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Dames & Moore, 1999 - USDA Forest Service

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Exposure Routes<br />

expected to be reduced under normal conditions by gravel and vegetative covering of the<br />

tailings piles.<br />

Suspension and Redeposition: Migration of Constituents from Soils or Mining<br />

Wastes to Oflkite Surface Soil. If fugitive particulate emission enter the ambient air<br />

through agitation and wind suspension, the particulates will be transferred downwind and<br />

eventually settle out of the atmosphere onto ground-level surfaces. These surfaces could<br />

include soil, plants, buildings, paved surfaces, and surface water.<br />

Exposure routes are the various ways that receptors may come into contact with substances. The<br />

determination of potential risk posed by constituents requires an assessment of all potential exposure routes<br />

including ingestion, inhalation, and dermal contact. Depending on site-specific conditions, not all exposure<br />

routes will apply to every site. Exposure routes may also vary for different receptors based on the different<br />

activity patterns for the receptors; thus viable exposure routes will vary by site and may vary by receptors at<br />

a particular site. The following exposure routes were evaluated for the Holden Mine Site:<br />

Inhalation of Suspended Particulates. Suspended particulates in ambient air may be<br />

inhaled by those persons near the source or downwind of the source. This exposure route<br />

is evaluated for the soil and tailings piles. In addition, air monitoring data is evaluated.<br />

Ingestion of Soil, Tailings and Sediment. Ingestion of Site constituents could occur<br />

through the incidental ingestion of tailings or surface soil impacted by site constituents<br />

(either at a source or downwind of a source). Residents in Holden Village. users of the<br />

vegetable garden, workers in the maintenance yard, and recreational users of the<br />

wilderness area, lagoon, or tailings piles could incidentally ingest soil when it settles on<br />

lips and is ingested, suspended particulates are inhaled and then swallowed when cleared<br />

from the lung, or din-covered hands touch the mouth or lips; Incidental ingestion of<br />

sediment during recreational activities in Railroad Creek, Copper Creek, or the Copper<br />

Creek diversion could also occur, although is unlikely. These exposure routes are<br />

evaluated in this assessment. Exposure to subsurface soil at the Site is not expected to<br />

occur.<br />

Ingestion of Homegrown Produce. Ingestion of Site constituents could occur through<br />

ingestion of home-grown produce which has been impacted by deposition of site-related<br />

particulates or been grown in soil containing site-related particulates. This route is<br />

evaluated; however, exposure to site constituents in home-grown produce is expected to<br />

be minimal since a very small portion of the villagers' total diet is attributable to home-<br />

grown produce from the garden.<br />

Ingestion of Surface Water. Ingestion of Site constituents could occur through<br />

incidental ingestion of surface waters from Railroad Creek, Copper Creek, seeps. 1500-<br />

level mine portal drainage, or from the 1500-level ventilator portal. In addition,<br />

recreational users of the area may intentionally ingest surface waters. Incidental<br />

ingestion of Copper Creek diversion water in the sauna dipping pool could also occur.<br />

These routes are evaluated in this assessment.<br />

G:\~\~5Lcpnu\boldcn-2\n174.doc 7-1 1<br />

17693405419Uuly 27.<strong>1999</strong>;5:16 PMDRAFT FINAL RI REPORT

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