13.01.2013 Views

Dames & Moore, 1999 - USDA Forest Service

Dames & Moore, 1999 - USDA Forest Service

Dames & Moore, 1999 - USDA Forest Service

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Sediment<br />

Railroad Creek and Site<br />

Historical and 1997 sediment data were segregated to represent sediments in Railroad Creek within the area<br />

of influence from the mine, sediments in Railroad Creek downgradient of the Site, and sediments within<br />

Copper Creek. There was insufficient data to calculate area background concentrations for sediment in<br />

Railroad and Copper Creeks; however, background ranges are presented in the screening tables for<br />

comparison purposes. It should be noted that analytical data from the various sampling events are not<br />

always comparable. The detection limits and range of detection appear inconsistent for some events. even<br />

though the samples were presumably analyzed by the same method. However, for the purposes of<br />

screening, all sample data were combined. It should also be noted that screening criteria for soil ingestion<br />

were applied to sediment data due to a lack of sediment cleanup levels. The exposure assumptions used in<br />

the soil ingestion cleanup levels (i.e., ingestion of 100 mg/day) are expected to significantly overestimate the<br />

potential risks based on ingestion of sediment.<br />

Railroad Creek Adiacent to Site<br />

The results of the screening for this exposure area are presented in Table 7.1-23. Based on the screening,<br />

aluminum, arsenic, beryllium, chromium, manganese, and molybdenum were selected as IHSs. However,<br />

aluminum, beryllium, chromium and manganese were within the range of background concentrations<br />

measured in Railroad Creek.<br />

Railroad Creek Downmdient of Site<br />

The results of the screening for this exposure area are presented in Table 7.1-24. Based on the screening,<br />

aluminum, beryllium, chromium and manganese were selected as IHSs. However, beryllium and<br />

manganese were within the range of background concentrations measured in Railroad Creek.<br />

Couwr Creek<br />

The results of the screening for this exposure area are presented in Table 7.1-25. Based on the screening,<br />

beryllium, chromium and manganese were selected as IHSs. However, concentrations of all of these<br />

constituents were within the range of background concentrations measured in Copper Creek.<br />

Comer Creek Diversion<br />

The results of the screening for this exposure area are presented in Table 7.1-26. Based on the screening,<br />

only chromium was selected as an IHS. However, the concentration of chromium was below the range of<br />

background concentrations measured in Copper Creek.<br />

Surface Water and Fish<br />

As with sediment, historical and 1997 surface water data were segregated to represent conditions in Railroad<br />

Creek within the area of influence from the mine, Railroad Creek downgradient of the site, and Copper<br />

Creek. Area background concentrations of total metals in surface water were statistically derived in Section<br />

5. For the purposes of the screening, analytical results for total metals were evaluated because total metals<br />

content is more appropriate for evaluating health risks than filtered (dissolved) metals content.<br />

~.\~pd.n~m~\rrpofi\h01do~2~\7-0<br />

doc 7-2 1 DAMES & MOORE<br />

17693-005-0 19Uuly 27,<strong>1999</strong>;s: 16 PMDRAFT FINAL RI REPORT

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!