User's Man
k
FOR THE APPLE® MACINTOSH™
o
CO
EPA550-CB-92-002
FNM!, .r ;:' ; -;ONAGENCY
V¥Ar;i:'!G".v^, LJt-' ••:-i'!J
OCTOBER 1992
j^* U.S. ENVIRONMENTAL ^$&^S&SiA^$f'A Chemical Emergency Preparedness
Sfe} PROTECTION AGENCY ^^•[^HlUil^^. and Prevention Office
NATIONAL OCEANIC
AND ATMOSPHERIC
ADMINISTRATION
came®
Washington, D.C. 2O46O
Hazardous Materials Response
and Assessment Division
Seattle, Washington 68115
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Terms and Conditions for
ALOHA™ for Macintosh and DOS Computers
The recipient agrees to the following conditions:
Use and Distribution Restrictions
CAMEO™ (and ALOHA™, when sold separately) is available on a not-
for-profit basis from the National Safety Council to those individuals and
organizations involved in the safe handling of chemicals.
The recipient may make sufficient backup copies to protect his site or
organization against loss of the information. The recipient may use the
information, by copying of disks or by installation on a local area network
or mainframe, at one site and within one organization. For purposes of
this restriction, a "site" means any one street address, and includes mobile
response units assigned to that site over which the recipient is respon-
sible.
Temporary classroom installation of no more than 25 copies is allowed for
a period not to exceed the normal course of instruction. The recipient shall
not distribute, electronically or by any other means, any portion of CAMEO
to individuals other than those included in the site or organization restric-
tions defined above or to any other organizations not part of the recipient
organization.
The recipient shall honor all disclaimers and other limits of liability
associated with those organizations that have provided data in the com-
pilation of the ALOHA™ chemical database.
Limitation of Liability
The United States Government has used its best efforts to deliver complete
data incorporated into CAMEO™ and ALOHA™. Nevertheless, the United
States Government and the National Safety Council do not warrant accu-
racy or completeness, are not responsible for errors and omissions, and
are not liable for any direct, indirect, or consequential damages flowing
from the recipient's use of ALOHA™.
The CAMEO and ALOHA software are being distributed "as is" and
neither the United States Government nor the National Safety Council
-------
Licenses and Trademarks
makes any warranty claims, either expressed or implied, with respect to the CAMEO
or ALOHA software, their quality, accuracy, completeness, performance, mer-
chantability, or fitness for any intended purpose.
Indemnification
The recipient shall indemnify and save harmless the United States and the National
Safety Council and their agents and employees against any and all loss, damage,
claim, or liability whatsoever, due to personal injury or death, or damage to
property of others directly or indirectly due to the use by the recipient of CAMEO
and ALOHA, or any other act or omission of the recipient, including failure to
comply with the provisions of the National Safety Council order form.
Editing
Any unauthorized editing or alteration of CAMEO or ALOHA chemical data or
information provided by the National Safety Council as agent of the U.S. Govern-
ment will result in the termination of the agreement between recipient and the
National Safety Council and U.S. Government. Upon receipt of notice of termina-
tion, the recipient shall immediately return all CAMEO and ALOHA information to
the National Safety Council, including all documents and all copies of software
containing CAMEO and ALOHA information.
Maintenance
Recipients should keep the National Safety Council informed of any address changes.
This information is necessary so that the U.S. Government or the National Safety
Council may notify users if any CAMEO or ALOHA program changes or updated
information become available.
ALOHA™ is a trademark of the U.S. Government. National Safety Council is a
nongovernmental, not-for-profit, public service organization. Apple® and Macin-
tosh™ are trademarks of Apple Computer, Inc. MacWrite and MacPaint are trade-
marks of Claris. Diamond Unpacking Code from Sextant Corporation was used to
compress ALOHA™ files. Microsoft, MS, and MS-DOS are registered trademarks,
and Windows and Windows/ 386 are trademarks of Microsoft Corp. Paintbrush is a
trademark of Zsoft Corp. 386 is a trademark of Intel Corp. PostScript is a registered
trademark of Adobe Systems, Inc., and HP is a registered trademark of Hewlett-
Packard Company. IBM is a trademark of International Business Machines. Pkware
was used to compress CAMEO™ DOS files. Clipper is a trademark of Computer
Associates. GFX Screen Dump is a trademark of C Source, Inc. dBase and Turbo C
are trademarks of Borland International, Inc.
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Your feedback is
welcome...
...in fact, it's essential to helping us improve both the ALOHA
program and the ALOHA manual. Please use the space on the next
page to let us know your comments and suggestions (don't be
bothered by the fact that we give you only one page for your
comments. We actually hope you'll have so many comments that
you cover several sheets!) Here are some questions to get you
started:
How can we make ALOHA better?
Does ALOHA cover appropriate issues (heavy gas, etc.)?
Which features do you think need improvement? What would
you like to see done?
How can we make the manual better?
Are things explained in a way that you can easily understand?
Is the type easy to read?
Is it organized so that you can find pretty much everything?
Does the manual explain how to use ALOHA to its fullest advan-
tage?
Are there some things that the manual could do a better job of
explaining—or are there things that we spend too much time on?
-------
Your Comments
Please use the lined page for your comments; simply fold it, tape
it, and mail it to us. Thanks!
-------
Your Comments
ALOHA is the best thing thafr ever happened to me...
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POSTAGE AND FEES PAID
U.S. DEPARTMENT OF COMMERCE
COM-210
THIRD CLASS
OFFICIAL BUSINESS
PENALTY FOR PRIVATE USE, $300
The ALOHA Manager
NOAA/HAZMAT
7600 Sand Point Way N.E.
Seattle, Wash. 98115
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Contents
Page
I Overview 1-1
2 Introduction to Air Modeling 2-1
3 The File and Edit Menus 3-1
4 The SiteData Menu 4-1
5 The SetUp Menu 5-1
6 The Display Menu 6-1
7 Sharing 7-1
Appendices
A Examples
I A Tank Source A-l-1
2 Direct Input (Heavy Gas) A-2-1
3 A Pipe Source A-3-1
4 ALOHA, MARPLOT, and a PICT Map A-4-1
5 ALOHA and BitPlot A-5-1
6 ALOHA and a MARPLOT Map A-6-1
B Troubleshooting
Macintosh B-l
Windows B-9
C AlohaSpy C-l
D BITPLOT D-l
Glossary 8-1
References 9-1
Index 10-1
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Qiopter /
Overview
In this chapter...
File and Edit menus.. 1-2
SiteData menu 1-2
SetUp menu 1-2
Display menu 1-3
Sharing menu 1-5
Installing ALOHA
Macintosh 1-5
Mac memory 1-8
Windows 1-9
Windows memory 1-11
Getting help 1-11
How to Use This Manual
This manual is divided into five chapters, beginning here in
Chapter 1 with a discussion of ALOHA's menus, hardware
requirements, and using on-line help. So that you use the
model knowledgeably and interpret its output correctly, you
should read Chapter 2, Introduction to Air Modeling.
Following the discussion of dispersion modeling in
Chapter 2, each chapter addresses a specific feature of the
model. These chapters explain ALOHA's menus and provide
examples to help you move confidently through the menu
items. Like the model itself, the manual moves successively
through the menubar, File, Edit, SiteData, SetUp, and
Display, and their respective menu items.
Rgure 1-1.
Main ALOHA
menus.
T»N«
Footprint
CIIK Mitral Ian...
DOM
town* Strength
Calculate...
Calculate Now
1-1
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Chapter 1: Overview
A glossary of air modeling terms and an index are included
at the end of the manual. There are four appendices:
O Examples
O Troubleshooting
O AlohaSpy
O BitPlot
File and Edit menus
You'll benefit most from this manual if you are already famil-
iar with some basic Macintosh and Microsoft Windows™
concepts, such as cutting and pasting, and using the File and
Editmenus, and the Clipboard. PrintAlI is an option that has
been added to ALOHA's File menu; this permits you to print
all of the ALOHA output windows that you have open on
your computer screen. (See Chapter 3, The File and Edit
Menus, for more information.)
SiteData menu
The SiteData menu is where you establish the physical loca-
tion of your spill source. Here, you'll tell ALOHA the Loca-
tion of your spill (in which city did it occur?), the Building
Type (what are the buildings like in the vicinity of the spill?),
and the Date and Time of the spill.
SetUp menu
The SctUp menu is where you give ALOHA the spill condi-
tions necessary for it to calculate the "footprint," starting
with the Chemical that is involved. Next, you establish the
Atmospheric conditions present for your spill. You can enter
this information in two different ways: 1) User Input (typing
it in yourself), or 2) having the data relayed by a portable
meteorological station, known as Station for Atmospheric
Measurements (SAM Station). The next information that
you enter is related to the Source of the spill: was it from a
1-2
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Chapter 1: Overview
puddle, tank, or pipe? If you know the amount of vapor
entering the air, you may want to choose Direct.
Finally, you select Computational to choose the type of dis-
persion computation that you wish ALOHA to use for calcu-
lating the spread and duration of the chemical cloud. The
options are:
O Let model decide, which lets ALOHA choose the type of
calculation, based on chemical properties and specifics of
the release,
G Use Gaussian dispersion only, or
G Use heavy gas dispersion only.
Also on this screen, you'll find the option Define dose. This
option allows you to vary the exponent ALOHA will use in its
dose calculation (dose is the accumulated amount of the
chemical to which a person is exposed at a particular loca-
tion).
Display menu
The Display menu gives you several different choices for how
you'd like to see ALOHA's results displayed. The first two
choices deal with how you wish the output displayed on your
screen. Under Options, you must select a Level of Concern
concentration for the footprint to be displayed. Would you
like the shape of the chemical cloud at ground level (its
Footprint) plotted on a grid, or displayed with a scale that
you set yourself? What Output Units (English or metric units
of measure) would you like to use with the footprint graph?
Next, you decide what type of output you'd like ALOHA to
Display:
1-3
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Chapter 1; Overview
Text Summary
Footprint
Concentration
Dose
Source strength
Tile Windows
Stack Windows
recaps the options that you've chosen as you
move through the ALOHA menus/ and sum-
marizes, in text form, the results of ALOH A's
calculations. This window is always visible.
calculates and displays the shape (when
viewed from above) of the chemical cloud at
your specified level of concern.
calculates the expected indoor and out-
door concentration levels at the speci-
fied location. This information is then
presented on a graph.
calculates the expected indoor and out-
door dose levels at the specified loca-
tion. This information is then presented
on a graph.
presents a graph indicating the amount
of the chemical that is released into the
atmosphere over time.
simultaneously shows you the output
from all of the windows that you have
open.
shows you the output, with the windows
stacked on top of each other so that only the
title bars are visible.
Calculate
Calculate Now
allows you to set when you would like
output windows updated.
updates all visible windows.
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Chapter 1: Overview
Sharing Menu
The Sharing menu allows you to display an ALOHA foot-
print on a background map using MARPLOT, the CAMEO
mapping module.
Load only one
version of ALOHA;
if you load both
versions, you can
run into problems
when you try to use
saved ALOHA files.
Installing ALOHA on your Macintosh
To install ALOHA, you will need to use only one of the two
disks provided (ALOHA™ math coprocessor version if your
Macintosh has a math coprocessor chip or ALOHA™ , if it
doesn't). An installer contained on each disk automatically
copies the files to your hard disk. Data are compressed on the
disks and so must be uncompressed into folders on your hard
drive. You'll receive two floppy disks with packed, or com-
pressed, ALOHA files:
Figure 1 -2.
Packed ALOHA
files.
ALOHA™ math cp
ALOHA™
ID!
i 1 item
ALOHA Folder J
i 1 item
ALOHA Folder J
1-5
-------
Chapter 1: Overview
To begin:
O Insert the floppy disk with the version of ALOHA that is
appropriate for your Macintosh (ALOHA™ math coprocessor
version if your Macintosh has a math coprocessor chip;
ALOHA™ if it doesn't).
O Double-click on ALOHA Folder f.
O Click Drive until you see your hard drive's name (in the
example below, the hard drive is named Athena).
O Click Save.
O You'll see an Unpacking timeline that gives you an idea of how
long (probably not more than one minute) it takes to extract the
files that are compressed onto the disk. Notice that the names
of the files currently being unpacked appear above the time-
line.
O When unpacking is completed, choose Quit from the File
menu.
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Chapter 1: Overview
After unpacking,
you should have
these files in the
ALOHA Folder.
ALOHA Folder
ALOHA
ALOHA Helps
ALOHA Resources
AlohaSpy
ChemLib
ChemManager
Citylib
The ALOHA files will be copied into
the ALOHA Folder on your Macin-
tosh desktop; don't remove the files
from this folder. Your ALOHA folder
should contain the files shown at left.
If you stop before you finish unpack-
ing any disk, throw away the ALOHA
Folder that has been partially filled
with the files unpacked so far. Start
over and insert the appropriate ALOHA disk, double-click
on ALOHA Folder J, and repeat the steps above.
Your new folders will include these files:
ALOHA: be sure that you load the correct version of
ALOHA for your machine. The coprocessor version
of ALOHA will not run on a Macintosh that does not
have a math coprocessor chip. You can run the non-coproces-
sor version of ALOHA on a machine with a math coprocessor
chip, but each time you use ALOHA you will be warned that
the other version will run faster on your machine.
ALOHA Resources has most of the resource infor-
mation that is needed to run ALOHA. Don't lock this
file.
ALOHA Helps is the database for the on-line help
available while you are using ALOHA.
ChemLib contains all of the available physical and
toxicological properties used by the air model for
over 700 chemicals. If you are using ChemManager,
unlock this file.
1-7
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Chapter 1: Overview
ChemManager allows you to modify or delete
chemical data that is already present in the chemical
library, or to add other chemicals for which you
have the required physical property information.
To use ChemManager, you must first unlock
ChemLib.
CityLib contains the location data used in the SiteData
menu. If you add or modify locations while running
ALOHA, CityLib will be updated automatically. This
file should not be locked.
AlohaSpy lets you save the results of an ALOHA
model run; a SPY file contains the information from
the windows in ALOHA when you saved the file.
A note about memory and speed
ALOHA runs on an Apple Macintosh with at least one mega-
byte of random access memory (RAM) and a hard drive. It
will run much faster on a Macintosh with a math coprocessor
chip. You must also have two megabytes of hard disk space
available to load ALOHA. ALOHA will also work on com-
puters that do not have the math coprocessor chip, although
it will be slower and, in some cases, significantly so.
ALOHA runs under either the Finder or MultiFinder, unless
you are working on a Macintosh with only one megabyte of
RAM.
Ask your Apple dealer for information about Macintosh
models with and without coprocessor chips.
1-8
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Chapter 1: Overview
Installing ALOHA Windows
O Place the disk containing the ALOHA Installer in either
Drive A or B.
O Choose the Run option from the Program Manager's File
menu.
G Type b:install (or a:install if you placed the diskette in
Drive A) in the command line box and click OK.
D You'll see the following dialog box:
O Specify the drive and directory where you wish to install
ALOHA, and click OK. The default directory is
C:\ALOHA; if this is sufficient, just click OK. The
installer will now decompress files and place them in the
specified directory.
Aloha Installer
Please specify the directory for
ALOHA lo be installed in. If the
directory does not exist II will be
created. Click 'OK1 to continue.
I C:\ALOHA
Cancel
1-9
-------
Chapter 1: Overview
O When the installation is complete, you will be notified.
Click OK.
Aloha Installer
Aloha has been successfully
Installed.
I C:\ALOHA
j'OKl I
O The installation process will create a group called ALOHA
in the program manager, and will place all executable
files in that group. You are ready to double-click your
way into ALOHA.
Program Manager
file Options Window Help
Wo
ChemManager BitPto AtohaSpy ALOHA
Word Setup Microsoft Wac
wordet
IcUator
Calendar
Figure 1-3.
Installing ALOHA
Windows.
1-10
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Chapter 1: Overview
A note about memory and speed
ALOHA runs in Microsoft Windows™, version 3.0 or above.
It requires at least one megabyte of Random Access Memory
(RAM) and about 2.5 megabytes of space on your hard drive.
ALOHA requires a PC using at least an 80286 microprocessor.
The model must be run in either Standard or Enhanced mode.
ALOHA can be run with or without a math coprocessor; it
will run faster if a coprocessor is installed. We recommend
that you run ALOHA on a PC using an 80386 microprocessor
or above, with a math coprocessor, and with at least two
megabytes of RAM.
Getting help
On-line help is available at any time in ALOHA. If you're
using ALOHA for the Macintosh, select About ALOHA™
under the A menu to see a brief explanation of each menu
item and dialog box in the air model (Figure 1-4). With
ALOHA Windows, you select About ALOHA™ from the
Control menu box; for both Macintosh and Windows, you can
also click the Help button next to the option in question
(Figure 1-5). Either of these approaches takes you to the same
Help information. Clicking Help, as in Figure 1-5, is a short-
cut that takes you directly to the topic of concern.
SetedingALOHA ^glili I ill! "*""Ma Setup Display
Help.
l-ll
-------
Chapter 1: Overview
Infiltration Building Parameters
Select building type or enter exchange parameter
O Enclosed office building
-------
Chapter 1: Overview
When you've finished looking at the Help screen, click Top-
ics to return to the Help index to select another topic, Print to
print the Help screen, or click Cancel to return to the previous
screen (Figure 1-7).
Figure 1-7.
Sample Help
screen.
ABOUT HELP
DESCRIPTION
About ALOHA provides on-line Information about the
CAMEO™ air model, ALOHA™. Each Help is organized
Into five categories: Description, Instructions,
Warnings, Notes, and Allowable Input. Use the scroll
bar to locate the information you need. To get
additional information about a topic, refer to the
ALOHA manual.
INSTRUCTIONS
(^Topics J
[ Print ]
1-13
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Chapter 2
Introduction to
Air Modeling
In this chapter-
Dispersion modeling 2-2
What is dispersion?...2-2
Use caution 2-8
ALOHA doesn't
model 2-13
The Areal Locations of Hazardous Atmospheres (ALOHA)
model is a tool for estimating the movement and dispersion of
gases. The air model estimates pollutant concentrations
downwind from the source of a spill, taking into consider-
ation the toxicological and physical characteristics of the
spilled material. ALOHA also considers the physical char-
acteristics of the spill site, the atmospheric conditions, and
the circumstances of the release. Like many computer appli-
cations, it can solve problems rapidly and provides results in
a graphic, easy-to-use format. This can be helpful during an
emergency response or planning for such a response. Keep in
mind that ALOHA is only a tool whose usefulness depends
on your accurate interpretation of the data.
ALOHA originated as an in-house tool to aid in response
situations. In its original format it was based on a very simple
approach used in the Workbook on Atmospheric Dispersion
Estimates (Turner 1974). It has evolved over the years into a
tool used for a wide range of response, planning, and aca-
demic purposes. However, you must still rely on your own
common sense and experience when deciding how to re-
spond to a particular incident. There are some processes that
would be useful in a dispersion model that have not been
included in ALOHA because of extensive input and compu-
tational time requirements (e.g., topography). These model
limitations will be discussed in this manual as they come up.
2-1
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Chapter 2: Introduction to Air Modeling
Dispersion modeling
There are a number of different types of air dispersion models,
ranging from simple models that do not require a computer, to
complex three-dimensional models that require massive amounts
of input data and powerful computers. The type of model to be
used depends a good deal on the scale of the problem, the level of
detail available for input and required for output, the background
of the intended user, and the turnaround time needed for an
answer.
ALOHA was designed with first responders in mind. The model
is most helpful for estimating plume extent and concentration for
short-duration chemical accidents. It is not intended for use with
accidents involving radioactive chemicals. Nor is ALOHA in-
tended to be used for permitting of stack gas or chronic, low-level
("fugitive") emissions. There are a number of other models avail-
able that will address larger scale and/or air quality issues (Turner
and Bender 1986).
Since the first responder typically does not have a dispersion
modeling background, a guiding criterion in ALOHA's develop-
ment was that the data required for input be easily obtained or
estimated on-scene. ALOHA's extensive on-line help can assist
you in making appropriate choices.
What is dispersion?
Dispersion is a term used in modeling to include advection (mov-
ing) and diffusion (spread ing). The cloud of dispersing vapor will
generally move in a downwind direction and spread in a cross-
wind and vertical direction (crosswind is the direction perpen-
dicular to the wind). A heavy gas can also spread upwind to a
small extent. There are really two separate dispersion models in
ALOHA: Gaussian and heavy gas.
2-2
-------
Chapter 2: Introduction to Air Modeling
ALOHA uses a Gaussian dispersion model to describe the
movement and spreading of a gas that is neutrally buoyant
(approximately the same density as air). The Gaussian equa-
tion describes the bell-shaped curve that many teachers use in
grading. In this curve, there are always a few grades at the
high and low ends, but most are in the C range. This curve is
used to describe many other phenomena, including how a
contaminant will be dispersed in the air from the source of a
spill. Figures 2-1 and 2-2 show such a Gaussian distribution
produced by ALOHA.
Figure 2-1.
Gaussian
cfstiiMJlion.
i
-a.
o
J
Crosswind Distance
At the source of the spill,
the concentration of the
pollutant is very large and
the Gaussian distribution
looks like a spike or a tall
column (Figure 2-1). As
the pollutant drifts farther
downwind, it spreads out
and the "bell shape" gets
continually wider and
flatter (Figure 2-2).
Figure 2-2.
Gaussian spread.
CranwM
Source of Sfa/l
2-3
-------
Chapter 2: Introduction to Air Modeling
The model can produce a diagram that shows the top view of
the plume, called the plume's "footprint." This diagram
connects all the points of the same concentration (for ex-
ample, the Immediately Dangerous to Life and Health (IDLH)
concentration). The area inside the footprint is the region that
is predicted to have ground level concentrations above the
limit you set during the model run. Choosing this value
(often called the level of concern or LOG) is discussed in the
Options section of Chapter 5, The Display Menu.
The heavy gas dispersion calculations that are used in ALOHA
are those used in the DEGADIS model (Spicer and Havens
1989). This model was selected because of its general accep-
tance and the extensive testing that was carried out by the
authors. In order to speed up the computational procedures
and reduce the requirement for input data that would typi-
cally not be known in an emergency spill scenario, a few
simplifications were introduced into ALOHA-DEGADIS,
making it different from the initial model. These simplifica-
tions include:
D the initial momentum jet model for elevated sources
(OOMS) is not included. ALOHA-DEGADIS assumes that
all spills originate at ground level;
G the mathematical approximation procedures used for
solving the model's equations are faster, but less accurate
than those used in DEGADIS; and
O ALOHA-DEGADIS models sources for which the release
rate changes over time as a series of short, steady releases
rather than as a number of individual point source puffs.
2-4
-------
Chapter 2: Introduction to Air Modeling
Throughout the creation of ALOHA-DEGADIS, NOAA
worked closely with the original authors of DEGADIS to
ensure a faithful representation of DEGADIS model dynam-
ics.
ALOHA-DEGADIS was checked against DEGADIS to ensure
that only minor differences existed in results obtained from
both models.
Considering the typical inaccuracies common to emergency
response, these errors are probably not significant. In cases
where technical accuracy is required, you should obtain the
original DEGADIS model and use it to investigate the sce-
narios of interest.
There are some instances, however, when ALOHA's heavy
gas calculations may estimate that the footprint is much
larger than its actual size. In order to speed calculation of a
heavy gas footprint, each spill is treated as a continuous
release at the highest release rate estimated for the scenario.
When the source strength is calculated, it is broken into five
steps which represent the average rate of release for each
segment of time. For the overall footprint estimate, ALOHA's
heavy gas calculations use the highest of the five steps, which
means that it uses the highest possible rate in its calculations.
However, when estimating the dose and concentration curves,
the heavy gas calculations use all five varying time-
dependent rates.
2-5
-------
Chapter 2: Introduction to Air Modeling
These differences are particularly noticeable when you're
working with large, time-dependent releases, such as those
from pressurized tanks. For example, you may find that the
concentration curve for a location within the footprint is
actually below the footprint level of concern. An estimate of
source strength or footprint length is "conservative" if it is an
overestimate. When release rate changes, ALOHA's heavy
gas footprint will always be at least somewhat conservative,
and sometimes, too conservative. To get a more accurate
picture of the computed concentrations, examine the concen-
tration curves for a few locations within the footprint.
When a gas that is heavier than air is released, it initially
diffuses very differently than a neutrally buoyant gas. The
heavy gas will first "slump," or sink, because it is heavier
than the surrounding air. As the gas cloud moves downwind,
gravity makes it spread; this often causes some of the vapor
to travel upwind of the source. As the cloud becomes more
diluted and its density approaches that of air, it begins behav-
ing like a neutrally buoyant gas. This takes place when the
concentration of heavy gas in the surrounding air drops
below one percent. For many small spills, this will occur in
the first few tens of yards. For large spills, this may happen
much further downwind.
Figure 2-3.
Plums spread as a
resuft of gravity.
2-6
-------
Chapter 2: Introduction to Air Modeling
The classification of a gas as heavy is not always straightfor-
ward. The molecular weight of air is approximately 29 and
the density of air is approximately 1.1 kilograms per cubic
meter. Gases that have molecular weights greater than that of
air will be heavy if enough is released. If the density of the
gas is substantially greater than the density of the air, ALOHA
considers the gas to be heavy. Gases that are lighter than air
under normal conditions, but are being shipped in a cryo-
genic (low temperature) state, form a heavy gas cloud be-
cause they are very cold, and therefore dense, at the time of
their release (like anhydrous ammonia, for example).
ALOHA allows you to choose to always use the heavy gas
calculations, always use Gaussian calculations, or to let the
model decide. Do this by choosing Computational from the
SetUp menu (see Chapter 4).
There are instances when you may want to specify the calcu-
lation method rather than letting the model choose. Such
cases include:
DISPERSION CHOICES O Heavy gas calculations can take longer to complete than
^^^^""^^^^™ Gaussian ones, especially if you are running ALOHA on
a computer without a math coprocessor chip. If a very fast
turnaround is required, you may wish to run the Gaussian
module first and the heavy gas module when time allows.
O In the case of a gas that may be heavy because of how it is
stored (e.g., cryogenic), ALOHA will warn you that the
selected chemical may flash boil and/or result in two-
phase flow. In this case, ALOHA may default to the
Gaussian calculation. In such cases, you should re-run
ALOHA using the heavy gas calculations, and compare
the potential threat zones as represented by the two foot-
print estimates.
2-7
-------
Chapter 2: Introduction to Air Modeling
When used in a planning or training session or when time
is not an issue, consider running some scenarios using
both the heavy gas and Gaussian modules. This will give
you a feel for how the models compare.
Use Caution
Be cautious when interpreting any model's results. Remem-
ber that these results are only as good as the information
you gave the model to work with. They reflect the amount of
guesswork that went into your input. Any model requires
accurate data from you in order to come up with valid esti-
mates. For example/ if you find that you don't know the exact
wind speed or temperature, and are instead doing a lot of
guessing, the information that you give ALOHA to work with
may not represent actual conditions. If this is the case, you
can't expect ALOHA's output to reflect what is really going
on.
ALOHA's results are only as
good as your input
In addition, ALOHA's calculations become significantly less
reliable in certain situations, even though you may be provid-
ing accurate input. In particular, pay careful attention to
these situations:
O very low wind speeds
G very stable atmospheric conditions
O wind shifts and terrain steering effects
O concentration patchiness, particularly near the spill source.
ALOHA doesn't take into account the effects of:
O fires or chemical reaction by-products
O particulates
O topography
CAUTION
ALOHA DOESNT
CONSIDER
2-8
-------
Chapter 2: Introduction to Air Modeling
Very low wind speeds
As the wind speed decreases, the wind direction may become
very inconsistent. ALOHA warns you in two ways that low
wind speeds may lead to problems.
First, ALOHA does not allow you to enter a wind speed that
is less than two knots (one meter per second). If you try to use
a wind speed of less than two knots, ALOHA tells you that the
wind speed is too low and forces you to reset the speed to a
minimum of two knots before you can continue.
Second, as the wind speed decreases towards two knots, the
"confidence" or "uncertainty" lines drawn around the foot-
print form a circle (see Footprint in Chapter 4, The SetUp
Menu), indicating that changes in wind direction may move
the chemical cloud in any direction.
Very stable atmospheric conditions
Very stable atmospheric conditions intensify the uncertainties
discussed above. Under the most stable atmospheric condi-
tions, there will often be very little wind at all. This situation
will usually occur late at night or during the early morning.
In these conditions, there is almost no mixing of the pollutant
into the surrounding "clean" air; none of this air is entrained,
or mixed, into the toxic cloud.
In a very stable atmosphere, the chemical cloud will spread
out in the same manner as cream poured into a coffee cup.
The cream will dilute and spread slowly into the coffee, but,
until you stir it, will take a very long time to mix completely
into the coffee. In the same way, a cloud will spread slowly
under very stable atmospheric conditions. Terrain features,
such as small valleys or depressions, may trap the gas until
wind and hence, mixing, is introduced.
2-9
-------
Chapter 2: Introduction to Air Modeling
These processes may lead to high concentrations of the gas
remaining for a long period of time and/or remaining even at
large distances from the spill source. The Bhopal, India,
accident involving the release of methyl isocyanate is an
example of what can happen under very stable atmospheric
conditions. Thousands of people died,-some of whom who
were quite a distance from the release.
For the first responder, a very stable atmosphere should send
up a flag: this is a dangerous situation where models are not
very reliable. To counter this situation, think about whether
the chemical will behave as a heavy gas; look for physical
depressions and topographic features that may trap or steer
the dispersing cloud.
Wind shifts and terrain steering effects
ALOHA allows you to enter only one wind speed and direc-
tion; this may not accurately describe conditions over the
entire affected area. For example, areas with hills or valleys
may experience wind shifts where the wind actually flows
between the hills or down into the valleys, turning where
these features turn. Since ALOHA does not account for shifts
in wind direction, the footprint it calculates will not reflect
these turns (Figure 2-4).
Figure 2-4.
Wind shifts
2-10
-------
Chapter 2: Introduction to Air Modeling
Figure 2-5.
Small-scale variations
in wind direction.
Recognizing the probability of wind shifts over distance and
time, ALOHA has set limits on the duration of a release and
size of a footprint. Though ALOHA will not draw any plume
longer than 10 km (6.4 miles), as a general rule, you should
think that any footprint more than a few miles long may be
influenced by variations in the wind direction. Similarly,
ALOHA only models the first 60 minutes of a release. After
that time, meteorological conditions are likely to have
changed.
Another important limitation of the air model is that it does
not resolve small-scale variations in the wind caused by
obstacles (Figure 2-5).
Wind flowing around large obstacles will create eddies and
unstable wind shifts; these can significantly change a cloud's
shape. For example, in an urban area with high-rise build-
ings, the wind patterns at ground level are totally controlled
by the through streets. These streets may generate a "street
canyon" wind pattern. ALOHA's footprint will appear to go
right over, or through, obstacles like these. Remember these
limitations when you're interpreting model results.
2-11
-------
Chapter 2: Introduction to Air Modeling
Concentration patchiness
ALOHA doesn't accurately represent variations associated
with near-fie Id (close to the spill source) patchiness. In the
case of a neutrally buoyant gas (which would be modeled
using Gaussian calculations), the vapor cloud will move down-
wind. Very near the source, however, the cloud can be
oriented in quite a different direction.
This kind of movement is familiar to anyone who has tried to
toast marshmallows over a campfire (you know—no matter
where you sit, the smoke from the fire always seems to come
straight towards you). In fact, what you see in a case like this
is the effect of individual drifting eddies in the wind, pushing
the cloud from side to side (Figure 2-6). These eddies, or
small gusts, are also responsible for much of the mixing that
makes the cloud spread out. As the pollutant drifts down-
wind from the spill source, these eddies shift and spread the
cloud until it takes on the form of a Gaussian distribution.
Figure 2-6.
Concentration
patchiness close to
the source.
2-12
-------
Chapter 2: Introduction to Air Modeling
In the case of a heavy gas, concentration patchiness still
occurs, though it is combined with the slumping and spread-
ing processes caused by gravity (see page 2-8).
ALOHA does not model...
...fires or chemical reactions
The smoke from a fire rises due to thermal energy, then moves
downwind. This rise is based on many factors which are not
considered by ALOHA. In addition, ALOHA does not ad-
dress the by-products resulting from fires or chemical reac-
tions.
WARNING Be careful that the chemical you select to model reflects the
^^••M chemical that is actually being released to the air in your
scenario. For example, when aluminum phosphide comes in
contact with water, it releases phosphine gas. If you wish
ALOHA to estimate a footprint associated with aluminum
phosphide, you will need to know the reaction rate and how
much phosphine is being generated.
...particulates
ALOHA does not include the processes needed to model
particulates.
...solutions and mixtures
At this time, the chemical database contains pure compounds
only. If you know the chemical properties (e.g., vapor pres-
sure, normal boiling point) for a mixture or solution, you may
enter these data and use ALOHA.
...topography
ALOHA does not consider the shape of the ground under the
spill or in the area affected by the pollutant. This can be
particularly important if a liquid is spilled onto a sloping
surface.
2-13
-------
-------
Chapter 3
The File and Edit Menus
In this chapter...
The File Menu 3-1
ALOHA Save Files 3-2
AlohaSpy 3-2
The Edit Menu 3-4
Introduction
With several important exceptions, the File and Edit menus
in ALOHA work in the same way as in other applications.
These exceptions are described below.
The File Menu
New
allows you to reset ALOHA before
beginning a new scenario. When you
choose this menu item, you will have
the option to save your old scenario
before resetting ALOHA.
New
Open...
86N
960
Close
Saue 3iS
Saue fls...
Page Setup...
Print... §6P
Print fill...
Quit
Open...
allows you to open an ALOHA save
file which you previously created
using the Save As... menu item (see
below).
Close
closes ALOHA's front window. You cannot close the Text
Summary window.
3-1
-------
Chapter 3: The File and Edit Menus
Save and Save As...
allows you to create and save
ALOHA save files and Spy
window archive files.
Snue Bi Bptlom
Select
format [ Help ]
M.OHH sane file
Mrchlue window* to
display from RlohoSpy
Cancel 1
ALOHA save files
If you have information
about chemical storage facili-
ties in your area, you can pre-
pare in advance for a spill response by creating a set of ALOHA
save files. You can store some information about the characteris-
tics of a spill in such files, thereby saving time during an actual
incident.
Remember, though, that because these files are intended for use
in spill response, not all information about a scenario will be
saved into an ALOHA save file. Information that is not expected
to change from day to day will be saved, including location,
chemical of concern, and dimensions of existing storage vessels
and containment areas. You'll still need to enter information
specific to a particular spill, including weather conditions and
size of the spill, when you use an ALOHA save file.
SPY files
You may also archive the results of an ALOHA model run as a SPY
file. These files will be useful to you whenever you wish to
document your results. A SPY file contains all the information
from the windows visible in ALOHA at the time the file was
saved. SPY files can be viewed and printed from ALOHA's
companion application, AlohaSpy (see Appendix C).
Figure 3-1.
ALOHA Save options.
3-2
-------
Chapter 3: The File and Edit Menus
Creating new files
To create an ALOHA save file, choose Save As... from the File
menu, then choose ALOHA from the Save As Options dialog,
type in a file name, and click OK. Now, when you enter new
information about the scenario into ALOHA, you can simply
choose Save to update this file.
Before creating a SPY file, be sure that all windows you'd like
to archive are visible. Then choose Save As... from the File
menu, choose SPY from the Save As Options dialog, type in a
file name, and click OK. You can use AlohaSpy to open, view,
and print the new SPY file.
Print...
prints the contents of the front ALOHA window.
PrintAII...
prints the contents of all visible ALOHA windows.
Quit (or Exit)
ALOHA saves your choice of location upon quitting the
application. Remember that if you wish to save the scenario
information for later use, select Save As... from the File menu
before quitting.
3-3
-------
Chapter 3: The File and Edit Menus
Cut %K
Copy 96C
The Edit Menu
Copy
allows you to copy pictures or selected
text from the front window to the clip-
board. This allows you to paste selected
items into a word processing or graphics
application.
Note
The Undo, Cut, Paste, and Clear menu items are not available
in ALOHA.
3-4
-------
Chapter 4
The SiteData Menu
In this chapter^
Location 4-1
Adding 4-3
Modifying 4-6
Deleting 4-7
Building Type 4-7
Date & Time 4-9
The SiteData menu is the first menu in ALOHA where you
enter information. There are four items where you can give
ALOHA information about your spill situation:
O geographic location;
O the building type in the area of the spill; and
O date and time of the spill.
