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AGS <br /> Each of these criteria will be used to evaluate OWS sites if any groundwater <br /> contamination exists. For such sites, available data will be reviewed and combined with <br /> leaching calculations (ASTM, 1995) to evaluate the potential for leaching of vadose <br /> zone contaminants to groundwater, including the impact of fluctuating groundwater <br /> levels on remaining contaminants in the vadose zone. Grab groundwater sample <br /> results will be used to evaluate the potential presence of separate-phase product at <br /> each site, and assess the feasibility of its removal to reduce contaminant loading in the <br /> area. Human and ecological receptors subject to potential contaminant exposures from <br /> the sites will be identified and evaluated with respect to potentially significant health <br /> risks, accounting for standard target health risk levels and ecological measurement <br /> endpoints. Specifically, ASTM (1995); USEPA (1989x), and California Department of <br /> Toxic Substances Control (DTSC) (1994x, 1994b and 1994c) guidelines will be used to <br /> identify complete exposure pathways and quantify associated health risks. <br /> An evaluation of risks to the beneficial use of groundwater will also be performed at <br /> each site. Fate and transport modeling consistent with ASTM (1995) guidelines, <br /> together with groundwater quality results will be used to estimate rates of chemical <br /> mass reduction in groundwater over time. I-i addition, biodegradation indicator <br /> parameters will be used to evaluate the occurrence of biodegradation and plume <br /> stability. <br /> Based on evaluation of these criteria, the need, if any, for active remediation will be <br /> determined. Per Tri-Regional guidelines; an NFAR letter will be requested for sites <br /> successfully meeting the above requirements. <br /> 19 <br /> \\LAURA\C\Wp.mn60\WPDOCW5-CLTS\19951950304p\Work Plan\Work Plan.doc <br /> 08/10/99 <br />