HomeMy WebLinkAboutNCD980557656_19990525_NC State University (Lot 86 Farm Unit 1)_FRCBERCLA LTRA_Air Dispersion Modeling March - May 1999-OCR, •. , . North Carolina State University .is •.
grant university and a constituent institution .
of The University of North Cmolina
Office of Finance and Business
Business Division
An Equal Opportunity/Affirmative Action Employer Environmental Health & Safety Cen
Campus Box 8007
Raleigh, North Carolina 27695-8007
March 25, 1999
Michael Townsend
Superfund Branch, Waste Management Division
US EPA Region IV
Atlanta Federal Center
I 00 Alabama Street, SW
Atlanta, GA 30303-3104
http:/ /www2 ncsu. ed u/ncsu/eh s/ Director
Environmental Affairs
Industrial Hygiene
Health and Safety
Radiation Protection
!Fax)
Subject: NC State University Lot #86 Superfund Site -Air Dispersion Modeling
Dear Mr. Townsend:
This is to provide ten copies of the air dispersion modeling report, "Dispersion Modeling Analysis for
N.C. State University, Lot 86 Site Raleigh, North Carolina." The copies of the report sent under cover
of my March 18 letter to you lacked the model results tables and had other quality problems. Please
accept my apologies for any inconvenience that this may have caused.
Concerning model selection, I believe that SLAB is more applicable to the situation than either the
ISC ST or SCREEN models. The principal parameters of this problem which define model selection
are duration of release and spatial scale of the area of concern. The situation represented by the SLAB
model is a short-term (accidental) release with receptors positioned very close to the source. With the
puff releases at the Lot 86 site having a duration of about 15 seconds and the nearest fence! ine
receptor being about 40 meters, it seems as though the SLAB model is the appropriate model for the
situation.
Both the !SC and SCREEN models are, at their core, Gaussian models. The Gaussian approach is
based upon a continuous release. Gaussian-based dispersion models arc not designed to compute the
dispersion and transport of a puff release.
Similarly, because the SLAB model is intended for simulation of puff releases, it's spatial scale of
"dependability" is measured in tens of meters. In contrast, the Gaussian models are best applied to
receptors beyond the nearest receptor at Lot 86, of about 40 meters.
Other specific issues that we discussed dealt with dense gas dispersion and designation of the release
as a vertical jet.
919.515.423,
919.515.685,
919.515.686(
919.515.685,
919.515.289!
919.515.630:
Michael Townsend
March 25, 1999
Page 2
• •
Dense gases. The SLAB model was originally designed to simulate the dispersion of dense gases.
However, the model version used in this assessment contains a database of physical characteristics for
a large number of gases, including density. For those chemicals which were not in the database,
physical parameters required by the model were obtained from other sources. Therefore, the model
uses actual contaminant density.
Vertical jet. Simulating the release as a vertical jet was judged to be the most suitable release category.
Observations of the puff releases shows that the release has enough buoyance ( exothermic reaction) to
allow it to achieve a vertical profile of a few meters, before dispersing horizontally. However, the
SLAB model simulated a surface release (release height~ 0 meters) to provide a conservative offsite
concentration estimate.
In conclusion, I believe that the SLAB model is appropriate for this application and that the model
parameters provide a conservative estimate of off site contaminant concentration.
I look forward to discussing this with you on March 30.
S.irely,
~.___
Duane Knudson
Enclosure
•
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• • NORTH CAROLINA DEPARTMENT OF
ENVIRONMENT AND NATURAL RESOURCES
DIVISION OF WASTE MANAGEMENT
March 24, 1999
TO: David Mattison
FROM: David Lilley '])-g L
RE: Comments prepared on the Dispersion Modeling Analysis for
NC State University, Lot 86 Site, Raleigh, NC
March 17, 1999
After reviewing the above mentioned document, I offer the following
comments:
I. Page 8, last line: Change "Table 4-1" to "Table 3-1".
2. Page 13, first paragraph: Tables 4-1 through 4-3 have not been included
in this report. Please submit them for review.
