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Blockbuster Video/Yellow Submarine, <br /> Phase II Remedial Investigaiton Results -Addendum <br /> Page 3 <br /> r <br /> Based upon the past and current information, we respectfully submit the following con- <br /> clusions and recommendations. <br /> Conclusions <br /> We believe any contamination that was left in place in the Stage 2 excavation is of <br /> minor consequence and that the site can be regarded as clean for the following reasons: <br /> 1. The bottom of the excavation was in a dense clay bed and -the dimensions of the <br /> contamination was decreasing rapidly with depth in the lower portion of the exca- <br /> vation. The pod of contamination was four feet by four feet (4'x4') in cross section <br /> at a depth of 18 feet and had pinched to only two by two feet (2'x2') at a 22. foot <br /> ' depth in the floor of the pit. This was probably due to the low permeability of the <br /> clay unit. At this rate, the pod of contarn�ination would pinch to zero at a depth of <br /> 26 feet, four feet (4') below the bottom=. of the excavation. Thus, it is apparent that <br /> ' the contaminated soil which remains could not be more than one (1) or two (2) <br /> cubic yards. <br /> 2. The source of the contamination, and most of the contaminated plume of soil, was <br /> removed so that there is no hydraulic head of contaminants which would drive the <br /> ' remaining contamination deeper. It is our understanding that-there are pians to-pave <br /> over the site, which would prevent any effect from rainwater infiltration. <br /> 3. All of the monitoring wells are clean. The depth to ground water is presently about <br /> 50 feet below the surface, 24 feet below the projected pinch out of the contamina- <br /> tion. Even the estimated high water table level, at 35 feet below the surface in <br /> ' 1986, is nine feet (9') below the pinch-out. <br /> 1 <br />