health and safety plan solid waste management unit assessment

NEL OILS 66-11
66.2 ENVIRONMENTAL FATE AND EXPOSURE PATHWAYS
A discussion of the environmental behavior of fuel oil is limited
by the lack of data defining its major components. The environmental
behavior of hydrocarbons selected from 'the major classes will be
addressed; however, trace elements and the many diverse additives will
not be specifically addressed. Many of the hydrocarbons characteristic
of diesel fuel have been addressed previously in the more extensive
environmental fate section of the JP-4 chapter since these hydrocarbons
are common to both petroleum fuels. The general discussions of
aliphatic and aromatic hydrocarbons and their behavior in
soil/ground-water systems will not be repeated here; the reader is
referred to the relevant sections of Chapter 64.
66.2.1 Equilibrium Partitioning Model
In general, soil/ground-water transport pathways for low
concentrations of pollutants in soil can be assessed by using an
equilibrium partitioning model. For the purposes of assessing the
environmental transport of diesel fuel, a group of specific
hydrocarbons was selected from the dominant hydrocarbon classes, i.e.,
alkanes, cycloalkanes, and aromatics: there were no availatile data to
confirm the presence of the selected compounds in a typical diesel fuel
sample. Table 66-3 identifies the selected hydrocarbons and presents
the predicted partitioning of low soil concentrations of those
hydrocarbons among soil particles, soil water, and soil air. The
portions associated with the water and air: phases of the soil are
expected to have higher mobility than the adsorbed portion.
Estimates for the unsaturated topsoil indicate that sorption is
expected to be an important process for all the dominant hydrocarbon
categories. Partitioning to the soil-vapor phase is much less
important than for other petroleum distillates since many of the lower
molecular weight aliphatic hydrocarbons (C, -C,) characterized by high
vapor pressure and low water solubility are not expected to be major
components of diesel fuel. The aromatics have slightly higher water
solubilities and transport with infiltrating water may be more
important for these compounds; volatilization, on the other hand, is
not expected to be important. In saturated, deep soils (containing no
soil air and negligible soil organic carbon), a significant percent of
the aromatic hydrocarbons is predicted to be present in the soil-water
phase and available for transport with flowing ground water.
Partitioning to the air and water phases is expected to be even less
important for the organic components of residual fuel oils compared to
components of diesel oil; sorption to soil particles is expected to be
significant;
In interpreting these results, it must be remembered that this
model is valid only for low soil concentrations (below aqueous
solubility) of the components. Large releases of diesel fuel (spills,
leaking underground storage tanks) may exceed the sorptive capacity of
the soil, thereby filling the pore spaces of the soil with the fuel.
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