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Lee Higgins -2- 29 July 2011 <br /> Chevron Environmental Manageme .. —ompany <br /> Tracy 6th Street Rail Yard Offsite-South <br /> • Borings South 5, 6, and 7 will be drilled approximately 200 feet further south in an <br /> alleyway within the residential neighborhood. <br /> • Borings South 8 and 9 will be completed further east along 3rd Street, and South 10 will <br /> be drilled near the southeast corner of the TRY project site in Evans Street. <br /> • Two soil samples will be collected from each boring within the upper 10 feet and <br /> submitted for analysis for use in preparing a health risk assessment. <br /> • Contingent step-out borings will be advanced if stained soil is observed in the original <br /> samples. The locations of potential step-out borings will be determined based on <br /> results of the primary sampling activities. <br /> • Soil samples will be submitted for analysis of total petroleum hydrocarbons as crude oil <br /> (TPHc); benzene, toluene, ethylbenzene, and xylenes (BTEX); and polynuclear <br /> aromatic hydrocarbons (PAHs). <br /> • Groundwater samples will be collected from the soil borings noted above. If TPH <br /> affected soil is observed, a groundwater sample will not be collected and the location <br /> for a step-out boring with sampling will be evaluated. <br /> • Groundwater samples will be submitted for analysis of TPH as diesel (TPHd), BTEX, <br /> and PAHs. <br /> Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff <br /> concurs with the Workplan with the following comment: <br /> • At least one soil sample exhibiting TPH affected soil from a boring along the east and <br /> west lateral portions of the Offsite - South, should be submitted for fuel fingerprint <br /> evaluation. <br /> By 10 January 2012, please submit the soil and groundwater investigation report. <br /> If you have any questions or comments, please contact Dean Hubbard at (559) 445-5179 or <br /> by email at dhubbard(awaterboards.ca.gov. <br /> / <br /> C . <br /> SHELTON R. GRAY C. DEAN HUBBARD <br /> Senior Engineering Geologist Engineering Geologist <br /> P.G. No. 6357 <br /> cc: Michael J. Infurna, San Joaquin County DEH, Stockton <br /> Gary Foote, AMEC, Oakland <br />