United States
Environmental Protection
Agency
Robert S. Kerr Environmental
Research Laboratory
Ada OK 74820
Research and Development
EPA/600/S8-88/001 May 1988
&EPA Project Summary
Interactive Simulation of the
Fate of Hazardous Chemicals
During Land Treatment of Oily
Wastes: RITZ User's Guide
D. L. Nofziger, J. R. Williams, and Thomas E. Short
An interactive software system was
developed to enable decision makers to
simulate the movement and fate of
hazardous chemicals during land treat-
ment of oily wastes. The mathematical
model known as the Regulatory and
Investigative Treatment Zone Model or
RITZ was developed and published
earlier by Short (1985). The model
incorporates the influence of oil in the
sludge, water movement, volatiliza-
tion, and degradation upon the trans-
port and fate of a hazardous chemical.
This manual describes the conceptual
framework and assumptions used by
Short (1985) in developing the model.
It then explains the micro-computer
hardware and software requirements,
the input parameters for the model, and
the graphical and tabular outputs which
can be selected. Illustrations of the use
of the software are also included. The
computational equations developed by
Short (1985) are presented for com-
pleteness but are not derived.
This Project Summary was devel-
oped by EPA's Robert S. Kerr Envir-
onmental Research Laboratory. Ada.
OK. to announce key findings of the
research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering
information at back).
Introduction
The Regulatory and Investigative
Treatment Zone Model, RITZ, (Short,
1985) was developed to help decision
makers systematically estimate the
movement and fate of hazardous chem-
icals during land treatment of oily
wastes. The model considers the
downward movement of the pollutant
with the soil solution, volatilization and
loss to the atmosphere, and degradation.
The model incorporates the influence of
oil upon the transport and fate of the
pollutant. This RITZ model forms the
basis of this interactive software system.
The software enables users to conve-
niently enter the required soil, chemical,
environmental, and management
parameters and checks the validity of
these entries. The user may then select
graphical and tabular outputs of the
quantities of interest.
This manual describes the basic con-
cepts of RITZ and lists the inherent
assumptions. The manual also describes
the use of the interactive software and
the hardware and software requirements
for it. Illustrative examples of the soft-
ware are presented. The appendix
includes a list of the mathematical
equations used in the software.
Basic Concepts, Assumptions,
and Limitations
A land treatment site is illustrated in
Figure 1. The treatment site consists of
two soil layers called the plow zone and
the treatment zone. The sludge (waste
material) containing oil and pollutant is
applied to the plow zone. It is thoroughly
mixed with the soil in that layer. As time
passes the pollutant and oil are degraded.
Some of the pollutant is carried down
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Land Treatment Site
Pollutant
Ramfall Vapor Losses
Evaporation
Sludge Applied to Plow Zone
Soil Surf ace
Volatilization
Degradation
Leaching
i
Pollutant
Leaching Losses
r tuw C.UHC
Depth
Treatment Zone
Depth
figure 1. Diagram of land treatment site.
through the soil with percolating water.
Some of the pollutant is volatilized and
moves into the air above the treatment
site.
The following assumptions were made
by Short (1985) in developing this model:
1. Waste material is uniformly mixed
in the plow zone.
2. The oil in the waste material is
immobile. It never leaves the plow
zone. Only the pollutant moves
with the soil water.
3. The soil properties are uniform
from the soil surface to the bottom
of the treatment zone. This
assumption will rarely, if ever, be
met in the field. The user can
estimate the impact of non-uniform
soils by comparing results for
several simulations covering the
range of soil properties present at
the site. The user can estimate the
impact of non-uniform soils by
using the averaging techniques
provided in the program and/or by
comparing results for several sim-
ulations covering the range of soil
properties present at the site. This
is referred to again in the last
paragraph of the summary.
•
4. The flux of water is uniform
throughout the treatment site and
throughout time. This assumption
will rarely be met in the field.
5. Hydrodynamic dispersion is insig-
nificant and can be neglected. This
assumption gives rise to sharp
leading and trailing edges in the
pollutant slug. These sharp fronts
will not exist in soils. As a result,
the pollutant will likely reach any
depth in the treatment zone before
the time predicted and it will
remain at that depth longer than
predicted by the model.
6. Linear isotherms describe the
partitioning of the pollutant
between the liquid, soil, vapor, and
oil phases. Local equilibrium
between phases is assumed.
7. First order degradation of the
pollutant and oil are assumed.
Degradation constants do not
change with soil depth or time. This
assumption ignores changes in
biological activity with soil depth.
It also ignores the influence of
loading rate, temperature, and the
quality of the environment for
microorganisms upon the degrada-
tion rate.
8. The pollutant partitions between
the soil, oil, water, and soil vapor
and does not partition to the
remaining fractions of the sludge.
9. The sludge does not measurably
change the properties of the soil
water or the soil so the pore liquid
behaves as water.
10. The water content of the soil is
related to the hydraulic conductiv-
ity as described by Clapp and
Hornberger (1978). That is,
k/ks = (0/0s)2b+3
where k is the hydraulic conduc-
tivity at a volumetric water content
of 6, ks is the saturated hydraulic
conductivity or the conductivity of
the soil at the saturated water
content, Os, and b is the Clapp and
Hornberger constant for the soil.
Field validation of the model is in
progress. The user is cautioned to
consider the assumptions in the model
and to apply the model only where
appropriate. The writers are aware the
assumptions are only simplistic approx-
imations to the continuum of nature.
Many of the assumptions were made to
either simplify the mathematical solution
or because there was insufficient exper-
imental data to permit more realistic
descriptions of the system.
The model presents results for the
specific parameters entered without any
measure of uncertainty in the calculated
values. The user is encouraged to
compare results for a series of Simula^
tions using parameters in the expected
ranges for the site to obtain an estimate
of this uncertainty. For example, if the
site containstwo soil layers, the user may
want to run the simulation twice, once
for the soil properties of each layer.
References Cited
1. Clapp, Roger B. and George M.
Hornberger. 1978. Empirical equa-
tions for some soil hydraulic prop-
erties. Water Resources Research
14:601-604.
2. Short, Thomas E. 1985. Movement
of contaminants from oily wastes
during land treatment. Proceedings
of Conference on Environmental
and Public Health Effects of Soils
Contaminated with Petroleum Pro-
ducts, Amherst, MA.
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D. L Nofziger andJ. R. Williams are with Oklahoma State University. Stillwater.
OK 74078; the EPA author Thomas Ł. Short (also the EPA Project Officer,
see below) is with Robert S. Kerr Environmental Research Laboratory, Ada,
OK 74820.
The complete report, entitled "Interactive Simulation of the Fate of Hazardous
Chemicals During Land Treatment of Oily Wastes: RITZ User's Guide,"
(Order No. PB 88-195 540/AS; Cost: $14.95, subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Robert S. Kerr Environmental Research Laboratory
U.S. Environmental Protection Agency
Ada, OK 74820
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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Official Business
Penalty for Private Use $300
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•frU.S. GOVERNMENT PRINTING OFFICE: 1988—548-013,
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