United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-93/028 March 1993
Summary
Decision-Support Software for
Soil Vapor Extraction Technology
Application; Hyperventilate
Curtis A. Kruger and John G. Morse
The U.S. Environmental Protection
Agency (EPA) estimate* that 15% to
20% of the approximately 1.7 million
underground storage tank (UST) sys-
tems containing petroleum products are
either leaking or will leak In the near
future. These UST systems could pose
a serious threat to public health and
the environment. Selection of appropri-
ate corrective action technologies that
can be rapidly Implemented and that
are efficient and cost-effective Is es-
sential to minimize the Impact of UST
releases on the environment and pub-
lic health. Soil vapor extraction (SVE)
is a proven, *i situ corrective action
technology that can remove volatile or-
ganic compounds (VOCs) and selected
residual petroleum hydrocarbons from
unsaturated soils. To assist regulators,
Investigators, and UST owners In evalu-
ating whether SVE is an appropriate
cleanup technology for use at UST
sites, decision-support software entitled
"Hyperventilate" has beeh developed
by U.S. EPA and Shell Oil Company
under a 1990 Cooperative Research and
Development Agreement under the Fed-
eral Technology Transfer Act
Hyperventilate Is an interactive, soft-
wars guidance system for evaluating
the feasibility of using SVE at a spe-
cific she based on site and contami-
nant characteristics. Hyperventilate Is
designed to (1) Identify the level of site
data required to evaluate SVE systems,
(2) evaluate soil permeability test re-
sults, (3) approximate the minimum
number of extraction wells likely to be
needed, and (4) provide a rough ap-
proximation of the system's desired and
maximum removal rates.
The document summarized here pro-
vides guidance In evaluating the use
of the IBM-compatible version of
Hyperventilate that requires a com-
puter equipped, at a minimum, with
an 80386 processor, 4 MB RAM, DOS
3.1, Microsoft Windows 3.x, and Spin-
naker PLUS 2.5. In the project report,
an overview of SVE principles and pro-
cedures Is presented along with the
basic model principles and a sensitiv-
ity analysis of Hyperventilate. A
sample application of the software is
also presented by using data from an
actual UST site. The case study dem-
onstrates how to estimate and deter-
mine Input parameters, goes through
the steps Involved in deriving esti-
mates to evaluate whether SVE Is ap-
propriate, and discusses Interpretation
of the case study results.
This Prefect Summary was developed
by EPA's Risk Reduction Engineering
Laboratory, Cincinnati, OH, to announce
key findings of the research project
that Is fully documented In a separate
report of the same title (see Project
Report ordering Information at back).
Introduction
Since promulgation of federal regula-
tions, the number of leaking UST systems
being discovered has rapidly outpaced the
capabilities and resources of both indus-
try and regulatory agencies to implement
and complete corrective actions at these
sites. Because the number of unaddressed
sites is increasing, decision-support soft-
Printed on Recycled Paper
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ware such as Hyperventilate can be a
valuable tool for expediting the process of
selecting and implementing effective cor-
rective actions.
The objective of Hyperventilate is to
help the user engage in a systematic,
iterative evaluation of the feasibility of SVE
as a remedial alternative at a given site.
The software uses data provided by the
user to develop a rough approximation of
the system's desired and maximum re-
moval rates. At no point does the soft-
ware give a definitive "yes" or "no" re-
sponse to the question of feasibility. The
software can provide two estimates of the
minimum number of vapor extraction wells
needed to achieve remediation. The first
estimate is developed by simply compar-
ing the anticipated extraction well radius
of influence with the radial area of con-
tamination. The second estimate is based
on a calculation of the volume of air that
needs to be extracted from the soil to
remove residual contamination. The user
is ultimately responsible for deciding if the
estimates generated by the software are
technically and economically practical for
a particular site. Hyperventilate is prima-
rily a software tool for evaluating SVE as
a remediation alternative; it is not intended
to be a detailed SVE modeling or design
tool.
Soil Vapor Extraction
Technology
SVE is a proven, cost-effective tech-
nique for removing VOCs and motor fuels
from contaminated soil in the unsaturated
or vadose zone. This technology is also
referred to as vacuum extraction, soil vent-
ing, aeration, in situ volatilization, and en-
hanced volatilization. SVE is the term se-
lected for use in the full report.
This report briefly discusses the prin-
ciples influencing contaminant behavior in
the vadose zone and describes site evalu-
ation procedures, system design compo-
nents, and system performance monitor-
ing.
Recent SVE system designs for remov-
ing VOCs have mostly been empirically
based because of the simplicity of the
process and a lack of analytical tools ca-
pable of aiding system design. Many nu-
merical models have practical applications
in actual field situations that can evaluate
the effectiveness of SVE in removing or-
ganic vapors. A variety of numerical mod-
els can be used to determine the role of
soil moisture, temperature, soil heteroge-
neity, and other factors in controlling the
migration of volatile constituents through
the unsaturated zone. The process of con-
taminant desorption from soil particles can
be used to determine final cleanup effi-
ciency. It also can result in significant dif-
ferences in removal rates for the various
types of soils and volatile organic compo-
nents.