Figure 4-1.
The SiteData menu.
SiteData
Location...
Building Type..
Date & Time...
Location
Here, you tell ALOHA the actual geographic location of your
spill. Once you have selected Location, you can type in the
initial letter of the location and move to the first city begin-
ning with that letter, or you can scroll to the location. To
choose a location for the incident, double-click on the location
you wish, or click on it once and then click the Select button.
If the city or location you are interested in isn't on the list, you
can add it. We explain how to add a city later in this chapter.
4-1
-------
Chapter 4: The SiteData Menu
ALOHA currently uses location information to calculate:
G the angle of the sun (ALOHA looks at latitude, longitude, and
time of day for this calculation), and
O the atmospheric pressure (ALOHA bases this on the location's
elevation).
The angle of the sun becomes important when a chemical has
formed a puddle on the ground. ALOHA will calculate the
amount of energy coming into the puddle from the atmosphere
and from the ground. For example, if the sun is high in the sky, the
amount of energy coming into the puddle is greater than it would
be in the early morning or late afternoon, when the sun is lower.
The more energy coming in, the higher the evaporation rate.
The model is not very sensitive to small errors in the location
information. If you are in a situation where you must guess at this
information, an estimate will be adequate if it is within one degree
in latitude and longitude, and a few hundred feet in elevation, of
the actual site.
Let's run through an example in which you'll add, modify, and
delete two cities, one in the U.S. and one outside the U.S. To begin,
choose Location from the SiteData menu. You see a scrolling
index of locations (mostly U.S. cities and towns).
4-2
-------
Chapter 4: The Sit eD at a Menu
Figure 4-2.
Location index.
Location Information
• HHlHUttN. MHBVLHND S
ABILENE, TEKRS
RIKEN, SOUIH CAROL INfl
RLRMEDA, CALIFOHNIfl
HLBRNV, NEW YORK
HLBHNV, OREGON
ALEXANDRIA BRV. NEW YORK
BLEKRNDRIR, LOUISIRNR
RLEHRNORIR, UIRGINIR
HLLEN, TEHHS
RMBLER, PENNSYLVANIA
RMES, IOIVR
RMESBURV, MASSACHUSETTS
RNACONDA, MONTANA
RNRHEIM, CRLIFORNIfl
ANN RHBOR, MICHIGAN
RALEE, MONTANA
ARLINGTON. TEMRS
1
1
1
«
<>
^^^"^^^
USSJ
[ Cancel ]
[ Rdd ]
[ Modify ]
[ Delete ]
[ Help ]
Figure 4-3.
Adding a U.S.
location.
Adding a U.S. location
Since Jupiter, Florida is not included in this index, click Add.
Type in the city name, its approximate elevation, and its
latitude and longitude (Figure 4-3).
Location Input
Enter full location name:
Location is Jupiter
Is location In o U.S. stole or territory?
® In U.S. O Not In U.S.
Select stote or territory
Enter approximate elevation
1 ® f t O m
Elevation is
SO
Enter approKimote location
deg. min.
Latitude
Longitude I BO
RLAAAMfl
ALASKA
RAIZONA
ARKANSAS
CALIFORNIA
COLORADO
CONNECTICUT
DEL AWARE
BIST OF COLUMBIA
Next, select Florida from the scrolling list of U.S. states and
trust territories. ALOHA checks that the information you
have entered is within the range of reasonable values for
Florida. (If you have entered a value that is not in the valid
4-3
-------
Chapter 4: The SiteData Menu
range, ALOHA will tell you which value is out of range; you
must correct this value before you can continue). Click OK.
Provided all of your input was within the acceptable ranges
for Florida, you return to the scrolling city index screen.
Jupiter, Florida appears al: the top of this screen. If you click
Cancel at this point, the information you added on Jupiter
will disappear and the city name will be removed. To save
this information, you must Select a location.
Figure 4-4.
Location index with
Jtpter, Florida.
If you enter a city in a state with multiple time zones (e.g.,
Indiana), you may see another set of dialog boxes asking you
to select the appropriate time zone.
NOTE
4-4
-------
Chapter 4: The SiteData Menu
Figure 4-5.
Adding a non-U.S. city.
Adding a location outside the U.S.
We'll use Hamilton, Bermuda as our example here. To add a
city or town that is not located in the U.S., click Add and type
in the name of the location without its country (you'll be asked
for that next). Click Not in U.S. Notice that the scrolling list
of U.S. states and territories disappears from the right side of
the window (Figure 4-5). Enter the approximate elevation,
and latitude and longitude coordinates, and click OK.
Location Input
Enter full location name:
Location Is Hamilton
Is location In a U.S. state or territory?
O m U.S. ® Not in U.S.
Enter approximate elevation
Eleuatlon Is fu~
Enter approHimate location
dag. mln.
Latitude 132 | |l8 | ®N OS
Longitude 164
Help
You should next see the Foreign Location Input dialog box
(Figure 4-6). Now, type in the name of the country and the
time difference between Greenwich Mean Time (GMT) and
the local standard time. The GMT offset must be entered with
a negative sign if the time difference is in hours behind GMT.
If you don't enter a sign, ALOHA assumes that the time
difference is positive. Finally, decide whether the time that
you want ALOHA to use in its calculations here is Standard
Time or Daylight Savings Time.
4-5
-------
Chapter 4: The Sit eD at a Menu
Foreign Location Input
Country name: | Bermuda
Offset from local STHNOHRO time to GMT: 2
Is current model time
time?
O Standard Time
hours
standard or daylight sailings
(i) Daylight Sailings Time
Cancel ] Hel
P
Figure 4-6.
Adding a foreign country.
Although ALOHA will automatically switch U.S. cities from
Standard to Daylight Savings Time (based on the date), the
time change for foreign locations will not be corrected auto-
matically .
When you click OK, you'll see that Hamilton, Bermuda has
been added to the location index:
WARNING
ftMUN, TEHAS
ftMMOND, INDIHNR
Figure 4-7.
Location index with
foreign addition.
Modifying a location
To change information that you've already entered for a
location, click Modify on the Location Information screen
(Figure 4-4). You will see the information that is currently in
CityLib. Select the item that you wish to change and type in
the new value.
4-6
-------
Chapter 4: The SiteData. Menu
Figure 4-8.
City deletion caution.
WARNING
Deleting a location
To remove a location from the index, select the location on the
list, and click Delete. ALOHA will ask you if you're sure that
you want to remove this location. At this point, you can
change your mind by clicking Cancel, or proceed with re-
moving the location from the list by clicking OK.
Caution !
Vou are about to delete a city permanently
from the city library, neuer to appear
again. Select OK if this is what you really
want to do. Otherwise cancel.
c
OK
J
If you've made a mistake and deleted the wrong city, your
only option at this point is to click Cancel. If you close the
Location dialog box and move on to the next menu item, the
city is permanently deleted.
Building Type
You can specify the type of buildings in the area of the spill.
ALOHA uses this information, together with data such as the
outside wind speed and temperature, to determine the rate at
which the chemical will infiltrate the buildings.
If you select a single or double-storied building, ALOHA will
use a default value to calculate the number of air exchanges
per hour (Wilson 1987). If you select Enclosed office build-
ing, ALOHA assumes that the air exchange rate is controlled
4-7
-------
Chapter 4: The SiteData Menu
and sets a default value based on the number of air exchanges
an average enclosed building would require to keep the
inside air from being "stuffy."
Infiltration Building Parameters
Select building type or enter eHChahge parameter
O Enclosed office building
<*) Single storied building
O Double storied building
O No. of air changes is
Help
per hour
Select building surroundings
Help 1
<§> Sheltered surroundings (trees, bushes, etc.)
O Unsheltered surroundings
I
J
Cancel
Figure 4-9.
Building parameters.
If you know the number of times per hour that the total air
volume within the building is replaced, enter this number
next to No. of air changes. You can use this to compare the
effects of different air exchange rates.
Unless you have specified the number of air changes or have
chosen Enclosed office building, you will need to tell ALOHA
whether the surrounding area is sheltered or unsheltered.
Sheltered surroundings will reduce the rate at which the
chemical can infiltrate the buildings. Below are some guide-
lines for choosing sheltered or unsheltered surroundings.
4-8
-------
Chapter 4: The SiteData Menu
If the buildings...
...are surrounded by trees or
other buildings in the
direction from which the
chemical cloud will be coming
...are in an open space, with
nothing near it
...if you are unsure
Click...
Sheltered surroundings
Unsheltered surroundings
Unsheltered surroundings.
Date & Time
Now enter the date and time of the spill. If you don't select
Date & Time, ALOHA will use the time on your computer's
internal clock to run your scenario. If the time on your
computer's clock is incorrect, reset the time on the Control
Panel. This time may be important as some of the calculations
ALOHA will do depend on the time of day.
Figure 4-10.
Date and time
options.
Date and Time Options
Vou can either use the computer's internal clock for the
model's date and time or set a constant date and time.
<•> Use internal clock O Set constant time
Internal Clock Time is:
Friflpr 17 13:27:41 1992
Cancel J
Help
4-9
-------
Chapter 4: The SiteData Menu
Set constant time lets you specify when you want the sce-
nario to begin. This is useful for contingency planning or
training exercises because you can set up scenarios to run at
different times of the day and/or year (and therefore under
different environmental and atmospheric conditions). The
computer's internal clock time will be automatically filled in
when you choose this option. You may then change any of the
values.
!•'•" • i — • =** Date
and Time Options
Vou can either use the computer's internal clock for the
model's date and time or set a constant date and time.
O Use internal clock <•> Set constant time
Inf
1
tut constant date
Month Day
4
(1-12)
( OK
27
(1-31)
||
a
nd time
Year
1990
Hour
115
Minute
1 15
[1900-...) (0-23) (0-59)
Cancel ]
Help ]
Figure 4-11.
Setting constant time.
4-10
-------
Chapters
In this chapter..
The SetUp Menu
Chemical 5-2
Chemical data 5-3
Adding 5-5
Modifying 5-7 After you've entere(j the information under the SiteData
anging a a 5-y menu, you need to select a chemical, set the atmospheric
mosp eric 5- conditions, and specify the type of source in your spill sce-
Userlnput 5*12 nario. These options are found under the SetUp menu. In
a lon addition, you can specify the type of computations that you
ource want ALOHA to use to calculate dispersion and dose.
Direct 5-31
e You should select the menu items in descending order.
T 5"3 Although you can select the Chemical and Atmospheric
Pipe 5-43
F items at any time, the Source option cannot be selected until
Computational 5-46 you have fmed jn thg Chemical and Atmospheric data.
Figure 5-1.
The SetUp menu.
Chemical...
RtmosDlteric
Source
User Input...
SRM Station..
Computational...
Chemical...
Rtmospherk >
Source t
Computational.
Direct..,
Puddle.
Tank...
Pipe...
5-1
-------
Chapter 5: The SetUp Menu
Chemical
Select Chemical from the SetUp menu to access a scrollable list of
the chemicals included in ALOHA's chemical library, ChemLib
(Figure 5-2). About 700 pure chemicals are included in the library.
No chemical mixtures are included in ALOHA's library, nor are
any chemicals with unstable structures, nor any chemicals of such
low volatility that they don't represent air dispersion hazards
(i.e., solids or liquids with very low vapor pressures). Chemicals
may be added to the library or deleted from it, and property
information about any chemical may be modified.
Chemical Information
flCFTHIDEHVDE
ACETIC RCID
ACETIC flNHVDfllDE
RCETONE
ACETONE CVHNOHVDRIN
RCETONITRILE
flCETVL BROMIDE
flCETYl CHLORIDE
HCETVLENE
RCETVLENE TETRRBROMIDE
flCETVL IODIDE
HCETVL METHVL CHRBINOL
RCROU1N
RCRVLIC RCIO
RCRVLONITRUE
HCRVLVL CHLORIDE
ROIPICRCIO
HDIPONITHILE
Cancel
Rdd ]
[ Modify
Help
Figure 5-2.
Chemical index.
Selecting a Chemical
Select a chemical by scrolling through the list until you find its
name, clicking on the name, and choosing Select. You can search
rapidly through the list by typing in the first few letters of the
chemical name. Once you have selected a chemical, you'll see
some of the most important properties of the chemical listed in the
Text Summary window (Figure 5-4).
5-2
-------
Chapter 5: The SetUp Menu
Chemical Data
The chemical library includes information about the physical
properties of each ALOHA chemical. The library also in-
cludes values for the IDLH (Immediately Dangerous to Life
and Health) and TLV-TWA (Threshold Limit Value - Time-
Weighted Average) toxic thresholds.
The ALOHA library contains information from two sources.
When available, information was obtained from a chemical
database compiled by the Design Institute for Physical Prop-
erties Data (DIPPR), known as the DIPPR database (Daubert
and Danner 1989). Additional property values were obtained
from the chemical database included in the Computer-Aided
Management of Emergency Operations (CAMEO™) hazard-
ous chemical information system (National Oceanic and
Atmospheric Administration 1992).
ALOHA uses information from the library to model the physi-
cal behavior of a chemical that you have selected. For ex-
ample, once ALOHA knows the temperature within a tank, it
can use library information to estimate the vapor pressure,
density, and other properties of the chemical stored in the
tank.
You need only the name of a chemical and its molecular
weight to run ALOHA, but you will be able to use only the
Direct source option and Gaussian dispersion module. You
will need values for additional chemical properties to make
source calculations using the Tank, Puddle, or Pipe source
options or to make heavy gas calculations. Check Table 5-1
for the properties necessary to use each option.
5-3
-------
Chapter 5: The SetUp Menu
Refer carefully to Table 5-1 before adding property informa-
tion about a chemical. ALOHA's chemical library contains a
few data fields for properties that the model either estimates
itself or does not currently use (we anticipate that these
properties may be useful in a future version of ALOHA).
Adding values for these properties will have no effect on
source or dispersion calculations, and you won't need to add
values for them to run any ALOHA calculation.
Gaussian Haavy Gas
Property
Chemical
name
Molecular
weight
Normal
boiling point
Critical
preMuie
Critical
temperature
Density ,
con«L presa.)
Heat cap. (liq,.
eontt. preu.)
Vapor premue
*
Direct Puddle Tenk Pipe
* •> * *
»> «> .$, •;*
O * * *
O * * *
O * * *
* *
* + *
* *
Direct Puddle Tank Pip*
«{« »J« .> .J*
<» »> ^ •>
*>•>*>«>
O C» G» C&
O °* c» c»
* * •> •»
•> «>
* * * *
* *
«j> c» e» c»
Required properties for entering a new chemical
(~) Only needed if the WMIKC i* given in unite of volume
c^ Either critical prcMure and critical 1
to be entered
,
Rnperature or vapor presaun need
Table 5-1.
Chemical properties
needed to use each
ALOHA source and
dspersion option.
5-4
-------
Chapter 5: The SetUp Menu
These properties are:
O Critical molar volume
O Diffusivity (molecular and thermal)
CJ Heat of vaporization
O Density (liquid)
O Heat capacity (gas at constant volume)
O Kinematic viscosity (gas and liquid)
Adding a chemical
You may add a chemical to the library either temporarily
(from within ALOHA) or permanently (using ALOH A's com-
panion application, ChemManager). You must know at least
the name and molecular weight of each chemical that you
add. You may add as many chemicals as you like to the
library.
Here's how to add an example chemical, argon, to the library
temporarily:
Choose Chemical from the SetUp menu, then click Add.
Type "ARGON" in the Chemical Name field. Next, type in
39.95 in the molecular weight field (Figure 5-3). To enter
additional property values, click on the name of the property
Figure 5-3.
Adding a chemical.
)»mltu («•>
Krtlf)
llMC*r
-------
Chapter 5: The Setup Menu
in the scrolling list (or click on Next Field until the property
name is highlighted). Enter property values in the appropri-
ate data fields, and choose appropriate units from the corre-
sponding popup menus.
You must add a reference temperature and pressure for all
properties which change their value when temperature or
pressure change. Click on Heat Capacity (gas, constant
pressure) and enter the value 520.3 J/kg K at 294 K and 1 atm
pressure.
Once you have entered all information about the new chemi-
cal, click OK. You'll be returned to the chemical index. Click
Select to select the chemical that you've just added.
Chemicals that you add from within ALOHA will be deleted
from the library when you quit from the program. Use
ChernManager (see below) to add chemicals permanently to
the library.
Review the Text Summary screen for useful information about
each chemical you've selected, added, or modified. For ex-
ample, when only the name and molecular weight of argon
have been added to the library, a note will appear on the Text
Summary window: "Not enough chemical information to use
the Heavy Gas option." This note alerts you that, although
T«Mt Summary
SITE onrn i women on
Locution PtMTUWO, OREGON
Building Air Cxchang« Pw How :.34 <9wlUr*d *ingl« «tori«J>
Oat* * TIM: *IXMI at NovMbor 17, 1M2 t 1430 hour.
CtCMICM. InFOnmTIOM:
Otwieal NOM: AflGON noIocular H«loM: M.W
1W-TUR: -unovoil- IOLH: -unovoll-
Footprint Law*I of Goncwn: ftuJi to b* Ml tafor* footprint MlKtio
•oiling Point: -303.53* F
Uojw h»«Mw« dt Mblont TMptratw*: gpMUr than I aim
ftatolint Salivation Cancan trot I on: 1,000.000 pa> or 100.M
HoU: Hot «naugn ehMleal data te UM Hwwy Oac option
Text Summary
window.
5-6
-------
Chapter 5: The SetUp Menu
argon's molecular weight is heavier than 29 kg/kmol, the
molecular weight of air, so that it may behave like a heavy
gas, ALOHA will have to use Gaussian dispersion calcula-
tions (unless you add additional property information).
Also, when you select a chemical which has been identified as
a confirmed, potential, or suspected carcinogen, a notation,
"Note: Potential or suspected human carcinogen," will ap-
pear on the Text Summary screen under the Chemical Infor-
mation heading.
Modifying a chemical
You may modify information about a chemical already in
ALOHA's library, or about a chemical that you have previ-
ously added. You can make either temporary (from within
ALOHA) or permanent (using ChemManager) modifications.
Here's how to temporarily modify information about argon,
which you just added to the library. You'll add the properties
necessary to run the heavy gas option.
First, choose Chemical from the SetUp menu. Scroll through
the chemical index until you find "ARGON" (or type the
letters " AR" for a faster search). Select argon and click on the
Modify button.
Figure 5-5.
Chemical index.
Chemical Information
HHSENIC TRICHLORIDE
RHINE
BCNZRLDCHYDE
Go through the same steps to modify a chemical property
value that you used to add values for a new chemical. Click
on the name of the property in the scrolling list (or click the
5-7
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Chapters: The SetUp Menu
Next Field button until you've highlighted the property
name). Enter property values in the appropriate data fields,
or modify existing values, and choose appropriate units from
the corresponding popup menus.
The first property in the scrolling list is Normal Boiling
Point Click on this property name, then enter "87.28" into
the empty data field, and choose Kelvin from the temperature
units menu. Next, click on Critical Temperature, and enter
the value 150.86 Kelvin. Click on Critical Pressure, and enter
the value 4,898,100 Pa. Click on Density (gas) and enter the
value 1.659 kg/m3at 294 K and 1 atm pressure.
You cannot modify all property values for ALOHA chemicals
already included in the library. Values that you cannot
modify, and their units, appear grayed-out. These are values
that ALOHA calculates internally, using either values for the
chemical's critical properties (molecular weight, boiling point,
critical temperature, and critical pressure) or information
from the DIPPR database. If you would like to use your own
property values for an ALOHA chemical, add the chemical
using a slightly different name (such as "CHLORINE-2"), and
enter your own values in the new data fields.
Modifications that you've made from within ALOHA will be
deleted from the library when you quit from the program.
Use ChemManager (see below) to permanently modify the
library.
Making permanent changes with ChemManager
You can use ChemManager to make permanent changes to
ALOHA's chemical library. To use this application, first quit
from ALOHA, then double-click on the ChemManager icon.
You'll see a screen very like the one that appears when you
choose Chemical from ALOHA's SetUp menu.
Notal ALOHA chemical
properties can be modified
5-8
-------
Chapter 5; The SetUp Menu
To add a chemical to the library, click Add. Then follow the
same steps used to temporarily add a chemical from within
ALOHA. First, type in the name of the chemical and its
molecular weight (you'll absolutely need these two pieces of
information). Then add values for all other properties that
you'll need to run ALOHA (check Table 5-1 to see which
properties are necessary for ALOHA's various source and
dispersion options). Be sure to add values for reference
temperature and pressure when these are needed
(ChemManager will remind you if you don't). When you're
finished, click OK to make your new chemical a permanent
part of ALOHA's library. Click Cancel to avoid adding the
chemical.
To modify a chemical, select the chemical from the scrolling
list of chemical names, then click Modify. Follow the same
steps used to make temporary modifications from within
ALOHA; make modifications to existing information, or add
new information to data fields. Remember that you cannot
change information in any grayed-out data fields; this infor-
mation is internally calculated by ALOHA. When you're
finished, click OK to make your permanent changes to
ALOHA's library. Click Cancel to avoid making these
changes.
To delete a chemical, select the chemical from the scrolling
list of chemical names, then click Delete. Click OK to delete
the chemical permanently from ALOHA's library. Click
Cancel to avoid deleting this chemical.
Remember that when you click OK within ChemManager,
you're making a permanent change to the ALOHA chemical
library. Be sure that you are entering accurate information.
To exit ChemManager without making permanent changes to
the library, click Cancel.
5-9
-------
Chapter 5: The SetUp Menu
Changes made to ALOHA's chemical library from within
ALOHA will not be saved when you exit from ALOHA. Use
ChemManager to make permanent changes to the library (see
below). To save any changes you've made to an ALOHA
chemical without making permanent changes to ALOHA's
chemical library, choose Save from the File menu
(Figure 5-6), and save this scenario as an ALOHA file (see
Appendix C for more on saving files using AlohaSpy). Any
modifications you have made to your chemical will be saved
in this file, which you can reopen from within ALOHA at any
time.
Saue Rs Options
Select saue format [ Help
RLOHR 11 RLOHR $aue file
SPY
Rrchiue windows to
display from RlohaSpy
Cancel
Figure 5-6.
Saving changes.
When you reopen an ALOHA file, the model will use the
modified chemical properties contained in the file to make
source and dispersion calculations. However, if you again
select (via the Chemical menu item) the chemical that you
previously modified, then the changes you made will be
replaced by information stored in the chemical library. Choose
Open... from the File menu and reopen your saved ALOHA
file whenever you want to run a scenario using the modified
chemical information included in the file.
5-10
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Chapter 5: The SetUp Menu
It is important to review the Text Summary screen. In our
example, a note appears with the chemical information: Not
enough chemical data to use Heavy Gas option (Figure 5-4).
This tells you that, although the vapors may behave like a
heavy gas, the model will have to use the Gaussian calcula-
tions. You can also see from the text summary screen that the
substance is a gas (the boiling point is well below the air
temperature). Argon is a simple asphyxiant; no IDLH or TLV-
TWA value has been assigned to it.
Atmospheric
The processes that ALOHA considers to move and disperse a
pollutant cloud include atmospheric heating and mechanical
stirring, low-level inversions, wind speed and direction,
ground roughness, and air temperature. Each of these pro-
cesses will be discussed in detail below.
Figure 5-7.
Atmospheric menu.
SOU* <
Computational...
User Input...
SflM Station..
You can enter atmospheric data into ALOHA in two ways:
O User Input..., which you use if you know weather and
wind conditions, or
O SAM Station..., which you use if you want real-time
weather data fed directly to ALOHA from a Station for
Atmospheric Measurements (SAM).
5-11
-------
Chapter 5: The SetUp Menu
User Input...
Here, you enter information about the atmospheric environ-
ment and the ground roughness at the spill site. This in-
cludes:
O stability class O ground roughness
O inversion height O cloud cover
O wind speed and direction O relative humidity
O air temperature
1. Stability class
There are principally two processes, heating and mechanical
stirring, that can affect mixing in the lower atmosphere.
a) Heating
Heating the atmosphere near the ground leads to the most
unstable conditions. Think about what happens to a pan of
water that you're heating on the stove. As heat is added to the
bottom of the pan, the bottom-heated water rises and mixes as
it moves toward the surface. As the heating becomes more
intense, so does the mixing.
This same type of heating happens in the atmosphere. On hot
summer days, the sun will heat up the ground and warm the
lower atmosphere. The lower air rises as it warms, tumbling
and mixing as it goes. Remember looking out over a dark
parking lot on a hot summer day and seeing the air seem to
shimmer? This shimmer is caused by thermal mixing.
Just as air that is warmed rises if it is warmer than the
surrounding air, air that is cooled sinks, or stays trapped in
the lower level of the atmosphere. The opposite extreme of
intense heating is intense cooling; rapid cooling of the ground
leads to the most stable atmospheric conditions. Cooling of
5-12
-------
Chapter 5: The SetUp Menu
the ground causes the lower layer of air to cool and become
more dense, making it very stable with little tendency to mix.
Clear, calm nights are a prime time for this type of intense
cooling to take place; for example, weather conditions where
you might expect a quick frost or low ground fog to develop.
These very stable conditions make for a very large threat zone
(see page 2-11). Very stable air is usually seen in the late night
or early morning hours.
b) Mechanical stirring
The second factor affecting stability in the lower atmosphere
is mechanical stirring caused by the wind. As the wind blows,
the friction caused by the earth slows down the air movement
closest to the surface. Air layers near the ground tend to mix
and tumble as they glide past each other at different speeds.
The stronger the wind, the more effective this stirring mecha-
nism becomes.
Mechanical stirring not only mixes up the air, it also disturbs
the temperature layers created by intense heating or cooling.
This secondary effect of mechanical mixing causes what may
at first seem like a contradiction: it mixes up very stable, cool,
ground layers, making conditions less stable. In the same
way, it mixes up very unstable warm layers, making condi-
tions more stable. The net effect of stirring mechanisms such
as strong winds is that they reduce the possibility of either
very stable or very unstable air so that all strong wind cases
tend to be in the intermediate (neutral) range of stability.
Meteorologists typically summarize atmospheric stability by
specifying the stability class in terms of a letter, ranging from
A to F. With A being the most unstable and F the most stable
conditions, you will use the same letter code in the air model
to specify the relationship of stability class, heating, and
wind speed at your spill site (Figure 5-8).
5-13
-------
Chapter 5: The SetUp Menu
B
F»
WEAK WINDS
9TRON6 WINDS
I WEAK WINDS
INICHT
| COOLIN6
(GJIOUNO TRAPPING)
f*
^(GOQO MIXING)
'In the very rare case, stability class F may have stronger winds.
Figure 5-8.
Stzbttydassand
mbong of a poUutant
cbud
Stability class is the first atmospheric condition that you enter
in ALOHA. You choose the single letter that best represents
the weather conditions present at your spill site. Using our
example from Figure 5-9 and Table 5-2 below, you would
choose C or D for your stability class because the wind speed
is between 11 and 13 knots. (You can see Table 5-2 while
you're running ALOHA by clicking the Help button next to
Stability Class on the Atmospheric Options screen or by
looking at the Stability Class topic in the Help index.) ALOHA
uses stability class information to classify the amount of
mixing occurring in the atmosphere. To dilute a cloud of toxic
gas, unstable (lots of mixing) conditions give shorter threat
distances than would stable (very little mixing) conditions.
The cloud is diluted faster when conditions are unstable.
2. Inversion height
Under normal conditions, as you move up in the atmosphere,
the air gets cooler. An inversion occurs when cooler air is at
the ground and warmer air is above. ALOHA needs to know
whether there is a low-level inversion that could trap the
pollutant near the ground (Figure 5-10). This type of inver-
sion is different from the inversion that causes smog. That
type of inversion is typically thousands of feet above the
ground and therefore, much too high to affect a cloud of
escaping chemical.
5-14
-------
Chapter 5: The SetUp Menu
Figure 5-9.
Atmospheric options.
I atmospheric Option*
Stability Class Is : Q «
Inversion Height Options
® No Inversion O ''
Wind Ootlons ore: 1
Wind Speed Is: 1 1 2
Wind is from : |SE
Hir Temperature is: |flO
Cround Roughness is: I
© Open Country
O Urhen or Forest
t^™ OK
OB QC ®D OE OF (
•re: | Help 1
luerslon Present, Height It:
Help I
Help ]
... i O Mrtcri
~|®Knot* OMPH O Meters/Sec. [ Help 1
_j
^j Enter degrees true or tent (I.e. E$C)
~1 Degree* (S)f OC \ Help }
Help ']
H O Input roughness(Ze): 3
~1 [ Cancel j
.0 21"
. .....J ® cm
Tabte5-2.
Stability dass and
wind speed.
Surface Iky NijfrP
Wind Speed Incoming Solar More than. 5
(toots) Radiation Cloud Conrr
<4
4-7
7-n
11-13
>13
Strong Moderate Sight
A A-B B
A-B 8 C
B fcC C
C C-D D
COD
E
E
D
D
D
•D for complete overcast coodttoiB dunng
-------
Chapter 5: The Setup Menu
If there is an inversion present and you know its height, click
Inversion Present and type in the appropriate number, being
sure to select Feet or Meters. If there is an inversion present
but you don't know its height, click Inversion Present and
estimate the height, making sure that the values you choose
fall between 10 feet (about three meters) and 5,000 feet (about
1,524 meters). If there isn't an inversion, click No Inversion.
If the heavy gas computations are used, ALOHA will not
factor in the inversion.
Figure 5-10.
Example of pollutant
dspersion with and
without a low level
inversion.
The heavy gas module doesn't
account for inversions.
3. Wind speed and direction
ALOHA will next need information on wind speed and direc-
tion. Since many hazardous vapors cannot be seen, imagine
a pollutant cloud using your own experience in looking at a
smoke stack or campfire. If you've ever done this, you know
how the wind's direction and speed will affect the movement
of the cloud.
I strong winds I
I
Figure 5-11.
Effect of wind speed
and Direction on
plume movement
5-16
-------
Chapter 5: The Setup Menu
Obviously, the wind direction will determine which way a
cloud will drift. The wind speed also has a pronounced effect
on what the cloud will do. For example, low wind speeds may
allow the cloud to meander; high concentrations typically can
be found in puffs drifting away from the source. As the wind
speed picks up, meandering near the cloud's source decreases,
while small-scale mixing in the atmosphere usually increases.
The model will make sure that the wind speed and atmo-
spheric stability class you set are consistent.
You can use the table below to help you estimate the wind
speed. (Notice that you have the option of miles per hour,
knots, or meters per second; be sure to look in the proper
column on the table and type in the corresponding value on
your computer screen. Since miles per hour and knots are
very close, Table 5-3 does not include both measures.)
Table 5-3.
How to estimate wind
Meters per second
International
Knots description
Specifications
< I
2-3
4-5
5-8
8-11
SI- 14
14-17
17-21
1-3
Calm
Light air
4-6 Light bteex
7-10 Gendebreete
11-16 Modente
17-21 Fresh
22-27 Strong
28-33 Near gale
34-40 Gale
Calm; smokes rises vertically
Direction of wind shown by smoke drift
but not by wind vanes
Wind felt on bar, leaves rustle; ordinary
vane moved by wind
Leave and small twigs in constant
motion; wind extends light flag
Raises dust, loose paper, small
branches are morad
Small trees in leaf begin to sway,
crested wavelets form on inland water
Large branches in motion; whistling
heard in telegraph wires; umbrellas
used with difficulty
Vnole trees in motion; inconvenience
feh walking against wind
Breaks twigs off trees; generally impedes
progress
5-17
-------
Chapter 5: The SetUp Menu
In our example we said that the wind was 12 knots; looking in
the knots column, this means that we would expect to see
small branches moving slightly, with only dust and loose
paper blown along the ground.
Now, enter the direction/rom which the wind is blowing. You
can enter this using letters (e.g., se, ne, sw) or in degrees true
(176°, 210°, etc.).
4. Air temperature
The model uses the air temperature in a number of calcula-
tions. This value is used to calculate the evaporation rate
from a puddle surface (the higher the temperature, the higher
the vapor pressure and the faster the substance evaporates).
Elsewhere, especially when you are entering information
about the source, you can use air temperature as a value for
ground, pipe, or tank temperature if these values are un-
known. Because it may be used for so many calculations, you
need to enter as accurate an air temperature as possible.
5. Ground roughness
Another process that contributes to mixing is the stirring
caused by air moving over "roughness elements"
(Figure 5-12), A roughness element is any surface feature that
interrupts the flow of air. Depending on the size of the spill,
roughness elements may become obstacles. For example, a
very small spill on the railroad tracks in an urban area will
only experience the roughness of the tracks and immediate
surroundings. If the nearest buildings are 500 yards away
and the cloud doesn't travel that far, the ground roughness
may be open country (see below). A cloud will generally be
narrower and travel further across open country than it will
over an urban or forest environment because of the relative
lack of roughness elements to create turbulence or curtail the
cloud's spread.
5-18
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ChapterS: The SetUp Menu
Figure 5-12.
Plume behavior over
different types of roughness
elements and obstacles.
You must tell ALOHA the ground roughness in the area over
which the cloud will be moving. You have three choices:
Open Country, Urban or Forest, or you may enter a roughness
(Zo) value.
O Open Country means that there are no buildings or other
obstacles close by.
G Urban or Forest means that there are many obstacles in
the area in which your spill has occurred. These obstacles
may take the form of skyscrapers, suburban homes, or
pine trees. Selecting an Urban or Forest ground rough-
ness will lead to more mixing and, hence, a shorter foot-
print.
Naturally, you can characterize few environments as totally
urban or totally open, so make your best guess by deciding
which type of ground roughness dominates the area where
the spill occurred. For example, if the spill occurred in a
5-19
-------
Chapter 5: The Setup Menu
downtown area with more tall buildings than open areas or
parking lots, you'd choose Urban or Forest as your ground
roughness. However, if the spill occurred in an area with
more open spaces than buildings, you'd choose Open Coun-
try. If it's not clear which category your spill location falls in,
run ALOHA twice, once for each category. In determining
the downwind distance to the given Level of Concern, you
will find that Open Country is a more conservative choice
than Urban or Forest That is, if you choose that option,
ALOHA will estimate a longer threat distance.
If you want to specify your own roughness length (Zo), you
may find the following table helpful (Brutsaert 1982). As you
can see from Table 5-4, choosing roughness length is more
complicated than entering the height of the roughness ele-
ments.
Surface Description Za (cm)
Mud flats, ice 0.001
Smooth tarmac (airport runway) 0.002
Large water surfaces (average) 0.01 -0.06
Grass (lawn to 1 cm high) 0.1
Grass (airport) 0.45
Grass (prairie) 0.64
Grass (artificial, 7.5 on high) 1.0
Grass (thick to 10 on high) 2.3
Grass (thin to 50 cm) 5.0
Wheat stubble plain (18 cm) 2.44
Grass (with bushes, some trees) 4
1-2 m high vegetation 20
Trees (10-15 m high) 40-70
Savannah scrub (trees, grass, sand) 40
large city (Tokyo) 165
Tabte5-4.
Z0 equivalences.
When ALOHA uses the ground roughness in its calculations,
it may readjust the value you have entered to be consistent
5-20
-------
Chapter 5: The SetUp Menu
with the requirements for the Gaussian and heavy gas mod-
ules. In the Gaussian case/ ALOHA only needs to know the
roughness category (Urban or Forest or Open Country). If
you enter a ZQ, ALOHA will categorize your value into one of
these two classes.
If the heavy gas calculations are used, ALOHA will assign a
value to the Urban or Forest or Open Country choice. If you
have entered a Z ALOHA will use this value, if it falls within
O
the range 0.05 cm to 10 cm. Values greater than or less than
these limits will be set to the nearest limiting value.
After you've selected the appropriate atmospheric conditions
and ground roughness, and clicked OK, ALOHA requests
information about the cloud cover and relative humidity in
the vicinity of the spill.
6. Cloud cover
ALOHA uses information on cJoud cover to help estimate the
amount of incoming solar radiation at the time of the spill.
With location, air temperature and your other atmospheric
selections, this information helps ALOHA to calculate the
rate at which the spill will evaporate. ALOHA gives you six
options for cloud cover, ranging from complete cover to clear.
The sixth option allows you to describe cloud cover in the
standard meteorological terminology of tenths. For example,
if you called the National Weather Service, they might tell
you that cloud cover that day was 5/10, in which case you'd
enter 5 as the value.
