Superfund and Mining Megasites Lessons from the Coeur d'Alene River Basin (2005) / Chapter Skim
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in the local environment and elevated blood lead levels in children in communities near the metal-refining and smelter complex. Initial cleanup efforts focused on the areas with the most contamination and the greatest risk of health effects -- a 21-square-mile "box" in the heart of the Coeur d'Alene River basin.
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Recognizing the impor tance of protecting current and future generations, remedial decisions regarding human health appropriately emphasized residential yard remediations. Given the prevalence of high concentrations of lead in soils of the studied communities and the potential for lead exposure of young children, the committee concludes univer sal blood lead screening of children age 1-4 years is warranted.
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aThe Integrated Exposure Uptake Biokinetic Model for Lead in Children (IEUBK model) was used at the Coeur d'Alene River basin site to select soil lead cleanup levels in residential yards.
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For instance, cleanup efforts were strongly opposed both locally and within the Idaho state government, partially stimulated by fear of the economic consequences of having the entire basin declared a Superfund site. In contrast, other groups demanded site remediation and strongly opposed any approaches that would allow metals-contaminated media to remain in the environment following cleanup.
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Instead, EPA inferred source areas contributions of metals largely from surface-water studies and not, for example, from studies of metal leachability from source materials. EPA's site characterization also did not adequately address groundwater -- the primary source of dissolved metals in surface water.
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The HHRA sought to estimate risks to human health associated with estimated concentrations of environmental contaminants, particularly lead and arsenic, and to calculate cleanup concentrations that would protect human health. EPA estimated potential lead intake by current and future populations of children according to current risk assessment procedures with a reasonable degree of certainty.
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Model A major controversy at the Coeur d'Alene River basin site arose because EPA did not base its risk assessment and remediation decisions on the blood lead levels that had been measured but on the IEUBK model to estimate potential levels and related health risks.
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The committee concluded that, in general, the design and functioning of the IEUBK model are consistent with current scientific knowledge; however, the committee concluded that there were some technical issues, particularly the uncertainties associated with the default assumptions for bioavailability of soil lead, soil and dust ingestion rates, and the parameter used to extrapolate from a single blood lead estimate to the distribution of concentrations throughout a population. EPA regulatory guidance on the use of the IEUBK model in conjunction with data from blood lead surveys is incomplete, particularly on actions to take when blood lead studies and IEUBK model results disagree by a substantial margin.
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A comprehensive revision of the 1998 EPA directive on IEUBK model use at large geographically complex sites is needed. The revision should establish a decision-making structure for determining site cleanup concentrations and specifications based on the IEUBK model's predictive capability, blood lead study results, economic feasibility, and long-term remedy protection.
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Of the PRGs, only the national ambient water quality criteria were adopted from the ERA as remediation goals in the ROD. Recommendations Further evaluations of the impacts of exposures to metals in the aquatic and terrestrial environment are needed to support remedial actions intended to promote recovery of biota within the basin.
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The feasibility and effectiveness of EPA's proposed remedial actions to protect fish and wildlife resources have not been adequately characterized. These actions can be roughly described as those intended to stem the influx of dissolved zinc to surface waters and as those intended to reduce the transport of lead-contaminated sediments through the basin and the effect of those sediments on waterfowl.
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Remedial Efforts to Address Zinc in Surface Water As part of its remediation planning, EPA should seek to locate those specific sources contributing zinc to groundwater (which is subsequently discharged to surface water) and set priorities for their remediation.
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The committee concludes that an effective program for mining megasites should emphasize long-term adaptive management. The desirable program components are a stable management structure, long-term monitoring components, active state and local involvement in the remediation process, a broad perspective regarding what actions should be undertaken in addition to cleanup, and long-term funding.
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Establish an independent external scientific review panel with multidisciplinary expertise to provide ongoing evaluations and advice to the relevant agencies on remediation decisions at mining megasites. Although this recommendation may appear to add to the bureaucratic process, at particularly complex sites it may well speed cleanup, avoid excess costs, and provide a mechanism for resolving technical disagreements.
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