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.

Surface Soil<br />

Cancer risks and noncancer hazard quotients ingestion of all IHSs in all exposure areas were below the<br />

allowable MTCA cancer risk and hazard quotient. The cancer risks ranged from 8.91 s 10''~ for ber?.lliurn<br />

at the USFS guard station to 5.66 x lod for arsenic in the maintenance area. The hazard quotients ranged<br />

from 4.1 5 x lod for beryllium at the USFS guard station soil to 2.04 x 10" for copper in the lagoon area soil.<br />

Lead was detected in maintenance yard and lagoon area soil at concentrations exceeding the screening<br />

criteria (1070 mgkg in the maintenance yard and 620 mgkg in the lagoon area). However. because no<br />

toxicity criteria exist for this constituent, site-specific risks could not be evaluated. USEPA guidelines<br />

recommend a cleanup level of 400 mg/kg for lead in soil at residential sites based on prediction of blood<br />

lead levels in children. Neither of these sites is residential and exposure time is expected to be significantly<br />

less than an assumed residential exposure duration of 7 day per week exposures for 30 years. The highest<br />

exposure concentrations are less than three times higher than the USEPA recommended levels. Therefore,<br />

concentrations of lead in soil in these two areas are not expected to cause effects in exposed populations. In<br />

addition, remedial actions in these two areas will likely significantly reduce the concentrations present.<br />

Total petroleum hydrocarbons were present in soil at the maintenance yard and lagoon area at levels<br />

exceeding h4TCA Method A level. Exposure concentrations ranged from 140 mglkg gasoline range<br />

hydrocarbons in the maintenance yard to 12,000 mg/kg diesel range hydrocarbons in the maintenance yard.<br />

Because no toxicity criteria exist for these complex mixtures, site-specific risks were not evaluated.<br />

However, as with lead, exposure times and durations at the maintenance yard and lagoon area are expected<br />

to be significantly lower than would be assumed for development of the Method A level, and therefore TPH<br />

is soil at these locations are not expected to be of concern for the limited time period that maintenance<br />

workers and recreational users are exposed populations. In addition, remedial actions in these areas should<br />

significantly reduce soil TPH concentrations.<br />

Sediment<br />

Cancer risks and noncancer hazard quotients for all IHSs in all exposure areas were below the allowable<br />

MTCA cancer risk and hazard quotients. Cancer risks ranged from 1.08 x 10'~ for beryllium in all three<br />

areas to 4.72 x 10" for arsenic in Railroad Creek sediments adjacent to the site. The hazard quotients ranged<br />

from 6.25 x l O" for beryllium in all three areas to 1.68 x 10" for molybdenum in Railroad Creek sediments<br />

adjacent to the site.<br />

- Air'<br />

The site-specific hazard quotients calculated for manganese in air was 4.0 x lo-', which is below the<br />

allowable MTCA hazard quotient. There were no cancer risks calculated for this media since manganese<br />

was not a carcinogen.<br />

Particulate Emissions fiom Soil<br />

In order to evaluate current conditions and the potential for soiVtailings in each exposure area to be<br />

transported to air via fugitive dust emissions, a simple USEPA model was utilized to develop a particulate<br />

emission factor (PEF) for each exposure area. Cancer risks based on transfers from soil to air for all IHSs in<br />

all exposure areas were below the allowable MTCA cancer risk. Cancer risks ranged from 3.96 x lo4 for<br />

G\~mW5~\hoIdm-2\ni7-O.da<br />

1769MOS019Uuly 27.199QJ: 16 PMDRAFT FINAL RI REPORT

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

Saved successfully!

Ooh no, something went wrong!