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Remediation Report - 152 East 1 Ith Street, Tracy, California Page 3 leaked into the tank pits The City of Tracy did not direct any soil or groundwater samples to be taken at the time the tanks were exhumed Directly north of the subject property (i e 152 East 11th Street), and across 1 Ith Street, there is a Beacon station located at 153 East 11th Street The station is owned by Ultramar Inc (Ultramar) of Hanford, California The SJCPHS has listed the Beacon Station as the site of an unauthorized release of hydrocarbon fuels and assigned that property Site Code 1389 Both saes are shown on Figure 2 Between 1986 and 1987, in connection with investigations of the release of hydrocarbon fuels at the Beacon station, a total of nine groundwater monitoring wells were installed for Ultramar on and around their property On Figure 2 those wells are designated ULT They include Well ULT-9 that was installed in the public sidewalk that passes along the north frontage of the 152 East 11th Street property in July of 1987 That well is down the groundwater gradient from the site that is the subject of this report, but upgradient from the Beacon station at 1.53 East I Ith Street A sample recovered from a depth slightly below the water table in the boring drilled to install well ULT 9 was found to be contaminated by volatile hydrocarbons at a concentration of 2,300 mg/Kg and groundwater samples periodically recovered from that well have contained up to 17,000 pg/L of total petroleum hydrocarbons quantified as gasoline Because soil and groundwater samples recovered from well ULT 9 were affected by components of fuel hydrocarbons, Ultramar surmised, without further investigation, that the location of the source of that contamination was on the Navarra's property at 152 East 11th Street and that hydrocarbons released there had migrated far enough down the groundwater gradient to have affected the subsurface beneath the Beacon Station Ultramar submitted their findings and conclusions from their groundwater-quality investigation to the California Regional Water Quality Control Board - Central Valley Region (CRWQCB) which, at that time, was the lead regulatory having oversight of Ultamar's Beacon station as the site of an unauthorized release of fuel hydrocarbons In response, the CRWQCB added the 152 East 1 I th Street property to their list of sites of unauthorized releases of fuel hydrocarbons and directed the Navarras to male a site investigation and submit a report on the findings In March of 1988, in response to the CRWQCB's directive, four groundwater-quality monitoring wells were installed for the Navarras on the 152 East I Ith Street property Contaminated soil was detected in the borings made to install those wells and the groundwater beneath the site was found to be affected by components of gasoline Later, the SJCPHS assumed the role of lead agency having primary oversight of Ultramar's Beacon station at 153 East 1 Ith. Street (Site 1389) and the Navarras property at 152 East 1 I th Street (Site 902 l) in 1993, under the direction of the SJCPHS, four