DL/dl/word/ra 1/27
401 OBERLIN ROAD, SUITE 150, RALEIGH, NC 27605
PHONE 919-733-4996 FAX 919-715-3605
AN EQUAL OPPORTUNITY/ AFFIRMATIVE ACTION EMPLOYER -SO% RECYCLED/I 0% POST-CONSUMER PAPER
• North Carolina State University.and·
grant university and a constituent institution
of The University of North Carolina
Office of Finance and Business
Business Division
An Equal Opportunity/Affirmative Action Employer Environmental Health & Safety C·
Campus Box 8007
Raleigh, Nonh Carolina 27695-8007
March 18, 1999
Michael Townsend
Superfund Branch, Waste Management Division
US EPA Region IV
Atlanta Federal Center
l 00 Alabama Street, SW
Atlanta, GA 30303-3104
http: //www2. ncs u. ed u/ncsu/e hs/ Director
Environmental Affairs
Industrial Hygiene
Health and Safety
Radiation Protection
{Fax)
RECEIVED
MAR 2 3 1999
SUPERFUND SECTION
Subject: NC State University Lot #86 Superfund Site
Dear Mr. Townsend:
As promised in the March 8, 1999, letter from David Rainer, with this subject, enclosed are ten ( I 0)
copies of the report, "Dispersion Modeling Analysis for N. C. State University, Lot 86 Site Raleigh,
North Carolina."
The modeling results support the University's contention that the "puff' releases of air borne
contaminants from the site do not cause a risk to the public or the environment.
Sincerely,
Duane Knudson
Enclosure ( l 0 copies)
cc: David Mattison, NC DENR
Grover Nicholson, NC DENR
Mary Beth Kurz
David Rainer
919.515.42
9t9.515.6f
919.515.6,
919.5156[
919.515.2[
919.515.6:
·• • •
Dispersion Modeling Analysis
for '
N.C. State University, Lot 86 Site
Raleigh, North Carolina
Prepared by:
OMNI Professional Environmental Associates, P. A.
P. 0. Box 13404
Research Triangle Park, North Carolina 27709
OMNI Project No. 99001
March 17, 1999
Section 1.0
Section 2.0
2.1
2.2
2.3
Section 3.0
3.1
3.2
' ' J.J
3.4
Section 4.0
Table 2-1
Table 2-2
Table 3-1
Table 3-2
Table 4-1
Table 4-2
Table 4-3
Figure 2-1
Figure 2-2
Figure 3-1
Appendix A
Appendix B
Appendix C
• •
Table of Contents
Introduction ............................................................................................................................... 1
Source and Site Description ............................................................................... ! ...................... 2
Site Description ......................................................................................................................... 2
Source Representation ............................................................................................................... 2
Chemical List ........................................................................................................................... .3
Modeling Methodology ............................................................................................................. 8
Model Selection Criteria ........................................................................................................... 8
Dispersion Model ...................................................................................................................... 8
Receptors ................................................................................................................................... 9
Meteorology .............................................................................................................................. 9
Air Dispersion Modeling Results ........................................................................................... 13
List of Tables
Source Parameters ..................................................................................................................... 6
Hazardous Chemical List .......................................................................................................... 7
SLAB Model Options ............................................................................................................. 11
Fenceline Receptor Parameters .............................................................................................. 12
Comparison of Calculated Fenceline Concentrations with the NIOSH IDLH. ..................... 15
Comparison of Calculated Fenceline Concentrations with the OSHA PEL-Ceiling ............ 16
Comparison of Calculated Fenceline Concentrations with the OSHA PEL-TWA ............... 17
List of Figures
Site Location ofN .C. State. Lot 86 NPL Site ........................................................................ .4
Potential Source Locations ....................................................................................................... 5
Raleigh. North Carolina Wind Rose ( 1987-1991) ................................................................ 10
Appendices
Sample SLAB Model Input Files
Sample SLAB Model Output ]:iles
SLAB Model Output Figures
•
Section 1.0
Introduction
•
N.C. State University is performing a remediation of contaminated soil at its Lot 86 National Priorities
List (NPL) Site using an in-situ mixing and encapsulation process. The Lot 86 NPL Site was formerly
used as a disposal site for laboratory wastes, including hazardous wastes.