5-21
-------
Chapter 5: The SetUp Menu
Select Cloud Couen
o o ® o
complete pertly
couer cloudy
[ Help
&
O OR Center
(0-1
deer
D
value 5
0)
7. Humidity
Relative humidity is another measure that ALOHA uses to
help calculate the rate at which the spill will evaporate into
the atmosphere. As with cloud cover, ALOHA gives you six
options for relative humidity, ranging from wet to dry. The
sixth option allows you to describe humidity in the standard
meteorological terminology of percentage. For example, if
you called the National Weather Service, they might tell you
that there was 50% humidity that day.
Note that, as you've entered more information, the Text
Figure 5-13.
Cloud cover options.
Select Humidity:
O OR O enter ualue
dry (0-100)
[ Cancel
Figure 5-14.
Humidity options.
Summary window has continued to be updated (Figure 5-15).
The window now includes information on the site, chemical,
and atmospheric conditions for the spill scenario.
5-22
-------
Chapter 5: The SetUp Menu
Figure 5-15.
Text summary.
T«Mt Summary
SITE ORTH INFORHIT10N:
Location: JUPITER, FLORIDA
Building fltr Exchange* P«r Hour: 1.07
Data t Tin*; Ucing coaputar'* internal clock
noloculor Might: 17.03 Kg/Kaol
10LH: 900.00 pp*
iMFomnTion:
Uind: 12 knots froa SE No Inuwcion Height
SUfcllltu Class: D nlr T*Bp*ratur«: 80* F
Ralatlu* HualdUy: SO* Ground noughnMS: Qpan country
Cloud Cowor: 5 t«nUw
SOURCE STOENOTH INFORIIflTIOM: - lwit Satirattan Conevitpatlon: 1,000.000 pp* OP 100 Of
I01B
SAM Station...
Several companies manufacture Stations for Atmospheric
Measurement (SAM) for use with ALOHA. For a list of
current manufacturers, please call NOAA at (206)526-6317.
Before using a SAM not specifically designed for ALOHA, be
sure that the data format is compatible with ALOHA, as
described below. Choose SAM Station... to enter atmospheric
information that you receive over a VHP radio frequency or
through a direct connection between your computer and a
SAM (Figure 5-16). Set up the SAM in the area where condi-
tions need to be monitored. The SAM will feed real-time
weather data to the computer and ALOHA will interpret and
use this information in its pollutant dispersion calculations.
Figure 5-16.
SAM selection note.
Note !
If OK 1$ selected, RIOHH will CHpect
meteorological data from the serial port.
The interface to SRM should be properly
connected, configured, and turned on.
[ Cancel ] [ Help
5-23
-------
Chapter 5: The Set Up Menu
A SAM transmits updated meteorological conditions every
30 seconds. If ALOHA has finished the previous dispersion
calculations and has drawn a footprint, the new SAM data
will be used to update the dispersion calculations and draw a
new footprint. If, on the other hand, ALOHA is still in the
process of calculating the dispersion when SAM data are
received, the new data will be ignored. Not until the footprint
has been drawn will ALOHA again begin acknowledging the
SAM data and resume the process of calculating a new foot-
print. Remember that the SAM can only update the data that
it collects. You will need to update the inversion, cloud cover,
and humidity conditions if these change during the incident.
When you select SAM Station, ALOHA assumes that you are
hooked into a SAM unit and are prepared to receive weather
data through it (Figure 5-16). ALOHA will alert you if it
doesn't receive data from the SAM after several minutes.
Windows users will need to specify the serial port to which
the SAM unit is connected.
After you click OK, ALOHA asks you for additional informa-
tion about atmospheric conditions in the vicinity of the SAM
that cannot be measured by the station.
I. inversion Height Options
Click No inversion if there is no inversion present. If an
inversion is present, click Inversion present and type in its
height. Make sure that you choose whichever unit of measure
is appropriate. (For more on inversion height, see pages 5-14
to 5-15.)
WARNING
5-24
-------
Chapter 5: The SetUp Menu
Figure 5-17.
Inversion height
options.
User input Tor SBM Unit
Inuerslon Height Options are: [ Help ]
® No Inuerslon
O Inuersion present, Height is:
®feet
O meters
2. Ground Roughness
Next, select the appropriate Ground roughness category.
(See previous discussion of ground roughness.)
Figure 5-18.
Ground roughness
and time options.
User input for SBM Unit
Inuersion Height Options are: [ Help
® No inuersion
O Inuerslon present. Height Is: |
©feet
O meters
Ground roughness is:
® Open Country
O Urban or Forest
Help I
OR OInput roughness(Zo):
3.0
cm
NOTE: The model time will be taken from the computer's Internal
clock. Be sure it Is set correctly.
f Cancel j
Make sure that your computer's internal clock is set to the
appropriate time for your spill; your SAM will run using this
time and ALOHA will use this time, along with the wind
speed and direction, to calculate the appropriate stability
class. After you click OK, ALOHA requests cloud cover and
humidity information for the location where your spill oc-
curred. (See previous discuss of cloud cover and humidity.)
If you save a scenario as an ALOHA file while the met station
is turned on, ALOHA won't automatically start receiving
data when you reopen the file. You must again select
Atmospheric and choose either User Input or SAM Station.
5-25
-------
Chapter 5: The SetUp Menu
SAM Options
After you click OK on the Cloud Cover and Humidity screen,
notice that a new menu item, SAM Options, appears to the
right of the Display menu. You can Archive the data received
through SAM as ASCII characters in a text file, look at Raw or
Processed data, or look at a Wind Rose displaying the last ten
wind vectors that ALOHA received from your SAM. You do
not have to use any of these options for ALOHA to use the
SAM data; they are truly "optional."
SflM Options
flrchiue Data...
Ram Data
Processed Data
Wind Rose
Met station sensors are scanned
every two seconds; the mean wind
speed, direction, and temperature
are based on five-minute running
averages of the scanned sensors.
Be aware that the data received
through these sensors are specific
only to the area where you have
set up your SAM. Wind speed and direction for other areas
covered by the dispersing cloud may not be reflected (see
Wind shifts on pages 2-10 to 2-11). Further, since ALOHA
can only receive data from one SAM at a time, footprint
calculations may be invalid if they are based on a SAM
located some distance from the spill source, and there is a lot
of variation in the terrain in between.
1. Arc/we Doto
You can save your processed meteorological data as a tab-
delimited text file for later referral. Choose Archive Data
from the SAM Options menu, name the file in the dialog box,
and click Save. You can later open this file in a word process-
ing application. Since data may not be received every 30
seconds if ALOHA is doing time-intensive calculations, the
archived data will include the time of each transmission. This
time is taken from the computer's internal clock; please be
Figure 5-19.
SAM Options menu.
5-26
-------
Chapter 5: The SetUp Menu
sure this time is accurate. You may change the time using the
Control Panel on the Macintosh or the Control menu box on
the IBM.
Rgure5-20.
Archive SAM data
flLOHfl |
Q flLOHft Helps
D ChemUb
<9* c h e mM
-------
Chapter 5: The SetUp Menu
O met station identification number
O mean wind speed (meters per second)
O mean wind direction (in degrees true)
O standard deviation of wind direction (in degrees)
O mean temperature (in degrees Celsius)
O instantaneous wind speed (meters per second)
O instantaneous wind direction (degrees)
D instantaneous temperature (again, in °C)
O battery voltage of the field unit
O the sum of the ASCII code of all the data sent (ALOHA
uses this number to trap bad or incomplete transmis-
sions).
3. Procured Ooto
Here, you see SAM data after ALOHA has processed and
interpreted it (Figure 5-22).
Ulnd
Ulnd Direction- 57 a»
-------
Chapter 5: The SetUp Menu
Theta is -1.00, SAM has not been transmitting for five min-
utes. ALOHA will not allow you to set the source or draw any
footprints until SAM has been running for at least five min-
utes.
4. Wind Rose
Selecting Wind Rose displays a diagram that summarizes the
direction and speed of the wind at a SAM's location. This
window shows up to the last ten wind observations received.
Each observation appears as a line, called a vector, that
indicates the wind direction by the angle at which each line is
drawn, and the wind speed, by the length of the line. Each
vector represents a five-minute running average, rather than
an instantaneous measurement.
Figure 5-23.
SAM wind rose.
WindRose
4.2 mph
The wind rose helps you to
visualize how much the
wind has been shifting. For
example, in low wind con-
ditions on a hot, sunny day,
you would expect fairly
unstable atmospheric con-
ditions. The wind rose
would show vectors that
are widely scattered. Conversely, under stable conditions,
the wind rose will show very little scatter; some of the vectors
may even be lying on top of one another. The last wind speed
received is displayed in the lower left corner. The vector
representing the last wind observation is drawn on the dia-
gram with a darker line. Notice that the vectors are drawn
from the center of the circle towards the direction TO which
the wind (and any cloud of chemical) is blowing. Both
processed and raw data will show the direction FROM which
the wind is coming. The wind rose will continue to be
updated until you disconnect your SAM or close the window.
5-29
-------
Chapter S: The SetUp Menu
Source...
The Source options let you tell ALOHA the amount and/or
circumstances of the chemical release.
Chemical...
fltmospheric
Computational...
Direct...
Puddle...
Tank...
Pipe...
Figure 5-24.
Source options.
ALOHA can estimate the duration of chemical releases last-
ing from a minimum of 60 seconds to a maximum of 60
minutes. After sixty minutes, atmospheric conditions are
likely to have changed. Remember, ALOHA uses constant
atmospheric conditions. If the circumstances of the release
lead to a spill that would last longer than 60 minutes, you will
see that the concentration, source strength, and dose curves
are truncated at 60 minutes. The text summary screen will say
"Release Duration: ALOHA limited the duration to 1 hour."
The 60-minute cutoff is a maximum; if conditions change
dramatically before an hour has passed, ALOHA's output
will not be valid. When this happens, reset the atmospheric
and source input and let ALOHA calculate a new footprint.
ALOHA reports two release rates. The maximum computed
release rate is the fastest release rate possible for your sce-
nario. It may be very fast in the case of a pressurized tank
release. The maximum average release rate is averaged over at
lest one minute. It will be considerably slower than the maxi-
mum computed rate in the case of a pressurized release.
ALOHA uses a series of average rates to make its dispersion
calculations.
5-30
-------
Chapter 5: The SetUp Menu
After you click OK, the source is calculated and you will be
returned to the Text summary screen. Review the informa-
tion you have entered as it appears on this screen. The
source strength information calculated by ALOHA includes
an estimate of how long the release will last, the total amount
released, and both the maximum computed and average re-
lease rates. If a pressurized liquid was stored in the tank,
ALOHA will indicate that the release was a two-phase flow.
In such cases, liquid, as a fine aerosol mist, and gas are
released rapidly and simultaneously from the tank. Two-
phase mixtures are denser than the gas phase of the chemical,
and often disperse as a heavy gas.
Choose the Source option that most closely resembles the
spill scenario.
Choose...
O Direct
O Puddle
a Tank
O Pipe
If...
...you can estimate the amount entering the
atmosphere,
...you can estimate the size of the puddle on
the ground,
...the substance is being released from a tank,
or
...a gas is escaping from a broken or punc-
tured pipe.
Direct
Choose Direct to enter your own estimate of how fast the
pollutant is entering (or has entered) the atmosphere. Was
the spill instantaneous (the entire amount escaped into the
atmosphere in the first 60 seconds) or continuous (the con-
tents are entering the atmosphere over time)? This estimate
must be for the amount of pollutant entering the atmosphere as
a gas. This may not equal the amount spilled, particularly if
5-31
-------
Chapter 5; The SetUp Menu
the substance spilled is a liquid (in such a case, you'd need to
estimate its evaporation rate).
User Input Source Strength
Select source strength units nf mass or uolume:
O grams O (diagrams ©pounds
O cubic maters O liters O cubic feat
1 Help ]
O tans(2,000 Ibs)
O gallons
Select en Instantaneous or continuous source: 1 Help 1
@ Continuous source O Instantaneous source
Enter the amount of „,
pollutant ENTERING Sou]
THE ATMOSPHERE:
„_. ^ ,_^^
(0 If ground source): °
t « 1
® pounds/sec
O pounds/min
O poundf/hr
©feet
O meters
[Help""]
[ Help"")
[ Cancel ]
If the spill is above ground level, you may also enter the
source height. This allows you to model neutral gas releases
from elevated pipes or other above-ground sources. If you
don't enter a source height, ALOHA assumes that the spill is
at ground level, and sets the source height to zero.
However, entering an elevated source height doesn't cause
ALOHA to evaluate releases of heated gases accurately. This
is because plumes of heated gas, like those from smokestacks
or fires, usually rise before traveling downwind, and ALOH A's
calculations do not account for downward movement of a gas
released at an elevated height if it is much heavier than air.
Therefore, ALOHA won't let you try to model an elevated
source when the chemical is a heavy gas. If you enter a non-
zero source height for such a case, ALOHA warns you that
heavy gas calculations can only be made for ground-level
releases. (A ground-level release is a more conservative
choice than an elevated release: ALOHA will predict a longer
footprint for a ground-level release.)
Figure 5-25.
Direct input of
source strength.
Heavy gas
calculations can
only be made for
ground-tevel
5-32
-------
Chapter 5: The SetUp Menu
Figure 5-26.
Pudde input
Puddle
If the spill is a liquid that has formed a puddle on the ground,
select Puddle, unless the source of the puddle is a tank that is
still leaking (in which case you should select Tank).
When you select Puddle, the first pieces of information that
you must give ALOHA are how large an area the puddle
covers, and how much of the chemical is contained in the
puddle (Figure 5-26).
Puddle Input ' ^ -t
Puddle urea i$: 500
Select one ar
<•) Uolume
O Ruerage
O Moss of
Uolume is:
| OK
id enter ap
of puddle
depth of p
puddle
50
1 (
square <§> feet
propriate data
uddle
-------
Chapter 5: The SetUp Menu
ALOHA now knows the puddle's surface area and the amount
of the chemical available for evaporation. The evaporation
rate will depend on these factors, as well as:
CJ incoming solar radiation (affected by location, time, cloud
cover);
O heat transfer with air (affected by air temperature, humid-
ity, initial puddle temperature); and
O heat transfer with ground (affected by ground temperature,
ground type, initial puddle temperature).
The ground conditions influence the amount of heat trans-
ferred between the ground and the puddle (for example, the
warmer the ground, the warmer the puddle; hence, there will
be a higher vapor pressure, resulting in a higher evaporation
rate).
Choose ground type by selecting default, concrete, sandy, or
moist. (ALOHA doesn't assume any of the chemical is ab-
sorbed into the ground, but uses ground type information to
help calculate energy transfer.) In most cases, concrete will
be the most conservative choice (it leads to the highest heat
transfer). The default selection is equivalent to unwetted
ground not covered by rock or concrete. This choice will
usually lead to evaporation rates that are somewhat slower
than those resulting from concrete, but faster than if you
chose sandy.
You must next select a ground temperature; the air tempera-
ture will be automatically filled in as an estimate of Ground
temperature. You may use this as a default value or you may
enter the ground temperature, if you know it. There may be
a large difference between air and ground temperatures in
some situations, such as in a parking lot on a hot day late in
the afternoon, or on a street during the early morning hours
5-34
-------
Chapter 5: The Set Up Menu
following a very cold night. Be sure to estimate air and
ground temperatures carefully in such situations.
The last piece of information ALOHA will need here is the
initial puddle temperature. You may again elect to use either
the air or ground temperature, or you may enter an initial
puddle temperature, if you know it.
Figure 5-27.
Ground type,
temperature, and
initial puddte
temperature.
Soil Type, flir and Ground Temperature
Select ground type
[ Help ]
©Default OConcrete QSandy OMoist
Input ground temperature
Help
© Use air temperature (select this if unknown)
O Ground temperature is 65| <§) F O C
Input initial puddle temperature [ Help J
<*> Use ground temperature (select this if unknown)
O Use air temperature
O Initial puddle temperature is [65 I ® F QC
OK
J
Cancel
After you click OK, ALOHA will calculate the source, and
you'll be returned to the Text Summary screen.
5-35
-------
Chapter 5: The SetUp Menu
ALOHA doesn't take into account any changes in atmo-
spheric conditions—such as changes in wind speed or air
temperature— when calculating the rate of evaporation from
a puddle. This is especially important to remember because
wind speed and air temperature are very important influ-
ences on evaporation rate. If these conditions change while
ALOHA is calculating the evaporation rate, you'll need to
enter the new values and re-run ALOHA.
WARNING
Puddle or tank?
Puddles may also be formed by leaks from tanks. If a tank is
the source of the puddle, choosing Tank allows the puddle
area to grow while the tank continues to leak.
Tanlc^
If the source of the spill was a tank rupture or tank valve leak,
choose Tank. ALOHA will need to know what the tank looks
like, how big it is, how much of a chemical, either liquid or
gas, could be stored in the tank, and the storage temperature
and/or pressure.
Tank Size and Orientation
Select tank type and
orientation:
HorizontoI
Vertical cyllndw-
Enter tura of three ualues:
-l«r>gU> •
diameter 13.0
i«,ngth |50
uolume
®reet O meters
® gallon* Qtu. feat
Cancel ] [Help ]
Figure 5-28.
Tank size and
orientation.
5-36
-------
Chapter 5: The SetUp Menu
Figure 5-29.
State and temperature of
chemical in tank.
Tank sum and orientation
ALOHA considers three type of tanks: a horizontal cylinder,
a vertically oriented cylinder, or a sphere. As you choose the
tank type and orientation, the bottom of the tank input screen
will change to reflect whatever additional information is
needed to help ALOHA determine the total volume of the
tank.
If, for example, you select a cylinder, the model will request
that two of the following three values be entered: diameter,
length, or volume. If you select a sphere, ALOHA needs to
know either the diameter of the container or the volume of
the tank. The model will fill in the calculated values for the
other input boxes as you enter the requested information.
OwnicaJ state
Next, tell ALOHA the nature of the material in the tank and
the temperature at which it is stored. You may tell ALOHA
that the tank contains liquid, the tank contains gas only, or
you don't know.
Chemical State and Temperature
Enter the state of the chemical:
©Tank contains liquid
QTank contains gas only
O Unknown
( Help
Enter the temperature within the tank: f
O Chemical stored at ambient temperature
® Chemical stored at[|52 | degrees
Help ]
Cancel
5-37
-------
Chapter 5: The SetUp Menu
Liquid in a tank
If you choose liquid, ALOHA will determine how much of the
chemical is in the tank once you have entered the mass or
volume of the chemical, the percentage of the tank that is
filled, or the liquid level in the tank. Remember that you have
already specified the size of the tank, so the model already
knows the maximum amount that may be in the tank (Figure
5-30). ALOHA won't allow you to overfill the tank!
Enter the mat* OR volume of MM liquid
The mas* of liquid Is:
O pounds
tons<2.000 Ibs)
O kilograms
Inter volume OR liquid level
The liquid
volume Is:
® gallons
-| O cuttle reel
-I O liters
O cubic meters
full by volume
Cancel
Help
Figure 5-30.
Liquid in tank.
Gas in a tank
If you choose gas, ALOHA will determine how much is in the
tank by asking you to enter the tank pressure or amount of
gas directly.
5-38
-------
Chapter 5: The SetUp Menu
Figure 5-31.
Tank pressure'
amount of gas
in a tank.
Mass or Pressure of Gas
Enter either tank pressure OR amount of gas
The tank pressure is :
OR
The amount of gas is : 0.095
O pounds
(§) tons(2,000 IDS)
O kilograms
O Cu. Ft. at STP
O Cu. M. at STP
|[ OK j| [ Cancel ") [ Help ]
Unknown in a tank
If you choose unknown, ALOHA will ask you to enter the
mass of the chemical in the tank. The model will then
calculate the state of the chemical based on tank volume,
temperature, and mass of the chemical in the tank
(Figure 5-32).
Figure 5-32.
Mass of unknown
chemical in tank.
Mass of Chemical In Tank
For a chemical of unknown state,
the chemical mass is required
The amount of
chemical in
O pounds
® tons(2,000 IDS)
O kilograms
[ Cancel ] [ Help )
5-39
-------
Chapter 5: The SetUp Menu
Ana ami typ* of leak
Now ALOHA will ask you about the opening from which the
pollutant is escaping. You must decide if the opening is best
described as a hole or a short pipe/ valve leak, and what shape
best describes the opening (Figure 5-33).
Urea find Type Of leak
Select the shape that best represents the shape of
the opening through which the pollutant Is ending
vttth
O Circular opening ® Rectangular opening
Opening length:
Opening width:
© Inches
Ofeet
O centimeters
O meters
Is leak through a hole or short pipe/value?
O Hole <§> Short pipe/ualue
Cancel
Help
Figure 5-33.
Area and type of leak.
If you specify that the opening is rectangular in shape, ALOHA
will ask you for the length and width of the hole. If you
specify a circular leak, you will need to provide a diameter.
The last piece of information that you must give ALOHA
about how the chemical is leaking out of the tank is whether
the leak is through a hole or a short pipe /valve. A hole is any
kind of break directly into the tank (e.g., a puncture or crack).
If there is any liquid in the tank, you must next tell ALOHA
where the leak occurs on the tank (Figure 5-34).
5-40
-------
Chapter 5: The Setup Menu
Figure 5-34.
Height of leak in tank.
Height of the Tank Opening
liq. l«u«l
1 OK 1
O>
f
I
1
i
The bottom of the leak fs:
1.99 | O'n- On. Ocm.@m.
above the bottom of the tank
fin
50.0 "1 % of the way to the top of
the tank
Cancel J [ Help ]
You may tell ALOHA where the leak is in one of three ways:
G move the scroll bar up to the approximate height of the
bottom of the leak (notice that the liquid level is shown),
O specify the distance from the bottom of the tank to the
bottom of the leak, or
O specify the height of the leak as a percentage of the total
tank height (e.g., 0% means that the hole is at the bottom
of the tank; 90% means that the hole is 90% of the way to
the top of the tank).
If the leak is a gas, you will be returned to the Text Summary
screen when you click OK. You will see a summary of the
information that you entered on the tank, and the source
strength results calculated by ALOHA (Figure 5-35).
5-41
-------
Chapter 5: The SetUp Menu
trronr*irian:
No lnu*r«lon H*lght
flir f«w*ratm: 93* F
Grow* Roughn***: Op*n country
sauce
Uav l*ak fra» hoi* in horizontal eg I indrioal l«* Ml*ct*d
Tai*. Oia»*t*r: S fMt Tank Ungth: 25 fM
Tar* UelUM: 3,672 gal lone
Internal T«>p«raikr»: 39* F Intvnal Prvs*. 2
Cn«leal Host In Tank: 0.023 tens
Circuit- Opening Dia«c(«r>: 6
A*l*cm Dtratian: I ainuia
nax Ce»ctit«d fel*an Rat«: 8.99
ftaK nvmraym Suitalncd R*|«OM Rat*: 0-327 pomdc/nc
(aw«raa*d ow*r a *inut* or Ber*>
Total taovit H*l*a>*d: 10.6
Figure 5-36.
Text summary of gas
teak from tank
If the chemical is stored as a non-pressurized liquid, a puddle
may be formed, so ALOHA will ask you for information about
the ground. This information is similar to the information
requested in the Puddle option. There are, however, two
differences.
First, ALOHA will have calculated the initial puddle tem-
perature, based on the temperature of the tank and flow
considerations, so you will not have to enter this information.
Second, you must let the model know whether the puddle is
diked.
Puddle Parameters
Select ground type
Help
® Default O Concrete Q Sandy O Moist
Input ground temperature
Help
<§> Use air temperature (select this If unknown)
O Ground temperature is [J80 deg. ® F O C
input maximum puddle diameter [ Help 1
® Unknown
O M«Himum diameter is | | ® ft O yd* O meters
Cancel
J
Figure 5-36.
Puddte input
5-42
-------
Chapter 5: The Setup Menu
ALOHA will ask you to enter the maximum puddle diameter.
If there are no barriers to prevent the liquid from flowing,
select unknown. If there is a barrier to liquid flow (e.g., a
containment or diked area), then enter the approximate diam-
eter of that barrier as the maximum puddle diameter. Re-
member to select the appropriate units, and click OK.
Figure 5-37.
Text summary of
liquid release
from tank
; Tent Summary
ATnOSPHERIC IfFOflnATICNicnRHUM. INPUT OF DflTfl)
Uind: 12 Knot* fro» SE
Stability Clan: 0
Relative Hu»ldltj: SOI
Cloud Cowv: 3 t«nths
No lnver*ion Height
Air Temperature: 80* F
Ground Roughness: Open country
SOURCE STRENGTH IWOflnflTlOM:
Liquid look fro» hoi* In horizontal cylindrical tank sell
:t*d
Tar* Diameter: 8 feet
Tar* UoluM: 7,920 gallon*
Internal Teeperatur*: BO* F
ChMlcal tta» In Tank: 30.9 tone
Circular Opening Oiawittr: 6 i
Opening l« I 60 fMt frea tank bottoa
Oround T*ap: equal to OBbi*nt
R*l*aM Duration: 30 mfnut«*
flax ConputMl H«|MM Ran: 710 pound*/• in
Men nvwaq* Sustalnid R«|MS« Bat«: 716 pauna's/ain
-------
Chapter 5: The SetUp Menu
Pipe input
Input pipe diameter
Diameter is 12
Input pipe length
Pipe length is 2-
The unbroken end of
© connected to ii
O closed off
c
| ® inches O cm
C
400 © ft o yds
the pipe is [
ifinite tank source
Select pipe roughness £
® Smooth Pipe
O Rough Pipe
n OK
Help J
Help ]
O meters
Help ]
Help ]
J [ Cancel 1
Figure 5-38.
Ppe input
The pipe length must be at least 200 times the diameter of the
pipe. After telling ALOHA the size of the pipe, you must
specify what the unbroken end of the pipe is connected to.
The pipe may be connected to an infinite tank source (that is,
ALOHA will assume that the temperature and pressure in the
tank remain constant), or may be closed off on the unbroken
end (for example, by a shutoff valve). Note that ALOHA does
not handle pipes that break in the middle, leading to two pipe
sources (one on either side of the break).
Pipe roughness refers to the texture of the inside of the pipe;
rough texture causes turbulence, which reduces the flow rate
of the gas in the pipe. A gas will flow more slowly through an
older, corroded (rough) pipe than through a newer (smooth)
pipe.
5-44
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Chapter 5: The SetUp Menu
Next, tell ALOHA the pressure and temperature inside the
pipe. You may enter a value for the size of the hole in a broken
pipe if the pipe is closed off at its unbroken end. If, instead,
the pipe is connected to a large reservoir, ALOHA will as-
sume that the hole diameter equals the pipe diameter.
Figure 5-39.
Pipe pressure/
hole size.
Pipe
Input pipe pres
Pressure is
Input pipe tern
O Unknown
(•> Tern pe rat
Input hole size
(•> Use pipe
O Hole area
ft
|| OK
Pressure and Hole Size
;$ure [ Help j
10000 (§)PSI ORtm QPa
perature Help ]
(assume ambient)
ure is 32 @) F O C
[ Help ]
diameter
is 113 square @ jn. Qcm.
^™^™\
]] [ Cancel
When you click OK, the source will be calculated and you'll
be returned to the Text Summary screen.
5-45
-------
Chapter 5: The SetUp Menu
Hind: S Mt«r*/«*c
Stability Clam: D
flclatlw* Hualdlty; 7SS
Cloud Couar: 10 tenths
fro* 050* trwi
Ha Inuwslan H«ight
nir Twpwotur*: 95* F
Ground RougtaM«: Op*n country
Pip. L*ngtn: 2400 fMt
Ita/iq In
In
SOURCE STRENGTH IHFOFHBTIOM:
Pip* DIOMUr: 12 Inch**
Pip* TM|Mratur«: 93* F Pip* Prws: 1
Pip* Roughrma: nueth Hel* %^M: 113 «q
Unbrelun and of tha pip* I* oenn«ct«i to «i Inflnlt* caure*
R*|MM Ourotlon: M.OHA ll«lt««l th« duration to I hour
Max Co»put*d R*I*OM tote: 206,000 pounds/Bin
Max nXwrag* Su*taln*d tatMM Rat*: 260,000 pounds/Bin
Total AMunt talMMd: 13,900, IOQ pounds
Figure 5-40.
Text summary of gas
release from pipe.
Computational...
Choose Computational to specify which type of calculations
you want ALOHA to use for estimating the dispersion. You
may choose to let ALOHA decide whether to use the heavy
gas or Gaussian calculations, or you may force the model to
use one or the other. This option also allows you to specify a
dose exponent.
Computational Preferences
Select spreading algorithm. If unsure, let
model decide.
Help
<§) Let model decide (select this If unsure)
O Use Gaussian dispersion only
O Use Heavy Gas dispersion only
Define dose:
Dose
•Jc'VrtdT
Help ]
OK
[ Cancel
Figure 5-41.
Options for footprint
calculations.
5-46
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Chapter 5: The SetUp Menu
Let mode/ decide
When you choose Let model decide and are running one of
the Tank, Puddle, or Pipe source options, ALOHA will iden-
tify chemicals that will behave as heavy gases. This is true
even if a chemical's molecular weight is less than 29 kg/kmol
(the "molecular weight" of air). However, if you chose Direct
as your source option, ALOHA may not have enough infor-
mation about the release to determine whether a heavy gas is
formed when the molecular weight of the chemical is less
than 29 kg/kmol. In these cases, it will default to the Gaus-
sian calculations.
Use Gaussian dispersion only
When you choose Use Gaussian dispersion only, ALOHA
will calculate the spread of the chemical cloud using the
Gaussian distribution discussed in Chapter 2. The Gaussian
calculations may be quicker than the heavy gas calculations,
particularly if you are using a computer without a math
coprocessor. In a response situation, you may elect to use the
Gaussian dispersion option to obtain an initial footprint esti-
mate. You may then recompute the footprint using Let model
choose when time allows.
A general rule is that for unstable atmospheres (stability
classes A and B), the heavy gas calculations will predict
longer footprints; in stable atmospheres (stability classes E
and F), the Gaussian footprints will be longer. Under neutral
(C and D) conditions, the computations will be approxi-
mately the same.
Use Heavy Gas dispersion only
When you choose Use Heavy Gas dispersion only, ALOHA
will calculate the spread of the pollutant using the heavy gas
computations discussed in Chapter 2. These calculations may
be slower than the Gaussian calculations, particularly if you
are using a computer without a math coprocessor. There are
5-47
-------
Chapter 5: The SetUp Menu
some instances, such as when a chemical has been stored at a
low temperature or under high pressure, when a chemical
with a molecular weight less than that of air may behave like
a heavy gas. ALOHA will warn you in some of the situations
where this may happen. If you think this may be true of a
chemical, choose Use Heavy Gas dispersion only.
D«j!n«
-------
Chapter 5: The SetUp Menu
The default value for n is 1. You should retain this value
unless you are consulting with a specialist who understands
the dose formula and knows the appropriate exponent to be
used in the formula for the chemical in question.
Sewngt/Mca/cu/ated footprint
After selecting a computational preference, click OK. You are
now ready to move on to the Display menu, where you will
specify how you would like your data displayed.
5-49
-------
-------
Chapter 6
The Display Menu
In this chapter...
Tile and Stack
Windows 6-2
Options 6-3
Text Summary 6-6
Footprint 6-8
Concentration 6-8
Dose 6-12
Source Strength 6-15
I Calculate 6-17
; Calculate Now 6-18
Once you've entered information about your scenario under
the SetUp menu, you can use the options on the Display menu
to look at various types of output. Output options are:
C3 text summary
O dispersion footprint
O graph of concentration over time at a given point (both in-
and outdoors)
O graph of dose over time at a given point (both in-
and outdoors)
G source strength (release rate over time).
Figure 6-1.
The Display menu.
Display
Tile Windows
Stack Windows
Options...
Text Summary
Footprint
Concentration...
Dose
Source Strength
Calculate...
Calculate Now
6-1
-------
Chapter 6: The Display Menu
When windows displaying this information are visible, you may
organize them by selecting Tile Windows or Stack Windows.
Tile and Stack Windows
The Tile and Stack Windows options allow you to organize the
information windows on your computer screen. Tile Windows
displays the windows side by side, or one above the other; Stack
Windows overlaps the windows one on top of the other, so that
only the front window is visible; the title bars of the remaining
windows are stacked behind. These windows can be expanded to
fill your screen. Each of the windows may be sized or moved.
Model ntoi: Htavu Ca> (Mt«d>
(Mr lp*»r>*d UK: «o>al> IDLH (10000 pp»
Hat ThrMt Zone for UK: IOC «n rww «ne««a«d
>*><•: footprint MR I dro»n bocouM if tots of
noar-fUld patcAJnatt MM pl*M pr«Mntatlo*
unreliable far (hart di>ti
Figure 6-2.
Tie windows.
Cnnonlretlon Ullndom
30
M
.InuUj
DOM UHn*)*k*
4.000
3.000-
_
2,000
'.MO
0
40
to
• InrtM
6-2
-------
Chapter 6: The Display Menu
Figure 6-3.
Stack windows
Footprint Window
Concentration Window
TeHt Summary
Options...
You can ask ALOHA to calculate the shape of the footprint
based on a given level of concern. You then specify how the
footprint should be displayed.
Figure 6-4.
Display options.
Display Option*
Select Level of Concern or Output Concentre lion:
O H'lH not ail
-------
Chapter 6: The Display Menu
The IDLH was not designed to be an appropriate measure of
exposure levels for the general population. It doesn't take
into account the greater sensitivity of children and the eld-
erly. Although it is the most commonly used toxic threshold,
it should be used with great care.
Hence, you should be cautious when using this value for any
type of evacuation decision. Make sure that you don't use
this estimate to evaluate the relative toxicity of different
chemicals, as a definitive way to identify safe or hazardous
conditions, or without reference to length of exposure.
When you select a chemical for your scenario, ALOHA au-
tomatically checks to see if the IDLH value is available from
the chemical library. If it is, ALOHA will set the default level
of concern to this value. If it is not available, IDLH Con-
centration will be grayed-out and you will not be able to
select this option.
A preferred way to determine the level of concern to be used
as an action criterion is through contingency planning. In this
way, communities can set predetermined levels of concern
for chemicals or classes of chemicals common to their region.
If such a value exists for the chemical you are using, enter that
value next to User specified cone., making sure to click ppm
or milligrams/cubic meter as appropriate. You may also use
User specified cone, to obtain footprint estimates for a vari-
ety of levels of concern.
Footprint options
Once you've chosen the level of concern that you want ALOHA
to use for calculating the potential threat zone, decide how
you want to view this information. If you click Plot on grid,
ALOHA will draw the footprint on a grid and scale the
drawing to fit on your computer screen.
WARNING
-------
Chopter6
In this chapter^.
Tile and Stack
Windows 6-2
Options 6-3
Text Summary 6-6
Footprint 6-8
Concentration 6-8
Dose 6-12
Source Strength 6-15
Calculate 6-17
Calculate Now 6-18
Figure 6-1.
The Display menu.
The Display Menu
Once you've entered information about your scenario under
the SetUp menu, you can use the options on the Display menu
to look at various types of output. Output options are:
O text summary
O dispersion footprint
O graph of concentration over time at a given point (both in-
and outdoors)
O graph of dose over time at a given point (both in-
and outdoors)
O source strength (release rate over time).
Display
Tile Windows
Stack Windows
Options...
TeHt Summary
Footprint
Concentration...
Dose
Source Strength
Calculate...
Calculate Noa»
6-1
-------
Chapter 6: The Display Menu
When windows displaying this information are visible, you may
organize them by selecting Tile Windows or Stack Windows.
Tile and Stack Windows
The Tile and Stack Windows options allow you to organize the
information windows on your computer screen. Tile Windows
displays the windows side by side, or one above the other; Stack
Windows overlaps the windows one on top of the other, so that
only the front window is visible; the title bars of the remaining
windows are stacked behind. These windows can be expanded to
fill your screen. Each of the windows may be sized or moved.
Ho* mrmt ZOM 'or LOC: LOC mmt MMT mmmmami
*>t«: Footprint aWt aram bveauM .ff«c« at
n*
-------
Chapter 6: The Display Menu
Figure 6-3.
Stack windows
Footprint Window
Concentration Window
TcHt Summary
Options...
You can ask ALOHA to calculate the shape of the footprint
based on a given level of concern. You then specify how the
footprint should be displayed.
Figure 6-4.
Display options.
