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enviroso Task 3 -Utility Clearance Proposed drilling locations will be marked and their locations cleared through Underground Services Alert (USA)prior to drilling. Task 4 -Confirmation Soil Borings A total of eight confirmation soil borings will be drilled using a hollow-stem auger drilling rig. Soil samples will be collected and analyzed to evaluate the effectiveness vapor extraction operations at the site. The locations of the eight confirmation borings are shown on Plate 2. These locations have been selected because they represent areas where soil contamination was detected from earlier investigation and confirmation boring samplings. Specifically, the eight drilling sites are adjacent to the following previous borings; MW-2, SB-2, SB-3, SB-4, ASB 1, CB-8, CB-9, and VEW-1. Soil samples from the proposed borings will be collected at depth intervals that correspond to previous depths where petroleum hydrocarbons were detected. Soil sampling depth intervals for the eight locations where petroleum hydrocarbons were previously detected in soils are presented on Plate 2. Chemical data from previous soil sampling at these locations are presented in Table 1. An Enviros geologist will supervise the drilling and describe encountered soils using the Unified Soil Classification System(USCS). Soil sample intervals will be screened in the field for organic vapor by measuring head-space vapors using an organic vapor meter (OVM). Each boring will be terminated at a depth at which field observations indicate petroleum hydrocarbons are not present. The confirmation soil boring samples will be collected in clean soil tubes using a hollow- stem auger drilling rig. Retrieved soil samples will be labeled, entered onto a chain-of- custody record, and preserved in a cooler with ice for transport to a State of California certified laboratory. An exploratory boring log will be prepared for each boring. Head-space vapor measurements will be recorded on the log. Standard drilling procedures are presented in Appendix A. Task 5 - Chemical Analysis Confirmation soil samples will be analyzed for TPH-G according to EPA Method 8015 (Modified) and BTEX and MTBE according to EPA Method 8020. Selected samples will also be analyzed for fractional organic carbon and Toxicity Characteristic Leaching Potential (TCLP) TPH-G and BTEX. Task 6 - Report Preparation Following the receipt of chemical analytical results from the laboratory, Enviros will prepare a written report describing field procedures, laboratory results, and boring logs; and presenting conclusions and recommendations. The scope of work described in this work plan will be performed under the supervision of a registered professional engineer. 96369 3