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California&gional Water Quality Cor*l Board <br /> Central Valley Region" <br /> Katherine Hart, Chair <br /> Matthew Rodriquez 11020 Sun Center Drive,#200,Rancho Cordova,California 95670-6114 Edmund G.Brown Jr. <br /> Secretaryfor (916)464-3291 •FAX(916)464-4645 Governor <br /> Environmental Protection http://www.waterboards.ca.gov/centralvalley <br /> TO: Case File FROM: Kristi Shelton <br /> WRC Engineer <br /> Abovegro .nd Tanks Cleanup Unit <br /> DATE: 2 August 2011 1 �^. <br /> SIGNATURE: <br /> SUBJECT: NO FURTHER ACTION REQUIRED, FORMER UNION OIL BULK PLANT <br /> NO. 788, 8203 EAST 11TH STREET, TRACY, SAN JOAQUIN COUNTY <br /> I reviewed the 8 March 2011 Final Soil Gas Re-Sampling Report and Closure Request <br /> prepared by Stantec Consulting Corporation (Stantec) on behalf of ConocoPhillips for the <br /> former Union Oil Bulk Plant No. 788 at 8203 East 11th Street in Tracy (Site). The report <br /> summarizes the site assessment activities and recommends site closure. The site history and <br /> rationale for issuing a No Further Action Required letter are summarized herein. All record <br /> owners of fee title located within 200 feet of the site's identified hydrocarbon plume were <br /> notified of the request for closure and given 30 days to respond. No comments were received. <br /> BACKGROUND <br /> The Site is in a commercial area in Tracy and is bounded to the north by Southern Pacific <br /> Railroad property. In 1918, four aboveground tanks (AGTs) were constructed in the western <br /> portion of the Site. Two AGTs (19,500 gallons each) stored diesel and super unleaded <br /> gasoline. The two other AGTs (20,000 gallons each) stored regular leaded and unleaded <br /> gasoline. In 1976, a release occurred from the underground piping between the AGTS and the <br /> loading rack. The piping was subsequently repaired. On 1 December 1993, the bulk plant <br /> was permanently closed, and in September 1994, Union Oil removed the AGTs, loading racks, <br /> and structures. ConocoPhillips owned the Site at the time of the release and is the only <br /> discharger referenced in the remainder of this memo. The Site is currently vacant and no <br /> longer in use. The current property owner plans to construct a commercial building at the Site. <br /> A Site Plan is shown on Figure 1. <br /> SOIL INVESTIGATIONS <br /> In December 1989, ConocoPhillips removed a partially buried 5,000-gallon tank from the <br /> southwest portion of the Site. The tank had been used for storage of transmission fluid, but <br /> had also contained heating oil. Two soil samples collected beneath the tank showed <br /> detections of total petroleum hydrocarbons as diesel (TPHd), xylenes, and ethylbenzene. <br /> In October 1990, ConocoPhillips installed three groundwater monitoring wells (U-1 through <br /> U-3). Soil samples showed detections of TPH as gasoline (TPHg), TPHd, benzene, <br /> ethylbenzene, and xylenes in all three borings, with maximum concentrations of <br /> 1,800 milligrams per kilogram (mg/kg), 710 mg/kg, 2.7 mg/kg, and 52 mg/kg at 6.5 feet below <br /> California Environmental Protection Agency <br /> 0 Recycled Paper <br />