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100 Pine Street, 1 Oth Floor <br /> San Francisco, CA 94111 GEOMATRIX <br /> (4151 434-9400 • FAX (41 51 434-1365 <br /> 11 January 1999 <br /> Project 4002.03 <br /> Ms. Katie Hower <br /> Chevron Pipe Line Company <br /> P.O. Box 6059 <br /> San Ramon, California 94583 <br /> Subject: Excavation Work Plan <br /> Former Lyoth Loading Station <br /> Tracy, California <br /> Dear Ms. Hower: <br /> Geomatrix Consultants Inc. (Geomatrix)has prepared this work plan for excavation oversight <br /> services to be performed by Geomatrix at the subject site(Figure 1) on behalf of Chevron Pipe <br /> Line Company(CPL). Geomatrix advanced ten soil borings at the site on 12 and 13 May 1998 <br /> (Figure 2) and analyzed soil samples collected from these borings for polynuclear aromatic <br /> hydrocarbons (PAHs). PAHs were detected in some soil samples at concentrations which may <br /> not be acceptable for public health(Table 1; field methods,boring logs, and analytical <br /> laboratory reports will be presented in a subsequent Geomatrix report). Based on these results, <br /> Geomatrix will oversee excavation to remove PAH affected soil. <br /> WORKPLAN <br /> Geomatrix will oversee excavation of PAH affected soil to a depth of 5 feet at the <br /> approximate location shown on Figure 2. The excavation will be extended laterally until no <br /> visible staining is observed. Geomatrix estimates that the excavation will be approximately <br /> 35 feet by 45 feet in area and 5 feet deep. Upon completion of the excavation and in <br /> accordance with Geomatrix protocols, Geomatrix will collect approximately five soil samples <br /> from the excavation sidewalls and bottom and submit them to an analytical laboratory for <br /> analyses for PAHs by EPA Method 8270 SIM. If the results of confirmation samples from the <br /> 5-foot-deep excavation indicate that the excavation should be continued because samples are <br /> above health-based criteria, Geomatrix will oversee additional excavation up to 10 feet bgs. <br /> Upon completion of the additional excavation, Geomatrix will collect an additional five soil <br /> samples from the excavation sidewalls and bottom and submit them to an analytical laboratory <br /> for analyses for PAHs. Upon completion of the excavation, the excavation will be backfilled <br /> with imported soil and compacted to grade. All excavated soil will be hauled off site for <br /> disposal at an appropriate landfill. Based on the contractor's (Sturgeon& Sons) estimates,the <br /> work should be completed in a 4-day period. <br /> Geomatrix Consultants, Inc. <br /> Engineers, Geologists, and Environmental Scientists <br />