As a result of technical impediments, the original mixing method, which included a shroud covering the
mixing process, was replaced with open trench mixing and encapsulation. Although the open trench
process is superior to the originally-selected method in terms of performance, it does allow for the
airborne release of reaction products. During the course of the excavation and remediation activities, it
became apparent that certain pollutants were being released to the atmosphere in "puffs" of short
duration, typically no more than I 0-15 seconds.
N.C. State has retained an environmental engineering consultant, OMNI Professional Environmental
Associates, P.A. (OMNI Professional) to perform a dispersion modeling analysis of the puff releases.
The purpose of this analysis is to determine, using the SLAB model, how the predicted fenceline
concentrations of the monitored and detected airborne contaminants' compare with the applicable OSHA
Permissible Exposure Limits (PEL) or other appropriate short-term exposure standards.
The following sections present the sources and their surrounding area as they were represented in the
dispersion modeling analysis, and the modeling methodology, and the modeling results.
A few other chemicals, known to be present at the site but not detected in the air sampling, were included in the modeling analysis.
Page I
• •
Section 2.0
Source and Site Description
2.1 Site Description
The N.C. State University Lot 86 National Priorities List (NPL) Site 1s located in Raleigh, North
Carolina. The site property is located between Wade Avenue and the State Fairgrounds, which are
located to the north and south of the site, respectively. The closest off-site receptor consists of a 4 foot
high construction fence, which is located along the northern boundary of the site, and is approximately
100 feet to the south of Wade Avenue. The northern boundary of the area to be excavated is
approximately I 30 feet in lateral distance from the fenceline. The elevation of the northern ,:xcavation
boundary is approximately I 0-15 feet higher than the elevation of the fenceline. Figure 2-1 shows the
location of the facility and surrounding terrain.
2.2 Source Representation
The portion of the site which remains to be excavated is a roughly rectangular piece of land, which rises
approximately I 0-15 feet above the surrounding terrain. This area constitutes the area of occasional,
potential puff releases of airborne contaminants. In order to deterrnine the worst-case fenceline
concentrations of emitted contaminants, one potential source location was analyzed under worst-case
meteorological conditions. The source has been placed on the northern boundary of the area to be
excavated, at a point representing the shortest distance from a source to a potential off-site receptor. The
source location is shown in Figure 2-2, and pertinent source parameters are listed in Table 2-1.
An emission rate of I 00 g/s was used in the modeling analysis, as opposed to the I g/s rate proposed in
the modeling protocol. The reason for this change is that the SLAB model was unable to provide
quantifiable fenceline concentrations (i.e., concentrations were too small for the model to handle) when
using an emission rate of I g/s. The concentrations obtained from modeling at an emission rate of 100
g/s were divided by a factor of JOO in order to obtain an effective fenceline concentration for an emission
rate of I g/s.
Page2
• •
2.3 Chemical List
OMNI Professional used the results of the single reaction release sample provided in the Revised
Monitoring Plan as the primary basis for determining the chemical parameters to be modeled. These
contaminants are believed to be acceptable for environmental modeling because they are listed.
Hazardous Air Pollutants (HAPs) under the Federal Clean Air Act. Four potentially hazardous chemicals
which are believed to be present at the site, were added to the list. The list of chemicals to be modeled is
shown in Table 2-2
Page 3
U.S.G.S. TCPCGR.APHIC WP
RAJ...EICH 'NEST, N.C. QUAORANCLE
DATED 1968. PHOTCRE'OS8 1987
OMNI PROFESSIONAL
ENVIRONMENT AL
ASSOCIATES, PA.
