health and safety plan solid waste management unit assessment

STODDARD SOLVENT 67-12
aliphatics, At this point, it should be mentioned that environmental
fate/exposure/toxicology chapters for xylene and naphthalena listed in
Table 67-2 were included in other chapters of the IRP Toxicology Guide.
67.2.3 Primary Routes of Exposure from Soil/Ground-water Systems
The above discussion of fate pathways suggests that the major components
of Stoddard solvent are volatile but vary in their potential
for bioaccumulation and sorption to soil. They range from moderately
to strongly sorbed to soil, and their potential for bioaccumulation
ranges from low to high. The variability in the properties of the
components suggests they have somewhat different exposure pathways.
Spills of Stoddard solvent would result in the evaporative loss of
the more highly volatile components, leaving those of lesser volatility
in the soil. The fraction remaining in the soil is expected to be
relatively mobile.assuming the spill is large enough to exceed the
sorptive capacity of the soil. Gravity will carry the bulk fluid to
the saturated zone of the soil. There, the more soluble components
(aromatic and lower molecular weight aliphatic compounds) will dissolve
into the ground water or form emulsions with it, while the insoluble
fraction will float as a separate phase on top of the water table. The
movement of dissolved hydrocarbons in ground water is much greater than
for the separate liquid phase, reaching distances of hundreds to
thousands of meters compared to tens of meters for the separate liquid
phase. In the presence of cracks and fissures, however, the flow of
the separate phase is greatly enhanced.
The movement of Stoddard solvent in ground water may contaminate
drinking water supplies, resulting in ingestion exposures. Groundwater
discharges to surface water or the movements of contaminated soil
particles to surface water drinking water supplies may also result in
ingestion exposures, as well as in dermal exposures from the
recreational use of these waters. The uptake of Stoddard solvent by
fish and domestic animals is not expected to be a significant exposure
pathway for humans because the hydrocarbons with the greatest potential
for bioaccumulation, polycyclic aromatic compounds, account for such a
ssuali fraction of the mixture.
Volatilization of Stoddard solvent in soil is another potential
source of human exposure. Once in the soil, the hydrocarbons
evaporate, saturating the air in the soil pores, and diffusing in all
directions including upward to the surface. The vapors may diffuse
into the basements of homes or other structures in the area, resulting
in inhalation exposures to the buildings' occupants. Exposures may be
more intensive when the soil is contaminated directly from leaking
underground storage tanks and pipes rather than from surface spills.
In such cases the more volatile components do not have an opportunity
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