Suspension of Material by Vehicular Traffic cont'd

DOE-HDBK-3010-94

4.0 Solids; Powders

The experimental results are tabulated in Table A.43a (resuspension by a passenger car) and

Table A.43b (resuspension by a 3/4-ton truck). The integrated average resuspension per

passage by or through the deposited material was calculated by mass balance using an

average source of 0.5 g ZnS/ft2. The resuspension rate for a passenger car driven past the

unaged deposited materials ranged from 4.8E-5 per passage to 1.1E-3 per passage and

increased with vehicles speed. The resuspension rates for a passenger car and 3/4-ton truck

driven through unaged deposited material ranged from 1.9E-4 per passage to 1.09E-2 per

passage and 2.5E-3 per passage and 6.7E-3 per passage, respectively. The measured rates

are plotted against vehicle speed on Figure 4-23 reproduced from the referenced source.

The resuspension rate decreased rapidly with time. The resuspension rates after four days of

aging are shown in Figure 4-24 reproduced from the referenced source and show an order of

magnitude decrease. The calculated effects of ageing are shown in Figure 4-25 reproduced

from the referenced source. In general, this correlation is of use only for the immediate

aftermath of an accident. The highest resuspension rate for unaged deposited material is

1E-2/passage for a passenger car driven through the material and is recommended as the

bounding value. In the absence of any measured RF values, a conservative value of 1.0 is

recommended as the bounding RF. However, the amount of material released as a respirable

aerosol should not exceed the total respirable material in the source, if known.

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