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�I <br /> expected with the removal of the tank & most of the contaminated <br /> soil, coupled with a hydraulic gradient to the north <br /> PLATES II through VI show the approximate lines of equal <br /> concentrations of BETX & TPHg based upon the December, 1995 <br /> results of the laboratory anlyses of the water samples The <br /> contours on all of the tested compounds indicate that the levels <br /> are increasing to the north, which is the indicated direction of <br /> groundwater flow <br /> SUMMARY & CONCLUSIONS : <br /> The results of work performed to date on this site can be briefly <br /> summarized as follows <br /> 1 The limits of soil contamination caused by the two 1, 000 <br /> gallon UST' s have been fairly well defined to the southwest <br /> (SB-3, ) the southeast (SB-2, ) and east (MW-2 ) The limits have <br /> not been delineated in the downgradient direction, where <br /> groundwater movement may have allowed degradation of the soil . <br /> 2 The limits of groundwater contamination have not yet been <br /> • fully defined in any direction, although MW-2 is very close to <br /> the easterly edge MW-3 showed a general decrease in most tested <br /> substances between August & December, indicating that the "zero,, <br /> line is moving to the north, in the direction of groundwater <br /> flow <br /> 3 . Additional work is needed to fully define the limits of both <br /> the soil and groundwater plumes <br /> RECOMMENDATIONS : <br /> In response to the October 31, 1995 correspondence from the San <br /> Joaquin County PHS, (copy attached, ) concerning the need for <br /> additional work, we propose the following work for complying <br /> with that letter <br /> 1 Place several "pushtype" soil probes around the perimeter of <br /> the existing plume in an attempt to fully define both soil and <br /> groundwater limits Soil & water samples will be obtained by <br /> accepted procedures and analyzed for BETX & TPHg <br /> 2 . After determining the extent of soil & water contamination, <br /> we will obtain proposals from qualified firms for preparing a <br /> workplan for placing additional monitoring wells, (if needed, ) <br /> and installation and testing of a system that will accomplish <br /> soil and water cleanup as required for site closure <br /> 2 <br />