Display Options
Select Leuel of Concern or Output Concentration:
O IIHH not
-------
Chapter 6: The Display Menu
The IDLH was not designed to be an appropriate measure of
exposure levels for the general population. It doesn't take
into account the greater sensitivity of children and the eld-
erly. Although it is the most commonly used toxic threshold,
it should be used with great care.
Hence, you should be cautious when using this value for any
type of evacuation decision. Make sure that you don't use
this estimate to evaluate the relative toxicity of different
chemicals, as a definitive way to identify safe or hazardous
conditions, or without reference to length of exposure.
When you select a chemical for your scenario, ALOHA au-
tomatically checks to see if the IDLH value is available from
the chemical library. If it is, ALOHA will set the default level
of concern to this value. If it is not available, IDLH Con-
centration will be grayed-out and you will not be able to
select this option.
A preferred way to determine the level of concern to be used
as an action criterion is through contingency planning. In this
way, communities can set predetermined levels of concern
for chemicals or classes of chemicals common to their region.
If such a value exists for the chemical you are using, enter that
value next to User specified cone., making sure to click ppm
or milligrams/cubic meter as appropriate. You may also use
User specified cone, to obtain footprint estimates for a vari-
ety of levels of concern.
Footprint options
Once you've chosen the level of concern that you want ALOHA
to use for calculating the potential threat zone, decide how
you want to view this information. If you click Plot on grid,
ALOHA will draw the footprint on a grid and scale the
drawing to fit on your computer screen.
WARNING
6-4
-------
1
Chapter 6; The Display Menu
Figure 6-5.
Footprint dsplay
options.
Select Footprint Output Option: [ Help ]
® Plot on grid end auto-scale to fit window.
O Use user specified scale.
Select Output Units:
® English units
O Metric units
[ Help
f Cencel j
If you select User specified scale, when you click OK, ALOHA
will ask what scale you wish to use. User specified scale is
useful if you want to print the footprint on a transparency and
overlay it on a map of known scale.
Figure 6-6.
Specifying a scale for
footprint plot.
User Specified Plot Scole
Pleese Input User Scale
® Incfi
Ocm
1 screen ®lnch equals:
O inches O miles
O feet O meters
O yards @ kilometers
Cancel
Help
Select Output Units
ALOHA will use the units that you select to represent the
footprint distance and source rate information. The units that
you select will not affect the meteorological, chemical, and
source information that you entered using the SetUp menu
(i.e., your inputs will remain in the units that you used and
will appear on the Text Summary screen as such).
6-5
-------
Chapter 6: The Display Menu
Text Summary
Choose the Text Summary menu item to make the Text Sum-
mary window the current front window. This window dis-
plays the options you've chosen as you've moved through the
ALOHA menus. It also summarizes, in text form, the results
of ALOHA's calculations, such as the length of the footprint
and type of dispersion calculation used. When you first open
ALOHA, you'll see short messages in the Text Summary
window. These indicate that you haven't yet told ALOHA the
location, chemical, or atmospheric conditions for your sce-
nario.
Pay careful attention
to this screen: make
sure that your input is
accurately reflected
and note warnings or
messages.
SITE CMTD IhTCFHBTION:
Location: Pl«o»» *al«ct your location
Building: Stwltarad ilngl* ilori«d
Data * T|M: Using Internal Macintosh clock
CHETIICfil. INFGnTflTIOrr - (SELECT
HTHOSPHERIC IhTOfWATIOM: - (SELECT HTnOSM«K>
Figure 6-7.
Text summary window.
Whenever you choose a menu item, enter information, and
click OK, your choices are summarized in the Text Summary
window. For example, when you choose a chemical, its name
will appear next to CHEMICAL INFORMATION; when you
enter atmospheric information, that information will appear
under ATMOSPHERIC INFORMATION, and so on. In the
example above, only a Building type and Date & Time have
been specified.
Footprint
When viewed from above, ground-level concentrations of a
dispersing chemical reach or exceed your specified level of
concern within an area that forms a "footprint." This shape
represents the spread of the gas cloud to the level of concern.
6-6
-------
Chapter 6: The Display Menu
Dashed lines are drawn on either side of the footprint. These
lines reflect the uncertainty in the wind direction based on the
stability class that you (or the SAM station) have chosen. The
wind usually will not remain constant from any one direc-
tion; the lower the wind speed, the more likely it is that the
wind direction will vary, and thus, the wider the uncertainty
lines become. These "uncertainty lines" give you an indica-
tion of how confident you can be of the direction of the
dispersing cloud.
Figure 6-8.
ALOHA footprint.
overhead view of gas cloud showing concentration > level of
concern
M
01
U. f*
0.25
0
0.25
0.75
-"
_.•—""""'""
0.5
^»«
f~
1 1.5 2
ni les
possible cloud movement based on uncertainty in the
wind direction
6-7
-------
Chapter 6: The Display Menu
You can never be 100% certain that the wind direction will fall
within the uncertainty limits unless you draw a circle (to
indicate that it's possible for the wind to come from any
direction). The outer lines drawn by ALOHA are based on a
95% confidence factor. This means that, 19 out of 20 times, the
wind will be from a direction that will keep the cloud of
pollutant between these lines. At very low wind speeds, you
will notice that these lines will form a circle.
Be aware that, whenever source strength changes during a
release or a release is very brief, a heavy gas footprint may
overestimate the threat zone. This overestimate can be sub-
stantial when source strength changes rapidly and drasti-
cally. This happens because ALOHA makes simplified calcu-
lations in order to produce a footprint plot in the short time
available during an emergency response. Except in cases
when release rate is constant, the model warns you of this by
placing brief messages both on the heavy gas footprint plot
(where you'll see the messages, "May be overestimate" and
"Check concentration") and in the Text Summary window.
When source strength is not constant for an hour, treat a
heavy gas footprint as an initial screening estimate. When
you see ALOHA's warning messages, check concentrations,
both at locations of concern and at a few points along the
footprint centerline. This will give you a better idea of what
ground-level concentrations may actually be downwind of
the source. Unlike the footprint calculations, ALOHA's heavy
gas concentration calculations are not simplified. Note that,
in some cases, concentrations may be lower than your level of
concern well within the footprint.
6-8
-------
Chapter 6: The Display Menu
Concentration
Besides examining ALOHA's footprint plot to see how far a
dispersing chemical cloud may spread, you may want to find
out about the concentration of chemical to which people at a
particular location within the affected area may be exposed.
This location could be a hospital, school, or large office build-
ing, as examples.
ALOHA displays a Concentration vs. Time graph showing
predicted concentrations for the first hour following the start
of a release, at a location that you have specified. You'll see
two curves on the graph. The solid (red on a color monitor)
curve represents the outdoor, ground-level concentration.
The dashed (blue on a color monitor) curve represents con-
centration within a building of the type you selected using the
Building Type... menu item in the SiteData menu.
In reality, concentration of a dispersing chemical at a specific
point can fluctuate widely. The concentration values pre-
sented by ALOHA represent concentration values that have
been averaged for five minutes.
An example of a concentration graph is shown below. This
graph shows concentrations downwind of an evaporating
puddle of acrolein. You can see that outdoor concentration
started to increase immediately after the spill began. Inside
sheltered, single-story buildings (the type selected for this
scenario) it took much longer for indoor concentration to
increase. Comparing indoor and outdoor curves on a Con-
centration vs. Time graph can be helpful in determining the
relative threats associated with remaining indoors versus
leaving the area through a dispersing pollutant cloud.
6-9
-------
Chapter 6: The Display Menu
Figure 6-9.
Concentration vs. Time
graph for an evaporating
puddle.
Designating a Location
You may choose either of the following ways to designate a
location for which you would like to see predicted concentra-
tion. (You'll first need to have chosen a chemical and entered
information under the source option.)
Choose Concentration from the Display menu.
Then type in the coordinates of a location either in terms of its
east-west and north-south distances or its downwind and
crosswind distances from the source. Once you have indi-
cated a location and clicked OK, ALOHA will automatically
calculate and display a concentration graph for that point.
Choosing coordinates
Your choice of coordinates will have important effects on the
information that ALOHA will present to you if the wind
direction changes (whether you're using a SAM station, or
you manually entered a new value).
Using fixed (east-west and north-south) coordinates
Choose this method if you wish to know the concentration
expected at a specific geographical location. This could be,
for example, a school 100 yards to the west and 400 yards to
the north of the spill location. This is the best method to
choose if you wish to monitor expected concentration at the
6-10
-------
Chapter 6: The Display Menu
school, and you are using a SAM station to track wind speed
and direction in ALOHA. If the wind shifts direction, the
concentration graph displayed by ALOHA may change, de-
pending on whether or not the shift in wind direction moves
the cloud closer to the school or farther away from it.
Figure 6-10.
Entering fixed
ooonSnatesfbra
location of concent.
Concentration and Dose Location
Specify the location at which you want to evaluate the
concentration and dose ouer time.
o
Relative Coordinates
' (Downwind,Crosswind)
Fined Coordinates
(East-UJest,Nor1h-South)
Input K, the east-west distance
from the source and V, the
north-south distance from the
source.
Input H:
Input V:
QEost
® North
©West
O South
Cancel
SOUTM/
100
400
Ev4ku«gn
Point
I
,J
© Vards
O Miles
O Meters
O Kilometers
Help
Using relative (downwind and crosswfnd) coord/nates
Choose this method when you wish to know the concentra-
tion expected at a position that can best be described in terms
of its downwind and crosswind distance from the spill source.
For example, suppose that you have estimated the straight-
line distance between the site of a spill and a nearby hospital
to be a quarter-mile. At the moment, the wind is not blowing
the chemical cloud directly towards the hospital, but the
wind is variable in direction.
You wish to know the concentration you could expect if the
wind were to shift and carry the cloud of escaping chemical
directly towards the hospital. You can find this out by using
ALOHA to obtain a concentration graph for a location a
quarter-mile downwind, with a crosswind distance of 0 miles.
6-11
-------
Chapter 6: The Display Menu
When you use relative coordinates, ALOHA will remember
the location of the point that you have specified in terms of its
downwind and crosswind distance to the source. Therefore,
the geographic location of the point that you have specified to
ALOHA will move when the wind direction changes.
IMPORTANT
Concentration and Dose Location
Specify the location at which you want to eualuate the
concentration and dose oiier time.
_ Relatlue Coordinates EvckMfen
(Downwind,Crosswind) PoM
_ Fined Coordinates
U (East-West, North-South)
\ Jl Wind dfe-«ettoi
/*
Input H, the downwind distance /x
from the source and V, the /
perpendicular distance from the **
downwind OHis.
Input H, the downwind distance: 0.25
Input V, the crosswind distance : 0
I OK ] [ Cancel j
W
O
[ Help
vards
Meters
Kilometers
ID
Figure 6-11.
Entering wind-relative
coordinates for a location
of concern.
In the Footprint window, double-dick on the location of
concern
You are not restricted to choosing a point within the foot-
print. ALOHA will display a concentration graph for the
point that you have indicated.
ALOHA will use relative (downwind and crosswind) coordi-
nates to remember your site's position. Remember that the
geographic location of the point that you have specified to
ALOHA will move when the wind direction changes.
6-12
-------
Chapter 6: The Display Menu
Figure 6-12.
Footprint pbt showing a
selected concentration
location. The cross-hair
symbol marks the port
where concentration has
been evaluated.
100
0
100
200 4OQ 600
Dose
There is no general agreement among toxicologists about the
proper definition of the term "dose." ALOHA defines dose as
the concentration of pollutant to which people are exposed,
taken to a power, multiplied by the period of time that it is
present. The exact equation used in ALOHA is
where C is the concentration computed by ALOHA, t is the
period of exposure, and n is the dose exponent. Toxicologists
adjust the exponent n to account for the differing toxic effects
of hazardous chemicals. When n is 1.0, dose is equivalent to
what many people call "exposure."
WARNING: Dose information is difficult to interpret because the effects
of most toxic chemicals on people are poorly understood. If
you don't know the appropriate dose exponent to use for a
particular chemical, or if you can't consult with a specialist
who can advise you on the correct exponent to use and help
you to interpret ALOHA's results, avoid using ALOHA's
dose calculations. Instead, use information from ALOHA's
footprint and concentration plots and your own knowledge
of a chemical to make response decisions.
6-13
-------
Chapter 6: The Display Menu
Using die dose exponent
You can adjust ALOHA's dose exponent, n, by choosing
Computational from the SctUpmenu. ALOHA will calculate
dose by multiplying concentration, taken to the n-th power,
by the exposure time. For example, if you set n to 1.0 and the
concentration is predicted to remain at a constant 100 ppm for
5 min at a particular location, ALOHA will predict that people
there will be exposed to a dose of 500 ppm-min. If you change
the exponent to 2.0, ALOHA will calculate dose as concentra-
tion squared and multiplied by exposure time. For the ex-
ample above, ALOHA would predict dose to be 50,000 ppm2-
min. (Note that the units of dose change when the exponent
changes.)
Obtaining a dose graph
Once ALOHA has made concentration calculations for a loca-
tion that you have specified, you may choose Dose from the
Display menu to see a Dose vs. Time graph for the same
location. This graph will display indoor and outdoor dose
predicted for the first hour after a release begins. On the
graph, outdoor dose is shown as a solid (red on a color
monitor) curve, and indoor dose as a dashed (blue on a color
monitor) curve. In the Text Summary window, you'll see
values for maximum indoor and outdoor dose at the end of
ALOHA's one-hour scenario representation.
6-14
-------
Chapter 6: The Display Menu
Figure 6-13.
Dose and concentration
vs. time graphs fora time-
dspsndent release.
Dosa Window
80,0001
c 60,000
•
40,000
20,000
0
20 40
• Inutm
60
Concentration Window
2,000-
1,300-
1.000-
300
0
20 40
• inulM
60
Source Strength
You may choose Source Strength from the Display menu to
get an idea of how rapidly (or slowly) a spilled chemical is
escaping into the atmosphere. When you choose this menu
item, ALOHA will display a graph showing the rate of release
of your chemical (the "source strength") predicted for the
first hour after a spill begins.
ALOHA produces two main types of source strength esti-
mates, depending on the type of release that you have chosen.
Source strength graphs for the two types of estimates differ in
appearance.
6-15
-------
Chapter 6: The Display Menu
Release rate for a Direct source, whether it's instantaneous or
continuous, will remain constant for the duration of the re-
lease. ALOHA expects an instantaneous release to last for 1
minute, and a continuous release to last for one hour. Graphs
of either type of Direct release look like the plot shown below.
I Source Strength (Release Bate)
1
M
2-
30
4O
Figure 6-14.
Source strength graph
for an instantaneous
Direct release.
J
Source strength predicted by the Puddle, Tank, or Pipe
source options may change over time.
For example, take the rate of release of a pressurized gas from
a tank rupture. Initially, the chemical escapes rapidly through
the rupture. As the tank pressure drops, the rate of release
slows. If you model such a release using ALOHA, you'll see
a curve that descends in steps on the source strength graph.
Sourct Strength (H»lta«« R«t»)
S too
200-
0
20
• Inutw
40
Figure 6-15.
Source strength graph for
a pressurized tank
6-16
-------
Chapter 6: The Display Menu
Source strength averaging
ALOHA calculates source strength as a series of up to 150
steps. These values must be averaged into fewer steps so that
dispersion and concentration calculations can be made rap-
idly. The averaged source strengths form a series of up to five
steps, each of at least one minute duration. The highest
release rate from each of the two series is reported on the Text
Summary window. The highest release rate from the first
series is the maximum computed release rate. The highest
release rate from the averaged series is the maximum aver-
aged release rate. The series of averaged steps is shown on
the Source Strength graph, since this is the information used
to calculate the footprint.
Calculate
You can choose how often you would like the data in the
windows in ALOHA updated. This is necessary because
some of ALOHA's calculations, such as those for heavy gas,
may take a few minutes. You have three options for deciding
when to update ALOHA output windows:
O Automatically update all visible windows
O Automatically update only front window
O Manual update of all visible windows
In all cases, ALOHA will not update any windows until new
data are available. The first two options are self-explanatory;
the last option means no window will be updated until you
select Calculate Now from the Display menu. All visible
windows will then be updated.
6-17
-------
Chapter 6: The Display Menu
To auke Multiple Choose
changes before "Manual
asking ALOHA to update of all
fBcakahitPm visible
ALOHA will OM> opiate its windows when y«i
(feme Cakilate Now from die Display MML
Otherwise, all visible window
to reaund yon that tfkir data has not yet been
To hare your daft
continuously
updated
regardless of (fae
tiawk takes-.
To have only
ALOHA'S «os»
recent
calculations
updated-
Choose
"Automatically
update ail
visible
windows"
Choose
"Automatically
update only
front window"
Whenever you add data, all of the windows wifl
be updated to reflect your additions. However,
any data you are receiving from the SAM station
during this update will be lost
Afl of tbe other windows will be grayed**, but
you can did on one of the bad windows to
bring it forward to be recalculated (you can only
choose the window from the Display man).
Calculate Now
You can only select Calculate
Now if you've done two things:
1) chosen Manual update of
all visible windows in the Cal-
culate Options dialog box, and
2) changed some of your infor-
mation under the SetUp menu.
The windows remain grayed-
out, indicating that they do not
reflect current conditions.
When you choose Calculate
Now, the output will be recal-
culated and the visible win-
dows will be updated.
Display
Tile Windows
Stack Windows
Options...
Teiit Summary
Footprint
Concentration...
Dose
Source Strength
Calculate...
Calculate Now
Figure 6-16.
Calculate options.
Figure 6-17.
Calculate Now option.
6-18
-------
Chapter 7
The Sharing Menu
In this chapter...
Sharing Info in Windows
BitPlot 7-1
MARPLOT-DOS ...7-3
Sharing Info on the Mac
MARPLOT 7-3
Introduction
ALOHA can communicate and share information with other
programs. Both in Windows and on a Macintosh, ALOHA can
share information with mapping applications so that a cur-
rent ALOHA footprint can be plotted on a map.
Sharing Information in Windows
When you're running ALOHA in Windows, you can choose
between two applications to plot an ALOHA footprint on an
electronic map of your city or community. ALOHA can share
information with two mapping programs, BitPlot and
MARPLOT-DOS. The program you choose depends on the
type of map that you have.
BitPlot
BitPlot is a Windows application that is installed in your
ALOHA directory when you install ALOHA. It uses maps
which are in the Windows device-independent bitmap (.bmp)
format. If BitPlot is present in your ALOHA directory, ALOHA
will display a Sharing menu for BitPlot.
7-1
-------
Chapter 7: The Sharing Menu
Sharing
BitPlot
Go to map
Figure 7-1.
ALOHA Windows
Sharing menu.
Select Go to Map from this menu to launch BitPlot or to bring
it forward if it is already running. A step-by-step example
describing how to use ALOHA and BitPlot together is in-
cluded as Example 5 in Appendix A. Refer to the appendix
describing BitPlot in this manual, or to BitPlot's on-line help
topics, for additional information.
Pie Ed* QpttoM Sharing
Figure 7-2.
An ALOHA footprint
plotted on a map in
BitPlot
7-2
-------
Chapter 7: The Sharing Menu
MARPLOT-DOS
MARPLOT-DOS is the mapping module of the CAMEO-DOS
package. To see your ALOHA footprint on a MARPLOT
map, you must run ALOHA and MARPLOT simultaneously
in Windows. See your MARPLOT documentation for addi-
tional information.
MARPLOT was designed to use special maps generated from
TIGER (Topologically Integrated Geographic Encoding and
Referencing) files, prepared by the U.S. Census Bureau. TI-
GER files are computer-readable geographic data bases for all
U.S. states, territories, and possessions. They include digital
descriptions of features such as political boundaries, water
bodies, transportation routes, and address ranges for street
segments. MARPLOT-readable maps incorporating this TI-
GER information are available from the National Safety Coun-
cil (1-800-621-7619, extension 6900) and other sources.
MARPLOT cannot directly read TIGER files; however, you
may use MARPLOT to generate maps from TIGER files.
Sharing Information on a Macintosh
When you're running ALOHA on a Macintosh, you can use
MARPLOT-Macintosh to plot an ALOHA footprint on an
electronic map of your city or community.
The Sharing menu
The programs that comprise the CAMEO package for the
Macintosh work together by means of the Sharing menu.
Any program that can communicate with ALOHA may install
a hierarchical menu under ALOHA's Sharing menu. In the
example below, MARPLOT has installed a menu in ALOHA's
Sharing menu. In return, ALOHA installs a menu under the
Sharing menu in MARPLOT.
7-3
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Chapter 7: The Sharing Menu
These menus will appear every time the two applications are
run simultaneously. A menu installed by another application
into the ALOHA Sharing menu belongs to the installing
application. Refer to the documentation from that program
for a description of how those menu items operate.
Sharing
fiboutShared Menus
Saue Shared Menus...
MflRPLOT
Go To Map )
Figure 7-3.
ALOHA's Sharing menu,
including a menu installed
bytheappfcation
'MARPLOT.
Before you quit ALOHA, you may wish to save the menus that
other applications have placed under ALOHA's Sharing
menu. Do this by choosing Save Shared Menus and selecting
those menus which you wish to be saved. These menus will
automatically be placed under the Sharing menu the next
time ALOHA is run. When you use a saved menu that belongs
to an application that isn't currently running, ALOHA starts
that application so that it can carry out the specified action.
MARPLOT-Macintosh
On a Macintosh, ALOHA relies on MARPLOT-Macintosh, the
mapping module of the CAMEO-Macintosh package, to dis-
play a footprint generated by ALOHA on a map. You must be
using either MultiFinder in System 6 or System 7 to use
MARPLOT with ALOHA. Like MARPLOT-DOS, it uses spe-
cial maps generated from TIGER files. MARPLOT-Macintosh
cannot read TIGER files directly, and cannot be used to
generate maps from TIGER files. Obtain M ARPLOT-readable
maps generated from TIGER files from the National Safety
Council. MARPLOT also can use standard Macintosh PICT
format files as background maps.
7-4
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Chapter 7: The Sharing Menu
In order to plot an ALOHA footprint on a background map,
you'll need to run ALOHA and MARPLOT simultaneously.
ALOHA will install a menu in MARPLOT'S Sharing menu
which will allow you to display an ALOHA footprint on a
MARPLOT map. Choose from among the following items
contained in the MARPLOT menu:
Figure 7-4.
ALOHA menu items
installed n MARPLOTS
Sharing menu.
Sharing
Rbout Shared Menus...
Saue Shared Menus...
HLOHH
Help...
Set Source Point
Set Cone Of Dose Point
Delete RLOHR Objects
Go To RLOHfl
Help...
Choose this item to see a help text describing ALOHA's menu
items in MARPLOT. When you're finished, click Cancel to be
returned to MARPLOT.
Set Source Point
Before choosing this item, click on the location of the spill on
your MARPLOT map. Then choose Set Source Point to tell
ALOHA the source location. ALOHA will place a symbol at
that location. The footprint, confidence lines, and concentra-
tion/dose point will automatically be placed on the map
when the necessary information is available in ALOHA.
Set Cone & Dose Point
Before choosing this item, click the location on your MARPLOT
map for which you'd like to see concentration and/or dose
7-5
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Chapter 7: The Sharing Menu
information. Then choose Set Cone & Dose Point to tell
ALOHA the concentration/dose location. ALOHA will place
a symbol at that location, then come forward to make concen-
tration calculations and display the results.
Delete ALOHA objects
Choose this item to remove all objects placed on the map by
ALOHA. ALOHA will then stop updating the map every time
it generates new information.
Go to ALOHA
Choose this item to bring ALOHA forward.
A step-by-step example describing how to use ALOHA and
MARPLOT together is included in Appendix A. See your
MARPLOT documentation, and MARPLOT'S on-line help
topics for additional information.
ALOHA will use fixed
(east-west, north-south)
coordinates to remember
the points position.
7-6
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Appendix A
Examples
..a tank source
..direct input (heavy gas)
..a pipe source
..ALOHA, MARPLOT, and a PICT map
..BitPlot and ALOHA
..ALOHA and a MARPLOT map
Note:
Here are six examples which are designed to help you understand
ALOHA for both the Macintosh and Windows platforms. You may
get slightly different answers if you use a computer without a
coprocessor.
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Example I
A Tank Source
In a small industrial park outside of Baton Rouge, Louisiana, a 500-
gallon, four-foot diameter vertical tank contains liquid benzene. On
August 20,1990 at 10:30 pm local time, a security guard discovers that
liquid is leaking out of the tank through a six-inch circular hole that is
10 inches from the bottom of the tank. He also notices that the liquid
appears to be flowing into a grassy field west of the industrial park.
The security guard thinks the tank had just been filled that evening.
The on-scene weather is partly cloudy, 80° F, with wind from the east at
7 knots. There is more than 50% cloud cover and the humidity is
greater than 75%. There is no inversion.
The local emergency planning committee (LEPC) has indicated that the
level of concern (LOC) for this product is 10 ppm. Using this scenario,
we'll determine the downwind distance to this LOC.
First...
Double-click on ALOHA and, after reading the ALOHA caveats,
click OK
Building Type.
Date » Time...
Choose Location from the SiteData menu.
A-l-1
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I location Information i
BflKCRSFIELD, CHLIFORNIR
BALTIMORE, MflRVLflNO
BRHNWELl, SOUTH CRROLINA
iflRSTOUl, CHLIFORNIfl
1RTRUIA. ILLINOIS
aRTRlMA, NEIil VOAK
^
IERUMONT, TEHRS
1EHUERTON, OREGON
IELLEUILLE, ILLINOIS
iENSON. NORTH CAROLINA
BERKELEY, CALIFORNIA
illLINGS, MONTRNH
BIRMINGHAM, ALABAMA
BISMARCK, NORTH DRKOTR
BLOOMFIELO, INDIANA
BOISE, IDAHO
HDOMUILLE .MISSOURI
CancBl
Modify
Help |
Use the scroll bar or type the character "B" to find the city. Once
you have located Baton Rouge, Louisiana, double-click on it or
click once and click Select.
Second..
For this case, we will not enter information about the building type
because buildings are not described in the scenario.
I Choose Date & Time... from the SiteData menu.
SiteData
Location...
Building Type...
Date C Time.
Select Set constant time and enter the month, day, year, hour
and minute for this scenario. You may tab to each of the fields
to enter the date. Remember, the hour must be entered as a
military time.
A-l-2
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Dale and Time Optloni
Vou can either use the computer's internal clock for the
model's date and time or set a constant date and time.
O Use internal clock
i Set constant time
Input constant date and time
Month Day Vear
|8 I [20 I |1990
(1-12) (1-51) (1900-...)
Minute
0_
<0-59)
[ Cancel
Help
3 Click OK.
The next menu for data input is the SetUp menu.
Third..
I Select Chemical... from the SetUp menu.
SetUp
Chemical.
Htmospheric
Soum>
Computational..
Use the scroll bar or type the character "B" to find the chemical.
Once you have found benzene, either double-click on the
chemical or select the chemical and dick Select.
A-l-3
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! Ctitmlcal information
ENZHLDENVDC
HFNPFNF.
1ENZENE. HCHLOROMETHVU-4-NITRO-
UNZENC PHOSPHORUS DICHLORIDE
IENZENE PHOSPHORUS THIOOICHL08IDE
ICNZENE SULF0NVL CHLORIDE
1ENZONITRILE
lENZOTRICHLORIDE
ICNZOVL CHLORIDE
IENZVL ALCOHOL
IENZVL BROMIDE
lENZn CHLORIDE
IENZVLIDENE CHLORIDE
IITBSCHNflTE
IQRNEQL
iORON TRIBROMtDE
iORON TRICHLORIDE
IQflON THIFLUORIDE
[Modify
Fourth...
Select User Input., from the Atmospheric submenu under the
SetUp menu.
Chemical...
SOUK e H SHM station...
User Input.
Computational...
Click the button for stability class E because the spill occurs at
night, the winds are between 4 and 7 knots, and the cloud cover
is greater than 50%. To help you make this choice, click Help
and look at the table. Nothing in the scenario indicates the
presence of an inversion, therefore, the default setting, No
Inversion, should not be changed.
A-l-4
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I atmospheric Options
Stability Clasi Is : O" O> OC OB ®E OF [ Help ]
Inversion Height Options or
® No Inversion Olnui
•: [ Help I
irslon Present, Height Is: |
wind notion* are: 1, Help I
Wind speed It: | 7
Wind Is from : |E
Air Temperature I*: 1 10
Ground Roughness Is; ('
® Open Country ofl
O Urban or Forest
t^^^K^^^
® Knots OMPB O Meters/Sec.
©Feet
O Meters
[ Help 1
Enter tfogrees true or tent ILo. ESE)
Daqr»* S>f OC f Help 1
Help ]
O Input roughnessfZo): [5!o
| { Cancel ]
Oin
®cm
After selecting the stability class, enter the wind speed and click
the button next to knots. Enter either E or 90 for the wind
direction. Remember, the direction entered is the direction
from which the wind is blowing. Enter 80 for the air
temperature and select the units button for degrees F.
Select the button for Open Country for the ground roughness
because the leaking chemical is flowing into a nearby grassy
field that is west of the industrial park. The wind direction is
from the east and the general area that we would expect the
benzene cloud to move is over the grassy field. If the wind
direction had been from the west, that is blowing towards the
industrial park, the Urban or Forest button should have been
selected.
A-l-5
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complete
cover
pertly
cloudy
O OR O «nt«r veliM |?
(0-10)
cleer
Select HuinMity:
O OR ® enter woiue
dry (0-100)
Cancel
Click OK when you've filled in all of the data.
The scenario describes the cloud cover as partly cloudy (greater
than 50%) and not completely overcast, so click the button
between complete cover and partly cloudy.
Click the enter value button and enter 75 for the humidity.
8
Click OK.
The information that you have entered into ALOHA will
appear on the text summary screen. Remember that, for this
scenario, we are not considering the infiltration rate into
buildings so you should ignore the building exchange rate.
A-l-6
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I Tent Stimmnnj
SITE DATA INFOAMATION:
Location: BATON ROUGE, LOUISIANA
Building Air Exchanges Par Hour: 0.67 (Sheltered sing!* storied)
Dot* t T!M: Fixed at August 20, 1990 I, 2230 hours
CHEMICAL INFORMATION:
Cheeical MOM: BENZENE Molecular Might: 78.11 kg/twol
TLU-TUH: O.10 ppa IDLH: 3000.00 ppe
Not*: Potential or cenfIreed huean carcinogen.
Footprint Level of Concern: 3000 pp*
Boiling Point: 176.10* F
Uqpar PrMcure at ftabl«nt Teaporatur*: 0.13 a\»
Hablent Saturation Concentration: 134,909 pa* or 13.51
*ln
nTnOSPtERIC IMFOROHTIOH:
-------
Enter 500 gallons for the volume and 4 feet for the diameter of
the tank. Be sure to select the correct buttons for the units.
Once the volume and diameter are entered, the correct length is
automatically calculated.
Click OK.
The scenario described the product stored in the tank as a
liquid. Since we would expect benzene to be a liquid at ambient
temperature (notice on the summary screen that it has a boiling
point of 176.16°F), we have no reason to suspect that the
chemical is stored at a temperature other than ambient. Click
Tank contains liquid and Chemical stored at ambient
temperature.
Chemical State and Temperature
Enter the state of the chemical:
©Tank contains liquid
QTank contains gas only
O Unknown
Help ]
Enter the temperature within the tank: [
® Chemical stored at ambient temperature
O Chemical stored atpoI degrees
Help
Click OK.
A-l-8
I
-------
The security guard thinks the tank was rilled in the everting, so
the most conservative estimate we can make is that the tank is
100% full and contains 500 gallons of product. Either enter the
liquid volume directly, 500, and select gallons for the units,
enter 100% full by volume, or scroll the bar to the top for the
liquid level. After the liquid volume is entered, the mass of the
liquid is automatically calculated.
Liquid Matt or lleluma
Enter tit* mass OR uolumt of the liquid
O pounds
Hio moss of liquid Is: |l.82 | ® tons(2.000 Ibsl
O kilograms
OR
Enter volume OR liquid (anal
Tlio liquid
I*: 500
© gallons
j O cubic foot
'Outers
O cubic meters
1100 I % full by uoluma
[ Cancel ] f Help ]
8
Click OK.
Click Circular opening, enter 6 for the hole diameter, and select
inches.
A-l-9
-------
10 Click Hole.
12
I^BHEs^S flirea i
Select the shape that
the opening through u
® Circular opening
Opening diameter:
1* leak through a hole
©Hole
» OK 1 (
md Type of Leak BBfc^^s
best represents the shape of
which the pollutant Is exiting
1 1 »«•«
« fc»Hh >
O Rectangular opening
® Inches
" O centimeters
O meters
or short pipe/ualue?
O Short pipe/ualue
Cancel ] [ Help
I I Click OK.
Enter 10 and select inches for the height that the bottom of the
hole is from the bottom of the tank. ALOHA will automatically
calculate the percent from the top of the tank.
Height of the Tank Opening
11
. llq. \uum\ 1
OK 1
O
1
I
35
O
The bottom of the leek i*:
PI q ] <§> In. O ft. O cm. O m.
above the bottom of the tenk
DR
f 1 5.7 1 % of the way to the top of
1 ' the tank
Cencel ] [ Help ]
13 Click OK.
A-l-10
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14 The product is flowing into a grassy field, but grass is not one of
the choices. For this scenario, clicking Default for ground type
is probably the best choice. You may wish to compare results
using other ground types.
' Puddle Parameters '
Select ground type
[ Help
i Default O Concrete O Sandy O Moist
Input ground temperature [ Help ]
© Use air temperature (select this If unknown)
O Ground temperature is [fro ] deg. ® F O
Input maximum puddle diameter
Unknown
O MaHimum diameter is
Help
®ft Oyds O meters
Cancel
I5 The scenario does not give the ground temperature so the best
choice is to click Use air temperature.
I 6 Because the product is flowing into a field, it is probably not
contained by a dike. For input maximum puddle diameter,
click Unknown.
17 Click OK.
The source strength information that you have entered into
ALOHA should appear on the Text Summary screen. This
screen contains a lot of information about the release. For
example, you know that the release of vapor into the
atmosphere is estimated to last for approximately 33 minutes
and the maximum amount of vapor released at any one time is
estimated at 125 pounds/minute (maximum computed release
rate). In the case of the puddle, we would expect the maximum
A-l-11
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release rate to correspond to the time when the puddle surface
is the greatest.
TeHt Summary
SOURCE STRENGTH INFOM1ATIOH:
Liquid look fro* hole In vertical cylindrical tank select ad
Tank Oioaeter: 4 feet Tank Length: 3.32 feet
Tor*. Uoluee: 500 gallons
Intamai TeeperoUre: 80* F
Chwlcal Has* in Tank: 1.BJ! tons Tank Is lOOff full
Circular Opening Diameter: 6 Inches
Opening I* 10 Inches fro* tank botto» Soil Type: Default
Oraund Teap: equal to aebient flax Puddle DiaMter: Unknown
Release Duration: 33 •inutes
Max Caeputed Release Rat*: 125 pounds/Bin
flax nverage Sustained Release Rate: 114 pounds/Bin
Total fleount Released: 3,073 pounds
2L
When ALOHA does its calculations, it averages the release rate
over five steps (these five steps are seen in the source strength
graph). The maximum average sustained release rate reported
on the text summary screen corresponds to this maximum
average step on the source strength graph. In some cases
(particularly pressurized releases which have very high release
rates for the first few seconds), these two maximum release
rates may be significantly different.
Sixth...
We can see the source strength graph at this point by selecting Source
Strength from the Display menu.
I Select Source Strength... from the Display menu.
Til* Windows
Stack Windows
Option*...
Tent Summary
Footprint
ti>i\i:aritr
-------
Let's think about the release rate implications of our scenario and try
and determine where the model may not be accurately representing
what is actually occurring. We have a tank that has formed a puddle;
the puddle is undiked so it can grow quite large and thin. This would
lead to a large evaporation rate for a short period of time. What would
happen if the puddle were constrained by small depressions in the
grass?
The puddle would not be able to spread out as far because the liquid
flowing away from the tank would fill up the depressions in the grass.
The puddle would then be smaller and deeper. This would make the
evaporation rate lower and it would take much longer for the puddle
to completely evaporate.
The release rate calculated by ALOHA in our scenario assumes that the
puddle gets large; therefore, ALOHA would predict the most
conservative (worst-case) downwind distance to the level of concern
and, in this instance, the duration of the release rate may be
underestimated.
