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1 <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD <br /> ' CENTRAL VALLEY REGION <br /> CLEANUP AND ABATEMENT ORDER NO. 5-00-707 <br /> FOR <br /> ' UNOCAL CORPORATION <br /> MONTGOMERY WARDS <br /> SURRY CALIFORNIA LIMITED PARTNERSHIP <br /> ' STONE BROTHERS AND ASSOCIATES GENERAL PARNERSHIP <br /> At <br /> ' 5606 PACIFIC (FORMER UNOCAL),AND 5400 PACIFIC(MONTGOMERY WARDS), <br /> STOCKTON, SAN JOAQUIN COUNTY <br /> ' The California Regional Water Quality Control Board, Central Valley Region, (hereafter Board)finds <br /> that: - <br /> ' 1. The former Unocal Station 95098 at 5606 Pacific Avenue in Stockton was operated as a gasoline <br /> dispensing facility by Unocal Corporation(Unocal)until 1985. Unocal leased the site from the <br /> ' property owner, the Surry California Limited Partnership. The Montgomery Wards Auto Service <br /> (Wards) at 5400 Pacific Avenue in Stockton was operated as a gasoline dispensing facility and <br /> auto service shop until 1986, and currently operates as an auto service shop. Wards leased, and <br /> ' is leasing the site from the property owner, the Stone Brothers and Associates General <br /> Partnership. Therefore, Unocal and Wards, as tank owners and operators, and the Surry <br /> California Limited Partnership and the Stone Brothers and Associates General Partnership, as <br /> ' property owners, are hereafter collectively referred to as Discharger. <br /> 2. In 1985, Unocal removed two 10,000-gallon gasoline underground storage tanks (USTs) from <br /> ' their site. The tanks were found to have leaked. As a result,Unocal installed ten monitoring <br /> wells and seven soil vapor extraction wells. From September to December 1988, as part of their <br /> soil remediation efforts,Unocal excavated approximately 6,000 cubic yards of contaminated soil <br /> ' from the site. Between 1988 and 1991,the property was redeveloped into an office building with <br /> parking lots. All monitoring wells and soil vapor extraction wells were destroyed or covered <br /> during excavation and redevelopment activities. Following directives from San Joaquin County <br /> ' Environmental Health Division(County), Unocal installed a total of seventeen additional <br /> monitoring wells (shallow and deep) between May 1992 and March 1999. Groundwater <br /> monitoring was conducted quarterly until December 1999, and is now on a semi-annual schedule. <br /> ' Shallow wells are screened from 30 to 50 feet, and the deep wells are screened from 60 to 66 <br /> feet. MtBE has been identified in groundwater at this site at a maximum concentration of <br /> 2,400 micrograms per liter(µg/1) in September 1997 by EPA Method 8020; however, <br /> ' groundwater samples from all wells collected in September and December 1998 showed non- <br /> detect for all fuel oxygenates by EPA Method 8260B. Fuel oxygenates were not analyzed in <br /> June 2000. 1,2-dichloroethane (1,2-DCA)was previously identified at this site at a maximum <br /> 1 <br /> 1 <br />