Laserfiche WebLink
►'% � �� <br /> Geomatrix [RD DD <br /> FEB 01 2007 <br /> ENVIRO <br /> January 30, 2007 PERMTIS Rr REA�ril <br /> Project 7066.001.1 SES <br /> Mr. Dean Hubbard <br /> California Regional Water Quality Control Board <br /> Central Valley Region <br /> 1685 E Street <br /> Fresno, California 93706 <br /> Subject: Work Plan, Soil and Groundwater Investigation Proposal <br /> TAOC Tracy Gravel Pits <br /> Valpico Road and MacArthur Road <br /> Tracy, California <br /> Dear Mr. Hubbard: <br /> On behalf of Chevron Environmental Management Company (Chevron) and Union Pacific <br /> Railroad Company (UPRR), Geomatrix Consultants, Inc. (Geomatrix), has prepared this <br /> work plan for the TAOC Tracy Gravel Pits Property in Tracy, California(the site; Figure 1). <br /> In a December 15, 2006 letter, the California Regional Water Quality Control Board— <br /> Central Valley Region(Water Board) requested a work plan to further delineate the extent of <br /> total petroleum hydrocarbons (TPH) detected in soil and groundwater. In addition, the Water <br /> Board requested sampling of an industrial well at an adjacent property. <br /> Therefore, this work plan proposes to advance 1)test trenches on site and off site to delineate <br /> the extent of soil impacts and 2) borings on site and downgradient of the site to delineate the <br /> extent of groundwater impacts. It also addresses collecting a groundwater sample from the <br /> industrial supply well. <br /> BACKGROUND <br /> During previous investigations, Geomatrix advanced 34 soil borings across the 34 acre site <br /> (Figure 2). Analytical results from soil samples indicate that total petroleum hydrocarbons <br /> (TPH) quantified as diesel (TPHd) and motor oil (TPHmo) are the primary constituents <br /> detected in soil samples collected from the northeast section of the site. In addition, <br /> polycyclic aromatic hydrocarbons (PAHs) were detected in several of these samples. <br /> Affected soil appears to be limited to the northeastern section of the site and is generally <br /> found at depths up to 16 feet below ground surface (bgs). During the last investigation <br /> (August 2005), groundwater was encountered at approximately 35 to 45 feet below ground <br /> surface (bgs). Grab groundwater samples from two borings advanced on the northern portion <br /> of the site during the last investigation also had detectable levels of TPHd. <br /> 2101 Webster Street, 12th Floor 510.663.4100 www.geomatrix.com <br /> Oakland,California 94612-3066 510.663.4141 <br />