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(YVATC A S S O C I A T E S I N C . Field observations indicated that the samples at these depths also exhibited the highest FID measurements. Soil samples SBI1-15.5, SB12-16.5, and SB13-14.0 contained detectable concentrations of TPHd at 390 ppm, 290 ppm, and 1,100 ppm, respectively. All the remaining soil samples were not detected. The September 1999 subsurface investigation activities are detailed in ATC's Summary Report, Subsurface Investigation, dated January 10, 2000. A groundwater pumping test was conducted during a 24-hour period starting on July 22, 1999 and ending July 23, 1999. The goal of the groundwater pump test was to provide aquifer data necessary to characterize the feasibility of operating a groundwater treatment system at the site. The radius of influence of groundwater extraction, groundwater drawdown, hydrogeologic properties of the aquifer, and the mass extraction rate of groundwater were to be determined by this pumping test. The results of the groundwater pumping test showed the radius of influence for groundwater extraction at the site is greater than 50 feet. Hydrogeologic properties of the aquifer, specifically, hydraulic conductivity (K), transmissivity (T), and the coefficient of storage (S) were measured. The average hydraulic conductivity (K) was calculated to be 0.001 meters/second, the average transmissivity (T) was calculated to be 6.79 square feet/minute, the Coefficient of Storage (S) was calculated using Cooper- Jacob solution to be 0.0015. In addition, based on analytical results of samples taken during the groundwater pumping test, 6,000 gallons of groundwater were extracted from the subsurface, and 0.00005 lbs. of TPHd were removed from the subsurface during the twenty-four hour test. The groundwater pumping test activities are detailed in the Summary Report of Pumping Test, dated September 19, 2000. OBJECTIVE The objective of this work is to evaluate the lateral extent of the groundwater plume to the north of the site. During the last two quarterly monitoring events, concentrations of TPHd in well MW3, located on the northeast portion of the property in the downgradient direction, were reported at approximately 1,600 ppb. ATC will advance additional soil borings to the north and west of well MW3 to obtain sufficient data to evaluate the lateral extent plume in these directions. SCOPE OF WORK Planning and Permits ATC has completed the necessary permit application for the soil borings. The permit application and associated fee (check no. 474) are attached to this workplan. A copy of ATC's health and safety plan is on file with PHS/EHD. ATC will also schedule field personnel and equipment and contact Underground Services Alert (USA) at least 48 hours prior to advancing the soil borings to allow time for utility companies to identify any underground lines, pipes, or cables that may be affected by groundwater investigation activities. w:\62574\62574.02\reports\pumpwkp.doc 3