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Page 2 Ms. Margaret Lagorio January 18, 1994 their and ESE's previous work. ACG has also been routinely monitoring groundwater quality at the facility since 1990. Due to regional drought conditions, groundwater levels in five of the monitoring wells (MW -2, MW -3, MW -4, MW -5, and MW -7) have dropped to a depth at or below the base of their screened interval. Currently, groundwater levels in the remaining three wells have been measured at a depth of about 52 to 54 feet. Proposed Scope of Work Burlington proposes to drill boreholes and install five groundwater monitoring wells (MW -9 through MW -13) at the locations shown on Figure 1. Since groundwater flow at the site is reported to be toward the northeast, monitoring well MW -9 will be situated in a hydraulically upgradient position relative to the former USTs. Wells MW -10 and MW -11 will be located in cross -gradient positions, and wells MW -12 and MW -13 will be situated downgradient. None of the current dry wells will be abandoned in case future groundwater levels elevate to once again make them relevant monitoring points. Boreholes will be drilled to a depth of 75 feet with hollow -stem auger drilling equipment. Soil samples will be collected from the boreholes at 5 -foot intervals, logged by a site geologist, screened for hydrocarbons with a photoionization detector, sealed, and stored on ice for subsequent testing. Drilling equipment will be steam -cleaned prior to each borehole. Sampling equipment will be cleaned prior to each sampling event. Drill cuttings will be stockpiled on, and covered by plastic sheeting at the site pending proper disposal. Monitoring wells will be constructed in each borehole. Monitoring wells MW -9, MW -11, and MW -12 will be constructed with 4 -inch diameter, flush -threaded, Schedule 40 PVC screen and casing. Wells MW -10 and MW -13 will be constructed with 2 -inch diameter, flush -threaded, Schedule 40 PVC screen and casing. Well screens will consist of 0.010 -inch, machine -slotted perforations extending from a depth of 25 to 75 feet to allow for future groundwater fluctuations. Number 2/12 sand will be placed as an annular gravel pack from the bottom of the well to at least 2 to 3 feet above the top of the screen. Approximately 2 to 3 feet of bentonite pellets will be placed over the gravel pack and hydrated to provide a seal. A cement -bentonite grout will be placed over the seal to a depth of about 1.5 feet below the ground surface. The well will be finished at the ground surface with a concrete -emplaced, traffic -rated cover.