N.C. State University Site 86 Location i.\'lap
Raleigh, North Carolina Figure 2-1
P.O. Box 13-104 • Research Triangle Park. NC 27709 Scale: I" = 2,000'
I OMNI PROFESSIONAL
ENVIRONMENTAL
Source and Receptor Locations
NCSU Site86
ASSOCIATES, P.A. Raleigh, North Carolina
P.O. Box 13-40..I • Research Triangle Park. NC 27709 Scale: I"= 100'
•
•
• •
Table 2-1
Source Parameters of the Emission Point
N.C. State, Lot 86 NPL Site
Source Parameters:
Source A
Discharge Height Above Ground Level (m)
Discharge Type
Source Area (m2):
Exit Temperature (°K):
Ambient Temperature (°K):
Discharge Flow Rate (g/s):
Discharge Duration (s):
0
Vertical Jet
1.0
298
298
100
15
Page 6
Detected Chemicals'
Chloromethane
Methylene Chloride
Chloroform
I, I, 1-Trichloroethane
Benzene
Carbon Tetrachloride
Trichloroethene
Toluene
Tetrachloroethene
Chlorobenzene
Ethyl benzene
Xylenes
1,3,5-Trimethylbenzene
1,2,4-Trimethylbenzene
Freon-I 2
Chloroethane
1,2-Dichloropropane
Styrene
1,2-Dichlorobenzene
Added Chemicals
Carbon Disulfide
Methyl Ethyl Ketone
Nitric Acid
Ethylene Dibromide
•
Table 2-2
Hazardous Chemical List
N.C. State, Lot 86 NPL Site
•
I. Chemicals detec1ed in the #2 Path and J-1 samples. listed in the Revised Final ,.-lir .\Joniroring Plan for the Xorth Carolina State University Lot 86 Site, dated 2/25/99.
Page 7
•
Section 3.0
Modeling Methodology
3.1 Model Selection Criteria
•
In order to ensure that the most accurate and reliable modeling data are obtained, OMNI Professional
based its model selection on the following criteria:
• The model must be capable of modeling short-duration or instantaneous releases of dense or
neutrally-buoyant gases;
• The model must have a low degree of error;
• The model must produce consistent results; and
• The model must allow the user to input meteorological conditions
According to Uncertanties in Hazardous Gas Model Predictions, by Steven Hanna, when eleven air
dispersion models (AFTOX, AIRTOX, B&M, CHARM, DEGADIS, GPM, HEGADAS, INPUFF,
OB/DG, SLAB, and TRACE) were analyzed, the SLAB model demonstrated one of the smallest mean
square errors, and produced the most consistent results of any of the eleven models for both
instantaneous and continuous gas releases. The SLAB model also allows the user to input
meteorological data. On the basis of these findings, OMNI Professional has decided to use Bee-Line
Software's SLAB/or Windows 95. Version 5.00a for purposes of this dispersion modeling analysis.
3.2 Dispersion Model
The SLAB model was run once for each of the specified chemicals using the distance between the
potential source location and the fenceline receptor in order to determine the highest possible off-site
concentrations. Worst-case meteorological conditions from the U.S. Environmental Protection Agency's
(EPA) Offsite Consequence Analysis Guidance were assumed for modeling purposes (wind speed=l.5
mis: class F stability).
~
The SLAB modeling analysis was based on the specifications summarized in Table,4'.-1.
Page 8
• •
3.3 Receptors
The modeling analysis utilized a receptor, located on the northern fenceline. This receptor is located at a
point representing the, shortest distance from a potential on-site source to an off-site receptor. The
receptor parameters which were used in the analysis are listed in Table 3-2.
3.4 Meteorology
The screening procedures for estimating impacts of the released chemicals on the receptor utilized the
worst-case meteorological data for wind speed and stability from EPA's Ojfsite Consequence Analysis
Guidance. The worst-case meteorological data corresponds to a wind speed of 1.5 mis, Class F
atmospheric stability, and 50 percent relative humidity. A surface roughness height of 1.0 meters has
been assumed (average surface roughness value for urban terrain, according to the SLAB On-Line Help
Manual). An average wind measurement height of IO meters has been assumed. The wind was assumed
to be blowing from the southwest (in a straight line between the source and the receptor) for each model
run. A wind rose for Raleigh, North Carolina has been included in Figure 3-1. According to Figure 3-1,
the wind in Raleigh. North Carolina blows from the southwest approximately 10 percent of the time. An
ambient temperature of 298°K was used in the model runs.
