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Nestle Foods Corporation 4 29 July 1990 <br /> report. This assessment indicated that under a worst case scenario (i .e. , no blending <br /> of the water with non-contaminated supplies) , that the carcinogenic risk associated <br /> with TCE levels in this water is 5.0 x 10-7, and that the non-carcinogenic hazard <br /> indices associated with the RE and DCE levels in this water are considerably less than <br /> one. <br /> Though it was assumed that the ingestion of contaminated groundwater (above the MCLS) <br /> is unlikely due to the reasons enumerated above, and due to Nestles's monitoring and <br /> remedial activities, an estimate of the relative risks associated with the consumption <br /> of contaminated groundwater was made. The attached table (Table 4-3) compares the <br /> actual contaminant levels observed in the monitoring wells with the MCLS for the <br /> contaminants of concern. The calculated ratio of contaminant concentration to MCL, in <br /> this table, gives a qualitative estimate of the degree of potential hazard associated <br /> with the consumptive use of the water obtained from these wells. As can be seen, <br /> several of the monitoring wells show a significant potential hazard. <br /> A noted objective of this assessment was to establish aquifer cleanup goals (paragraph <br /> 1 . 1 APPROACH AND ASSUMPTIONS) . However, though potential state and federal ARAR's were <br /> listed, no cleanup goals for the chemicals of concern were established. In addition, <br /> the chemicals of concerns for this site were determined based upon several factors, <br /> including frequency of occurrence, areal detection, concentrations, toxicity, and <br /> environmental fate factors such as mobility. The chemicals selected as chemicals of <br /> concern for the Nestle site include 1, 1-dichloroethane, 1 ,2-dichloroethane, 1, 1- <br /> dichloroethene, cis-1,2-dichloroethene, methylene chloride, trichloroethene, and vinyl <br /> chloride. <br /> I have reviewed this report and have the following comments: <br /> 1) The report satisfactorily demonstrates that the current public health risks <br /> associated with groundwater contamination from Nestle are negligible. <br /> However, this is due to the institutional policies currently in effect that <br /> remove contaminated wells from the drinking water supply (municipal and <br /> private) , and preclude new wells from being constructed within the <br /> boundaries of the contaminant plume. <br /> We consider aquifer use restrictions as practicable interim solutions to <br /> groundwater contamination, but we do not consider them suitable as long-term <br /> solutions. Therefore, this risk assessment should delineate the current <br /> extent of the contamination associated with unacceptable health risks, <br /> assuming that no institutional controls are in place to limit the <br /> consumptive use of the ground water. Future risks boundaries (assumed <br /> negligible in this report due to the "static" nature of the groundwater <br /> flow) , should then be determined by using the Phase VI groundwater model . <br /> The Feasibility Study must include a risk management analysis of remedial <br /> action alternatives which considers both aquifer cleanup objectives/goals <br /> and the time required to achieve these objectives. The baseline risk <br /> assessment provides a common basis for this evaluation and comparison of <br /> remedial action alternatives. <br /> 2) The "static" nature of the contaminant plume at the Nestle site remains a <br />