SITE INFORMATION AND CORRESPONDENCE_2001-CURRENT

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Fact Sheet Former Montgomery Wards and Former Unocal Station #549tCENE® 5400 and 5606 Pacific Avenue, Stockton, California G Case Nos. 390258 and 390014 MAY U 6 Z011 As part of environmental the aste Central Regional sheet is being providedControl Btoard residentss//o(RWQCB) review for properties surrounding the above-named former Montgomery Wards and former UnA service station sites. Residents/property owners may contact the RWQCB (see contact information below) if they would like to obtain additional information or make comments regarding the case closure review. Comments are due 08 June 2011. This fact sheet summarizes the investigation and cleanup of petroleum hydrocarbon contamination at two adjacent former facilities (Site) — a former Montgomery Wards, LLC (Wards) auto service center site located at 5400 Pacific Avenue, and a former Unocal service station site (No. 5098) located at 5606 Pacific Avenue in Stockton, California. The former Wards site is currently occupied by a Macaroni Grill restaurant, and the former Unocal site by a bank and AT&T store. Environmental activities at the Site have been conducted pursuant to the requirements of Cleanup and Abatement Order (CAO) Number 5-00-707, issued by the RWQCB on September 8, 2000 to the responsible parties for the Site: Wards, Unocal, Surry California Limited Partnership, and Stone Brothers and Associated General Partnership (Stone Brothers). In 1985, fuel underground storage tanks (USTs) and associated piping and dispensers were removed from the former Unocal station. Petroleum hydrocarbons were discovered in the soil beneath the former Unocal site at that time. Between September and December 1988, soil remediation was conducted at the former Unocal site by excavating approximately 6,000 cubic yards of soil. In 1989, the RWQCB issued a letter for the former Unocal site confirming that petroleum hydrocarbons in soil had been adequately cleaned up, but the extent of petroleum hydrocarbons in groundwater had not yet been defined. Subsequent phases of investigation were performed to characterize the lateral and vertical extent of petroleum hydrocarbons in groundwater beneath the former Unocal site. Between 1988 and 1991 , the former Unocal site was redeveloped into the existing building. In 1986, one 550-gallon waste oil UST and two 10,000-gallon fuel USTs were removed from the former Wards site. Petroleum hydrocarbons were not detected in the single soil sample collected beneath the waste oil UST, and no further assessment was conducted at that time. In 1988, four bulk oil USTs (two 1 ,000-gallon and two 500-gallon) were removed from the former Wards site. Petroleum hydrocarbons were not detected in the two soil samples collected beneath the former USTs. Additional site assessment; which included taking soil borings and the installation and sampling of groundwater monitoring wells; revealed the presence of petroleum hydrocarbons in soil and groundwater beneath the former Wards site. The San Joaquin County Public Health Services, Environmental Health Division concurred in a letter dated November 24, 1999, that a commingled petroleum hydrocarbon plume existed between the former Wards and Unocal sites. The RWQCB issued a cleanup and abatement order (CAO No. 5-00-707) requiring cleanup of the commingled plume, after a water supply well at Delta College was impacted and later abandoned. To address the petroleum hydrocarbons in soil and groundwater beneath the Site, a soil vapor extraction (SVE) system was installed and began operation in October 1999. The SVE system reduced petroleum hydrocarbon concentrations in soil and groundwater. However, petroleum hydrocarbon contamination still remained in the sandy and silty soils underlying the Site and was submerged at significant depth beneath the groundwater table, making the contamination more difficult to remediate.