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`.oe <br /> Department of"toxic Substances Control <br /> Edtin P. Lowry, Director <br /> 10151-C{ri�ydon Way, _jb('ci <br /> Winston li. I lickox Sacramento, California 95827-2106 Gray Davis <br /> Secretary For Governor <br /> Environmental <br /> Protection November 18, 1999 <br /> Ms. Katie Hower <br /> Pipeline Project Manager <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road <br /> San Ramon, California 94583 <br /> REVIEW OF SOIL AND GROUNDWATER INVESTIGATION AND SCREENING <br /> HEALTH RISK ASSESSMENT OF THE MANSFIELD PROPERTY/OLD.VALLEY <br /> PIPELINE RIGHT - OF - WAY <br /> Dear Ms. Hower: <br /> This letter supersedes the letter dated November 16, 1999,.from the Department of <br /> Toxic Substances Control (DTSC) concerning the Mansfield property. <br /> DTSC has completed its review of the subject report prepared by Geomatrix <br /> Consultants and submitted by Chevron. This report documents the hazardous <br /> substance characterization of soil and groundwater at the site. The purpose of the <br /> characterization was to gather data to assess the lateral and vertical extent of <br /> petroleum hydrocarbon-affected soil along the pipeline right-of-way, to evaluate <br /> groundwater quality, and to evaluate potential human health risks posed by residual <br /> petroleum hydrocarbons. <br /> According to the information provided in the subject report, the Old Valley Pipeline <br /> transported heavy petroleum (crude and fuel oil) from Bakersfield to Richmond, <br /> California, from the early 1900s to the 1950s. Benzene, toluene, ethyl benzene, <br /> xylenes, and several polynuclear aromatic hydrocarbons were detected in <br /> concentrations below the Preliminary Remediation Goals in four soil samples affected <br /> by residual petroleum. <br /> In general, DTSC concurs that the analytical data supporting this investigation is <br /> adequate in both quantity and quality, and that the residual levels of petroleum-related <br /> hydrocarbons in the soils at the site are below levels that would constitute an <br /> unacceptable risk to human health and the environment. This concurrence only <br /> applies to the contamination due to the petroleum pipeline release and does not apply <br /> to any other potential contamination issue at the site. Although DTSC finds that no <br /> additional work is needed to characterize the site for any contamination due to the <br /> California Environmental Protection Agency <br /> ® Printed on Recycled Paper <br /> e Printed on Recycled Paper <br /> OSP 99 25436 <br />