Source Strength (Release Bate)
2001
2 150 H
I
•£ 100-
30-
10
20 30
•inutas
40
J
If the terrain contains any features (e.g., ditch or ground depression)
that may constrain the puddle from spreading, we can try to estimate
the effective diked area and enter this as the maximum puddle area.
In this scenario, no other information was given.
A-l-13
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Seventh...
I Select Computational... from the SetUp menu.
Chemical...
Htmospherlc
Source
2 Click Let model decide (select this if you're unsure).
Computational Preference*
Select spreading elgortthm. If unsure, let
model decide.
Help I
© let model decide (select this If unsure)
O Use Emission dispersion only
O Use Heeuy Ges dltpertlon only
Define dose:
I Help
Dose-JcMdT n-[I.O
•*§ i
Cancel
Click OK.
A-l-U
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Eighth...
I Select Options... from the Display menu.
Displai)
Tile Windows
Stack Windows
TeKt Summary
Footprint
Concentration...
Dose
Source Strength
Calculate...
Calculate Now
2 The scenario describes the level of concern as 10 ppm. Click the
button for User specified concentration and enter 10. For the
units, click the button for ppm.
3 Click Plot on grid and auto-scale to fit window.
4 Click the Output Units button for English units.
Display Options
Select Leuel of Concern or Output Concentration: [ Help
O IOLH Concentration
® User specified cone, of 110J
©ppm
O milligrams/cubic meter
Select Footprint Output Option: [ Help"
© Plot on grid and auto-scale to fit window.
O Use user specified scale.
Select Output Units:
® English units
O Metric units
Help
Cancel
Click OK.
A-l-15
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Ninth...
I Select Footprint from the Display menu.
Display
Tile Windows
Stack Windows
Options...
Text Summary
Fuotpi nit
.Concentration...
Dose
Source Strength
Calculate...
Calculate Now
Once you select Footprint, a bar graph should briefly appear on
the screen. The bar graph will indicate how much time the
model needs to finish calculating the footprint. It will also
indicate which module is being used for the calculations. For
this scenario, the Gaussian module was used.
Footprint Illindoii
750
2,000
Notice that ALOHA opted to use the Gaussian calculation even
though the molecular weight of benzene is greater than air.
This is one of the instances when the concentration of benzene
in the air is not enough to make the air /benzene density much
greater than that of pure air. From the Text Summary screen,
A-l-16
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we can see that the maximum concentration of benzene that
could be in the air at 80°F is 134,995 ppm; or a maximum of
13.5% of the air/benzene mixture directly above the puddle is
benzene (ambient saturation concentration).
After a few moments/ the screen will display the footprint for
the vapor cloud. The solid line around the footprint indicates
the level of concern of 10 ppm. The dashed lines reflect the
uncertainty in the wind direction for the atmospheric stability
class E. This means that in a five-minute period, we could
expect the benzene cloud to rotate within the area drawn by the
dashed lines or "uncertainty lines." The dashed lines represent
a "certainty" level of 95%; or, 19 out of 20 times the footprint
will be within these lines.
A verbal summary of the footprint information should appear
at the bottom of ALOHA's text summary screen. For this
scenario, the downwind maximum threat zone for the level of
concern of 10 ppm is 1338 yards.
I Text Summary
SITE DATA INFOVMTIOH:
Location: MTON ROUOC, LOUISIMW
Building Hlr Exchanges Por Hour: 0.67 (Shaltorod slnglo storlad)
Oat* t TIM: Flxod at ftugu*t 20, I MO t 2330 hours
CHOIICflL irFORMRTION
Chaftlcal MOM
TUJ-TUni o. 10 ppa
Nat*: Potential or conflr-Md nuaan corct
Footprint Lav*I of Concom: 10 ppa
Boiling Point: 176.16' F
Uopor Prassura at ftablont T«*p*ratura: 0.13 at*
M>lont Saturation Concentration: 134,999 ppa or 13.SB
no I ocular Ualgnt: 71.11 kg/knol
IDLH: 3000.00 ppa
flmOSPHERIC !hTOfinnTION:
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Example 2
Direct Input (Heavy Gas)
A paper mill located at a highly industrialized area in Columbia,
South Carolina stores large amounts of liquid chlorine. On May 15,
1990 at 13:00, a reckless forklift operator breaks open a pipe. About 2,000
gallons of liquid chlorine are sprayed out in a fine mist and
immediately evaporate. The chlorine is normally stored at a
temperature of -30°F. The paper mill's single-storied office building is
located about 100 yards directly downwind of the accident. The
building has been recently landscaped with bushes and trees. Since the
weather for the past few days has been rather cool, most people in the
building have kept their windows closed.
At the time of the spill, the sky was completely overcast, the air
temperature was 70° F and the wind was from 360° at 10 knots. The
relative humidity was 67%. We will use ALOHA to help determine
the indoor concentrations of chlorine for the paper mill's office
building.
Pint,..
I Double-click on ALOHA and, after reading the ALOHA caveats,
dick OK
Choose Location from the SiteData menu.
A-2-1
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Use the scroll bar or type the character "C" to find the city. Once
you have found Columbia, South Carolina, either double-click
on the city or select the city and click Select.
COLLE6E PARK, MRRVLRNO
COLORADO SPRINGS, COLORRDO
COLUMBIA, MRRVLRNO
COLUMBIA, MISSOURI
COLUMRIR, SOUTH CRROLINR
COLUMBUS, OHIO
CONCORD, CALIFORNIA
CONCORD, MASSACHUSETTS
CONCORD, NEW HAMPSHIRE
CONROE, TEKAS
CONIUHV, NEW HAMPSHIRE
COOPERSTOUJN, NEW VORK
CORROPOLIS, PENNSVLIIANIH
CORNIN6, NEW VORK
CORONR, CALIFORNIA
CORPUS CKAISTI.TEHAS
CORUALLIS, OREGON
CRCSTON. lOUJfl
[ Cancel J
[ Add
Modify ]
Delete
[ Help
Second...
I Choose Building Type... from the SiteData menu.
SiteData
A-2-2
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The scenario describes the office building as being single-
storied. Since the building has windows that open, we might
suspect that the air exchange rate is not controlled and the
choice of single-storied building would be most appropriate.
Because the building is landscaped, you should
select Sheltered surroundings.
' Infiltration Building Parameter! '
Select building type or enter euchenge parameter
O Enclosed office building I He|p 1
® Single storied building
O Double storied building
O No. of air changes is || | per hour
Select building surroundings ( Heip ]
® Sheltered surroundings (trees, bushes, etc.)
O Unsheltered surroundings
3 Click OK.
Third...
I Choose Date & Time... from the SiteData menu.
Location...
Building Type...
A-2-3
-------
Select Set constant time and enter the month, day, year, hour
and minute for this scenario. You may tab to each of the fields
to enter the date and time.
Date and Time Options
You can either use the computer's internal clock for the
model's date and time or set a constant date and time.
O U** internal clock
i Set constant time
Input constant date and time
Month Day Veer
|5 | |15 I 11990
(1-12) (1-31) (1900-...)
Hour
Minute
(0-23) (0-59)
Cancel
Help
Click OK.
Fourth...
I Select Chemical... from the SetUp menu.
Setup
Chemical.
Atmospheric
SOUICP
A-2-4
-------
Use the scroll bar or type the character "C" to find the chemical.
Once you have found chlorine, either double-click on the
chemical or select the chemical and click Select.
! ClMmical Information
CRMPMENC
CRHPHOM
CARBON BISULFIDE
CRMON 01 OH IDE
CHRBON MONOHIDE
CRRBONTETRHBRQMIDE
CRRBON TETRRCHLORIOE
CRRBONVl FLUORIDE
ARBONVL SULFIOE
HRUONE
CHLORINE
CHLORINE OIOHIOE
CHLORINE TRIFLUORIDE
HLORMCPHOS
CHLORORCETHLDEHVOE
CHLORORCETICflCID
CHLORDHCETVL CHLORIDE
CHLOHORNILINE
Cancel
[ Rdd
Modify
Help
fifth...
Select User Input., from the Atmospheric submenu in the
SetUp menu.
Determining the stability class for this scenario is relatively
easy.
A-2-5
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When the sky is completely overcast, the stability class is always
D regardless of the wind speed and time of day. Click Help if
you need assistance in making this choice. Click the button for
stability class D.
i ATMOSPHERIC OPTIONS
Stability Class U : Q« OB QC ®D Qt OF [ Help ]
Inversion Height Options are: [ Help )
® No Inversion O Inversion Present, Height Is:
Wind Option* are: [ Help 1
i ®Feel
--—-<—<— ' O Union
Wind Speed Is: (in ® Knots OMPH O Meters/See. I Help 1
Wind is from : |N | Enter negroes true or taut (I.e. ESE)
Mr Temperature Is: [TO"] Degrees ®F QC C_
Ground Roughness Is: [ Help )
0 OP«. country OR Q |np(|t rougnn.,.<2oj:
® lirben or Forest
Help I
[ToiriS'n
1 1 ©cm
|" OK "l [ Cencel ]
After selecting the stability class, enter the wind speed and select
the units button for knots. Enter either N or 360 for the wind
direction. The air temperature is 70 and the selected units
should be degrees F. Nothing in the scenario indicates the
presence of an inversion, therefore, the default setting, No
Inversion, should not be changed.
The button for Urban or Forest should be selected for the
ground roughness as the spill is in a highly industrialized area,
that is, an area that contains many buildings and obstacles.
Click OK when you've filled in all of the data.
A-2-6
-------
The scenario describes the cloud cover as completely overcast,
so click the button under the complete cloud cover icon.
Claud Cower and Humldlt
partly
cloudy
O m O antar ualua [10
(0-10)
claar
Selact Humidity:
ft
O OR
dm
> enter value [
Oat* I T!M: Fixed at flay tS, 1990 t 1300 hour*
CHEJIICflL INFOflrWTIOH:
ChMical NOM: CHLORINE
TLV-TUR: 0.90 pfM
Footprint L«w«l of Conesrn: 3O pp«
Boiling Point: -29.25* F
Uopor Pr«*sur« at n«bl«nt Tmpiratur*: groator than 1 atM
flnbiont Saturation Conewitratlan: 1,000,000 pp» or 100.OX
Nolocular Uclght
IDLH: 30.00 pp*
RTTIOSPHERIC JNFORTInTIOfliaiflMUflL
Mind: 10 knots from M
Stability Class: 0
Relative Hueldlty: 6711
Claud Cover: 10 tenths
INPUT OF DRTR)
No Inversion Holght
Rlr Toaparaturo.: 70* F
Ground Roughntcs: Urban or forest
111
t il
•2s
O
01 iee
A-2-7
-------
Sixth...
I Select Direct., from the Source submenu in the SetUp menu.
The scenario describes the pipe breaking and spraying 2000
gallons of chlorine instantly into the atmosphere. ALOHA
assumes that an instantaneous release is one that occurs in 60
seconds. For this scenario, however, it would probably take a
little more than 60 seconds for all of the product to be released
into the atmosphere. We can still use an instantaneous source
since we do not have any more information, but the model's
estimates may be conservative as a result. Click the buttons for
gallons and instantaneous source.
User Input Source Strength
Saloct source strength units of mass or volume: ( Help ]
O grams O kilograms O pounds O tons(2,000 Ibs)
O cubic motors O liters O cubic feat © gallons
Soloct on Instantaneous or continuous source: [ Help
O Continuous source ® Instantaneous source
Enter the amount of
pollutant ENTERING 12000
TUB RTMOSPHERE: '
gallons
Enter source height
(0 If ground source):
©faet
Canes, ]
Enter 2000 for the amount of pollutant entering the
atmosphere. Do not change the default of ground-level for
source height.
A-2-8
-------
4 Click OK.
5 The chlorine was refrigerated at -30°F and stored as a liquid.
The text summary screen indicates that the boiling point for
chlorine is -29.25°F, so it is barely in the liquid stage. Click
Liquid and Chemical temperature. Enter -30 for chemical
temperature. Be sure to select the correct units.
Uoluma Input information
Is tho chemical stored at a gas or liquid?
O Sas ® Liquid
Entar the temperature at which the chemical is stored.
O BmblMit Temperature
® Chemical lempereture ls| -3Q| j degrees ®F
OK
Cancel
Help
6 Click OK.
7 An aiert box warning you that the chemical may flash boil
and/or result in two-phase flow will appear on the screen. If
you are unsure what this means, click Help. Otherwise, click
OK.
A-2-9
-------
The source strength information that you have entered into
ALOHA should appear on the Text Summary screen. The Text
Summary screen will also remind you that the chemical may
flash boil and/or result in two-phase flow.
TBH< Summary
Sowc« Hoiohl: 0
SOURCE STRENGTH INFOWflTIOH
Oir«ct Soura: 2000 gallons
Sawn State: Liquid
Source T««fi«ratur«: -30* F
RaloOM Diratian: 1 •inute
RO.IMS* Rate: 439 pounds/MC
Total ftaount ftalaoMd: 26,002 pounds
Note: This chMical Bay flash boil and/or rasult in tee phaso fl
Seventh...
I Select Computational... from the SetLJp menu.
Chemical...
Atmospheric
Source
Computational.
The scenario describes the chlorine as being stored at very cold
temperatures; the chlorine will behave as a heavy gas. Click Let
Model Decide. ALOHA will be able to determine that the
appropriate dispersion calculations will be for a heavy gas.
Computational Preference
Salect *pra«llng algorithm. If uniure, lit
model decide.
I H«lp
® Let model decide (select thl« If unsure)
O Use Goutsian dispersion only
O Use Heavy Ges dlseerslen only
Define dese:
I "eli> I
Dose -It WOT
t
"•T"1
n -11.0
[ cencel
A-2-10
-------
Do not change the default for Define dose. Don't use this
option unless you have some technical expertise or guidance to
do so.
dick OK.
Eighth...
I Select Concentration from the Display menu.
Display
Tile Windows
Stack Windows
Options...
Tent Summary
Footprint
Concentration.
Dose
Source Strength
Calculate...
Calculate Now
A-2-11
-------
The scenario describes the paper mill's office building as being
about 100 yards directly downwind of the spill. Enter the
downwind distance of 100 yards and the crosswind distance of 0
yards. Be sure to select the correct units.
Specify the location at which you want to evaluate the
concentration and dose oiier time.
_ Rotative Coordinates Ev N
from the source and V, the s*nte
perpendicular dlstence from the
downwind eMls.
Input H, the downwind distance: [ 100
Input V, the crosswlnd dlstence : |4
[ OK J [ Cancel ] [
®Vards
O Miles
O Meters
O Kilometers
Help ]
Click OK.
Once you have clicked OK, a bar graph should appear on the
screen. The bar graph will indicate how much time the model
needs to finish calculating the graphs. It will also indicate
whether Gaussian or heavy gas calculations are being used. For
this scenario, the heavy gas calculations were used and, if you
are using a Mac Plus (or other Mac without a math
coprocessor), it may take a few minutes for ALOHA to do the
calculations.
A-2-12
-------
After ALOHA has completed its calculations, the Concentration
window will appear. The dotted line indicates the estimated
concentrations inside the office building. The solid line is the
estimated concentration outside of the office building (on a
color monitor these will appear blue and red, respectively).
Concentration Window
30,000-
40,000-
30,000-
20,000-
10,000-
0
20
•lnut*s
40
You can see from the concentration window that the chlorine
cloud passes by the office building within the first few minutes.
After that, the outdoor concentration drops back to zero. The
indoor concentration is very difficult to determine from this
graph; however, the Text Summary screen will display the
maximum values.
A-2-13
-------
Here is ALOHA's footprint for this scenario.
TeHt Summary
SITE OflTfl INFOWRTIOfl:
Location: COLUnBIM, SOUTH CMOLINH
Building Rlr Exchanges Per Hour: O.i7 (Sheltered single storied)
Date t TIM: Fixed at Hay 19, 1990 t 1300 hours
Molecular Ueight:
IOLH: 30.00 ppa
CHEfllCnL IMFORHnTIOn:
Chee.lcal Noae: CHLORINE
TtV-TUn: 0.50 ppa
Footprint Level of Coneorn: 30 DDK
Bailing Point: -29.25* F
Uaper Pressure at Rebient Tesperature: greater than I at«
tabiant Saturation Cancantrot ion: 1,000,000 po« or 100.01
70.90 kg/k»ol
flTMOSPHEBIC IMFOWWTtOM:(tWMUHL INPUT OF
Ulnd: 10 knots fro* M
StobiIity Class: D
Relative Hueidity: 671
Cloud Cower: 10 tenths
ho Invorslon Height
flir T««p«roturo: 70* F
Ground Roughness: Urban
Source Height: 0
SOURCE STRENGTH INFORtWTIOH:
Direct Source: 2OOO gallons
Source State: Liquid
Source Teeperature: -30* F
Release Duration: 1 ainute
Release Rate: 439 pounds/sec
Total Reount Released: 26,092 pounds
Note: This eheftical eag flash boll and/or result In too phase floe.
FOOTPRINT INFORmTION:
Model Hun: Heavy Oas
User specified LOG: equals IOLH (30 ppa.)
Max Threat Zorfc far LOC: 9.3 elles
Note: The Heavy Oas footprint Is an initial
For short releases It may be an over estI eatIon.
Be sure to check concentration information at specific locations.
Tine DEPENDENT INFORnflTIOn.
Concentration Estimates at the point:
Doanvind: 100 yards
Off Centerline: 0 yards
(tax Concentration:
Outdoor: 42,100 ppe
Indoor: 7M ppe
Note: Indoor graph Is shown alth a dotted line.
Ing.
A-2-14
-------
Example 3
A Pipe Source
At a rural road construction site near Portland, Oregon, a heavy
equipment operator accidentally cuts open a methane pipe on
November 17,1990 at 1430. The pipe runs 1,000 feet to the emergency
shutoff valve but the valve has been left open. The inside diameter of
the smooth pipe is 8 inches. The methane in the pipe is at ambient
temperature and the pressure is 100 PSI.
The on-scene weather is completely overcast skies, with an air
temperature of 44°F and 78% relative humidity. The wind is from the
SE at 15 knots.
Although methane is relatively non-toxic, the lower explosive limit
(LEL) is about 5% or 50000 ppm. We will use ALOHA to help
determine the downwind distance for the explosive atmospheric
concentration.
Rrst..
I Double-click on ALOHA and, after reading the ALOHA caveats,
click OK
Choose Location from the SiteData menu.
A-3-1
-------
Use the scroll bar or type the character "P" to find the city. Once
you have found Portland, Oregon, either double-click on the
city or select the city and dick Select.
POCHTELLO, IDHHO
POMONH, CRIIFORNIR
POMPRNO tERCH, FLORIDH
PONTIRC. MICHIGAN
PORTHRTHUR.TCXHS
PORT HURON. MICHIGAN
PORTLDNO, MRINC
PORTLAND, ORE60N
PORTSMOUTH, NEW HRMPSHIRE
PORTSMOUTH, UIR6INIH
PRESCOTT, RRIZONM
PRINCETON, NEW JERSEY
PHOOO, UTRH
QUINCV. CRLIFORNIR
QUINCV, ILLINOIS
RACINE, WISCONSIN
RRHWRV. NEW JERSEV
RHLFI6H. NORTH CAROLINA
Cancel
Add
Modify
Delete
Second...
I Choose Date & Time... from the SiteData menu
SiteDdtd
Location...
Building Type...
Date G Time.
Select Set constant time and enter the month, day, year, hour
and minute for this scenario. You may tab to each of the fields
to enter the date. Don't forget to enter the hour as a military
time.
A-3-2
-------
Date and Time Options
You can either use the computer*! Internal clock for the
model's date and time or set a constant date and time.
O Use Internal clock ® set constant time
Input constant date and time
Month Day Veer
II I |l7 | 11990
(1-12) (1-31) (1900-...)
Minute
(0-59)
Cancel ] [ Help ]
3 Click OK.
Third...
I Select Chemical... from the SetUp menu.
Atmospheric
SOUKP >
Computational...
Use the scroll bar or type the character "M" to find the chemical.
Once you have found methane, either double-click on the
chemical or select the chemical and click Select.
A-3-3
-------
Chemical Information
METHANE
METHANESULFQNVL FLUORIDE
METHYL flCETKTE
METHVLRCETVLENE-PROPRDIENE
HETHYL RCRVLRTE
METHYLBL
METHYL RLCOHOL
METHYL RLLVL CHLORIDE
HETHVLRMINE
METHVIRMVL RCETRTE
HETHYL RMYL KETONE
METHYLRNILINE
METHYL BROMIDE
5-METHYL-t-BOTENE
METHYL BUTYL ETHER
METHYL BUTYL KETONE
METHYL CHLORIDE
HETHVL CHLOBOFORMRTE
[ Cancel )
[ Modify ]
Help
Fourth...
Select User Input., from the Atmospheric submenu in the
SetUp menu.
Chemical... |
DI ,
Source »| SRM Station... |
Computational...
Click the button for stability class D because the sky is
completely overcast. Remember, stability class D is always
selected if the sky is completely overcast regardless of the wind
speed and the time of day. Since the scenario does not mention
anything about an inversion, the default setting, No Inversion,
should not be changed.
A-3-4
-------
HTMOSPHERIC OPTIONS
Stability Class I*: Qn QB O C
Inversion Height Options are: [
0 Ql Qf [Help
Help
]
® No Inversion O Inversion Present, Height is:
Wind Options are: I Help 1
Feet
O Meters
Wind Speed is: HIS
Wind is from : ISE
flir Temperature is: 44
I ® Knots O MPH O Meters/Sec.
| Enter degrees true or tent (i.e. ESE)
I Degrees ® F O C
Help
Ground Roughness is: [
® Open Country
O Urban or Forest
Help
O Input roughness(Zo):
OK
Cancel
After selecting the stability class, enter the wind speed and select
knots. Enter SE for the wind direction. Don't forget that the
wind direction is entered as the direction from which the wind
is blowing. Enter 44 for the air temperature. Be sure to select
the correct units (Degrees F).
Click Open Country because the spill occurs at a rural road
construction site. Since the scenario does not describe the
location of the accident in great detail, it may be a good idea to
run the model a second time with Urban or Forest selected as
well.
Click OK when you've filled in all of the data.
A-3-5
-------
6 Click the button for the complete cover and enter 78 for
humidity.
Claud Couer and Humidity
Select Cloud Coven
complete
cover
!>r.,
O O
partly
cloudy
0..
O OR O enter value
(0-101
clear
Select Humidity:
O
O
uvet
O O
medium
[ Help
O OR ® enter value
dry
(0-1001
[ Cancel )
Click OK.
The information that you have entered into ALOHA should
appear on the Text Summary screen. For this scenario, we are
not considering the infiltration rate into buildings; you should
ignore the building exchange rate as it will not be used.
Jem Summery
SITE OATH
Location: PORTUtfO, OREGON
Building Air Exchanges Per Hour: 1.34 (Sheltered single storied)
Oat* t TIM: Fixed at tteueeber 17, 1990 I 1430 hours
CHEHICflL INFORHflTION:
Cheeicol NOB*: tCTHRHE Ho)ecuI or Uolght: 16.04 kg/keol
TLU-TUA: -unovail- IOLH: -unavaiI-
Footprlnt Law*) of Conc*m: N**ds to p* s*t b*for* footprint scloetlon
Selling Point: -238.M* F
yopor Pr»*tur» at n*6l*nt Ti«p«rotur*: gr*at*r than I at*,
rw>l*nt Saturation Concentration: 1,000,000 pp* or 100.011
flTMOSPHEBIC INFonriRTIOH:(nRNURL INPUT OF DflTfl)
Hind: IS knots fro* SE Mo Inversion Height
Stability Class: D Air T*»p*ratur*: 44* F
Ralatlu* HuMldltu: 7M Oround floualwwss: Open
Cloud Cou*r: to tenths
country
A-3-6
-------
Fifth...
I Select Pipe... from the Source submenu in the SetUp menu.
Chemical...
Atmospheric
Computational... Tank...
Enter 8 for the pipe diameter and select for units, inches. Enter
1000 for the pipe length, selecting feet for units.
Pipe Input
Input pipe diameter [ Help
Diameter is [8 |® inches Qcm
Input pipe length
[ Help 1
Pipe length Is hooo I ® ft O yds O meters
The unbroken end of the pipe is [ Help ]
® connected to Infinite tank source
O closed off
Select pipe roughness
© Smooth Pipe
O Rough Pipe
[ Help ]
Cancel
In the scenario, the pipe is connected to a safety valve but the
valve has been left open. This means that the pipe will
continually release methane. We do not know how much
methane will be supplied to the pipe, but we do know that the
pipe is supplied by a very large source, that is, this source is
much larger than the amount of methane in 1,000 feet of pipe.
Since the source is very large, we can say the pipe is attached to
A-3-7
-------
an infinite source. The best choice for this scenario is to click
the button for connected to infinite tank source.
If the safety valve for the pipe had been closed, we would have
then selected the button for dosed off.
The scenario described the inside of the pipe as being smooth,
so you should click Smooth Pipe.
Click OK.
Enter 100 for the pipe pressure and select for the units, PSI.
Pipe Pressure and Hole Size
Input pipe pressure
Pressure Is hooj
[ Help ]
PSt
Input pipe temperature
<•> Unknown (assume ambient)
OTemperature is 44
Hole size equals pipe diameter.
[ Help
[ Cancel ]
In this scenario, the temperature of the pipe is given as
ambient, so dick Unknown (assume ambient).
8
Click OK.
The information that you have entered into ALOHA should
appear on the Text Summary screen. Remember, for this
scenario we are not considering the infiltration rate into
A-3-8
-------
buildings; you should ignore the building exchange rate as it
will not be used.
TeHt Summary
SOURCE STRENGTH INFORMATION:
Pip* Oioeeter: * inches Pipe Length: 1000 feet
Pipe T*ep*retur*: 44* F Pip* Press: 100 Ibs/sq in
Pip* Roughness: saooth Hole Rrea: 90.3 sq in
Unbroken end of the pipe is connected to an infinite
Release Duration: ALOHR Halted th* duration to 1 hour
Hex Computed Release Rat*: 1,410 pounds/eIn
fox Hverage Sustained Release Rat*: 1,410 pounds/ein
Coveregad ower o ainute or eore)
Total ftaount Released: M,560 pounds
Sixth...
I Select Computational... from the SetUp menu.
Chemical,
Atmospheric r
Source p
Computational...
Select Let model decide (select this if you're unsure).
Computational Preference*
Select spreading algorithm. If unsure, let
model decide.
Help
® Let model decide <*eleet thl* If unsure)
O ute Gou»*lan dispersion only
O Die Heeuy Ges dUperilen only
Define dote:
I Help I
Cancel
Click OK.
A-3-9
-------
Seventh...
I Select Options... from the Display menu.
Tile Windows
Stack Windows
Tent Summary
Footprint
Concentration...
Dose
Source Strength
Calculate...
Calculate Now
The scenario describes the level of concern as 50000 ppm. Click
User specified concentration and enter 50000. For the units,
click ppm.
Oisplnu, Optlom
Select Level ef Concern or Output Concentration:
O I OC.H nol «i>ail«ble
Help
> User specified cone, of ISOOOOJ ] ® ppm
1 ' O milligrams/cubic meter
Select Footprint Output option: f
<•> Plot on grid end auto-scale to fit window.
O Use user specified scale.
Select Output Units:
© English units
O Metric units
Help
Cencel
3 Select Plot on grid and auto-scale to fit window and English
units.
4 Click OK.
A-3-10
-------
Eighth...
I Select Footprint from the Display menu.
Display
Tile Windows
Slack Windows
Options...
TeHt Summary
Footprint
Concentration...
Dose
Source Strength
Calculate...
Calculate Noui
The footprint that ALOHA gives us is too short to plot
(approximately 60 yards). This near the source, concentration
patchiness could be significant (see the Use Caution section of
Chapter 2, Introduction to Air Modeling). When using this
information, we can see that the explosive threat is likely to be
on the order of one hundred yards. We would also suspect that
the direction of cloud travel is fairly consistent since the wind
speed is 15 knots. However, for this short a threat distance and
considering near-field patchiness, it is prudent to consider a
circular danger zone in the one hundred-yard range (again, see
Chapter 2).
Footprint Window
Dispersion Module: Gaussian
User specified LOG: 50000 ppe
rtax Threat Zone for LOG: 57 yards
Note: Footprint mas not drawn because
effects of near-field patchiness Make pluM
presentation unreliable for snort distances.
A-3-11
-------
-------
Example 4
...Using ALOHA, MARPLOT,
and a PICT map
At 11:15 am on February 14,1992, the Seattle, Washington Police find
several 12-quart plastic containers labeled "anhydrous hydrazine" in
the middle of a vacant, concrete parking lot. The lot is at the
intersection of 5th Avenue South and South Donovan Street. The
police officers report that some of the product has been spilled, and
that there is a strong odor directly downwind of the containers. The
fire department is then notified of a potential chemical spill.
When the fire department arrives, they find one police officer
complaining of eye and nose irritation. Using a pair of binoculars, the
Assistant Chief assesses the spill site. The chief sees that a 40 square
foot puddle has formed around the containers. Three of the
containers appear to be open and lying on their sides.
The firefighters report the following on-scene weather observations:
the air temperature is 45° F, the sky is almost completely covered with
clouds, the winds are from the west at 15 mph and the relative
humidity is 70%.
A representative from a state environmental agency suggests running
the air model with a level of concern of 0.03 ppm. Assuming that the
contents of three containers have spilled, what is the extent of the
footprint for this concentration? What area on a map does this
footprint cover?
A-4-1
-------
first...
Before obtaining estimates of source strength and dispersion
from ALOHA, you'll begin by preparing and loading a map of
Seattle in MARPLOT. You should find a folder titled "Seattle"
in your MARPLOT folder. This contains a PICT file, rather
than a MARPLOT map derived from TIGER data. Be sure that
this file is in a folder by itself. Then double-click on the
MARPLOT icon to launch the application.
Choose New from the File menu.
Open...
Scll'e
C lose
s« tit PICT
Paqp Setup..
Print...
XO
>:ut
>:P
Import...
Ei Athena
D Seattle
[ Desktop ]
[ Help... ]
[ Cancel 1
A-4-2
-------
You'll need to indicate the position of two points on the map to
MARPLOT, so that the program knows where on the earth the
mapped area lies, and how large an area the map encompasses.
You'll do this by choosing two points on the map scale bar, and
telling MARPLOT the location of these two points.
First, click on the zoom in tool
, from the row of four tools
above the top right comer of the map.
Set Latitude Hnd Longitude
Click to zoom In.
| Point 1: lat: O.OOOOOQ* N
long; 0.000000* 11) [
Point 2: lot: o.oooooo* N
long: 0.000000* m [ ne»t?t
A-4-3
-------
Click once within the map legend to zoom in. Then click on
1-2-1. You'll use this tool to position Point 1. Your screen
should now look like the one below.
Set Latitude Bud Longitude
Click to position Point 1.
PARKS, ETC
HOSPITAL
SCHOOL
CHEMICAL FACLITIES
STREETS
HKMVAVS
FWEVAYS
CITY LMITS
Point I: lot: 0.000000* N
long: 0.000000* Ul
Point 2: lot; O.DOOOOD" N long; D.OOOOOD* II) { He»e(
Go to the scale bar of the map, and click on the bar at the '0 feet'
mark. You'll see the following dialog box. For Point 1, you'll
enter the geographic coordinates of Seattle Click on the Use
deg/min/sec button. Then enter Seattle's coordinates: 47° 21' N
and 122° 12' W. Click OK.
Set the Lot/Long for Point 1
Latitude: Peg;|47 | Min:[2lJ SecrJQ.QQ | | North V|
Longitude: Deg:|t22| Min:fT2~l Sec:jo.OO I I Ulest ~|
O Uleiv degrees as decimal
© Use deg/min/sec
[ Help... ] | Cancel
NOTE To find the coordinates of Seattle or any other
city In ALOHA's city library, go to ALOHA,
choose Location from the SiteData menu, click
on the city's name within the scrolling city list,
then click on the Modify button to see
A-4-4
-------
ALOHA's values for the coordinates of the
city,
Now set the position of Point 2. Click on the map scale bar at
the "2000 feet" mark.
Set Latitude Hnd Longitude '
Click to position Point 2.
Quick scroll
Point I: lot: 47.350000* N long: 122.200000* III [ Reiet
Point 2: lot: o.oooooo- N long: 0.000000* ill |
8
Click the Distance from Point 1 button.
Would you like to specify the second point by
giving its distance from point 1 or by giuing its
latitude/longitude coordinates?
Distance from Point 1
Latitude/Longitude Coordiantes
Enter "2000" in the distance field, and choose 'feet' from the
pop-up units menu. Click OK
A-4-5
-------
Specify Pittance
Point 2 Is
2000
feet
from Point 1.
[Cancel J
10
II
Your screen should look like the one below. Note the Qs and
C9 marking the locations of Points 1 and 2 on the map scale
bar. If you need to reposition either point, click on the
corresponding Reset button, or click on the map again with
either the Lzj (if you wish to reposition Point 1) or l-5-l (if you
wish to reposition Point 2) tool.
Sat Latitude find Longitude "
Click to reposition Point 1.
PARKS. ETC
HOSPITAL
SCHOOL
CHEMICAL FACLITIES
Oi.FACI.mE5
STREETS
HK5HVAYS
FREEWAYS
CITY LIMITS
Point 1: lat: 47.35DQOD'N long: 122.200000* IU [Beset
Point 2; »n<: 47.349945'N long: 122.191898* ll> [Reset
Once you're satisfied, click OK. The Seattle map should appear
in the MARPLOT window.
A-4-6
-------
12 Now that you've loaded the Seattle map, you're ready to run
ALOHA. Choose Go to ALOHA from the ALOHA submenu in
MARPLOT'S Sharing menu. This will launch ALOHA and
bring it forward.
Shoring
Hbout Shared Menus...
S«ue Shared Menus...
fret Info
Unlink
XI
Help...
CBHEO
Set Source Point
Set Cone f> Dose Point
Delete RLOHH Objects
Go To HLOHfl
Second...
I After reading the ALOHA caveats, click OK.
Choose Location from the SiteData menu.
SiteData
Location.
Building Type...
Date fr Time...
A-4-7
-------
Use the scroll bar or quickly type the characters "SE" to find
Seattle, Washington in the scrolling list. Once you have located
Seattle, double-click on it or dick once, then click Select.
I Location InformtlM 1
IANTA Ft. NEW MEXICO
MNTR MUNICH, CM.IFMNIR
iHNTN PHULA, CALIF WHIM
EHNTA ROSA, CALIFORNIA
IAULT $71 MARIE. MICHIGAN
SAVANNAH, 6EOH6IH
SCHOHAAIE, NEW VORK
JEBFOBD, DELAWARE
Q^^^^^^QJQQQ
SNRUINEE, OKLHHOMH
SHERMAN, TEHRS
S10UN FRLLS. SOUTH DHK01R
SMITHTOUIN, NEW VORK
SNOHOMISM, UIASHIN6TON
SOMERSIVORTH. NEUJ HHMPSHIRE
iOMERUILLE, MHSSRCHUSE1TS
SOUTH REND, INDIRNR
SPRHKS. NEURDfl
Add
[ Modify
[ Help
Third...
We'll ignore Building Type during this scenario.
I Choose Date & Time... from the SiteData menu.
SiteData
Location...
Building Type...
Udte G Time
A-4-8
-------
Select Set constant time and enter the month, day, year, hour
and minute for this scenario.
Date and Time Options
You can either use the computer's internal clock for the
model's date and time or set a constant date and time.
O Use Internal clock ® Set constant time
Input constant date and time
Month Dag Vear
112 | [14 | 11992
(1-12) (1-31) (1900-...)
Cancel
Help
Click OK.
Fourth...
I Select Chemical... from the SetUp menu.
Setup
Chemical.
Rtmospheric
Source
Computational.
A-4-9
-------
Use the scroll bar or quickly type the characters "HY" to find
"hydrazine, anhydrous." Double-click on this name or dick
once on it, then click Select.
I Chemicil Information!
IVOROCHiORIC DC ID, RNHVDROUS
4VDROCVHNIC RCID, RNHVDROUS
KVDROFLUORIC RCID, RNHVDROUS
HYDROGEN
HYDROGEN BROMIDE
HYDROGEN CHLORIDE
HYDROGEN CVRNIDE
HYDROGEN FLUORIDE
HVDR06EN PEROXIDE
HVDR06EN SELENIDE
HYDROGEN SULFIOE
HVDHOHVE1MYLRCRVLRTE
IRON PENTACRRBONVL
ISORMVLHCETHTE
ISORMVL RLCOHOL
ISOBUTRNE
ISDBUTRNOL
[ Cancel
Modify ]
[ H«lp
Check the Text Summary window to review information about
the properties and toxicology of hydrazine. ALOHA alerts you
that this chemical is a potential or confirmed human
carcinogen. Boiling point of hydrazine is well above air
temperature, so it's a liquid.
