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12 WOM Mr, Kenneth Olds November 15, 1988 202/799-5055 Page 4 stat'.. water level in the well was about 2.5 feet above the top of the screened interval. This situation is thought to have caused dissolved hydrocarbon levels in the water sample collected from Mw-1 to be non-representative of hydrocarbon concentrations in the upper part of the aquifer. Dissolved TPH as diesel concentrations ranged from 72 ppb in Mw-1 and 5o ppb in MW-4 to non-detectable in the remaining three wells. These levels indicate no significant contamination of • we s groundwater by diesel in the lng samples�oandgtotallead lElvels was detected in the analyzed water were either below or near the method detection limits. In summary, hydrogeologic and chemical data, obtained from existing wells in November 1987 and September/october the five 1988, indicated that the dissolved TPH as gasoline plume did not extend during this period to MW-3 and MW-4, which are located up nor gradient from the tank pit, nor did itiexttenndfromttherunderground However, down gradient from the tank p is not defined• diesel tank, the impact on groundwater, if any, In order to define the downgradient extent of the dissolved hydrocarbon plume, GTI recommends drilling three additional boreholes and installing monitoring wells in them. Locations of the proposed monitoring wells are shown in Figure 1. Selected of the boreholes would be soil samples collected during drilling and BTEX concentrations. analyzed for TPH as gasoline and diesel, The three new wells would be surveyed for elevation control. A round of groundwater monitoring and sampling of all monitoring be forme . The wells associated with the project would anddTPH asrgasoli ne and water samples would be analyzed f - - chemical data would ---these ----The-_updated hydrogeologic and �ti