Environmental Engineering Reference
In-Depth Information
10.4.2.1 Diffusion Models
The CSOIL exposure model was developed in the Netherlands by the National
Institute for Public Health and the Environment (RIVM) and used to derive Soil
Quality Standards (Rikken et al.
2001
). A commercial version is available as the
Risk-Human model from the Van Hall Business Centre, which allows the user to
perform site-specific Risk Assessments. The model includes only diffusive vapor
transport and originates from the HESP model (Van den Berg
1991, 1994, 1995
).
The model calculates the indoor air concentration for a typical Dutch dwelling with
a crawl space as a result of vapor intrusion from groundwater or vadose zone con-
tamination. More information about the commercial version can be found via the
website:
http://www.risc-site.nl
/.
Huijsmans and Wezenbeek (
1995
) evaluated the accuracy of the CSOIL model
and demonstrated that in some situations the functionality of the CSOIL model was
not sufficient, e.g., if a concrete basement, slab-on-grade or pure product is present.
The indoor air concentration predictions for some of the aromatic VOCs (degrad-
able) were a factor 36 to 360,000 higher than the measured indoor air concentrations.
The predictions for some chlorinated VOCs (much less or not degradable) were a
factor 2 to 690 higher than the measured indoor air concentrations.
The Vlier-Humaan model is used in Flanders to derive soil clean-up values and
to perform site-specific Human Health Risk Assessments. The model calculates a
dose and an indoor air concentration as a result of the presence of contaminants in
soil or groundwater and compares the dose and indoor air concentration with a TDI
(Tolerable Daily Intake) and a TCA (Tolerable Concentration in Air), respectively.
The model includes only diffusive vapor transport and originates from the human
exposure to soil contaminants (HESP) model (ECETOC
1992
). The basic model for
volatilization was derived on the basis of publications from Jury (Jury et al.
1983
and
1990
) and adapted for certain exposure characteristics that fit the situation in
Flanders. Buildings foundations that can be considered include slab-on-grade floor,
concrete basement and crawl space. All background information is available in the
technical guidance document part 1 to 4 (Provoost and Cornelis
2004a
,
b
,
c
,
d
).
More information about the commercial version of this model can be found via the
website:
http://www.risc-site.nl
/.
10.4.2.2 Diffusion and Convection Models
The J&E Model is a screening-level model that considers 1-dimensional upward dif-
fusion from a subsurface source through the water-unsaturated zone, advective flow
into the building through a foundation crack due to under-pressurization, and dilu-
tion in the building due to ventilation. It is in widespread use, since the US EPA
commissioned the production of spreadsheet versions of the J&E Model (EQM
2004
). The first generation of the J&E Model (Johnson and Ettinger
1991
)did
not consider biodegradation (which was added in Johnson et al.
1999
), barometric
pumping (e.g., Massmann and Farrier
1992
;Parker
2003
), preferential pathways,
fractured subsurface media, or other processes that may be important in some
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