TeHt Summary
SITE OBTH INFORMATION:
Location: SEATTLE, WASHINGTON
Building: Sheltered single storied
Data t T(M: Fixed at February ", 1992 I. 1119 hours
CHEMICfft. INFORMATION:
Chemical NOM: HVDH8ZINE, RNHVOROUS Molecular Ueight: 32.04 kg/kMl
TLW-TUfl: 0.10 pp* IDLH: 80.00 Dp*
Note: Potential or confirmed hunan carcinogen.
Boiling Point: 236.30* F
Freezing Point: 34.77* F
A-4-10
-------
Fifth...
Select User Input., from the Atmospheric submenu in the
Setup menu.
The wind speed is about 15 mph and it's almost completely
cloudy. By clicking on the stability class Help button (in the
upper right corner of this screen), you can see that the best
choice for stability class is D. Click on the button for stability
class D.
atmospheric Options
Stability Class It: Qfl OB OC ®D OC OF
Inversion Height Options i
® No Inversion O Inversion Present, Height is:
Wind Optloni ore: [ Help |
O Meters
Wind Speed Is: 115
Wind Is rrom: ui
fllr Temperature Is: 45
Ground Roughness Is: (
O Open Country
Urban or Forest
^m
OK
O Knots OMPH O Meters/Sec.
Enter degrees true or text (e.g. ESE)
Degrees ®F OC [ Help ]
Help
OR O Input roughness (Zo):
Cancel
There's no inversion, so the default setting, No inversion,
should not be changed.
Enter "15" as your value for wind speed, then click on the mph
units button. Enter either "W" or "270" to indicate that the
wind is from the west.
A-4-11
-------
S Type in 45 as the air temperature, and dick F.
This spill is in an urban, industrialized area, with many
buildings and obstacles. Click on the Urban or forest button.
7 Once you've made these selections, click OK.
Cloud Cover ond Humidity
O O O O O OR ® enter itolue
templet* pertly
cover cloudy
cloer
(D-IO)
Select Humidity:
O O O O
uiet medium
O OH ® enter value |?0
dm (o-iooi
[ Cencel
8 The sky is almost completely cloudy. Type "9" in the cloud
cover data field.
9 Relative humidity is 70%. Type "70" in the humidity data field.
10 Click OK.
A-4-12
-------
I 1 Check the Text Summary screen to be sure that you've entered
these data correctly.
Text summary
nTnOSPHBHIC INFORf1flTIW1:
-------
Puddle area Is: j 40 [ square ©feet O yards O meters
Select one and enter appropriate data
© Uolume of puddle
O Huerage depth of puddle
O Mass of puddle
Volume is: 19
® gallons Q liter*
O cubic feet O cubic meters
Cancel ] (_
Mela
J
Three 12-quart containers have leaked hydrazine. There are
four quarts in a gallon, so 9 gallons of hydrazine have spilled
into the puddle. Click on the button for Volume of puddle,
then type "9" in the puddle volume data field. Click gallons,
then click OK.
The puddle has formed on a concrete parking lot, so click
Concrete.
Soil Type, flir and Ground Temperature
Select ground type [ Help ^J
O Default ©Concrete Q Sandy O Moist
Input ground temperature
Help ]
i Use air temperature (select this If unknown)
®F QC
O Ground temperature is 45
Input initial puddle temperature
Help
© Use ground temperature (select this if unknown)
O Use air temperature
O Initial puddle temperature is J45 I © F O C
OK
[ Cancel ]
A-4-14
-------
No estimate of ground or puddle temperature is available, so
leave both equal to air temperature, the default value. Click
OK
Check the Text Summary screen to be sure that you've entered
the source strength data correctly, and to review ALOHA's
estimates of maximum and averaged release rates and other
information about the release. ALOHA expects the release to
last more than one hour, and predicts that 2.8 pounds of
hydrazine will have evaporated during the first hour of the
spill.
TeHt Summary
SOURCE STRENGTH IHFOnmTlQM:
PuddU flr«a: 40 *quar« foot Pudd»« UaluM: 0 gallons
Sail TUP*: ConeroU Ground TMpwatur*: 45* F
Initial Puddla T«op«ratur>; Ground toBooratura
Ftalooso Duration: nUJHR Halted tha deration to 1 hour
tVnc Ca^MJtad Ralaan Ratal 0.047 pound*/• in
nax Muw^g* Suctainwl RalMM Data: O 0469 pound*/• in
Covorogod ov*r a •Inut* or mor+)
Total fkwunt R«l«aMd: 2.10 pounds
A-4-15
-------
Seventh...
Choose Source Strength... from the Display menu to view
ALOHA's graph of source strength, or release rate, for the first
hour of the spill. ALOHA does not expect evaporation rate to
change during this hour. The model expects the puddle to be
cooled as it evaporates, but warmed by its environment at the
same time, so that its temperature (and hence its evaporation
rate) remain unchanged.
Display
Tile Windows
Stack Windows
Options...
Tent Summary
Footprint
Concentration...
Dose
Calculate...
Cnli:ul
-------
Eighth...
I Choose Computational from the SetUp menu.
Chemical...
Rtmospheric
Source
Check to be sure that Let model decide is selected (This is the
default setting). Click on this button if it is not selected, then
click OK
' I Computational
Select spreading algorithm. If unsure, let
model decide.
Help \
® let model decide (select this If unsure)
O Use Gaussian dispersion only
O Use Neatiy Gas dispersion only
Define dose:
Dose
f"
-Jci
H«IP
(T)dT
n •
Cancel
A-4-17
-------
Ninth...
I Select Options... from the Display menu.
Display
Tile Windows
Stack Windows
Tent Summary
Footprint
Concentration...
Dose
Source Strength
Calculate...
Calculate! Sow X«
The state official suggested a level of concern of 0.03 ppm. Click
User-specified cone, and enter "0.03." Click ppm.
Check to ensure that Plot on grid and autoscale to fit window is
selected.
Click English units, then click CSC.
Duping Options
Select Leuel of Concern or Output Concentration:
O IDLH Concentration
elp
® user specified cone, of
©ppra
O milligrams/cubic meter
Select Footprint Output Option:
® Plot on grid end euto-*cole to fit window.
O Use uier specified scale.
Help
Select Output Units:
® English units
O Metric units
Help 1
f Cancel 1
A-4-18
-------
Tenth...
I Choose Footprint from the Display menu.
Tile Windows
stack Windows
Options.
TeHt Summary
Footprint
Concentration...
Dose
Source Strength
Calculate...
(nlnulale Noui »
ALOHA will display a diagram of the footprint for this
hydrazine release. Check the Text Summary window to see the
maximum downwind distance that the footprint may extend
(the Maximum Threat Zone). ALOHA expects the footprint to
extend downwind for about 211 yards. Although the molecular
weight of hydrazine is about 32 kg/kmol, and is heavier than
that of air (which is about 29 kg/kmol), ALOHA chose the
Gaussian dispersion model instead of the Heavy Gas model.
That's because the model expects the hydrazine to evaporate so
slowly that it does not form the dense blanket of gas typical of a
heavy gas release.
A-4-19
-------
Tent Summary
FOOTPRINT INFORMATION:
Oispars ion Module: Gaussian
Uw >p«cifi*d LOC: .03 ppm
Hoot Threat Zone far LOC: 211
/S| ^ B"iJJ*iSi"(iiiiii"ii
TMfl.Jv
E/eventh...
You're ready to use MARPLOT to plot this ALOHA footprint on
the map of Seattle. Select Go to Map from the MARPLOT
submenu under ALOHA's Sharing menu to bring MARPLOT
forward. The Seattle map should still be displayed in
MARPLOT'S window.
Click on the zoom in tool,
, in the tool palette to the left of
the map, then click once in the middle of the map to zoom in
so that you can read street names. Search near the middle of
the map for the intersection of 5th Avenue South and South
Donovan Street.
A-4-20
-------
Once you've identified this intersection, choose
from the
tool palette. Click once on the intersection. MARPLOT will
place a visible crosshair mark, or "click point" at this location.
Note If you don't see a crosshair click point mark at
the point where you clicked, choose
"Preferences" from the File menu, make the
click point Visible, then click OK.
Preferences
i-Scale Format
O1 :N
O 1 In - N yd
® Window Distance
-Uieiu Lot/Long Coordinates-
® as a decimal
O in deg/min/sec
Click Point-
©Uisible
O Inuisible
Uniti:| yards
Background Colon | C~1 White
[ Help... ] [ Cancel
Choose Set Source Point from the ALOHA submenu in
MARPLOT'S Sharing menu. An ALOHA footprint should
automatically appear on the MARPLOT map (this may take a
few seconds).
Shannq
Rbout Shared Menus...
Slwml Menus...
Bet Info
Unlink
CflMEO
XI
Help.
Set Source Point
Set Cone 9 Dose Point
Delete flLOHfl Objects
Go To flLOHfl
A-4-21
-------
Choose the zoom in tool to zoom in more closely, if you like.
The footprint should look like the one below.
CHeK Ft: 47.33M70*H 122.1M304TI 11230 K M3 yd | Top Ov«rla
You can see from this footprint plot that ground-level
concentrations of hydrazine may be high enough to be of
concern for the area along S. Donovan Street between 5th and
7th Avenues S. The confidence lines drawn on either side of
the footprint delineate the area within which the cloud of
hydrazine is 95% likely to remain, if the wind shifts it about
during the release. You can see that hydrazine concentrations
aren't predicted to reach your level of concern more than half a
block north or south from Donovan Street.
Remember, though, that ALOHA was designed to give you
"ballpark" estimates of source strength and dispersion. It
cannot give you completely accurate predictions for a real
release, because no model can account for every uncertainty.
For example, if the wind shifted direction or changed speed, the
footprint might be longer or shorter, or oriented in a different
direction. Likewise, you had to guess the exact amount of
hydrazine in the puddle. In real response situations, ALOHA
gives you a "best guess" rather than an exact answer.
A-4-22
-------
Example 5
...Using BitPlot with ALOHA
in Windows
The Seattle, Washington Fire Department responds to a freight train
derailment on August 25,1992 at 10:15 am. The police dispatcher
reports that the derailment has occurred about 3 miles south of the
downtown area next to the intersection of 16th Ave. South and East
Marginal Way. When the firefighters arrive on-scene, they find
several tank cars off the tracks and on their sides. There is no fire, but
one tank car is damaged, and a large volume of fine mist and vapor
can be seen spraying out of a crack in the tank bottom. The entry team
members cannot get very close to the tank, but they estimate that this
crack is about 36 inches long and 1/2-inch wide.
The train's crew is unharmed and immediately hands the train's
consist to a police officer. From the consist, the entry team finds that
this tank car was carrying 19,789 gallons of liquid methyl chloride and
that the tank car capacity is 24,750 gallons. They estimate the tank
diameter to be about 10 feet.
The firefighters report the following on-scene weather observations:
there are some high cirrus clouds visible and they estimate that the
coverage is about 20%. The winds are from the northeast at about 10
mph. The humidity is about 50% and the air temperature is 75° F.
The fire chief notes that residential neighborhoods to the southwest of
the derailment are in the path of the dispersing chemical cloud. Most
of the homes are single-storied structures surrounded by shrubs and
trees. The closest residence is about 600 yards downwind from the
derailment, at the intersection of Southern Street and 12th Ave. S.
A-5-1
-------
A lexicologist recommends 100 ppm as an appropriate level of
concern. What is the downwind distance to this concentration? What
is the estimated maximum indoor concentration for the house closest
to the derailed rail car? What is the expected maximum outdoor
concentration at that point?
First...
I Double-click on ALOHA and, after reading the ALOHA caveats,
click OK
2 Choose Location from the SiteData menu.
SiteData
Location.
Building Type...
A Time...
Use the scroll bar or quickly type the characters "SE" to find
Seattle, Washington in the scrolling list. Once you have located
Seattle, double-click on it or click once and click Select.
Location Information
SAN JOSE. CALIFORNIA
SAN LUIS OBISPO. CALIFORNIA
SAN PEDRO, CALIFORNIA
SANDWICH. MASSACHUSETTS
SANTA ANA. CALIFORNIA
SANTA BARBARA. CALIFORNIA
SANTA CLARA. CALIFORNIA
SANTA FE. NEW MEXICO
SANTA MONICA. CALIFORNIA
SANTA PAULA. CALIFORNIA
SANTA ROSA. CALIFORNIA
SAULT STE MARIE. MICHIGAN
SAVANNAH. GEORGIA
SCHOHARIE. NEW YORK
SEAFORD. DELAWARE
SEArTLE. WASHINGTON
Cancel
A-5-2
-------
Second...
I Choose Building Type... from the SiteData menu.
SiteData
Qate ft Time...
The residences are mostly single storied buildings, so click on
the Single storied building button. Because the buildings are
surrounded by trees and other buildings, you should select
Sheltered surroundings. Click OK
Infiltration Building Parameter:
Select building type or enter exchange parameter
O Enclosed office building 1 HelP I
© Single storied building
O Double storied building
O No. of air changes is | ""] per hour
Select building surroundings
Help I
® !Sheltered surroundings (trees, bushes, etc.)!
O Unsheltered surroundings
OK
J
Cancel |
Third...
I Choose Date & Time... from the SiteData menu.
Location...
Building Type...
A-5-3
-------
Select Set constant time and enter the month, day, year, hour
and minute for this scenario. Click OK
Yaw can either we the computer** Internal dodc for the modefe dote
and time, ar aet a constant date and time.
O Uae Internal dock © Set a constant time
Input a constant date and time :
Month Day Year
8 |2S | 1992
Hour Minute
J10 15
(1-121 P-31} (1900-.,-) (0-23) (0-59]
OK f Cancel
1 1 Help |
Fourth...
I Select Chemical... from the Setup menu.
SetUp
Chemical.
Atmospheric I
Source >
Computational...
Use the scroll bar or quickly type the characters 'ME' to find
methyl chloride. Double-dick on "METHYL CHLORIDE" or
click once on this name, then click Select.
A-5-4
-------
METHYL CHLOROFORMATE
METHYL ACHYLATE
METHYLAL
METHYL ALCOHOL
METHYL ALLYL CHLORIDE
METHYLAMINE
METHYUMYL ACETATE
METHYL AMYL KETONE
METHYLANiLJNE
METHYL BROMIDE
3-METHYL-1-BUTENE
METHYL BUTYL ETHER
METHYL BUTYL KETONE
Cancel |
Add
Modify |
Help |
Check the Text Summary window to review information about
the properties and toxicology of methyl chloride. ALOHA alerts
you that this chemical is a potential or confirmed human
carcinogen. Its boiling point is well below ambient air
temperature; this indicates that the chemical was stored in the
tank car as a pressurized liquid.
SITE BUT* INFOHNHT10H:
Location: SEATTLE. IMSHIHBToH
Building: Sheltered single storied
Date and Tine: Fixed at August 25, 1VV2 1t15 hours
CHEMICAL INFORMATION:
Chemical Nane: HETHVL CHLORIDE
Molecular Height: 5«.»9 kg/kMl
TLU-TM: $•••• ppa IDLH: 1MII.M ppa
Note: Potential or confirmed toman carcinogen.
Footprint Level of Concern: 1M ppn
lolling Point: -11.Ǥ- F
vapor Pressure at ftnblent Tenperature: greater than 1 atn
••blent Saturation Concentration: 1,•••,••• ppm or 1M.tt
A-5-5
-------
Fifth...
I Select User Input., from the Atmospheric submenu in the
SetUp menu.
SetUp
Chemical...
•B^^^P^H
Source
pheric
Computational...
User Input.
SAM Station.
The firefighters estimated the wind speed to be 10 mph, with
about 20% of the sky obscured by clouds. By clicking on the
stability class Help button (at the upper right corner of the
screen), you can see that for this combination of strong solar-
radiation and 10 mph winds, the best choice for stability class is
B. Click on the button for stability class B.
•tniospheric Oplions
Stability Class I«:O A ©BOcOoOEOF I Heln I
Inversion Height Options are : I Help I
® No Inversion O Inversion Present Height is : [~~
-|® Feet
JO Meters
Wind Options are : I Help 1
Wind Speed Is : |lo j O Knots <8> MPH O Meters/sec
Wind Is from : JNEj Enter degrees true or text (e.g. ESE)
"] Degrees F O C
Air Temperature is:
75
I rje
-------
5 Type "75" as the air temperature, and click F.
6 This spill is in an urban, industrialized area, with many
buildings and other obstacles. Click on the Urban or forest
button.
7 Once you've made these selections, click OK.
8 The sky is described as about 20%, or 2/10 cloudy. Type "2" in
the cloud cover data field.
9 Relative humidity is 50%, so ensure that this button is selected
(it's the default value).
Cloud Cover and Humidity
Select Cloud Cover:
I Help I
O O O O O OR ® enter value :
complete partly dear (0-10)
cover cloudy
Select Humidity:
O O ® O
wet medium
O OR O enter value : |50 [X
dry (0-100] -
Cancel |
10 Click OK.
A-5-7
-------
Check the Text Summary screen to be sure that you've entered
these data correctly. Under the heading, "Site Data
Information," you can see the air exchange rate that ALOHA
has calculated for the residences near the spill site.
SITE PATA INFORMATION:
Location: SEATTLE. MftSNIHETOH
Building Air Exchanges Per Hour: 0.77 (Sheltered single storied)
Date and Tin*: Fined at August 25, 1M2 1t15 hours
CHEHICM. IHFOAHATIOH;
Chenlcal Nan*: NETHVL CHLORIDE
Molecular Height: so.** kg/knol
TLU-TMA: 50.M ppa IW.H: 1MM.M ppn
Note: Potential or confirmed ltu*an carcinogen.
Footprint Level of Concern: 1H op*
Boiling Point: -11.4i* F
Uapor Pressure at tablent Temperature: greater than 1 atn
Mbient SaturatiM Concentration: 1,•••,!•• ppn or 1M.it
ATNDSPHERIC INFORMATION: (MANUM. INPUT OF DATA)
Mind: 10 nph fron NE NO Inuerslon Height
stability Class: I Air Tenperature: 75* F
Relative Hunidlty: 50k Ground Roughness: Urban or Forest
Sixth...
Select Tank... from the Source submenu in the SetUp menu.
Chemical...
Atmospheric
2 Click Horizontal Cylinder.
3 The tank car is 10 ft in diameter and has a capacity of 24,750
gallons. Enter "10" for diameter, don't enter a value for length,
then enter "24,750" for volume. Click feet for diameter and
gallons for volume. ALOHA will calculate and display the
correct length automatically. Click OK.
A-5-8
-------
Enter fcn> of ttrae vak»«
O meter*
\24Ht
J 9g«Mai» O cu. feet
The methyl chloride is stored as a liquid. The tank temperature
wasn't reported, so air temperature is the best guess. Click the
buttons for Tank contains liquid and Chemical stored at
ambient temperature. Click OK.
Chemical State and Temperature
Enter state of the chemical:
® Tank contains liquid
O Tank contains g»s only
O Unknown
Enter the temperature within the tank:
© Chemical stored at ambient temperature
O Chemical «tored at
degrees
'F OC
After the heading The liquid volume i«, type in the responders'
estimate of the amount of methyl chloride in the tank car.
Click on the gallons button. Click OK.
A-5-9
-------
Enter the maw in the tank OR volume of the liquid
. . O pOMdS
The mass In «tc tank it: (*jj I toMfcOOO lb«|
O kllogr
OR
Enter Hquld level OR volume
The liquid
volume Is: |19.7B3)
® gallons-
O cubic feet
O liter*
O cubic meter*
180.0
% (UK by volume
Cancel
Help |
Click Rectangular opening and enter "36" for the opening
length and "1/2" for the opening width. Click inches . "Hole"
is the default leak type; ensure that this button is selected. Click
OK.
Atea exWng
O Circular opening
> Rectingular opening
Opening length: [
Opening width:
1/2
J Ofeet
~] Ocenttmetera
Ol
Is leak throng* a hale or short plpe/valvef
9 Hole O Short pipe/verve
A-5-10
-------
The hole is at the bottom of the tank car. This is the default
setting, so just click OK.
The Mbmi •! the teak is:
It
J Ota. •«. Oi
Om.
•fccvc *e bottom of ate tank
,OR.
X >( the w*y tattle top of
the tank
Help I
Check the Text Summary screen to be sure that you've entered
the source strength data correctly, and to review ALOHA's
estimates of maximum and averaged release rates and other
information about the release. ALOHA expects the release to
last about 36 minutes. Because the methyl chloride was stored
as a pressurized liquid, ALOHA expects it to escape from the
tank as a two-phase flow of aerosol (a fine mist of liquid
droplets) and vapor.
Text Summary
SOURCE STRENGTH INFORMATION:
Liquid leak from hole in
Tank Dianeter: 10 Feet
horizontal cylindrical
ank Length: *;
tank selected
feet
Tank Uolune: 24751 gallons
Internal Tenperature: 75" F
Cheaical Mass in Tank: 75.1 tons
Tank Is ••% full
Opening Length: 36 inches Opening Vidth: 1/2 Inches
Opening is • f«t fron tank bottou
Release Duration: 36 ninutes
Hax Conputed Release Rate: 27.710 pounds/Kin
Max Average Sustained Release Rate: 13,AM pounds/nln
(averaged over a Minute or nore)
Total Hwrant Released: 151.600 pounds
Note: The release was a two phase flow.
A-5-11
-------
Seventh...
Choose Source Strength... from the Display menu to review
ALOHA's graph of source strength, or release rate, over the
duration of the spill.
Display
Hie Window
Stack Windows
Options...
Teg! Summary
footprint
Concentration...
Dose
Calculate...
Calculate
You can see from the source strength graph that ALOHA
expects the release rate to be highest at the beginning of the
release, when the pressure in the tank is greatest, and then to
decline as chemical escapes and pressure drops. The maximum
computed release rate shown on the Text Summary screen,
27,700 pounds/min, would have occurred just as the tank began
to leak.
mrrr Release Hair
pounda/kinvrt*
20,000 !
IS,000
10,000
5,000 .
0
10
20
minut«>
30
40
A-5-12
-------
Eighth...
I Choose Computational from the SetUp menu.
Check to be sure that Let model decide is selected (Unless you
specify otherwise, ALOHA will default to this setting). Click on
this button if it is not. Click OK.
Computational Preferences
Select spreading algorithm. If unsure, let
model decide.
® Let model dedde [select mis If unsure)
O Use Gaussian dispersion only
O Use Heavy Gas dispersion only
Define dose:
Dose
J>dt
n= 1.0
Help I
OK
Cancel
A-5-13
-------
Ninth...
1) Select Options... from the Display menu.
lile Windows
Stack Windows
Text Summary
footprint
Concentration...
Dose
Source Strength
Calculate...
Calculate MOW
Ctrl+M
The toxicologist has recommended that you use the TLV-STEL
value for methyl chloride, 100 ppm, as your level of concern
(The TLV-STEL is a 15-minute workplace exposure limit).
Since ALOHA's chemical library doesn't include a value for
TLV-STEL, click User-specified cone and enter "100." Be sure to
dick ppm.
Check to ensure that Plot on grid and autoscale to fit window is
selected. Click on this button if it is not.
A-5-14
-------
Click the English units button. Then click OK
Select Level of Concern or Output Concentration: I Help ~l
OIDLH not available
® User specified cane, of [mo
®ppm
O milligrams/cubic meter
Select Footprint Output Option:
® Plot on grid ond auto-ocale to fit window.
O Uoe uoer opedfied scale.
Select Output Unto:
® English units
O Metric unto
Help |
Cancel |
Tenth...
I Choose Footprint from the Display menu.
Display
Jile Windows
Stack Windows
Options...
Text Summary
Footprint
Concentration...
Qose
Sotifce Strength
Calculate...
Calculate
Ctrl+M
A-5-15
-------
miles
0.75
0.25
0
0.25
0.75
Hay ovarest!
Check concen :ratio i
a ate 1< mgth
0.5
0.5 1
miles
1.5
ALOHA will display a diagram of the footprint for this methyl
chloride release. Check the Text Summary window to see the
maximum downwind distance that the footprint may extend
(called the Maximum Threat Zone). You'll also see that
ALOHA chose to use the Heavy Gas model to make its
calculations, and that the model reminds you that a Heavy Gas
footprint represents an initial screening. ALOHA must
simplify its Heavy Gas calculations so that a footprint can be
completed and displayed in a short time. For pressurized
releases such as this one, such a footprint can be an
overestimate. In a moment, you'll check concentration at a
location downwind of the source for a more accurate estimate
(concentration calculations are not simplified).
iext Summary
FOOTPNIKT INFORMATION:
Model Run: Heavy cas
User specified IOC: 1M ppn
Nan Threat Zone For LOG: 1.7 idles
Nan Threat Zone for IDLM: 173 yards
Note: The Heavy 6as footprint is an Initial screening.
For short releases it may be an owerestimation.
Be sure to check concentration information at specific locations.
A-5-16
-------
Eleventh...
You're ready to use BitPlot to plot this ALOHA footprint on a
map of Seattle. Select Go to Map from the BitPlot submenu
under ALOHA's Sharing menu to launch BitPlot or to bring it
forward if it is already running.
Scaring
BilPlot
G.O to map
Go to the Maps directory in the ALOHA folder and click on the
Seattle map. Click OK.
Flejfa
Where is the map?
Pjroctorie*:
eVatohaVKaps
OK
aloha
Cancel |
Liat Fiet of lype:
Dftvea:
[Aloha Map FUe» l'.BMP)jjJ
Next, you'll need to enter your map scale. You will see the
Seattle map displayed on your screen inside a scrolling window.
Move the crosshair cursor to the 0 feet point on the scale bar
inside the map legend, and dick your mouse button at that
point. Then move the crosshair to the 2000 feet point on the
scale bar and click the mouse button again.
A-5-17
-------
Scale by Mou
— NOWAYS
^— FMEVAVI
gOCMCM.F«CI.ITK* — CITY UMTS
Enter "2000" the distance between the two points. Click on the
popup units menu and choose feet for distance units. Click OK
when you're finished.
Scale by Mouse
Distance Equals:
OK
] | Cancel | | Redo | | Help |
Next, you'll need to indicate the location of the spill. Scroll the
map down until you can see the intersection of East Marginal
Way and 16th Avenue South. The train tracks cross 16th
Avenue on the south side of this intersection; this is the
location of the leaking tank car. Click once on this point. You
should see a red cross marking this point. If you didn't click in
just the right spot the first time, just click again. When you're
satisfied, click OK
A-5-18
-------
Cancel |
Help
Quick Scroll
Martc • source location on the map
Once you have positioned the source, BitPlot will display the
ALOHA footprint on the map. On this footprint plot, the
innermost oval represents the Maximum Threat Zone, the area
where ground-level concentrations of methyl chloride are most
likely to exceed 100 ppm, your level of concern. On either side
of this oval, you can see confidence lines. These delineate the
area within which ALOHA is 95% sure the chemical cloud will
remain, if the wind shifts it about during the release.
A-5-19
-------
Next, to find out the concentrations expected inside and outside
the nearest residence, you'll need to indicate the building
location so that ALOHA can calculate and display a
Concentration vs. Time graph. The closest homes are located
near the intersection of Southern Street and 12th Avenue
South, across the river and southwest of the spill location.
Double-click on this intersection. ALOHA will come forward
automatically, and will display a Concentration graph for your
location.
2,000 ,
1, SOO
1,000 .
500
0
20
40
You can also view estimates of maximum indoor and outdoor
concentrations in ALOHA's Text Summary window. ALOHA
predicted that people at the residence nearest the spill may be
exposed to a maximum outdoor concentration of about 1400
ppm, within 20 minutes of the start of the release, and a
maximum indoor concentration of about 150 ppm at the end of
the first hour.
A-5-20
-------
Text Summary
TIME DEPENDENT IMFOHHflllOH:
Concentration Estimates at the point:
Downwind: 593 yards
Off Centerline: 38 yards
Max Concentration:
Outdoor: 1,151 ppn
Indoor: 154 ppn
Note: Indoor graph is shown with a dotted line.
8 When you've finished viewing the graph and Text Summary,
choose Go to map from the hierarchical BitPlot menu item
under ALOHA's Sharing menu to return to BitPlot.
Don't be concerned if the numbers that you see on your screen
don't exactly match the ones shown here. ALOHA's estimates
are affected by exactly where on the map you click. ALOHA was
designed to give you "ballpark" estimates of source strength
and dispersion. It cannot give you completely accurate
predictions for a real release, because no model can account for
every uncertainty. For example, if the wind shifted direction or
changed speed, concentrations at the location you selected could
be higher or lower than ALOHA's estimates. Likewise, you had
to guess the temperature of the methyl chloride in the tank,
and the firefighters had to guess the dimensions of the hole in
the tank. If you or the firefighters were wrong, ALOHA's
estimate of release rate was inaccurate. In real response
situations, ALOHA gives you a "best guess," rather than an
exact answer.
A-5-21
-------
-------
Example 6
Using ALOHA and a
MARPLOT map
On June 4,1992, a train traveling on the Southern Railway near Manassas,
Virginia, collided with a stalled truck at U. S. Highway 29 (also numbered
211). During the hour from 15:00 to 16:00,4,000 pounds of chlorine gas
were released from a derailed tank car. The land between the tank car
and the intersection of Gallerher Road with U. S. Highway 29 is flat with
no obstructions. Two workmen repairing potholes at this intersection
were overcome by fumes and treated at a local hospital for chlorine gas
inhalation. At the time of the release, winds were out of the ENE at about
12 knots, one-third of the sky was covered by clouds, the humidity was
about 80% and the air temperature was 72° F.
Given this information, what is the concentration of chlorine that the
workmen may have been exposed to?
You'll evaluate this scenario first by using ALOHA to obtain a source
strength estimate and a footprint, then by plotting the footprint on a
MARPLOT map in order to obtain a concentration estimate for the
location where the workmen were injured.
First..
I Double-click on the ALOHA icon to launch the application.
2 After reading the ALOHA caveats, click OK.
A-6-1
-------
You'll need to add Manassas, Virginia to ALOHA's city library.
Choose Location from the SiteData menu.
Click Add.
ABERDEEN, MRRVLRNO
RBILENE, TEMRS
HI KEN, SOUIH OmOUNH
RLRMEDR, CRLIFORNIR
RLBRNV. NEW VORK
RLBRNV, OREGON
RLCHRNOftlH BflV, NEW VORK
HLEHftNORIH, LOUISIRNR
RLEKRNORIR, UIRGINIH
RLLEN.TEXHS
AMBLER, PENNSYLVANIA
BMES, IOU1H
HMESBUHV, MHSSflCHUSETTS
RNRCONDH, MONTRNfl
HNRHEIM, CRLIFORNIi
HNCHORR6E, RLHSKfl
RNN RRBOR, MICHIGAN
RNNHPOLIS. MRRVLBND
Cancel
Rdd
Modify
Delete
Help
A-6-2
-------
Type "Manassas" in the location name field. Click In U. S. Enter
"200," the approximate elevation of Manassas, and click feet.
Enter the city's latitude and longitude, 38° 50' N and 77° 30' W.
Click N and W. Choose "Virginia" from the scrolling list of state
names. Click OK.
location input
Location I* MANAfSAI
is location In a U.S. state ar territory?
® In U.S. O Nat in U.S.
Entar approximate alauatlon
Elauatlon is fzoo I ® ft O m
Salact stala or tannery
UIBGIN
LURKE ISLRND
UIHSNIN6TON
WEST VIRGINIA
WISCONSIN
UIVOMIN6
Entar approMlmate location
dag. min.
Latitude (39^ [5bT|®N O*
Longitude J77 '
Click Select.
I location Information
MHNHSSHS, IMFIGINIH
1BNCHESTIH, IOUIR
MANCHESTER, NEW HAMPSHIRE
MRNHATTAN, KANSAS
MRNSFIELO, MHSSRCHUSETTS
MANSFIELD, OHIO
MARIETTA, KEORGIR
HRROUCTTE, MICMI6RN
HRRTINCZ. CRLIFORNIM
MHRVSUILU. CRLIFORNIA
HEMPHI S.TENNESSEE
HENL9 PARK, CRLIFORNIM
MENOMONEE FRLLS, WISCONSIN
MENTOR, OHIO
MESR, ARIZONA
MESQUITC, TEHAS
MIAMI, FLORIDA
NIBMISBUR6. OHIO
Cancel
Add
Modify
Delete
[ Help
A-6-3
-------
Second...
We'll ignore Building Type during this scenario, since we're
interested in estimating outdoor concentration. Choose Date &
Time... from the SilteData menu.
SiteData
Location...
Building Type...
Date G Time
Select Set constant time and enter the month, day, year, hour and
minute for this scenario.
Data and Time Option*
You can ei
model's da
OU«
Input com
Month
16
(1-12)
1 °
t^B^^^B
ther use the computer's internal clock for the
te and time or set a constant date and time.
> Internal clock <•> Set constant time
ttant date and time
Day Year Hour Minute
|4 | |1992 | |I5 | |0 |
(1-31) (1900-...) (0-23) (0-59)
K ]] [ Cancel J [ Help ]
Click OK.
A-6-4
-------
Third...
I Select Chemical... from the Setup menu.
SetUp
Chemical.
Rtmospheric
Source
Computational.
Use the scroll bar or quickly type the characters "CH" to find
"chlorine." Double-dick on this name or click once on it, then
dick Select.
Chemical Information
CHMPHENC
CRRBON BISULFIDE
CHRBON DIOMIDE
CRRBON MONOXIDE
CARBON TETRRBROMI BE
CRRBON TETRACHlOftlOE
CHHBONVt FIUOH10I
CARBONVL SULFIDE
CHLORMEPHOS
CHLORORCETflLDEHVDE
CHLOROHCETIC RCID
CHLORORCETYL CHLORIDE
CHLORORNIIINE
CHLOROBENZENE
Cancel
Rdd
Modify
Help
Check the Text Summary window to review information about
the properties and toxicology of chlorine.
Te«t Summary
SITE DflTB INFORmTION:
Location: rtRNRSSRS, VIRGINIA
Building: Sholtorod singU storlod
Data t T!M: Fixod at Jun* 4, 1992 t 1500 hours
CtdlCM. ItFOMMTION:
Otwiieal NOM
TLU-TUN: 0.90 ppo
Boiling Point: -29.25* F
Frouing Point: -149.83* F
ttoIocular tteight:
IOLH: 30.00 ppo
70.90 kgAnol
01
I
A-6-5
-------
Fourth...
I Select User Input., from the Atmospheric submenu in the Setup
menu.
The wind speed is 12 knots and one-third of the sky is covered by
clouds. By clicking on the stability class Help button (in the upper
right corner of this screen), you can see that the best choice for
stability class is C. Click C for stability. No inversion is present,
so there's no need to change the default No inversion selection.
Type in the wind speed and dick knots. Type in the wind
direction and air temperature and dick F for temperature units.
The area between the derailed tank car and the injured workmen
is flat and free of obstacles, so choose Open Country for ground
roughness. Click OK.
Rtmospherlc Opttoni
Stability Gins Is: Q " OB ®C QD O E OF f
Inversion Height Options on
® No Inversion O "»i»«
i: [ Help )
irslon Present, Height Is:
Wind ODtJon* are: 1 Help 1
Ullnd Spaed Is: |)2
DIM It from : |ene
Mr Temperature Is: (72
Ground Roughness Is: (
® Opan Country
O Urb«i or Forest
1 S
Help ]
O Meters
® Knots OMPB O Meters/See. | Help |
Enter degrees true or tout (e.g. ESE)
Oaoraat ffl)F OC ( Help ]
H«lp ]
i 1 Oln
O Input roughness (Zol: |5.B |
| [ Coiicol ]
A-6-6
-------
The sky is about one-third cloudy, so type in "3" for cloud cover,
and then enter "80%" as the relative humidity value. Click OK.
Cloud Coiiar and Humldlt
Select Cloud Ceuer
*w
O O
complete
cover
Select Humidity:
*?'
O 0
met
c
JAC,
O O
partly
cloudy
&
O O
medium
[ *•» I
*Sr
V-.-
O OR ® enter uelue 3
(0-10)
cleer
{ Help ]
A£
O OR ® enter value [80 |%
dry (0-100)
[ Cencel J
Check the Text Summary screen to be sure that you've entered
these data correctly.
