calculate the load for the major layer, contained
several scientists and regulatory agencies. At the
sublayers are added to the first sublayer of that
present state of scientific knowledge, SESOIL is a
well-developed seasonal soil compartment model.
particular major layer.
Despite its several difficulties, the model is popu-
lar among regulators and users because of its sim-
Distribution of benzene mass
plicity compared to research models. It can be used
Benzene mass distribution in the column was
as a preliminary leachate assessment screening
calculated by adding the masses of the contami-
nant from all the phases for the year of contami-
Different authors found different input parame-
nant loading. Volatilized mass was added to the
ters sensitive to their local conditions in reference
mass in moisture, adsorbed on soil and in soil air
to a particular contaminant. The MOFAT, POSSM
for each sublayer down through the soil column.
and VALOR models can also be considered for
The computed mass was added to the sublayer
leachate assessment in Alaska.
above it in the next time step. Diffused mass was
added and divided by the time cycle.
Benzene concentration distribution
for lowest sublayer
Abriola, L.M., R. Rathfelder, M. Maiza and S. Yadav
Benzene concentrations (g/mL) were checked
(1992) VALOR Code Version 1.0: A PC Code Simulat-
from the output file for each year until the benzene
ing Immiscible Contaminant Transport in Subsurface
reached the lowest soil zone. Also recorded was the
Systems. Palo Alto, California: Electric Power Re-
greatest benzene concentration as well as its travel
Anderson, M.R. (1992) Development of generic soil
cleanup levels based on analysis of the leach-ate
pathway. Portland: Oregon Department of Envi-
Maximum pollutant depth
Drewett et al. (1993) assumed groundwater depth
at 5330 cm; therefore, benzene transport was simu-
Bonazountas, M. and J. Wagner (1981, 1984)
lated at 5330 cm as illustrated in Figure 1.
SESOIL: A Seasonal Soil Compartment Model. Cam-
bridge, Massachusetts: Arthur D. Little, Inc.
Bonazountas, M. and D. Kallidromitou (1993) Math-
ematical hydrocarbon fate modeling in soil systems.
Several workers (Melancon et al. 1986; Ander-
In Principles and Practices for Petroleum Contaminat-
son 1992; Odencrantz et al. 1992; Hetrick et al. 1989,
ed Soils (E.J. Calabrese and P.T. Kostecki, Ed.). Boca
1993; Ladwig et al. 1993) performed sensitivity anal-
Raton, Florida: Lewis Publishers, p. 131322.
yses on SESOIL, compared it with other vadose zone
Bonazountas, M., J. Wagner and B. Goodwin (1982)
chemical transport models, and modified input pa-
rameters according to the local conditions. They
Pathways. Cambridge, Massachusetts: Arthur D.
emphasized that vadose zone models need to be
Little, Inc., EPA Contract No. 68-01-5949 (9).
calibrated with measured site-specific data. The
Calabrese, E.J. and P.T. Kostecki (1992) Risk Assess-
ment and Environmental Fate Methodologies. Boca
and validation under Alaskan conditions are:
Raton, Florida: Lewis Publishers, Inc.
1. Adjust the input parameters of SESOIL accord-
ing to different climatic regions of Alaska.
in the subsurface: Realties, issues, and prospects.
2. Propose soil input parameters as per the soil
types of Alaska.
(P.T. Kostecki and E.J. Calabrese, Eds.). Boca Raton,
3. Study the chemical characteristics of different
Florida: Lewis Publishers, Inc.
chemicals spilled at DOD installations.
Donigian, A.S. and P.S.C. Rao (1986a) Overview of
4. Compare the SESOIL chemical transport simu-
terrestrial processes and modeling. In Vadose Zone
lations with other vadose zone models avail-
Modeling of Organic Pollutants (S.C. Hern and S.M.
able in the literature.
Melancon, Eds.). Chelsea, Michigan: Lewis Pub-
lishers, p. 335.
Donigian, A.S. and P.S.C. Rao (1986b) Example
model testing studies. In Vadose Zone Modeling of
Several computer models are in use to assess the
Organic Pollutants (S.C. Hern and S.M. Melancon,
cleanup levels of hydrocarbon-contaminated soils.
Ed.). Chelsea, Michigan: Lewis Publishers, p. 103
Vadose zone models were extensively reviewed by