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- Length of the impacted
stream system is approximately 30 miles.
- Principal contaminants are mining-related metals, particularly arsenic,
copper, lead, manganese and zinc released over several decades of mining.
- The stream system is partitioned into 15 contiguous physical regions
based upon one or more of the following criteria; geomorphological observations,
the presence of contaminant sources, the influence of major tributaries,
the expected types and concentrations of contaminants, and the types
of
potentially affected media.
- The stream system is stratified into three contiguous exposure regions
according to existing and/or potential future land uses.
- Exposure pathways include soil ingestion, groundwater ingestion, dust
inhalation, dermal absorption, ingestion of home-grown produce, ingestion
of chicken
meat and eggs from home-raised poultry, and ingestion of beef from locally
ranged cattle.
- This is a two-phase investigation. Objectives
of the first phase are to develop a data-informed site model of contaminant
disposition in the
environment,
estimate potential health risks, identify Phase II data needs, and provide
recommendations for supplemental data acquisition and/or expedited action
pursuant to completing a final risk assessment.
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