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Page Title:
7.2 Tier 1 Initial Evaluation of Volatile Emissions |
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 Table 7-2 (Concluded)
N-Nitrosodimethylamine
Nitrobenzene
1.0
5.0
Pentachlorophenol
0.50
Phenol
5.0
19
PCBs
Chlorodiphenyl (42%) Arochlor 1242
1.0
Chlorodiphenyl (54%) Arochlor 1254
0.50
a
TWA refers to 8 hour time waited average in parts of vapor per million parts of contaminated air by
volume at 25 degrees C and 760 torr.
b
Milligrams of substance per cubic meter of air. When entry is in this column only, the value is exact;
when listed with a ppm entry, it is approximate.
c
Reference 29 CFR 1990.103. Identified as a possible occupational carcinogen. Further
recommended by the National Institute for Occupational Safety and Health (NIOSH) that
occupational exposure to contaminant be limited to lowest feasible concentration.
d
Benzene soluble fraction, Anthracene, BaP, Phenanthrene, acridine, chrysene, pyrene.
e
Included in the thirteen OSHA-regulated carcinogens. Exposures of workers to these 13 chemicals
are to be controlled through the required use of engineering controls, work practices, and personal
protective equipment, including respirators.
7.2 Tier 1 Initial Evaluation of Volatile Emissions
The Tier I evaluation for a proposed project (Chapter 3) will result in
determination of the need for contaminant evaluations, identification of pathways
of concern, identification of contaminants of concern, and decisions based on
existing information.
It is important to consider prior evaluations of the volatilization pathway in
Tier I to determine if additional evaluations are needed. If prior tests or
evaluations are available, and project conditions and dredged material
characteristics are unchanged, new evaluations would not be required.
After consideration of Tier I volatilization information, one of the following
conclusions is reached for volatile emissions (Figure 7-1).
1. Information is sufficient to reach a decision without further evaluation.
2. Information is not sufficient to reach a decision regarding volatile
emissions. Conduct Tier II and/or Tier III evaluations.
7.3 Tier II Volatile Emissions Screen
Tier II provides a screening tool, which gives a conservative estimate of
volatilization from a submerged sediment and an exposed sediment scenario based
on partitioning from bulk sediment. The screen relies on bulk sediment data, site
conditions, and applicable OSHA exposure standards. If adequate bulk sediment
data are not available, samples should be collected and bulk sediment chemistry
should be determined. It is possible to skip the screen and go directly to the Tier
III laboratory test that quantifies emission from exposed sediment. However, this
is not an efficient use of resources in most cases, since bulk sediment data are also
needed for screening evaluations for other pathways.
7-8
Chapter 7
Guidance for Evaluation of Volatile Emissions
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