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5 RECOMMENDED ACTION <br /> Prior to defining the mass of the pollutant, its mobility and fate, additional exploration is <br /> ' necessary While a very conservative- large amount of mass- might be assumed, closely <br /> defined spatial parameters, estimated density and speciation of the petroleum <br /> ' hydrocarbons will serve to achieve closure faster and at a lesser cost The earlier <br /> recommendations towards an expeditious completion continue with additional comment <br /> ' 5.1 Define Plume Boundary Offsite <br /> Additional borings are necessary to define the extent of the contamination to the north <br /> tand east Until a clean boring or one with very little contamination is completed an <br /> estimate of the volume of contamination would be highly speculative <br /> ' Prior to constructingthe Monitoring Wells directed b PHSIEHD, I strongly suggest <br /> 9 Y g <br /> ' further definition using DPT methods be completed (Reference Figure 5 for marked <br /> boring locations It is very likely that contamination extends onto the neighboring <br /> parcels Upon formal agreement for entry, borings will be conducted on those parcels <br /> as well as the subject site <br /> After further definition of the petroleum hydrocarbon boundary the two monitoring wells <br /> directed by the PHSIEHD may be positioned to achieve the most meaningful results <br /> ' The next step <br /> A series of DPT borings (BH D-1 through BH D-5) will be done to ground water about 52 <br /> FT bgs to define north and easterly extent of plume First, three borings will be placed <br /> respectively at 100 FT northwest of sites NE corner, 100 FT N of corner and 100 FT <br /> north east of corner Two holes will be placed, one at 75 FT out from northeast corner <br /> and another 100 FT further south Dependent upon field findings a second set of borings <br /> ' (BH E-1 through BH E-5) will step in or out from the first set If deemed necessary by the <br /> project manager (Dan Barber) and the PHSIEHD representative <br /> ' A heavy duty P du Geo robe device similar to the second one employed in Dec 2000 at the <br /> ' site will be used <br /> Soil samples will be collected at 5 FT intervals from 15 to 35 FT bgs along with a ground <br /> water sample at each boring <br /> 5-1 <br />