispenser island. Approximately 35 cubic yards of soil were removed during over- <br /> excavation activities of the impacted soil. Following over excavation, concentrations of BTEX were <br /> 0.087 mg/kg, 0.026 mg/kg, 0.0064 mg/kg, and 0.044 mg/kg, respectively, at approximately 11.5 feet <br /> below ground surface(bgs). TPHg was not detected at 11.5 feet bgs. <br /> On July 30, 1996, BC drilled and installed one 2-inch-diameter groundwater monitoring well (MW-1, <br /> shown on Figure 2) to a depth of 25 feet bgs near the southwestern dispenser island. Laboratory <br /> analysis reported total xylenes in all three soil samples analyzed with concentrations ranging from <br /> 0.0064 mg/kg to 0.0089 mg/kg. No other hydrocarbons were detected. <br /> URS Corporation <br /> Crown Corporate Center <br /> 2870 Gateway Oaks Drive, Suite 300 <br /> Sacramento,CA 95833 <br /> Fel: 916.679.2000 <br /> 'Fax:916.679.2900 K:US BP ARC01054501Site Investigation Report.doc <br />