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amecO During excavation activities, dust control measures, such as application of water, will be used if necessary to minimize generation of airborne dust. In addition, dust monitoring will be conducted as described in Section 5.2.4. The excavation will be secured with temporary barricades to prevent entrance into the excavation area. The entire site is surrounded by fencing to prevent trespassing; it is anticipated that the fencing will remain in place during excavation activities. Because affected soil was present at approximately 3.5, 5.0, and 5.5 feet bgs, one composite sample, comprised of two subsamples from approximately 3.5 and 5.5 feet bgs, will be collected for confirmation sampling from the sidewalls at approximately 30-linear-foot intervals. In addition, one bottom confirmation sample will be collected per 1,500 square feet(ft2). A ' minimum of 2 bottom and 4 sidewall composite samples will be collected and analyzed, regardless of final excavation dimensions. Confirmation samples will be collected in clean, stainless steel tubes sealed with Teflon®sheets, plastic end caps, and silicon tape. The samples will be stored in an ice-cooled chest prior to submittal to the analytical laboratory. Confirmation soil samples will be analyzed for PAHs and TPH using U.S. Environmental Protection Agency (U.S. EPA) Methods 8270 SIM and 8015, respectively, on a 24-hour turnaround. The excavation will be left open until analytical results have been received. If concentrations of PAHs or TPH exceed their respective remedial goals in the soil sample from a 30-ft wide section, the 30-ft wide section will be excavated a minimum of an additional 1 foot laterally. Additional sidewall samples will be collected and analyzed until concentrations of target chemicals of concern (CDCs) are below their respective remedial goals or the practical limits of the excavation have been reached. If concentrations of PAHs or TPH exceed their respective remedial goals in the soil sample from a bottom sample, approximately 1500 ft2 of excavation floor around the sample will be excavated to a depth of 1 foot. Additional excavation bottom samples will then be taken and analyzed. The excavation will continue laterally and vertically until the PAH and TPH concentrations are less than their respective remediation goals (see Table 3); however, as stated above, the excavation will not extend beyond the Site boundary into the greenbelt area or extend vertically below approximately ' 10 feet bgs, the maximum depth to which a receptor was assumed to be exposed based on direct exposures in the SLRA. ' Finally, the excavated areas will be surveyed upon completion of remedial activities and return of analytical data confirming remedial goals have been met. 5.2.3 Backfilling and Grading ' After the excavation activities have been completed, the excavation will be backfilled with on- site soil from the soil mound. The soil mound volume above 58.4 feet in elevation is AMEC Geomatrix, Inc. I:\Doc_Safe\6000s\6628.001\3000 REPORTS\Excavation Work Plan-8.12.08\1 Text,cover and slips\Text.doc 7