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Dames & Moore, 1999 - USDA Forest Service

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Measurement Endpoints<br />

Measurement endpoints are parameters obtained by site-specific environmental sampling or laboratory<br />

testing. The measurement endpoints selected for the Site include a variety of anal>zical and observational<br />

data. Information derived from these measurement endpoints were used to evaluate assessment endpoints.<br />

The specific measurement endpoints (data) used in this assessment are:<br />

Surface water samples. These provide data on PCOC distributions and concentrations<br />

at the Site, and permit evaluation of potential ecological risks to aquatic receptors<br />

exposed via PCOCs in surface water and to terrestrial receptors through ingestion<br />

(drinking).<br />

Sediment samples. These provide information on PCOC distributions in sediments at<br />

the Site, and permit evaluation of ecological risk to aquatic receptors exposed via PCOCs<br />

in sediment.<br />

Tailings piles and soils samples. These provide data on PCOC distributions in soils and<br />

tailings piles at the Site, and provide an estimate of PCOC concentrations in the soil<br />

ingestion fraction in dose modeling for mammals (where applicable).<br />

Fish tissue samples. These provide baseline evidence of presence/absence of PCOCs in<br />

the Site's aquatic food-web, can be used to estimate PCOC concentrations in diet for<br />

calculating dietary dose to fish-eating birds or mammals, and may be used to directly<br />

assess impacts to fish where applicable body burden toxicity information is available.<br />

Benthic community assessments. These are indicative of potential impacts as expressed<br />

directly by the characteristics of the benthic communities.<br />

~ i scommunity h assessments. These are indicative of potential impacts as expressed<br />

directly by the populations in fish communities.<br />

7.23.2 Toxicity Benchmarks<br />

Toxicity benchmarks are screening level estimates of the concentrations of chemicals that are expected to<br />

cause no adverse effects on plants or animal populations. These generally take the form of state or federal<br />

promulgated criteria, but may also include databases or guidelines developed by state, federal, or private<br />

organizations which are recognized as estimates of safe concentrations. In this document. several tiers of<br />

toxicity analysis were conducted. In the first tier, media concentrations of metals were compared to federal<br />

or state screening values. Those metals that were below these screening values were eliminated from hrther<br />

analysis. Those metals that exceeded these screening values were carried through the risk assessment. In<br />

the second tier of analysis, more site- and receptor-specific toxicity was sought in the peer-reviewed toxicity<br />

literature and these values became the toxicity benchmarks for evaluating risk. The following section deals<br />

with tier 1, elimination of COCs. The tier I1 toxicity reference values are also found according to specific<br />

receptor, below.<br />

G:\~uWOJLcpomUloldrn-2\n17-O.doc<br />

17693-005419Uuly 27. <strong>1999</strong>.5:16 PMDRAFT FINAL RI REPORT<br />

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