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- y _ � A S S O C I A T E S I N C, ethylbenzene and xylenes. After the tank was removed, the area of excavation of the former tank was backfilled. On January 8, 1998, an ATC geologist supervised the advancement of one soil boring to 41.5 feet below ground surface (bgs). A site plan showing the location of soil boring SB 1 is included as Figure 2. Soil samples were collected at five foot intervals and submitted for analysis of total petroleum hydrocarbons as gasoline and diesel (TPHg and TPHd) by EPA Method 8015; and volatile organic compounds (VOCs) by EPA Method 8260. A Hydropunch groundwater sampling probe was advanced in the soil boring and a groundwater sample was collected. The groundwater sample was analyzed for TPHg, TPHd, VOCs, and halogenated volatile organic compounds (HVOCs) by EPA Method 801018020. Subsequent to the sample collection, the open sampling hole was tremie grouted to the surface with neat cement. Petroleum hydrocarbon constituents were detected in soil samples collected from boring SB 1. The highest reported constituent concentrations were observed in the soil sample collected at 5.5 feet bgs. The petroleum hydrocarbons appeared to attenuate rapidly with depth as indicated greatest by soil sample from 35.5 feet bgs, which contained only trace levels of isopropylbenzene, 1,2,4-trimethylbenzene, and 1,3,5-trimethylbenzene. Trace amounts of petroleum hydrocarbon constituents were also detected in the groundwater sample collected from soil boring SB 1. SCOPE OF WORK Workplan Preparation ATC has completed the well permit application for the proposed subsurface investigation. The permit application and necessary fees (check #135) are attached to this workplan. ATC will also schedule field personnel and equipment, notify Underground Service Alert to locate underground utilities as required, and perform any other necessary field preparation and job start-up activities. Executive Summary Preparation ATC has completed the Executive Summary document to be posted during the Public Comment period. The Executive Summary is enclosed with this workplan. Soil Excavation, Transport, and Disposal Prior to completing the subsurface investigation, ATC will supervise the excavation of the impacted backfill material located in the former UST location. The estimated volume of soil to be excavated is approximately 72 cubic yards and the proposed excavation area is shown on Figures 2 and 3. Soil volume calculations are contained in Attachment 1. Excavated backfill material will be field screened with a photoionization detector (PID) to confirm that all impacted soil has been removed. Actual excavation limits will be determined by PID readings and site access limitations. wA17295kep xtslwkpadd.&c 2