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California Tonal Water Quality Cont Board .m <br /> Central Valley Region k f <br /> Karl E.Longley,ScD,PE,Chair -tee <br /> Linda S.Adams Arnold <br /> Secrelarvfor Fresno Branch Office Schwarzenegger <br /> Environmental 1685 E Street,Fresno,California 93706 <br /> Protection (559)445-5116• Fax(559)445-5910 Governor <br /> hnp://www.waterboards.ca.gov/centraIvaIIey <br /> 14 February 2007 G MENED <br /> FFs 1 5 2007 <br /> ENVIRONMEN i" HEALTH <br /> M. Scott Mansholt PERMIT/SERVICES <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road, Rm K2066 <br /> San Ramon, CA 94583-2324 5 <br /> REVIEW OF WORKPLAN, SOIL AND GROUNDWATER INVESTIGATION, TAOC TRACY <br /> GRAVEL PITS, TRACY, SAN JOAQUIN COUNTY <br /> Regional Water Board staff has reviewed the referenced workplan, dated 30 January 2007 <br /> prepared for Chevron and Union Pacific Railroad (UPRR) by Geomatrix Consultants, Inc. <br /> (Geomatrix). The project site, jointly owned by Chevron and UPRR, is located on Valpico <br /> Road, west of MacDonald Road in south Tracy. <br /> In a 15 December 2006 memorandum to Chevron and UPRR, Regional Water Board staff <br /> requested a worklan to further delineate the extent of total petroleum hydrocarbons (TPH) <br /> detected in soil and groundwater during previous site investigations. In addition, we requested <br /> sampling of an industrial water supply well at an adjacent property, northwest of the site. <br /> The workplan proposes to advance up to 95 trenches onsite and offsite to delineate the extent <br /> of TPH-affected soil. Trench locations will be excavated on the northern portion of the site at <br /> approximately 100-foot centers using a standard backhoe. Up to two soil samples will be <br /> obtained from each trench at 5 and 10 feet. Additionally, if visually affected soil is <br /> encountered, a sample will be obtained and a second will be collected below affected soil to <br /> vertically delineate impacted soil. All soil samples will be submitted for analysis of TPH as <br /> diesel (TPHd), TPH as motor oil (TPHmo), and polynuclear aromatic hydrocarbons (PAHs). <br /> Several samples will be selected for Title 22 metals analysis. <br /> Nine borings will be advanced onsite and downgradient of the site to delineate the extent of <br /> affected groundwater. A groundwater sample will be obtained from six offsite locations, three <br /> onsite locations, and the industrial well and submitted for analysis of TPI-Id, TPH as gasoline <br /> (TPHg), benzene, toluene, ethylbenzene, and xylenes (BTEX), and PAHs. The analysis will <br /> also include total dissolved solids (TDS), general minerals, electrical conductivity, ammonia <br /> as nitrogen, nitrate as nitrogen, and total nitrogen. <br /> California Environmental Protection Agency <br /> cpi Recycled Paper <br />