Tent Summary
SITE DATA INFOAhWriOH:
Location: mmSSAS. UIKINIA
Building Rip Exchanges Par Hour: 1.O4 iwit Tmptrotur*: araatw than I ate
ftabivnt Saturation Concvttratian: 1,000,000 pf» or 100.011
Uaiaht: 70.90 kq/knol
30.OO pan
ATMOSPHERIC IHFOntHTION:(nRHURL irf>UT OF DATA)
Hind: 12 knot* fro* VM
Stability Clan: C
talotiw* Huaidity: MM
Cloud Cow: 3 t*nth>
No Inversion Heioht
Air Toj^mtura: 72* F
Oround Roughnan: Opan country
2L
A-6-7
-------
Fifth...
This is a release from a tank car, but you don't have all the
information that you would need to model the release with
ALOHA's Tank source option. You can model this release as a
Direct Source, however. Choose Direct., from the Source
submenu of the SetUp menu.
Chemical...
Htmospheric
Computational...
Puddle.
Tank...
Pipe...
The chlorine was released over the course of an hour. Click
pounds. Click Continuous source, then type "4000" as the
release amount. Click on the pounds/hour button. Leave the
source height as "0," and click OK.
Bier input Source Strength
Select source strength unlti of mess or uokune: ( Help ]
O gramm O kilogram* ® pounds O tons(2,000 Ibs)
O cubic meters O liters O cubic feet O gallons
Select an Instantaneous- or continuous source: ( Help ]
® Continuous source Q instDntaneous source
Enter the amount of
pollutant ENTERING 4000
(0 II ground source): °
I - 1
O paunds/svc
O pounds/mln [ Heip'~)
pounds/hr
®'M; nggi
O wotori v •
[ Cancel
ALOHA will display the warning below. The model recognizes
that because the boiling point of chlorine is well below air
temperature, the chemical may have been stored as a pressurized
liquid. If so, it may flash-boil when released through a tank hole.
During flash-boiling, much of the stored liquid turns instantly to
-------
vapor as it leaks, so that a mixture of liquid droplets and vapor (a
two-phase flow) is released to the atmosphere. ALOHA's Tank
release calculations account for these processes, but the Direct
Source option does not. Since we don't have the necessary
information to run the Tank option, we'll use the Direct Source
calculations as the best approximation that we can make,
recognizing that the model will treat this release as a steady flow
of gas from the tank instead of a two-phase release. Click OK.
Note!
This chemical may flash boil
and/or result in two phase
now.
[ Help
Check the Text Summary window to be sure that you entered
these data correctly.
TeHt Summary
SOURCE STRENGTH IMFORHHTIOH:
Direct Soi*-c«: 4000 powds/hr Save* Height: 0
Release Deration: RLOHA lieiUd the dwation to 1 hour
Release Rate: 66.7 pounds/Bin
Total nvowt Released: 4,000 poods
Not*: This cheaical »oy flash boil end/or result in tea phase flow.
A-6-9
-------
Sixth...
I Choose Computational from the SetUp menu.
Chemical...
Atmospheric
Source
Check to be sure that Let model decide is selected (unless you
specify otherwise, ALOHA will default to this setting). Click OK.
Computational Preferences
Select spreading algorithm. If unsure, let
modal decide.
I Help I
® Let modal decide (select this If unsure)
O Use Gaussian dispersion only
O Usa Heavy Sas dispersion only
Mdr
[ Help
n -
Cancel
A-6-10
-------
Seventh...
I Select Options... from the Display menu.
Tile Window*
Stack Windows
Text Summary
Footprint
Concentration...
Dose
Source Strength
Calculate...
(ulnil«1« Now >
2 Check to be sure that IDLH Concentration is selected.
3 Check to ensure that Plot on grid and autoscale to fit window is
selected.
Click English units. Then click OK.
Select Level of Concern or Output Concentration:
® IOLH Concentration
Q User specified cone, of
<8>ppm
O milllgrim*/cubic meter
Select Footprint Output Option: f~
® Plot on grid and auto-teals- to fit window.
O U*e user specified scale.
Select Output Units:
® English units
O Metric units
[ Help
f Cancel 1
A-6-11
-------
Eighth...
Choose Footprint from the Display menu.
Tile Windows
Stack Windows
Options...
Tent Summary
Footprint
Concentration...
0»s«
Source Strength
Calculate...
Co leu Idle Noiu »
ALOHA will display a diagram of the footprint for this chlorine
release. Check the Text Summary window to see the maximum
downwind distance that the footprint may extend (the Maximum
Threat Zone). ALOHA expects the footprint to extend downwind
for about 362 yards.
Te»( Summary
FOOTPRINT INFORHflTfOH:
Model Run: H«ovy Gas
User specified LOG: equals IDLH (30 ppm)
Hox Thr«ot Zone for LOC: 362 yards
Not*: Th* Heovy Cos footprint is on initial screening.
For short r«l«as«s It nay b« an overestimation.
Be sure to check concentration information at specific locations.
A-6-12
-------
Ninth...
You're now ready to plot this footprint on a map of the area in
MARPLOT, and to obtain a concentration estimate for the
workmen's locatioa Select Go to Map from the MARPLOT
submenu under ALOHA's Sharing menu to bring MARPLOT
forward.
Choose Open from MARPLOT'S File menu.
Sm>«
£ l».s«
Save A* PICT
Print...
XS
XIU
XP
import...
Eitpail,..
Preferences...
Quit
xo
A-6-13
-------
Click on the map folder titled "Prince William County." Click
Choose Map "Prince Willia...."
Choose folder containing the n
iQMHRPLOTmnp* ^|
D Liberty County
D Pnn«e lihllidm Countg
Choose Map "Prince Willie..."
ne
£
O
p:
o Athene
[ Eject ]
[ Desktop ]
nssn
[ Help... ]
[ Cancel ]
You're about to change the map settings to make streets and
railways visible. You'll need to zoom the map in before you do so.
(Otherwise, so many features will be visible on the map that you
won't be able to distinguish among them.) First, we'll choose
units for the map scale. Choose Preferences from the File menu.
New...
Open...
Saue
Close
XN
380
xs
XIU
Saue Rs PICT...
Page Setup...
Print... XP
Import...
EHport...
A-6-14
-------
Choose yards from the popup menu as your units of map scale.
Also check to be sure that Visible dick point is selected. (This
means that MARPLOT will place a small crosshair mark wherever
you last dick on the map.) If you wish, you may also change the
map's background color and /or the formats for displaying the
map scale and the geographical coordinates of locations on the
map. Click OK.
Preference*
,-Scale Format
O 1 In • N yd
© Window Distance
Uieui Let/Long Coordlnates-
® a* a decimal
O In deg/min/sac
Click Point-
la) Visible
O Inuitible
Uniti;| yardi
Background Color I 1 White
Help...] [Cancel ]
Choose Set Scale... from the View menu.
Uieui Entire Map
Center On Click Point
Zoom In
Zoom Out
Redraw
Saue Current Uiew...
Edit Uiews...
Go to Uieui...
Go to Lat/Long...
XE
XT
X-
XD
XII
XR
XG
Mark Point >
Show Inset Ulew
Hide Tool Palette
A-6-15
-------
Enter "500" in the middle data field, so that the map scale
becomes 1 inch to 500 yards. Click OK.
Set Scale
1 : 118000
1 in- 500
Current Window Width - |tH8
Help I] [Cancel
yd
yd
8 Choose Feature Settings... from the Features menu.
Features
Feature Settings.
Find Street... XV
Identify Feature Near Click Point... XK
Show Oil Features
Show Street Name*
Highlight Street
Unhighllght Street
Click on Primary Roads, then click Display Settings....
Feature Settings
Feature Name
[County Boundaries
• Primaiu Roads
Secondary Roads
County Roads
Ml Other Roads
Railroads
Miscellaneous Features
Non-uisible Boundaries
Display Line Type
Show |£
Hide •
Hide -Hi
Hide If
Hide *\
Hide ; '
Hide 3
Line Width: 1 Pt
•v) Colon) ••Black
-------
10 Click on Show at all scales, then click OK.
Feature Display
Feature: Primary Roads
i-Display Criteria
® Show at all scales
O Hide at all scales
O Show at scales greater than: 1 In
||278
Width of window at this scale: 2164
yd
yd
[ Help... ) [ Cancel
I I Repeat this procedure for the following features: Primary Roads,
Secondary Roads, County Roads, All Other Roads, and Railroads.
(As a shortcut, you can toggle a feature's setting by holding down
the option key, then clicking on the feature's name in the Feature
Settings screen.) Your Feature Settings screen should look like the
one below. When you've finished, click OK.
Feature Settings
Feature Name
Display
Line Type
County Boundaries
Primary Roads
Secondary Roads
County Roads
All Other Roads
Miscellaneous Features
on-visible Boundaries
(Display Settings...] [ Help...^) ( Cancel ]
MARPLOT will automatically redraw the map, with streets and
railroad lines visible.
A-6-17
-------
12 Choose Show Street Names from the Features menu.
Feature Setting*...
Find Street... XV
Identify Feature Neer Click Point... XK
Show Rll Features
Shou' Strppt Names
Highlight Street
Unhlghllght Street
13 Now you'll search on the map for the area where the accident
occurred. Choose Find Street from the Features menu.
Identify Feature Near Click Point... XK
Show Rll Features
-------
15 Click "GALLERHER ROAD," then click Show on Map.
Find street
FOREST LflHE
FORESTUOOD LflHE .flLT
FORRESTER LflHE
FORUtl URV .ALT
FRIE CT
CHINES RORD
GflLES CT
GflLLEHHER RD RRHP us,
^^A^w^^y^^•A^^^^.;«^^*>^v.^^^^^^*.^^^^^^^^^^^^^•.^^^^^^^^%'.v.^^'.^*.•.•.•.
GARNER OR
Search list for name starting ivith:
IGHLL
Narroui search to
part of a street:
[ Intersection...
[address Range..T
Shoui on Map
Cancel
Help...
Search
16 Your map should look like the one below. If you have a color
monitor, Gallerher Road will appear in red, and all other streets
and roads will be drawn in black. U.S. Highway 29 (211) crosses
the map as a straight line from the lower left to the upper right of
the map. The Southern Railway, which is not labeled, crosses the
map as a winding line from the upper left corner to the middle
right side of the map.
A-6-19
-------
i 7 Find the point where the Southern Railway line crosses U. S.
Highway 29 (211).
Choose I——I from the tool palette, then click once at that point to
set a source location for ALOHA. MARPLOT will place a visible
crosshair mark, or "click point" at this location.
18 Choose Set Source Point from the ALOHA submenu under
MARPLOT'S Sharing menu.
flbout Shared Menui...
Save Shared Menus...
Set Cone v DOM Point
A-6-20
-------
19 An ALOHA footprint should automatically be drawn at that point
(this may take a few seconds).
If you wish, click on
in the tool palette, then click on the
footprint to zoom in for a closer view.
Now you'll choose the location for which you'd like an ALOHA
Concentration graph. Find the intersection of Gallerher Road and
U. S. Highway 29 (211). {The leading edge of the footprint should
nearly touch this intersection.)
Be sure that you've selected the arrow tool,
palette, then click on this point.
, from the tool
A-6-21
-------
21 Choose Set Cone & Dose Point from the ALOHA submenu under
MARPLOT'S Sharing menu.
Sharing
Rbout Shared Menus...
Saue Shared Menus...
Get Info
Unlink
XI
Delete RLOHfl Objects
ALOHA will come forward and will display a Concentration
graph for the location you choose. Review the graph and the Text
Summary window. ALOHA estimated that the workmen were
exposed to an outdoor concentration of about 25 ppm, somewhat
less than the IDLH for chlorine, for about an hour after the start of
the release.
Concentration Window
20-
10-
20
40
60
limit*
A-6-22
-------
TeHt Summary
TIME OEPEMDENT IMFORflflTIOM:
Concentration Estimates at th* point:
Downwind: 365 yards
Off Centerline: 21 yards
(lax Concentration:
Outdoor: 25.3 pp*
Indoor: 10.1 pp*
Note: Indoor graph is shown with a dotted line.
0 \
ft
The purpose of running this scenario in ALOHA and MARPLOT was to
get an estimate of the concentration of chlorine to which the workmen
were exposed. Don't be concerned if the numbers that you see on your
screen differ slightly from those shown here. ALOHA's estimates are
affected by exactly where on the map you click. ALOHA was designed to
give you "ballpark" estimates of source strength and dispersion. It
cannot give you completely accurate predictions for a real release,
because no model can account for every uncertainty. For example,
ALOHA predicted that the workmen were exposed to a steady
concentration of about 25 ppm of chlorine. That concentration would
have been high enough to cause adverse health effects in the workers.
However, if the wind shifted during the course of the release, the
concentration at the workmen's location could have been higher or lower
than ALOHA's estimate. If the chlorine was stored as a pressurized
liquid, its initial release rate was probably greater than ALOHA
predicted. Downwind concentrations then would have been higher, too.
If you were responding to a real event, you might wish to obtain values
for the tank car's dimensions, the amount of chlorine it contained, the size
and location of the hole, and other information that you'd need to run
ALOHA's more realistic Tank option.
A-6-23
-------
-------
Appendix B
Troubleshooting
This section addresses some of the issues that may raise the most
questions in ALOHA. These include things that are not truly problems
but may be troublesome when you're trying to interpret what ALOHA
is saying or asking of you. In most cases, when you encounter a problem
while running ALOHA, the model will alert you of the problem and
suggest a solution. These cases are not discussed here. Less often, you
may encounter problems and be unsure of how to solve them. Following
are some of these cases.
B-l
-------
Appendix B
I want to modify a chemical
(either inside ALOHA or using
Chem Manager), and I can't
change a property—it appears
gray.
The property in question is inter-
nally calculated by ALOHA from
information in its chemical library.
You must add a new chemical
(with a different name, such as
chlorine-2) and enter a new value
for the property.
I have drawn a footprint, but
when I double-click inside to
get the concentration and
dose curves, I get a message
saying that the concentration
at that point is insignificant.
Your footprint was drawn using
the heavy gas calculations. Re-
member that, for the footprint cal-
culation, the heavy gas calculations
use the maximum average release
rate as though it were continuous
for the entire 60 minutes or sec-
onds (whichever is appropriate).
In a case where the release rate is
high to start with, then decreases
significantly (e.g.,a pressurized re-
lease), the heavy gas model will
overpredict the footprint ALOHA
calculations of concentration and
dose made for a particular loca-
tion, however, account for changes
in the release rate over time, and
are not overpredicting. Gaussian
footprint calculations also account
for changing release rate overtime.
R-2
-------
Appendix B
I am trying to model the
release of gas from a gas
pipeline, but ALOHA will not
run because it says the pipe is
too short. It tells me that the
length must be at least 200
times the diameter of the pipe.
In some instances the pipe may be
too short relative to its diameter. If
this is the case, and the diameter of
the pipe is greater than 20 cm, you
may use the Tank option instead,
selecting the configuration of a
horizontal tank. If the length of
your pipe is less than one meter
and it is connected to a tank source,
you may also use the Tank option
and select short pipe/valve as the
type of leak. Both of these alterna-
tives should produce conservative
estimates of downwind dispersion.
I'm using a Macintosh, and
ALOHA will not open my save
file. I either get an error
message, or the file opens,
then gets lost.
Your save file may not be compat-
ible with the version of ALOHA
that you are using. The current
ALOHAcannotreadany save files
made with previous versions of
ALOHA. In addition, check to see
whether you have installed both
the math coprocessor and the non-
math coprocessor versions of
ALOHA on your hard drive. If
you have, ALOHA may save a
math coprocessor version-file as a
non-math coprocessor-version file.
Remove the version that you do
not need (e.g., if you're using a
machine without a math coproces-
sor, remove the math coprocessor
version of ALOHA).
B-3
-------
Appendix B
I have a SAM hooked up, and
I have set the SAM options
using the Atmospheric menu,
but the Source menu option is
grayed out—I can't set my
source.
The SAM has not been collecting
data for five minutes or it has not
received valid data. In order for
the SAM to send information to
help determine the most appro-
priate stability class, it must have
at least five minutes' worth of data.
Your Text Summary screen should
tell you that you do not have five
minutes' worth of data yet or that
the transmissions have not been
valid. Inaddition,lookattheShow
processed data option under the
SAM Options menu. If it reports
sigma theta as -1.0, the station has
been running for less than five
minutes.
ALOHA tells me that my val ue
is not within allowable limits.
ALOHA will accept values for
numeric inputs within specified
ranges. These restrictions help
ensure that you do not inadvert-
ently use unrealistic values for an
input. If you enter a value outside
of the allowable range/ ALOHA
will warn you and tell you what
the limits are. You must reset the
value before ALOHA will con-
tinue. Most of these ranges are
summarized in the table in this
appendix. Check ALOHA's on-line
help topic for more information
about any ALOHA input.
B-4
-------
Appendix B
The Text Summary screen
shows a Maximum Computed
Release Rate that is signifi-
cantly higher than the Maxi-
mum Sustained Averaged
Release Rate. How should I
interpret these numbers?
ALOHA averages the release rate
over five steps. The maximum
computed release rate corresponds
to the very highest release rate pos-
sible with the given scenario. The
maximum sustained averaged re-
lease rate is averaged over at least
a minute. If these values are sig-
nificantly different, the maximum
release rate was sustained for less
than a minute. This is most com-
mon in the case of pressurized re-
leases.
When I change atmospheric
conditions, ALOHA tells me
that it is unable to verify the
consistency between my new
atmospheric data and the
source data. Then I have to
reset the source.
Puddle, Tank, and Pipe source
strength calculations are directly
affected by atmospheric condi-
tions. Changing atmospheric con-
ditions will change these source
calculations so source strength
must be recomputed. The Text
Summary screen will remind you
which source option was last used.
If you return to the same source
option, information about the sce-
nario will still be there EXCEPT
information about the amount re-
leased (puddle size, height of hole
in tank, etc.).
B-5
-------
Appendix B
I want to make a few changes,
but every time I make one
change I have to wait for
ALOHA to recalculate and
redraw everything before I can
make the next change.
You should select Calculate from
the Display menuand tell ALOHA
that you only want to update
ALOHA's windows when you se-
lect them manually. To do this,
choose Manual update of all vis-
ible windows. The Calculate op-
tion is set by default to update the
windows automatically every time
something is changed.
When saving an ALOHA file,
not all of my data is saved.
ALOHA will save all information
which does not pertain to meteo-
rological conditions and the
amount spilled. The model was
developed as a tool for first re-
sponders; saving a wind speed
and release scenario that would
most likely never be exactly re-
peated may be misleading. Hence,
all information EXCEPT meteoro-
logical conditions and information
about the amount spilled can be
saved. If you want to archive the
results of an ALOHA scenario run
for later viewing, save a Spy file.
B-6
-------
Appendix B
When I save an ALOHA file in Spy files can only be opened by
the Spy format, I can't open it AlohaSpy. These files cannot be
opened or used by ALOHA.
from ALOHA.
I am trying to run a scenario,
and a progress bar saying
"Heavy Gas Calculations in
Progress" has been up forever!
How long will this take to run?
Heavy gas calculations may be
slow to complete/ especially if
you're using a computer without a
match coprocessor. Use the
progress bar to get a rough esti-
mate of how long ALOHA will
take to finish calculating. If you've
waited three minutes and the bar
is about half-way across the dia-
log, you have about three minutes
to go. If you don't have that long to
wait, you may cancel the calcula-
tions and then run the Gaussian
module. You should rerun the sce-
nario with the heavy gas module
as time allows.
B-7
-------
Appendix B
The Text Summary screen
warns me that it is unable to
save the archived SAM data
because the disk is full.
The floppy disk or hard drive to
which you are archiving SAM data
has no more room left. Insert an-
other disk (or hook up another
ha rd drive) and continue archiving
your data.
I'm using a Macintosh. While
unpacking ALOHA, I get the
message, "Can't write to
destination file."
You have run out of space on your
hard drive or have tried to unpack
the file to the original floppy disk.
If you tried to unpack to your hard
drive and received this message,
remove unneeded files from your
hard drive, including the partially
filled ALOHA™ folder, until you
have at least two megabytes of
hard disk space available, and be-
gin the unpacking process again.
If you received the message be-
cause you tried to unpack to the
floppy that the file came on, click
OK, then begin the unpacking
process again, this time clicking
the Drive button till your hard
drive appears.
8-8
-------
Appendix B
I'm running BitPlot with
ALOHA in Windows. I have a
map file that I created by
scanning in a paper map.
However, I can't open it in
BitPlot. What's wrong?
A variety of graphic file formats
are available for users of DOS and
Windows. The scanned map that
you created is likely to be in .pcx
ormat. You must convert it to .bmp
format before BitPlot can read it in;
that's the only format that BitPlot
recognizes. We describe how to
make the conversion in the BitPlot
Appendix.
I'm running BitPlot with
ALOHA in Windows. I have
the current ALOHA footprint
displayed on a map in BitPlot,
and I'm trying to print it. It's
so slow! Am I doing something
wrong?
Bitmapped graphics may print
very slowly because the graphic
must be resized while it's being
printed. If your time is limited and
you need a printout of the foot-
print, print out the footprint dis-
played on a grid from within
ALOHA.
I'm running BitPlot with
ALOHA in Windows while I'm
responding to a spill. I'm also
using a SAM station to collect
weather data. I've had a
footprint displayed in BitPlot
for the last half hour. I know
the wind has shifted direction
but the footprint hasn't
changed at all. What*s wrong?
Whenever you bring BitPlot for-
ward in Windows, you'll halt data
transmission from the SAM to
ALOHA. The same thing can hap-
pen when you use MARPLOT and
ALOHA together on a Macintosh.
Bring ALOHA forward to update
the weather data and footprint.
B-9
-------
Appendix B
I thought I knew what an
ALOHA footprint looks like.
But on my current footprint
plot, I see a big, shaded circle
around my source point. What
is it?
There are two possible explana-
tions, depending on your scenario.
Is your source a puddle of spilled
liquid (either standing by itself or
pooling under a leaking tank)? If
so, and if the puddle is large in
diameter relative to the size of the
footprint, you may be seeing it on
the footprint plot.
You may also have a heavy gas
footprint. If a heavy gas is escap-
ing into the atmosphere at a fast
enough rate, it will form a large
"blanket" of gas over the source
point before it moves downwind.
If the blanket is big enough,
ALOHA will show it on your foot-
print plot.
We have two computers in Individualcomputerscancomeup
our office that sometimes give wim different answers when they
different answers for the same ^ ^ same calculations. m
ALOHA scenario. ,
particular, different computers will
round off numbers differently as
they make their calculations. This
can have a visible effect on
ALOHA's source and dispersion
estimates. You may have one ma-
chine with a math coprocessor and
one without, or a Macintosh and
an IBM-compatible, or your com-
puters may differ in other ways.
B-10
-------
Appendix B
I'm using a Macintosh. I just
copied ALOHA onto my hard
drive. I started the program,
and chose Location from the
SiteData menu. But instead
of seeing the list of cities, I got
an error, "Error returned
from FillCityListO". Then
when I chose Chemical from
the SetUp menu, I got another
error, "Error returned from
FillChemListO". Did I break
ALOHA?
You may have very little room re-
maining on your hard drive.
ALOHA needs about 100 kilobytes
of space to create index files for its
city and chemical libraries. The
program displays the errors that
you saw if it can't find enough
room. From your Desktop, click
on the icon for your hard drive,
then choose Get Info from the File
menu to see how much room you
have left. You can solve this prob-
lem by removing some files from
your drive to make more room for
ALOHA's index files.
I'm running ALOHA under
Microsoft Windows. Every
now and then, I get an error
message, "System Error -
Cannot write to device AUX."
Then I'm given a choice of
choosing "Cancel" or "Retry."
Am I doing something wrong?
What should I do here?
This error message is Windows'
way of alerting you that some-
thingiswrong. Itcanappearwhen
you're trying to select an item from
the menu, print an ALOHA docu-
ment, or at other times. It's hard to
figure out what the problem may
be when this message appears. The
best thing to do is to choose "Can-
cel," then quit ALOHA, and
restart the program.
B-ll
-------
Appendix B
Allowable Input
•m . J •
properties
SiteOata
Air exchange rale
Elevation
latitude
Longitude
Month
Day
Hour
Minute
Meteorological
Air temperature
Cloud cover
Ground roughness
Inversion height
Relative humidity
Wind speed
Source Input
Amount entering the
atmosphere (Direct)
Ground temperature
Pipe diameter
Pipe hole size
Pipe length
'ipe pressure
ftpe temperature
Puddle area
Puddle depth
Puddle mass
*uddle volume
Source height
Tank diameter
Tank length
Tank mass
Tank opening
Tank pressure
Tank temperature
Display
Dose setting
User spec. cone.
User spec, scale
Mustb
.^greater than
(or equal to)
0.01 per hour
-500 ft (-153 ra)
0°
Oe
1
1
0
0
-1000P(.73"C)
0/10
0,0004 ill (0.001 cm)
10 ft (3m)
0%
2kts(lra/s,2.3mph)
0 (any units)
-58eF (-50"C)
04 in (1cm)
0
200 limes pipe diameter
twice ambient
boiling point
4 sq. in. (25 sq. on)
0.1 in (0.25 cm)
0.22 Ibs (0.1 kg)
0.03 gal (.10
0
0.7 ft (20 on)
1.7 ft (50 cm)
0
0.04 in (0.1 on)
1.1 aim
-459'P (-273*0
1
0
1:0
e~
...less than
(or equal to)
60 per hour
28,000 ft (8,535m)
90"
180°
12 . .
31
23
59
150°F(65'C)
10/10
78 in (200 cm)
5000 ft (1.524m)
100%
I00te(51m/s, llSmph)
1,000,000.000 (any units)
188°P(70CC)
32.8 ft (10m)
diameter of the pipe
6.2 mi (10 km)
680 aim (10,000 psi)
2,795^(1535*0
12,100 sq.yds (10,000 sq.ra)
110 jds (100m)
1 10 tons (100 metric tons)
2,640,000 gal (10000 cu.m)
5000 ft (1,525 m)
3.280 ft (1,000 ra)
3,280 ft (1,000m)
2,000,000 Ibs (907,200 kg)
circular, cross-sectionai
area or 10% of surface area
—whichever is smallest
68 aim (1,000 psi)
iMsnowo
5
1,000,000 ppm
1:1,267,200
B-12
-------
Appendix C
AlohaSpy
AlohaSpy is a companion application to ALOHA. Use it to
view or print archived Spy files that you have previously
saved from within ALOHA. You may wish to create a Spy file
whenever you have run an ALOHA scenario and would like
to save your results for later viewing. An archived Spy file
contains the information from all the windows visible in
ALOHA at the time the file was saved.
Spy files can be opened
only wih AlohaSpy.
Whenever you'd like to create a Spy file, first check that all of
the windows that you'd like to archive are visible in ALOHA.
Then select Save As... from ALOHA's File menu. Click SPY
on the Save As Options dialog, type in a file name, andclick
OK.
Double-click on the AlohaSpy icon when you wish to use the
application to view or print Spy files. Each menu item avail-
able in AlohaSpy is described below.
C-l
-------
Appendix C: AlohaSpy
Open Window Archive... XO
Close Window ftrchlue
Close
Page Setup.
Print...
PrintHII...
Quit
AlohaSpy's File menu
Open Window Archive...
opens a Spy archive file that
has been created in ALOHA. If
you are currently viewing a
Spy archive file, selecting a
new archive file to open will
close the current file.
Close Window Archive
closes an open Spy archive file.
Close
closes the front window of the current archive display.
Print...
prints the contents of the front window.
KID
XP
XQ
Edit menu
Copy
copies the contents of the front window to
paste into another application.
Until) %&
Copy 9§C
[ tear
The Undo, Cut, Paste,
and Clear menu items are
not available in AlohaSpy.
C-2
-------
Appendix C: AlohaSpy
TeHt Summary
•Footprint lillndouf
Concentration Window
Dose Window
Source Strength (Release Bale)
Windows menu
Tile
allows you to view all of
the open archive win-
dows simultaneously on
the screen, with the win-
dows arranged side by
side and fit to the screen.
Stack
layers all of the open archive windows on top of each other,
so that only the title bars from the back windows, along with
the entire front window, are visible.
Menu items displayed below the Stack menu item represent
the individual window names. To open a closed window or
bring a window forward, choose the desired window name
from this list. A check mark is placed next to the name of the
current front window.
C-3
-------
-------
BitPlot
Appendix D
BitPlot
In this appendix...
Plotting a footprint ...D-l
Opening a map D-2
Entering scale D-3
locating source D-4
Displaying footprint .D-5
Modifying footprint ..D-6
Cone. vs. Time D-6
No BitPlot D-7
Converting .pcx Oles D-8
Introduction
BitPlot, a companion application provided with ALOHA Win-
dows, is installed in your ALOHA directory when you install
ALOHA (and it needs to be kept in the same directory as
ALOHA). It allows you to use a simple electronic map of your
city or community with ALOHA. When you open such a map
in BitPlot, mark the location of a spill on the map, and run a
footprint calculation in ALOHA, BitPlot will display the
ALOHA footprint on your map.
BitPlot can use any map saved as a Windows device-indepen-
dent bitmap (.bmp) file. Such files have names ending with a
.bmp extension. BitPlot cannot directly use files produced
with vector-based graphics programs such as AutoCAD.
However, it is possible to convert many vector-based graph-
ics files to .bmp format by first converting them to .pcx
format. BitPlot cannot use MARPLOT maps; use MARPLOT
if you wish to plot an ALOHA footprint on a MARPLOT map.
Refer to the MARPLOT manual for information about how to
do this.
Plotting an ALOHA footprint in BitPlot
Once you have created a background map for footprint plot-
ting, and have saved it as a .bmp file, you can load it into
BitPlot and plot a footprint on it. You must be running both
ALOHA and BitPlot simultaneously in order to do this.
D-l
-------
Appendix D: BitPlot
In ALOHA, choose a chemical, enter atmospheric conditions,
complete a source option, and ask for a footprint. If BitPlot is
present in your ALOHA directory, ALOHA will display a hierar-
chical BitPlot menu item under its Sharing menu. Select Go to
map from the BitPlot menu item to launch BitPlot or to bring it
forward if it is already running.
Sharing
BitPlot
Go to map
Opening a new map
When you first open BitPlot, the program will display a dialog box
titled "Where is the map?" (You can access this dialog later by
choosing Open Map... from BitPlot's File menu.) Choose the map
file that you'd like to open. Click OK to open the map.
Where is the map?
D-2
-------
Appendix D: BitPlot
Entering the map scale
Next, you'll need to enter your map scale. You will see your
map displayed on your screen inside a scrolling window.
You'll need to know the distance between any two points
visible on your map. These can be physical places, such as the
grocery store on Main Street and the Post Office on Elm, or
tick marks on a map legend. We recommend that whenever
you create a map for use with ALOHA and BitPlot, you place
a scale bar in the upper left corner to facilitate setting the map
scale. Scroll the map until both points are visible on your
screen. Move the cross-hair cursor to the first point, click
your mouse button once, then move the cross-hair to the
second point and click the mouse button again.
»•*>«. rrc —~ srarra
-J- HOSPITAL _ HOHV4YS
SOOX —_ FIHEVAV3
ocMCM.rw:i.im$ ^— ctrviwirs
D-3
-------
Appendix D: Bit Plot
You'll see the following dialog box:
Scale by Mouse
Distance Equals: I2BM
QIC | | Cancel ] Redo | Help |
Enter the distance between the two points in the input field
next to 'Distance Equals:'. Click on the pull-down units menu
and choose appropriate distance units. If you made a mistake
when you chose your two points, click Redo. You'll be
returned to your map for another opportunity to choose two
points and set a distance. Click OK when you're finished.
Locating the spill source
After you click OK, you'll see your map again on your screen.
Scroll the map until you can see the spill location on your
screen. You can navigate rapidly around on your map by
clicking on the approximate spill location on the small map in
the Quick Scroll window in the lower left corner of the screen.
The full-sized map will center on the point that you clicked.
Once you have located the spill point on the full-sized map,
click once directly on it. You will see a blinking red cross-hair
mark at that point. If you make a mistake, just click again on
the correct location; the cross-hair mark will be relocated to
the new click point. Once you are satisfied, click OK to set
your source point.
D-4
-------
Appendix D: BitPlot
Remember that
ALOHA does not
account for hills,
valeys, and other
terrain types when it
makes footprint
calculations. The
footprint that you will
seeinBitPbtwHI
simply be plotted over
the map.
Displaying the footprint
If a footprint is already displayed in ALOHA, it will auto-
matically be drawn on your map in BitPlot. (If you haven't
completed footprint calculations in ALOHA, choose Go to
ALOHA from BitPlot's Sharing menu to return to ALOHA or
to start ALOHA if it's not yet running. Complete footprint
calculations in ALOHA, then choose 'Go to map' from the
hierarchical BitPlotmenu item under ALOHA's Sharing menu
to return to BitPlot; your footprint will automatically be
drawn on the BitPlot map when you do so.)
D-5
-------
Appendix D: BitPlot
Options
Opposition Source
Footprint Line Color
Footprint Line Thickness
Confidence Line Color >
Confidence Line Thickness >
Copying, printing, and modifying the footprint
You may choose to change the line thickness and color of the
footprint and the confidence lines drawn by BitPlot. Choose
from among the hierarchical Line Color and Line Thickness
menu items in the Options menu to make these changes.
Checkmarks in the menu
will identify the colors and
thicknesses that you have
chosen. Also, the settings
that you choose will be
saved and will be in effect
for your next BitPlot ses-
sion.
Choose Copy from the Edit menu if you wish to copy the map
and footprint displayed in BitPlot's window into the Win-
dows Clipboard.
Choose Print from the File menu to print the footprint dis-
played on the background map. Note that printing of
bitmapped graphics from BitPlot can be very slow, because
the graphics must be resized before being printed.
Getting a Concentration vs. Time graph
If you'd like to see ALOHA's Concentration vs. Time graph
for a location on your map in BitPlot, just double-click on that
point on the map. ALOHA will come forward automatically,
and will display a Concentration graph for your location.
When you've finished viewing the graph, choose Go to map
from the BitPlot submenu under ALOHA's Sharing menu to
return to BitPlot.
Whan you indicate a
location to ALOHA by
clicking on your map in
BitPlot, ALOHA wil
remember the location in
terms of its fixed east*
west, north-south
coordinates.
D-6
-------
Appendix D: BitPlot
If you later wish to reposition the source location, choose
Reposition Source from the Options menu. You can close the
map by choosing Close Map... from the File menu. You also
can open a new map at any time, by choosing Open Map...
from the File menu. Opening a new map will automatically
close any map that you had already opened.
Figure E-1.
An ALOHA footprint displayed on
a background map in BftPbt
File Edit QpUom Sharing
If you won't be using BitPlot...
If you do not wish to use BitPlot, you may remove it from your
computer by deleting the program BitPlot.exe and its associ-
ated help file BitPlot.hlp from your ALOHA directory.
D-7
-------
Appendix D: BitPlot
Converting .pec files to use with BitPlot
Graphic files saved in .pcx format are a common type of
bitmapped graphic file available to users of DOS and Win-
dows. This is a typical format for maps or other images
created using a scanner.
You can easily convert .pcx files to ,bmp files with your
Paintbrush program, which should have come packaged with
your copy of Windows. If you have a map in .pcx format that
you would like to use with BitPlot, follow these steps to make
a .pcx to .bmp conversion:
I Open your .pcx file in Paintbrush. Choose Open from
the Paintbrush File menu to do this. Click once to
highlight the name of your map file, then click on the
OK button.
2 Next, choose Save As from the Paintbrush File menu.
Choose Monochrome bitmap (.BMP) from the
pulldown list of file types. The file name extension for
your file will automatically change to .bmp, the appro-
priate extension for files to be used with BitPlot. (You
may also save BitPlot maps as 16-color bitmaps - but
you will rarely want to do so. Color graphic files
require about four times as much space in memory as
monochrome maps.)
3 Finally, click OK to save your converted map file. It's
now ready to be loaded into BitPlot whenever you
need it.
D-8
-------
Glossary
ALOHA
The air dispersion model, Areal Locations of
Hazardous Atmospheres, also known as the
CAMEO Air Model. (ALOHA is a trademark of
the U.S. Government.)
ALOHA Helps
ALOHA
Resources
•The file containing all of the text that ALOHA
uses during on-line Help inquiries.
