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California Fftional Water Quality Col I Board <br /> Central Valley Region <br /> Katherine Hart, Chair <br /> Linda S.Adams Edmund G. Brown Jr. <br /> Acting Secretary for 1685E Street, Fresno, California 06 Governor <br /> Environmental Protection (559)445-5116 • Fax(559)445-5591910 <br /> http://w\Aw.waterboards.ca.gov/centraIvaIley <br /> 6 January 2011 RECEIVED <br /> JAN 0 7 2011 <br /> Lee Higgins ENVIRONMENTAL HEALTH <br /> Chevron Environmental Management Company PERMIT/SERVICES <br /> 6111 Bollinger Canyon Road <br /> B R 1 Y/3484 <br /> San Ramon, CA 94583 <br /> REVIEW— SOIL AND GROUNDWATER INVESTIGATION WORKPLAN, TRACY RAIL YARD <br /> OFFSITE - WEST AREA, TRACY, SAN JOAQUIN COUNTY <br /> Chevron Environmental Management Company (Chevron) submitted a Workplan for <br /> Additional Soil and Groundwater Investigation (Workplan) dated 23 December 2010, for the <br /> Tracy Rail Yard Offsite - West Area. The Workplan was prepared on behalf of Chevron by <br /> AMEC Geomatrix, Inc. (AMEC). <br /> The project is adjacent to the west generally lateral to and downgradient of the Tidewater <br /> Associated Oil Company (TAOC) 6 Street Tracy Rail Yard site in central Tracy. The Offsite <br /> West Area property consists primarily of single-family residences. The City of Tracy Boyd <br /> Service Center maintenance facility is adjacent to the west. <br /> As a result of earlier investigations associated with the TAOC 6th Street Tracy Rail Yard (TRY) <br /> project, impacted soil and groundwater on the Offsite West Area downgradient to the west was <br /> investigated in 2005. Borings were drilled in residential streets where elevated concentrations <br /> of petroleum hydrocarbons were detected in soil and groundwater. The lateral extent of <br /> impacts was not adequately defined and additional characterization is needed. The Workplan <br /> proposes drilling six soil borings and one contingent boring to collect samples of soil and <br /> groundwater for analysis of the site petroleum hydrocarbon chemicals of potential concern. <br /> According to AMEC's Workplan: <br /> • The lateral and vertical extent of affected soil has not been defined in several areas of <br /> the Offsite West Area project and additional soil borings and sampling are needed. <br /> Two offset borings, TRY-31 and TRY-32 in Rockingham Court and TRY-33 and TRY-34 <br /> in Baldwin Court will be drilled to obtain soil and/or groundwater samples for analysis. <br /> • The lateral extent of affected groundwater downgradient to the north of the site has not <br /> been defined and additional borings and sampling are needed. Drilling of boring TRY- <br /> 30 is proposed in East 6th Street approximately 300 feet north of the Offsite West Area. <br /> California Environmental Protection Agency <br /> C10ecycled Paper <br />