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4.0 REMEDIAL. ACTION REQUIREMENTS To identify remedial action requirements and develop remedial objectives, current site condi- tions are compared to those necessary to achieve the site-specific goals outlined in the previ- ous section Where goals are achieved, remedial action is not required, conversely, where goals are not achieved, action may be required In this section, remedial action requirements are specified On January 23, 1995, groundwater quality within an area defined by Wells MW-2R, MW-10, MW-12, MW-13, and MW-14 did not meet water quality goals For example, dissolved benzene concentrations were detected in groundwater samples collected from Wells MW-11 and MW-13 at levels greater than the water quality goal of 1 0 ppb It is also important to note that dissolved hydrocarbon concentrations are attenuating and are relatively low Based on recent water quality data, some form of remedial action will considered to achieve water quality goals At minimum, action is required to finish plume delineation, determine if migration is a factor, and monitor dissolved plume containment and ultimately restore groundwater quality to background conditions With regard to vertical residual plume movement, any potential threat to comprorruse site water quality goals, as they apply to deep groundwater bodies, appears negligible This asser- tion is based on the fact that soil samples taken at the maximum depth for each soil boring installed to date show compliance with proposed soil-based groundwater quality goals In addition, the same attenuation mechanisms that may be stabilizing the dissolved plume in a lateral sense, work in the vertical sense as well It does not appear action addressing vertical migration is necessary at this time A review of soil chemistry data (December 1993, June 1995) generated as a result of tnvesti- gatvon activities indicate that leachable hydrocarbon concentrations still exist in soils beneath the site The TPPH-g concentrations in soil, as characterized by boring data generated in 1995, suggest hydrocarbon concentrations in soil still threaten groundwater The greater burdon of soil contamination occurs in the zone closer to the water table, considering that prior interim remedial measures effectively targeted shallower soils As such, soil-based action is required • 3201337B/CAP AMID DOC 12 November 30, 1995