Page 269 - Fundamentals of Air Pollution

230 16. Air Pathways from Hazardous Waste Sites

• The degree of risk to human health and the environment posed by
such constituents.

II. MULTIMEDIA TRANSPORT

Air contaminant releases from hazardous waste sites can occur from
wastes placed aboveground or belowground. The following are categories
of air contaminant releases:
• Fugitive dust resulting from:
—Wind erosion of contaminated soils
—Vehicle travel over contaminated roadways
• Volatilization release from:
—Covered landfills (with and without gas generation)
—Spills, leaks, and landforming
—Lagoons
The Environmental Protection Agency has detailed procedures for conduct-
ing air pathway analysis for Superfund applications (2). Decision network
charts are given for all expected situations.
Figure 16-1 and 16-2 present the decision networks that guide contami-
nant release screening analysis. Figure 16-1 deals with contaminants in or
under the soil and Fig. 16-2 addresses aboveground wastes. Any release
mechanisms evident at the site will require a further screening evaluation
to determine the likely environmental fate of the contaminants involved.

III. CONTAMINANT FATE ANALYSIS

Simplified environmental fate estimation procedures are based on the
predominant mechanisms of transport within each medium, and they gen-
erally disregard intermedia transfer or transformation processes. In general,
they produce conservative estimates (i.e., reasonable upper bounds) for
final ambient concentrations and the extent of hazardous substance migra-
tion. However, caution should be taken to avoid using inappropriate analyt-
ical methods that underestimate or overlook significant pathways that affect
human health.
When more in-depth analysis of environmental fate is required, the ana-
lyst must select the modeling procedure that is most appropriate to the
circumstances. In general, the more sophisticated models are more data,
time, and resource intensive.
Figures 16-3 through 16-5 present the decision network for screening
contaminant fate in air, surface water, ground water, and biota. Pathways
must be further evaluated to determine the likelihood of population ex-
posure.