Contaminant Risk Factors - Urban Watersheds: Geology, Contamination, and Sustainable Development - page 362

TABLE 10.11
Summary of CRF SOIL Values for the LNAPL and DNAPL
VOCs, PAHs, and CRF SOIL for Other Selected Compounds
Compound

Soil Type CRF SOIL

Mean LNAPL CRF SOIL Clay 30.17

Silty clay 4.37

Sand silty clay 3.89

Sand 2.24

Mean DNAPL CRF SOIL for degradation
sequence from PCE to vinyl chloride

Clay 3,408.00

Silty clay 1,116.00

Sand silty clay 1,073.00

Sand 965.00

Mean PAH CRF SOIL Clay 662.58

Silty clay 66.16

Sand silty clay 55.23

Sand 16.82

PCBs Clay 17,992.00

Silty clay 2,800.00

Sand silty clay 2,524.00

Sand 1,457.60

Pesticide chlordane Clay 28,850.00

Silty clay 2,663.00

Sand silty clay 2,215.00

Sand 1,876.00

Chromium VI Clay 10.20

Silty clay 4.00

Sand silty clay 3.50

Sand 3.00

Lead Clay 234.00

Silty clay 11.70

Sand silty clay 9.94

Sand 3.03

Mercury Clay 41,800.00

Silty clay 19,140.00

Sand silty clay 17,600.00

Sand 15,600.00

Arsenic Clay 7,800.00

Silty clay 2,950.00

Sand silty clay 2,850.00

Sand 2,400.00

Source: Kaufman, M.M. et al., Environ. Geol ., 56, 1009, 2009.

CRF SOIL values were significantly higher for each contaminant group where the soil was
composed of clay, but lowest for each contaminant group in sandy soils. This observation
is the result of several physical/chemical factors, including

• Density
• Grain size