SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

C. Dean Hubbard October 13, 2006 Page 9 and construction scenarios. Finally, the calculated emission rates were used to calculate the ambient air concentrations for industrial and construction scenarios. My modeled ambient air concentrations in the table below included the following: • I replaced some chemical-physical parameters, namely acenapthylene- diffusivity in air,D; to read 4.4E-02 cm2/sec, and diffusivity in water, DW to read 7.5E-06 CM2/sec. • I used the default loam type soil properties' parameters used by Geomatrix in the indoor air modeling. • I used the correct exposure duration, namely 1.8E+8 sec under industrial, and 7.2E+6 sec under construction scenario. OEHHA-Calculated Ambient Air Concentrations of Volatile Chemicals of Potential Concern Pathway Soil Ambient Air Ambient Air Concentrations, Concentrations, Concentrations, in µg/kg Industrial Worker, Construction in mg/m3 Worker, in m /m3 Acenaphthene 460 1.32E-05 6.61 E-05 Acenaphthylene 170 5.19E-06 2.60E-05 Anthracene 110 8.89E-07 4.44E-06 Benzo(b)fluoranthene 350 4.76E-07 2.38E-06 Chrysene 1,090 2.52E-06 1.26E-05 Fluorene 1,330 1.64E-05 8.19E-05 Naphthalene 1,510 1.69E-04 8.45E-04 Phenanthrene 2,610 2.27E-05 1.13E-04 Pyrene 920 1.55E-06 7.75E-06 It should be noted that the ambient air concentrations calculated following the Geomatrix model appear to be greater than the indoor ones calculated by Johnson &Ettinger model. While the indoor air concentrations are expected to be greater than the ambient air concentrations, the above results may be due to conservativeness of the ambient air model presented by Geomatrix. Toxicity evaluation 10. Section 5.3, Toxicity Criteria Used in Health Risk Assessment should include the CalEPA Toxicity Criteria database Reference Exposure Levels. Risk Characterization