The file that contains most of the resource code
for ALOHA.
Aerosol
AlohaSpy
Liquid or solid particles suspended in a gas.
AlohaSpy is a companion application to
ALOHA. Use it to view or print ALOHA model
runs.
Ambient
pressure
The atmospheric pressure at a given location.
Ambient
saturation
concentration
Ambient
temperature
The concentration of the vapor in equilibrium
with the atmosphere. The value shown on the
ALOHA screen represents the maximum con-
centration at which the vapor could be sus-
tained in a closed room at the given (ambient)
temperature and pressure. Substances that are
gases at ambient temperature and pressure have
an ambient saturation concentration of 100%,
or 1,000,000 ppm.
The temperature of the air at a given location.
8-1
-------
Glossary
Anhydrous
Without water. Some chemicals are commonly
shipped or stored as a solution, using water as
the solute.
Archive data
Atmospheric
stability
Automatic
update
An option that allows an ASCII tab-delineated
file to be created from data transmitted to
ALOHA by a meteorological station (SAM).
A measure of the tendency of a "parcel" of air to
move upward or downward. In the air model
the stability is scaled from A-F, where A im-
plies very unstable conditions and F is for very
stable conditions.
An option that lets you automatically update
all v isible windows that are opened in ALOHA
each time that location, building type, source
strength, or display options are changed (see
Calculate).
Average
Boiling point
The sum of « values divided by n.
The maximum temperature at which a
substance's liquid phase can exist in equilib-
rium with its vapor phase. Above the boiling
point a liquid vaporizes completely. (The boil-
ing point is also the temperature at which the
vapor pressure of a liquid is equal to the ap-
plied atmospheric pressure.) The boiling point
depends on the chemical's composition and
pressure. As pressure increases, the boiling
point of a substance also increases. The "nor-
mal" boiling point is the temperature at which
a liquid under one atmosphere of pressure boils.
8-2
-------
Glossary
Calculate
CAMEO Air
Model
ChemLib
ChemManager
For example, the normal boiling point of pure
water is 100°C. Because pressure variations can
be significant within a tank or pipe, the tem-
perature at which a liquid boils under these
conditions can differ significantly from its nor-
mal boiling point.
Located on the Display menu, this option lets
you choose whether the windows in ALOHA
will be updated manually or automatically.
The air dispersion model that is used in con-
junction with Computer-Aided Management
of Emergency Operations (CAMEO™ 4.0). The
CAMEO Air Model is also known as ALOHA.
ALOHA's library of chemical properties. This
library contains available physical and toxico-
logical properties for each chemical in ALOHA.
An application that can be used to perma-
nently add, modify, or delete chemicals in the
ChemLib.
City Lib
ALOHA's location library. This library con-
tains latitude and longitude, elevation, and time
zone information.
Cloud cover
The fraction of the sky overhead that is ob-
scured by clouds.
Computational
Located on the SetUp menu, this option lets
you select the type of dispersion calculation to
use in ALOHA (Gaussian or heavy gas). You
can also change the dose exponent in the dose
vs. rime equation with this option.
8-3
-------
Glossary
Concentration
The amount of a chemical in the air. It is usually
expressed in ppm (by volume) or milligrams
per cubic meter.
Conservative
estimate
An estimate is "conservative" if it is an overes-
timate.
Continuous
source
A release of pollutant into the air that lasts for
a period of time. The maximum time that
ALOHA considers is sixty minutes.
Crosswind
The direction perpendicular, or at right angles,
to the wind.
Cryogenic
A term relating to substances at low tempera-
tures. For purposes of the air model, this term
refers to the use, storage and possible spilling
of gases liquefied by refrigeration.
DEGADIS
DEnse GAs DISpersion model. These are the
computations that ALOHA uses to calculate the
dispersion of a heavy gas.
DIPPR
Design Institute for Physical PRoperty data.
Many of the chemicals in ALOHA's chemical
library use physical and chemical data from
DIPPR.
Daylight
savings time
One hour is added to the local time during the
spring for most U.S. locations; ALOHA checks
the date that you enter and automatically makes
this correction. If you select a location where
the daylight savings time correction is unknown
(e.g., outside the U.S.), ALOHA will ask you for
this information.
8-4
-------
Glossary
Density
Direct Source
The mass of a substance per unit volume.
A source option that allows you to enter the
amount of vapor entering the atmosphere. This
can be entered as an instantaneous or continu-
ous release.
Dispersion
Dose
Dusts
Eddies
The distribution of molecules or finely divided
particles into a gaseous or liquid medium (e.g.,
the distribution of a toxic chemical cloud in the
atmosphere).
The accumulated amount of chemical to which
a person is exposed.
Fine, solid particles at rest or suspended in a
gas (usually air). These may have damaging
effects on the environment, may be dangerous
by inhalation or contact, and frequently consti-
tute an explosion hazard when dispersed in air.
Parcels of air of various sizes that leave their
normal position within an otherwise orderly,
smooth flow. For example, air that encounters
an obstacle must go over or around it. This
change in the direction of air flow often causes
"swirls" of air, or eddies, to tumble off the back
of the obstacle. Impediments to airflow can
range from simple friction (grass) to larger ob-
stacles (buildings), leading to eddies generated
at many different sizes.
8-5
-------
Glossary
Entrainment
Flash boil
Footprint
Freezing point
Fumes
The mixing of environmental air into a preex-
isting organized air current so that the environ-
mental air becomes part of the current. For
example, as a toxic cloud moves and mixes air
into it, the pure gas cloud quickly becomes a
gas/air mixture.
The sudden vaporization of a liquid. This most
often occurs when a chemical is a gas at stan-
dard temperature and pressure, but is stored as
a liquid by pressurization. If the storage con-
tainer is breached, the sudden reduction in
pressure can superheat the material (leave the
material in a liquid state above its boiling point),
at which point it will flash boil.
One of ALOHA's graphical outputs. The "foot-
print" gives a picture that shows an overhead
view of the ground-level dispersion of a vapor
cloud out to the level of concern that you set.
The temperature at which the solid and liquid
phases of a substance exist in equilibrium. The
freezing point depends on the chemical compo-
sition and the applied pressure. The "normal"
freezing point is defined at a pressure of one
atmosphere. For example, the normal freezing
point of water is 0°C.
The characteristic smoky appearance and chok-
ing cloud resulting from the release of fuming
materials, such as highly reactive liquids, gases,
or molten metal (e.g., concentrated hydrochlo-
ric acid, sulfur monochioride). Fuming corro-
sive materials produce dense, choking, smoke-
8-6
-------
Glossary
like emanations on contact with the moisture in
air. Some liquefied gases that react with water
when they evaporate may also be said to fume
(e.g., anhydrous hydrogen fluoride, anhydrous
hydrogen chloride). Fumes from hot or molten
metals may not have a dense, smoke-like ap-
pearance but are hazardous, usually by inha-
lation.
GMT
Gas(es)
Greenwich Mean Time or Coordinated Univer-
sal Time. The reference time along the prime
meridian or 0° longitude at Greenwich, En-
gland.
A very even dispersion of molecules of a mate-
rial above its boiling point at the ambient tem-
perature with the ability to occupy a space with
uniformity. Typical gases include oxygen, air
(a mixture of nitrogen, oxygen, and trace
amounts of other gases), chlorine, and carbon
dioxide.
Gaussian
Ground
roughness
A bell-shaped, or "normal," probability curve.
ALOHA can use a Gaussian distribution to de-
scribe the movement and spreading of a gas
that is neutrally buoyant.
A description of the size of the obstacles on the
ground that the toxic cloud is moving over. In
ALOHA, you can select either Urban or Forest
or Open Country, or enter a roughness length.
8-7
-------
Glossary
Ground
temperature
Ground type
Heavy gas
IDLH
The temperature of the ground surface. The air
model uses the temperature of the ground to
estimate the amount of heat that is transferred
from the ground to an evaporating puddle.
The physical composition of the ground be-
neath a puddle. The ground type is especially
important for a spill of refrigerated liquids,
where the heat required for evaporation is of-
ten supplied by the ground rather than by the
atmosphere.
A gas that has a density greater than that of the
surrounding air. There are several reasons why
a gas may be a heavy gas, or may behave like a
heavy gas: 1) because its molecular weight is
greater than that of air (29 kg/kmol), 2) because
it is stored cryogenically (refrigerated), or 3)
because aerosols form in sufficient amounts
during a release to make the mixture behave
like a heavy gas.
Immediately Dangerous to Life or Health. This
value represents a maximum concentration from
which a person could escape within 30 minutes
without any escape-impairing symptoms (like
severe eye or respiratory irritation) or any irre-
versible health effects. (NIOSH/OSHA Pocket
Guide to Chemical Hazards, 1987).
8-8
-------
Glossary
Infinite tank
source
Instantaneous
source
An approximation used to describe a situation
in which the volume of a discharging, pressur-
ized tank is much greater than the volume of a
long pipe connecting it to its discharge point.
The pressure and temperature of the material
in the pipe can then be taken to be constant
throughout the duration of the release.
A release that occurs very rapidly. ALOHA
assumes that an instantaneous release lasts one
minute.
Inversion
Latent heat of
vaporization
Level of
concern
Manual update
Mass
An atmospheric condition in which a shallow,
unstable layer of air near the ground lies be-
neath a markedly stable layer of air above. The
height of the abrupt change of atmospheric
stability is known as the "inversion height."
An inversion can cause the surface concentra-
tion of a poilutant to remain considerably higher
than might be expected:
The amount of heat released when a unit mass
of a substance vaporizes.
The concentration at which you wish ALOHA
to draw a footprint.
When this option is selected, the visible win-
dows will be updated only when you select
Calculate Now from the Display menu.
Amount of chemical by weight.
8-9
-------
Glossary
Maximum
sustained
average
release rate
Maximum
computed
release rate
Military time
Mist
The highest average release rate sustained for
at least a minute. This value will be seen on the
source strength graph. Note that a pressurized
release may have a very high rate for the first
few seconds and a considerably lower release
rate once the pressure inside the releasing ves-
sel has been reduced. In this case, the maxi-
mum sustained average release rate may be
considerably lower than the maximum com-
puted release rate.
The maximum release rate that could occur
from the given scenario. This rate can be sig-
nificantly higher than the maximum sustained
average release rate seen on the source strength
graph of ALOHA, particularly in the case of a
pressurized release. (See maximum sustained
average release rate).
Time based on a 24-hour clock (e.g., 1330 is the
military expression of 1:30 p.m.)- The spill time
for the air model is taken from either the inter-
nal clock in the Macintosh or the spill time that
you enter. The time that you enter must be in a
military time format.
A dispersion of fine droplets in a gas cloud
(mostly air) resulting from air entrainment,
spray atomization, or condensing of a material
as its vapor cools. Mists are also referred to as
aerosols.
8-10
-------
Glossary
Mixing
For the purposes of ALOHA, mixing is the
process by which the air gets mixed. This
includes both mechanical (wind and ground
roughness-induced) and thermal (heat-in-
duced) mixing.
Mole
A quantity of a substance that contains 6.02 x
10" molecules. The molecular weight of a
chemical is the mass of one mole of that chemi-
cal.
Molecular
weight
The sum of the atomic weights of all the atoms
in the molecule (the weight of one molecule of
the chemical).
Neutrally
buoyant gas
A gas that behaves like air or has the same
density as air.
Open country
An area of few, or widely spaced, obstacles,
such as a parking lot or open field.
Parts per
billion (ppb)
Commonly used to express the concentration
of a gas or vapor in air: parts of vapor or gas per
billion parts of contaminated air. ALOHA uses
ppm (1 ppm = 1 ppb x .001).
Parts per
million (ppm)
Commonly used to express the concentration
of a gas or vapor in air: parts of vapor or gas per
million parts of contaminated air. In ALOHA,
ppm is by volume, not by weight.
Particulates
Fine, solid particles. ALOHA does NOT model
particulate dispersion.
8-11
-------
Glossary
Patchiness
Pipe
Pipe pressure
Isolated puffs of higher concentrations of a pol-
lutant often caused by eddies or by the varying
orientation of a dispersing chemical cloud.
Think of patchiness as campfire smoke, which
varies with wind direction, speed, and inten-
sity of turbulence.
A type of carrier for hazardous materials.
ALOHA considers only gas leaks (no liquid
leaks) from pipes. Pipe lengths must be at least
200 times the diameter of the pipe.
The pressure of the gas inside a pipe before the
leak occurred.
Plume
Plume rise
A cloud of dispersing chemical, referred to
throughout this manual as "footprint."
The term used for gases in a plume being trans-
ported upward (e.g., out of a smokestack).
ALOHA does not incorporate plume rise calcu-
lations.
Processed data
A menu item that will display the meteorologi-
cal station's data. These data have been pro-
cessed.
Puddle
Puff
Raw data
Liquid pooled on the ground.
In short-duration footprints, the cloud of dis-
persing chemical appears as a series of puffs.
An option that displays unprocessed ASCII data
that has been transmitted by the meteorological
station.
8-12
-------
Glossary
Relative
humidity
The percentage of the measured vapor pres-
sure to the saturation vapor pressure at the
observed temperature. ALOHA lets you select
dry, medium, or wet, or enter a percent value.
Release
duration
Rough pipe
The period of time over which the release oc-
curs. ALOHA limits this period to one hour.
An interior pipe surface that is pitted or cor-
roded.
Roughness
length
A measure of the size of the "roughness ele-
ments," such as grass, trees, or buildings, that
act as obstacles to the movement of air. The
average size of roughness elements determines
ground roughness. See Zo.
Running
average
An average taken in overlapping segments (e.g.,
the average of the first five values, then the
average of the second through sixth values,
then the average of the third through seventh
values, etc.). See Average.
SAM
STP
Saturation
concentration
Station for Atmospheric Measurements. The
meteorological measurement station that can
be directly linked to the air model through a
computer serial port.
Standard Temperature and Pressure. Chemi-
cal properties (e.g., boiling point) are often
expressed at standard temperature, 0°C and
standard pressure, one atmosphere.
The maximum concentration that a vapor in air
can maintain without raining out.
8-13
-------
Glossary
Serial port
A data interface on the back of the computer
that can be hooked up to other peripheral de-
vices, such as a SAM, scanner, printer, or digi-
tizing tablet. ALOHA uses a serial port to re-
ceive ASCII data from SAM.
Sigma theta
Smoke
The standard deviation of the wind direction.
The SAM Station transmits a sigma theta based
on a five-minute running average. The stability
class is then determined by the sigma theta and
the wind speed.
A mixture of gases, suspended solid particles,
and vapors resulting from the combustion pro-
cess. Color varies from thick black for hydro-
carbon fires to light gray for cellulose (wood)
smoke burning in an air-rich environment. Class
A (wood/paper) fires release a rich yellow to
brown smoke in air-lean environments such as
basements or concealed spaces. Hazardous
components may include varying percentages
of HC1, NO/s, sulfur compounds, acrolein, and
free radicals.
Smooth pipe
Solution
A smooth interior pipe surface.
A mixture of compounds in which the mol-
ecules of the chemical are intermixed. Many
commonly encountered solutions are mixtures
of soluble chemicals and water. For example,
alcohol in water or table salt in water.
8-14
-------
Glossary
Source height
Source
strength
Stability class
Stable
The distance above the ground level from which
a chemical has been released. This allows you
to model releases from elevated pipes or other
above-ground sources, but you must know the
amount entering the atmosphere and choose
the Direct source option.
The amount of a pollutant entering the atmo-
sphere, either all at once (instantaneously) or
over a period of time (continuously).
(see Atmospheric Stability).
A term used in atmospheric dispersion to indi-
cate that the atmosphere has little tendency to
mix.
Stack Windows
Located on the Display menu, this option lay-
ers all the windows containing ALOHA data on
the computer screen. The active window will
be the front window and only the titles of the
other windows will remain visible.
Standard
deviation
Street canyon
A measure of how much individual values de-
viate from the average value.
An area with high-rise buildings that channel
the wind parallel to the streets.
8-15
-------
Glossary
TLV-TWA
Threshold Limit Value-Time Weighted Aver-
age. The time weighted average concentration
for a normal 8-hour workday and a 40-hour
workweek, to which nearly all workers may be
repeatedly exposed, day after day, without ad-
verse effects (Threshold Limit Values and Bio-
logical Exposure Indices for 1990-91, American
Conference of Governmental Industrial Hygien-
ists).
Threat distance
The downwind distance along the centerline of
a chemical cloud, out to the level of concern
that you set. ALOHA's footprint length, re-
ported in the Text Summary window, is a threat
distance.
Threat zone
The area downwind of the source of an escap-
ing pollutant, within which concentrations of
pollutant are high enough to threaten people.
ALOHA's footprint is a diagram of a threat
zone.
Text summary
screen
Tile Windows
The window always open while you are in
ALOHA. This window summarizes your input
and the model's calculations as you move
through ALOHA.
Located on the Display menu, this option
places all of the windows containing ALOHA
data next to each other on the computer screen.
8-16
-------
Glossary
Time-
dependent
dispersion
Time-
dependent
source
Two-phase flow
Unstable
Urban
A time-dependent value is something that
changes over time. ALOHA's dispersion mod-
ules take into account release rates that change
over time. The dispersion modules do NOT
account for changing atmospheric conditions.
A release rate that changes over time.
A gas-aerosoi mixture that may be released
when a pressurized liquid is stored in a tank.
A term used in atmospheric dispersion to indi-
cate that the atmosphere has a great tendency
to mix.
For the purposes of ALOHA, an area where
there are a lot of obstacles interrupting the flow
of air. This would include suburban areas as
well as areas that are forested.
Vapor
Vapor pressure
Volatility
Wind direction
The gas produced by the evaporation of a liq-
uid or sublimation of a solid. For example, the
gas produced when liquid water evaporates is
water vapor.
The pressure of a vapor in equilibrium with its
liquid or solid form at a given temperature.
The tendency of a liquid or solid to form a
vapor.
A measurement of which way the wind is com-
ing from, expressed in either angular or one- to
three-letter directional terms.
8-17
-------
Glossary
Wind rose A diagram that summarizes the last ten values
received from the SAM for wind direction and
speed.
2 A term used to define ground roughness. Ap-
proximately 1/30 of the height of the underly-
ing obstacles.
8-18
-------
References
Brutsaert, Wilfried. 1982. Evaporation into the Atmosphere:
Theory, History, and Applications. Boston: D. Reidel Publish-
ing Company. 299pp.
Daubert, I.E. and R.P. Danner. 1989. Physical and Thermody-
namic Properties of Pure Chemicals: Data Compilation. Bristol,
Pennsylvania: Hemisphere Publishing Corporation. Three
Volumes.
Havens, Jerry, University of Arkansas, Fayetteville, NOAA
DEGADIS evaluation report, memorandum to Jerry Gait,
NOAA, 1990.
Havens, Jerry and Tom Spicer. 1990. LNG Vapor Dispersion
Prediction with the DEGADIS Dense Gas Dispersion Model.
Topical Report (ApriI1988-July 1990). Chicago: Gas Research
Institute.
National Oceanic and Atmospheric Administration. 1992.
CAMEO™ 4.0 for the Apple Macintosh Computer.
Washington, D.C.: National Safety Council. 235pp.
National Instituteof Occupational Safety and Health (NIOSH).
1990. Pocket Guide to Chemical Hazards. Washington, D.C.:
U.S. Government Printing Office.
9-1
-------
References
Spicer, Tom and Jerry Havens. 1989. User's Guide for the DEC ADIS
2.1 Dense Gas Dispersion Model. Cincinnati: U.S. Environmental
Protection Agency. EPA-450/4-89-019.
Turner, D. Bruce. 1974. Workbook of Atmospheric Dispersion Esti-
mates. Springfield, Virginia: National Technical Information Ser-
vice.
Turner, D. Bruce and Lucille W. Bender. 1986. Description of
UNAMAP (Version 6). Springfield, Virginia: National Technical
Information Service. 13pp.
Wilson, DJ. 1987. Stay indoors or evacuate to avoid exposure to
toxic gas? Emergency Preparedness Digest 14(l):19-24.
9-2
-------
Index
adding chemicals (see
ChemManager and ChemLib)
adding locations, 4-5 to 4-6
advection, 2-2
aerosol, 5-31
air exchanges, 4-7,4-8
air dispersion modeling, 2-2 to
2-13, 5-47
air infiltration rates (see air ex-
changes)
air temperature (see temperature)
ALOHA
allowable input, B-12
design of, 2-1,2-2
features, 2-2,2-3,2-4
Gaussian model, 2-2 to 2-3,2-7
heavy gas model, 2-2 to 2-7
installing
Mac, 1-5 to 1-8
troubleshooting, B-8
Windows, 1-9 to 1-11
running
Mac, 1-8
Windows, 1-12
use caution, 2-8 to 2-13
doesn't consider, 2-13
ALOHA DECADE, 2-4 to 2-5
ALOHA Helps, 1-11 to 1-12,9-10
ALOHA Resources, 1-7
AlohaSpy, 1-8,3-2 to 3-3,5-10, C-l
toC-3
Archive, C-2
Edit menu, C-2
Hie menu, C-2
SAM, 1-2,5-27,5-28
Stack, C-3
Tile, C-3
troubleshooting, B-7
Archive data, 5-26
aluminum phosphide, 2-13
Atmospheric (menu), 5-11 to 5-29
atmospheric stability class, 5-12 to
5-15,547, A-l-5, A-2-5 to
A-2-6,A-5-6
10-1
-------
Index
a
bell-shaped curve, see Gaussian
distribution
BitPIot, B-9, D-l to D-8,7-1 to 7-3
footprint, D-l, D-5, D-6
map scale, D-3
MARPLOT DOS, 7-3
new map (opening a), D-2
.pcx to .bmp file conversion, D-8
SAM, 5-23
Archive Data, 5-26 to 5-27
Macintosh, B-9
Processed Data, 5-28 to 5-29
Raw Data, 5-27 to 5-28
SAM Options, 5-26 to 5-29
Windows, B-9
Wind Rose, 5-29
spill source (locating), D-4
Building Type, 1-2,4-7 to 4-9, A-20
Calculate, 1-4,6-17 to 6-18
Calculate Now, 1-4,6-18
chemical
mixtures, 2-13
reactions, 2-8,2-13
required property fields, 5-3 to 5-5
solutions, 2-13
chemical library, (see ChemLob)
ChemLib, 1-7,5-2 to 5-11 (see also
ChemManager)
adding a chemical, 5-5 to 5-7
modifying a chemical, 5-7 to 5-8
deleting a chemical, 5-9
saving changes, 5-10 to 5-11
ChemManager,!-8,5-5 to 5-11
CityLib, 1-8 (see also Location)
dosed-off pipe (Tank source), 543,
A-3-8
cloud cover, 5-12,5-21 to 5-22,5-26
Computational, 2-7,5-46 to 5-48
Let model decide, 1-3,5-47
Use Gaussian dispersion only,
1-3,547
Use Heavy Gas dispersion only,
1-3,2-7,547,549
Concentration, 14,6-1,6-9 to
6-14,7-6
and dose location, A-2-12
indoor, 6-1,6-9
outdoor, 6-1,6-9
over time, 548
Concentration vs. Time, 6-9 to
6-10
concentration patchiness near the
source (see near-field patchi-
ness)
confidence lines, 2-9,6-7to 6-8
continuous release, 5-30 to 5-33
dose and concentration vs. time
graphs, 6-14
source strength graph, 6-15
Copy, 6-15
crosswind distance, 2-3,6-11
cryogenic gases, 2-7
10-2
-------
Index
DEGADIS,2-4to2-8
DIPPR,5-3,54,5-ll
Date & Time
Mac, 1-2,4-9,5-35, A-l-3, A-2-7,
A-3-3, A-t-9, A-&4
Windows, A-5-4
degrees true, 5-19
deleting a chemical (see ChemLib)
deleting a location, 4-7
diffusion, 2-2
Direct source option, 5-31,4-32
to 5-33,5-48,6-15 to 6-16
dispersion choices in ALOHA, 2-7
to 2-8
dispersion modeling (see air
dispersion modeling)
Display menu, 1-1,1-3 to 1-14,
5-49,6-1 to 6-18
MARPLOT, A-3-10 to A-3-12
Options, 1-3,6-3 to 6-5
dose, 1-3,1-4, 546,548,6-1,6-12 to
6-14
concentration, 6-9 to 6-12,6-14
indoor, 6-1,6-9to 6-10
outdoor, 6-1,6-9 to 6-10
over time, 5-48 to 5-49
Dose vs. Time, 6-8,6-11,6-14
double-storied building, 4-7 to 4-9
E
eddies, 2-12
Edit menu, 1-2,3-1,3-4
AlohaSpy, 3-2 to 3-3, C-l to C-3
elevated source, 5-32 to 5-33
enclosed office building, 4-7 to 4-9
evaporation rate, 5-34 to 5-36
File menu, 1-1, 1-2, 3-1 to 3-3
AlohaSpy, 3-2 to 3-3, 5-10, C-l to
C-3
MARPLOT, A-3-10
Finder, 1-8
Hres, 2-13, 5-32
flash boil (see two-phase flow)
footprint, 1-3, 1-4, 2-4 to 2-5, 2-6,
2-9, 2-11, 6-1, 6-3, 64 to 6-5, 6-6
to 6-8, 6-9, 6-12 to 6-13, A-l-16
BitPlot, 1-2, A-5-1 to A-5-21, B-9,
concentration, 6-7 to 6-14
DEGADIS,2-4to2-5
Gaussian, 2-3, 5-7, 547 to 548
heavy gas, 24, 2-6, 2-7, 2-8, 547
to 548,6-8,8-10
location (designating a), 6-10 to
6-12
MARPLOT, A4-1 to A4-22,
A-6-1 to A-6-23
plot on grid, 6-5 to 6-7
SAM, 6-7
troubleshooting, B-2
10-3
-------
Index
uncertainty lines, 2-9,6-7 to 6-8
user-specified scale, 64,6-5
wind shifts, 2-11
fugitive emissions, 2-2
gases (heavy) (see heavy gas
calculations)
gas in a tank, 5-38 to 5-39
Gaussian, 2-2 to 24, 2-7 to 2-8,2-12
calculations, 2-8,5-11,5-21,5-47,
chemical properties required,
54 to 5-5
footprint, 1-3,2-3,2-4, 242,5-17
to 549
Go to Map, A4-20
gravity, 2-6,2-12 (see also slump-
ing)
ground
level release, 5-12, 5-32 to 5-33
roughness, 5-8 to 5-21,5-25, A-l-5,
A-2-6, A-3-5, A-4-12, A-5-7,
A-6-6
temperature, 5-34 to 5-35,5-42
type, 5-34,5-35
H
hardware considerations,
Macintosh, 1-8
Windows, 1-11
heat transfer, 5-12 to 5-13,5-34 (see
also ground temperature)
heavy gas, 1-3,2-4 to 2-8,2-13,5-11,
5-21,5-31,547 to 548,6-8,6-17,
A-2-9toA-2-14
chemical properties required,
54to5-5
footprint 2-5,2-13
time steps,2-5
Help (on-line), Ml to 1-13
hole (in tank), 540 to 541
humidity, 5-22,5-25,5-34, A-l-6,
A-2-7, A-3-5 to A-3-6, A-4-12,
A-5-8, A-6-7
IDLH (see also level of concern),
24,5-20,6-3 to 64
immediately dangerous to life and
health (see IDLH)
indoor air dose calculations, 6-1,
6-9
infiltration rates (see air changes)
infinite tank source, 543
Input (allowable), B-12
installing ALOHA
Macintosh, 1-5 to 1-8
Windows, 1-9 to 1-11
instantaneous release, 5-31,6-16
Source Strength, 6-15
internal clock, 5-27
Mac, 4-9,4-10,5-26, A-l-3, A-2-7,
A-3-3, A4-9, A-64
104
-------
Index
Windows, A-5-4
inversion, 5-14,5-15,5-16,5-24
LOG (see level of concern)
large obstacles (and footprint), 2-11
leak size (see hole)
Let model decide (see
Computational)
level of concern, 2-4,6-3 to 64 (see
alsoIDLH)
user-specified, 6-4
Loading (see installing)
Locating spill source (BitPIot), D-4
Location, 1-2,4-1 to 4-7,6-9 (see
also City Lib)
adding, 4-3 to 4-6, A-6-3
deleting, 4-7
modifying, 4-6
troubleshooting, B-ll
scale
BitPIot, D-3
mass of chemical in tank,5-38 to
5-39
math coprocessor chip, 5-47,1-5,
1-7,1-8,1-11
Macintosh, 1-8
Windows, 1-11
maximum computed release rate,
5-30,8-5
maximum average release rate,
5-30, B-5
mechanical stirring, (see mixing)
memory (see also Finder and
MultiFinder)
Macintosh, 1-8
Windows, 1-11
met station (see SAM)
mixing, 2-9,5-13,5-14,5-15
mixtures (chemical), 2-13
modifying the Location Index, 4-6
MultiFinder, 1-8,74
M
MARPLOT, 7-3 to 7-6
MARPLOT-DOS, 7-3
Macintosh dock time, 4-9,4-10,
5-26, A-l-3, A-2-7, A-3-3, A-4-9,
A-64
Maps, 7-3 to 7-6, D-l to D-3
BitPIot, D-l to D-3
MARPLOT, 7-3 to 7-6, A-4-1 to
A4-22,A-6-ltoA-6-23
N
near-field patchiness, 2-8,2-12 to
2-13
neutrally buoyant, 2-3
non-pressurized liquid (see tank)
non-pressurized release, 5-42
10-5
-------
Index
obstacles (see ground roughness)
Open country, 5-18 to 5-21,8-11,
A-l-5, A-3-5, A-6-6 (see also
ground roughness)
Options (Display menu), 1-3,6-1,
6-3 to 6-5
footprint, 64 to 6-5
outdoor dose calculation (see dose)
output units, 1-3,6-5
P
ppb,8-ll
ppm, 6-4,8-11
particulates, 2-8,2-9,2-13
patchiness (see near-field patchi-
ness)
phosphine, 2-13
PICT (and MARPLOT), A-4-1 to
A4-22
Pipe source option, A-3-1 to A-3-
13,B-5
diameter, 5-43 to 5-44
gas, 5-43 to 544
hole, 5-45 to 546
length, 543 to 544
liquid, 544
rough, 5-44
smooth, 544
plume spread (see footprint)
pressurized releases, 2-6,5-44,5-48,
B-2
non-pressurized release, 5-43
PrintAU, 1-2
Puddle, 5-31,5-33 to 5-36,542 to
543,8-5
MARPLOT, A4-1 to A4-22
diameter, 543
temperature, 5-34,5-35,542,
A4-14
radioactive chemicals, 2-2
relative humidity (see humidity)
roughness (see ground roughness)
rough pipe (see pipe)
SAM, 1-2,5-23 to 5-29,6-7, B4
archive data, 5-26 to 5-27, B-8
footprint, 6-7
Macintosh, B-9
processed data, 5-28
raw data, 5-27 to 5-28
SAM Options, 5-26
troubleshooting, 84,6-8
Windows (BitPlot), B-9
wind rose, 5-29
Save
troubleshooting, B-6
Save As (see AlohaSpy)
scale (see map scale or Options)
sea smoke, 5-15
-------
Index
set constant time (see Date &
Time)
SetUp menu, 1-1,1-2 to 1-3,5-1 to
549, A-l-3 to A-l-12, A-24 to
A-2-10, A-3-3 to A-3-9, A4-9 to
A4-15
Windows, A-54 to A-5-1, A-6-5 to
A-6-10
Sharing menu, 7-1 to 7-6
BitPlot, 7-1
help, 7-5
MARPLOT DOS, 7-3
Macintosh, 7-1,7-3 to 7-6
scale, A48 to A49
maps, A-4-1 to A4-22, A-6-1 to
A-6-23
scale, A-4-21
Set Source Point, A-4-21
sheltered surroundings, 4-8 to 4-9,
A-2-3,A-3-6,A-5-3
short pipe/valve (see tank)
sigma theta, 5-28 to 5-29
single-storied building, 4-7,4-8, A-
2-3,A-3-6,a-5-3
SiteData menu, 1-1,1-2,4-1 to 4-10,
A-l-1 to A-l-3, A-2-1 to A-2-4,
A-3-1 to A-3-3 A-4-7 to A4-9,
A-5-2 to A-5-4, A-6-2 to A-64
slumping (chemical cloud), 2-6,
2-12
smoke, 2-12,2-13
smokestack, 2-2,5-32
smooth pipe (see pipe)
solar radiation, 4-2,5-21,5-34 (see
also cloud cover)
solutions (chemical), 2-13
Source
height, 5-32 to 5-33
locating (BitPlot), EM
SetUp menu, 5-30
strength, 1-4,5-33,544,6-1,6-15
to 6-17
Source Strength (Display menu),
£44,6-15 to 6-17
spherical tank, 5-37
spreading, (see diffusion)
Spy (see AlohaSpy)
stable atmospheres, 2-8,2-9 to 2-10
and wind rose, 5-29
stability class (see atmospheric
stability class)
Stack Windows, 14,6-2 to 6-3
AlohaSpy, C-3
Station for Atmospheric
Measurements (see SAM)
stirring (see mixing)
street canyon, 2-11,8-15
sun angle (see solar radiation)
r
TIGER, 7-3
TLV,8-16
Tank, 5-31,5-36 to 5-43,547, A-l-1
toA-l-17,B-5
chemical stale in, 5-37 to 540
gas in a tank, 5-38 to 5-39
10-7
-------
Index
leak location, 540 to 541
liquid in a tank, 5-38
non-pressurized liquid, 5-42
rough pipe, 5-44
size, 5-37
smooth pipe/valve, 544
temperature, 542
unknown in a tank, 5-39
temperature
air, 5-18,5-34 to 5-36
ground, 5-34 to 5-35
pipe, 545
puddle, 5-18,5-34,5-35,542,
A-4-14
tank, 5-18,507
terrain steering effects, 2-8,2-10 to
2-11
Text Summary, 14,5-6,5-31,5-42,
5-43,6-1,6-6, A-l-7, A-l-12, A-
1-17, A-2-7, A-2-10, A-2-14, A-
3-6, A-3-9, A-4-10, A-4-15, A4-
20, A-5-5, A-5-8, A-5-11, A-5-16,
A-5-21, A-6-5, A-6-7, A-6-9, A-
6-12, A-6-12, A-6-23, B-5, B-8
threat zone (see footprint)
Threshold Limit Value (see TLV)
Tile Windows, 14,6-2
Aloha Spy, C-3
time (see Date & Time)
dependent release, 2-6,6-14,
6-15 to 6-15
dose and concentration graphs,
6-13 to 6-15
Source options, 6-15 to 6-16
topography, 2-1,2-8,2-11,2-13 (see
also streeet canyon effect)
troubleshooting, B-l to B-12
two-phase flow, 2-7,5-31, A-2-9
u
uncertainty lines (see confidence
lines)
unpacking ALOHA files
Macintosh, 1-5 to 1-8
Windows, 1-9 to 1-11
unsheltered surroundings, 4-8 to
4-9
unstable atmospheres (see atmos-
pheric stability class)
Update Windows, 6-17 to 6-18
Urban or Forest, 5-19 to 5-22, A-2-
6, A-4-11, A-5-6
use caution, 2-8 to 2-13
Use Gaussian dispersion only (see
Computational)
Use Heavy Gas dispersion only
(see Computational)
User input (Atmospheric menu),
5-12,5-23,5-26
VHP radio frequenc (for SAM),
5-24
vapor pressure, 5-5,5-35
10-8
-------
Index
vertically oriented cylinder (tank), 7
5-37
Z . 5-19 to 5-21(see also ground
volume t
roughness)
puddle, 5-31 to 5-34 ^^ (MARpLOT) A^_3
tank,5-37 V
to A-4-6
w
wind
around obstacles, 2-10 to 2-11
direction, 2-10 to 2-11,5-16 to 5-18,
6-7to6-8
rose, 5-29
shifts (see wind direction)
speed, 2-8,2-9,5-15,5-16 to 5-18,
6-8,6-11,6-12
stability, 2-8,2-9 to 2-10,5-12 to
5-15,5-47
street canyons, 2-11,8-15
windows (Tile and Slack), 1-4,6-2
to 6-3
AlohaSpy,C-2,C-3
updating, 6-17 to 6-18 (see also
Calculate)
Windows™
internal clock, A-54
troubleshooting, B-ll
Workbook on Atmospheric Dispersion
Estimates, 2-1
10-9
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