SITE INFORMATION AND CORRESPONDENCE

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r MEMORANDUM • CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD o CENTRAL VALLEY REGION 3443 Routier Road,Suite A Phone:(916)255-3000 Sacramento,CA 95827-3098 CALNET: 8-494-3000 To: Wendy Cohen From: Joel Weiss Senior Engineer Associate gineering Geologist Date: 14 January1997 Signature: v Subject: TEXACO TRADING AND TRANSPORTATION INC., RENOWN PROPERTY, TRACY, SAN JOAQUIN COUNTY I have reviewed an 18 September 1996 submittal from Ms. Karen Polyniak of Texaco Trading and Transportation Inc. and the 9 December 1996 Fourth Quarter 1996 Groundwater Monitoring Report prepared by Fugro West, Inc. for the Renown Enterprises Inc. property in Tracy. I have also reviewed the 3 March 1989 Phase II Groundwater Investigation Report prepared by Dames &Moore. The 18 September submittal summarizes the environmental investigations previously conducted at the site beginning in 1985. The fourth quarter 1996 groundwater sampling event was the first to occur since January 1989. The Renown property supported crude oil processing activities and a crude oil heating and pumping station from the early 1900s until the 1960s. The site is divided into eastern and western parcels,but most of the sampling has been on the eastern parcel. Contamination was discovered in 1985 during grading activities for residential development. During the grading activities, a good deal of soil was excavated, stockpiled and moved around. Soil sampling throughout the parcels has revealed contamination at the surface down to at least 20 feet below the surface. Contaminants found include oil and grease,total petroleum hydrocarbons (TPH) measured as gasoline and diesel, and polynuclear aromatic hydrocarbons (PNAs). From the documents I reviewed, it appears that oil and grease has been detected in surface soils at concentrations as high as 90,000 mg/kg. PNAs were reported in site soils at concentrations up to 2,800 mg/kg(benzidine). In some places soil contamination tends to decrease with depth. Volatile organic compounds and aromatic compounds such as benzene were rarely found in the soils. There are currently five groundwater monitoring wells at the site (wells E,F,REW-1,REW-2 and REW-3). Groundwater is encountered at approximately 12 feet below the ground surface with a gradient to the north. Four former monitoring wells (wells A,B, C and D) also existed at the site, and it is unclear what happened to these wells. Water levels in the five existing wells were gauged a total of four times each (twice in 1988, once in 1989 and once in 1996),but there is no sampling data available prior to 1989. Two wells in the center of the site have free product. One upgradient well appears to be clean and the two downgradient wells have up to 1,000 ug/1 of TPH as motor oil. Chemical analyses of the free product have shown the presence of various PNAs (for example, 170,000 ug/kg of 2-methylnaphthalene) and TPH at a concentration of 483,000 mg/kg.