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i <br /> Department of Toxic Substances Control <br /> Edwin F. Lowry, Director <br /> 101$1 Croydon Way, Suite 3 <br /> Winston H. Hickox Sacramento, Cafif86ia 95827-2106 Gray Davis <br /> Agency Secretary Governor <br /> California Environmental <br /> Protection Agency <br /> November 16, 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 OLD VALLEY PIPELINE RIGHT- OF- WAY <br /> Dear Ms. Hower: <br /> The Department of Toxic Substances Control (DTSC) has completed its review of the <br /> subject report prepared by Geomatrix Consultants and submitted by Chevron. This <br /> report documents the hazardous substance characterization of soil and groundwater at <br /> the site. The purpose of the characterization was to gather data to assess the lateral <br /> and vertical extent of petroleum hydrocarbon affected soil along the pipeline <br /> right-of-way, to evaluate groundwater quality, and to evaluate potential human health <br /> risks posed by residual 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 environments. 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 /> MM.bdj <br /> mAsmp=b\yosvold\mm17w.119 <br /> . ® Printed on Recycled Paper <br />