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t <br /> State Department of Transportation <br /> March 25, 1986 <br /> Page 2 <br /> Analysis was performed for total hydrocarbons only because the prior samples were <br /> negative for BTX and PCB 's. Results received on January 28, 1986, showed 2400 ppm <br /> and 5000 ppm in the south and north samples respectively. Further excavation was <br /> proposed and approximately 50 cubic yards of soil were removed by OHM on March 3, <br /> 1986. Three soil samples were collected by OHM personnel 12 to 18 inches below the <br /> surface in the excavation. Diesel odor was still present in the soil sampled. <br /> Analysis results for total hydrocarbons received on March 19, 1986, showed 280 ppm, <br /> 29 ppm and 3200 ppm in the south, center and north portions of the excavation <br /> respectively. <br /> In view of the impending construction of the crosstown freeway over this site, the <br /> presence of clay type soils , the 45-50 ft. depth to groundwater and nature of the <br /> stored material (diesel and oil ) , the San Joaquin Local Health District will defer <br /> full site assessment to define the vertical and horizontal extent of contamination <br /> provided the following conditions apply: <br /> 1. At least one groundwater monitoring well will be installed downgradient and <br /> adjacent to the tank removal site within 90 days of this letter to verify <br /> whether contamination has reached groundwater. Installation of this <br /> monitoring well must be done under permit and inspection of this agency with <br /> appropriate soil and groundwater sampling during and after construction. <br /> 2. The excavation will be filled with clean soil and construction over the site <br /> will preclude percolation of surface water through the contaminated soil <br /> which could result in vertical migration of contaminants to the groundwater. <br /> 3. If this site is found to be a source of groundwater contamination on current <br /> or future investigation Cal-Trans shall assume responsibility for any further <br /> site assessment and soil and/or groundwater clean up deemed necessary by the <br /> San Joaquin Local Health District, the Central Valley Regional Water Quality <br /> Control Board, the Department of Health Services Toxic Substance Control <br /> Division or other regulatory agency. <br /> If a written response to this letter is not received by the San Joaquin Local Health <br /> District within 30 days of the date of this letter, the terms of this agreement shall <br /> be considered accepted by the State Department of Transportation. <br /> If you have any questions , please contact Laurie Cotulla, R.S. of my staff at (209) <br /> 466-6781 Ext. 77. <br /> Jogi Khanna, M. D. , MPH <br /> District Health Off ircer <br /> C. Leland Hall , Director <br /> Environmental Health Division <br /> CLH/LC:jw <br /> cc: Ron Lesan , Cal -Trans <br /> Dale Steele, Cal-Trans <br /> OHMaterials <br /> Gordon Boggs , RWQCB <br /> Brad Parsons , DOHS-TSCD <br />