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.

Selection of.Target Risk and Hazard Index<br />

As specified in MTCA, a target risk level of 1 x 10" and a target hazard quotient of one were selected for<br />

development of the'Method C levels (WAC 173-340-700[j][c]). Cumulative risk is also evaluated in the<br />

risk characterization section. MTCA specifies that the curnularive cancer risk must not exceed 1 x 10" and<br />

the cumulative hazard index for each toxic effect endpoint must not exceed one.<br />

Development of Method C Levels<br />

Method C levels are summarized in Table 7.1-40. The following equations were utilized for calculating<br />

site-specific Method C criteria:<br />

Ingestion of Soil and Sediment<br />

Screening criteria cleanup levels based on ingestion of soil in a residential setting are developed assuming a<br />

child's exposure. Screening criteria for the maintenance area and USFS guard station were developed<br />

assuming adult exposures. Equations for this pathway are as follows:<br />

Carcinogens:<br />

RISK x ABW 1 x LIFE x UCF<br />

Screening Criteria (mgkg) =<br />

CPFxSIRx ABlx DURlx FOCI<br />

Noncarcinogens:<br />

where:<br />

Screening Criteria (mgkg) = RfDxABWlxUCFxHQ<br />

SIR x ABI x FOCI<br />

RISK = Acceptable cancer risk level (unitless)<br />

ABW 1 = Average body weight over period of exposure (kg)<br />

LIFE = Lifetime (years)<br />

UCF = Unit conversion factor (1,000,000 mgtkg)<br />

CPF = Cancer potency factor (kg-daylmg)<br />

IUD = Reference dose (mgkg-day)<br />

SIR = Soil ingestion rate (mglday)<br />

ABl = Gastrointestinal absorption rate (unitless)<br />

DURl = Duration of exposure (years)<br />

FOC l = Frequency of contact (unitless)<br />

C:\~pdrtlUWIS\rrponrUloldm-2\ri\74~doc 7-27<br />

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

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

Saved successfully!

Ooh no, something went wrong!