Basic Model Principles
Hyperventilate, an interactive, software
guidance system, is a useful tool for evalu-
ating the feasibility of using SVE at a
specific site. Hyperventilate was designed
for use as a guide to achieve the follow-
ing: (1) identify the level of site data
needed to evaluate SVE systems, (2) de-
termine if soil venting is appropriate at a
site, (3) evaluate soil permeability test re-
sults, and (4) approximate the minimum
number of extraction wells likely to be
needed.
The software is available for both the
Apple Macintosh and IBM-compatible per-
sonal computers. Hyperventilate version
1.01 for the Apple Macintosh requires an
Apple Macintosh computer equipped with
2 MB RAM and the Apple HyperCard Soft-
ware Program 2.0 or greater. HyperVen-
tilate version 2.0 for IBM PC-compatible
requires a computer equipped with at least
an 80386 processor, 4 MB RAM, and VGA
through the use of Spinnaker PLUS (a
run-time version) in a Microsoft Windows
(3.0 version) environment. Hyperventilate
is composed of a system of multiple stack
cards in which each computer screen view
is called a card. Related cards that follow
in sequential order are organized into card
stacks, and the main card stack is called
the 'Soil Venting Stack.* To obtain further
explanation of individual cards within this
stack, secondary card stacks can be ac-
cessed through the "Soil Venting Help
Stack.* Other supporting stacks include
the "Air Permeability Test* stack, the "Aqui-
fer Characterization* stack, and the "Sys-
tem Design* stack. The multiple card file
system has the flexibility to allow the user
to access part of the software without
having to work through the entire pro-
gram.
The Hyperventilate software system
addresses the following nine major card
topics associated with implementing SVE:
Information about SVE,
General overview of the "Shell Oil
Company Practical Approach,"
Site investigation needs,
Feasibility of soil venting,
Analyses of field test information to
provide permeability estimates and
aquifer characterization,
SVE system design estimates,
System monitoring needs,
Ways to determine when the system
should be shut down, and
Economics of implementing SVE.
Most SVE system parameters are esti-
mated under the topics that deal with SVE
feasibility, system design, and field test-
ing.
Computer Software Structure
Hyperventilate is interactive software
with a dual nature. On one level, it is
tutorial, intended to help the user under-
stand the nature and distribution of hydro-
carbons in the subsurface and to deter-
mine if SVE is an appropriate remedial
technology at a given site. On another
level, ft is computational, allowing the user
to work through several sequences of op-
erations to determine if SVE is appropri-
ate for use under specific site conditions.
Hyperventilate comprises 100 cards di-
vided into five stacks. Twenty-eight of
these cards from the main stack, referred
to as the "Soil Venting Stack,* take the
user through the systematic evaluation of
SVE. The other four stacks support the
main stack as Help cards (Soil Venting
Help Stack) or by providing details con-
cerning the Air Permeability Test, Aquifer
Characterization, or System Design.
Document Contents
Section 1 includes a capsulized discus-
sion of the SVE technology and the fac-
tors that influence contaminant fate and
vapor-phase transport in the vadose zone.
Section 2 provides a detailed summary
of the Hyperventilate software. The major
elements discussed in this section include
the basic model principles, software char-
acteristics, and the computer software
structure.
Section 3 presents a model application
case study with the use of data from an
actual UST she. The case study demon-
strates the process of reviewing a reme-
dial investigation/corrective action plan in
order to determine input parameters for
Hyperventilate. Initially, the software will
help to examine the site from a very basic
point of view—one that includes a number
of simplistic but important assumptions
about subsurface conditions and contami-
nant behavior that are explained within
the software. Data needs for this part of
the analysis are not rigorous, and an in-
teractive approach is encouraged. Subse-
quently, the software will help revise the
initial assumptions, develop better input
data, and refine the understanding of the
use of SVE at the site.
Section 4 discusses model analysis. The
modeling analysis of Hyperventilate is con-
ducted to address two considerations: (1)
variations in output parameters that were
identified over a range of input parameter 1
values, and (2) the sensitivity of each out-
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put parameter to changes in input param-
eter values. The purpose of this analysis
is to identify those site conditions and
system design considerations that most
strongly affect the potential success of a
vapor extraction system at a given site
and to identify those parameters over
which a system designer can exert some
measure of control.
The full report was submitted in fulfill-
ment of Contract No. 68-C2-0108 by In-
ternational Technology Corporation under
the sponsorship of the U.S. Environmen-
tal Protection Agency.
•U.S. Government Printing Office: 1983 — 750-071/60203
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C. A Krvgeris with Midwest Research Institute, Falls Church, Va 22041, and
John G. Morse is *Qh International Technology Corporation Knoxvttle, TN
37923.
Chl-Yuan Fan is the EPA Project Officer (see below).
The complete report consists of paper copy and two diskettes (one for IBM-PC
and one tor Apple Macintosh) entitled "Decision-Support Software for Soil
Vapor Extraction Technology Application: Hyperventilate."
Paper Copy (Order No. PB93-134880/AS; Cost: $27.00; subject to
change)
Diskettes (Order No. PB93-502664/AS; Cost $140; subject to change)
The above items 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
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Edison, NJ 08837
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-93/028
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