Page 9
WNW
w
\
\
WSW
N
NNW NNE
20%
NW
15
I
\
I \ 7.3% I \ j
\ \ \ ·\ ,#~' I· I ' \ \~~ I ' I
SW
SSW SSE
s
. 3,.5 -5,5, ___ s.1115111·••1111.,0_1
-.:.o·..:o_-..:2:::,oc::==1•• ,-Fgl 2.0 -3,5 5.5 • 8.5
(M/Sec)
NE
ENE
\ E I j
I /
ESE
SE
OMNI PROFESSIONAL
ENVIRONMENT AL
ASSOC!A TES, PA
Raleigh, North Carolina Windrose (1987-1991)
Figure 3-1
P.O. Box 13404 • Research Triangle Park, NC 27709
• •
Table 3-1
SLAB Model Options -N.C. State Lot 86 NPL Site
SLAB for Windows 95, Version 5.00a
Option
Surface Roughness Height
Wind Speed
Wind Measurement Height
Atmospheric Stability
Ambient Temperature
Relative Humidity
Selected Parameter
I meter
Worst-Case (1.5 mis)•
10 meters
Worst-Case (Class F) •
298°K
50% *
* Based on the U.S. EPA OCA Guidance Document (1996) for worst-case meteorological conditions.
Page 11
•
Receptor I: Fenceline Receptor
•
Table 3-2
Fenceline Receptor Parameters
N.C. State, Lot 86 NPL Site
Distance between Source A and Receptor I: 130 feet (39.6 m)
Page 12
• •
Section 4.0
Air Dispersion Modeling Results
Fence line concentrations of the selected contaminants were evaluated using the source parameters given
in Table 2-1, the modeling options given in Table 3-1, and the receptor parameters given in Table 3-2.
The maximum predicted concentrations are listed and compared with the appropriate NIOSH IDLH,
OSHA PEL-Ceiling, and OSHA PEL-TWA values in Tables 4-1, 4-2, and 4-3, respectively.
The maximum predicted fenceline concentrations are well below the applicable IDLH values for all
contaminants which have an assigned IDLH (see Table 4-1). The fenceline concentrations range from a
minimum of 2x I 0·3 percent of the IDLH to a maximum of 8 percent of the IDLH, with a mean of 0.57
percent of the IDLH and a median of 0.12 percent of the !DUI. Based upon these results, it is unlikely
that the fenceline concentrations of any of the contaminants modeled could exceed the IDLH values.
The maximum predicted fenceline concentrations are also below the applicable OSHA PEL-Ceiling
(PEL-C) limits for all contaminants which have an assigned PEL-C (see Table 4-2). The fenceline
concentrations range from a minimum of 0.18 percent of the PEL-C to a maximum of 30 percent of the
PEL-C, with a mean of 3 .62 percent of the PEL-C and a median of 0-45 percent of the PEL-C. Based
upon these results, it appears unlikely that the fenceline concentrations of any of the contaminants
modeled could exceed the PEL-C limits.
The maximum predicted fenceline concentrations are below the OSHA PEL-TWA limits for all
chemicals except for benzene and nitric acid. However, the PEL-TWA is an 8-hour average exposure,
while the chemical "puffs" have a duration of 15 seconds or less. Thus, the fenceline concentrations of
benzene and nitric acid, when averaged over a period of 8 hours, will be well below the applicable PEL-
TWA.
Three chemicals, chloromethane, Freon-12, and chloroethane, were not present in the SLAB chemical
database. The fenceline concentrations of these chemicals were estimated by extrapolating from the
Page 13
•
fenceline concentrations of other chloromethanes (e.g., dichloromethane, trichloromethane (chloroform),
and tetrachloromethane ( carbon tetrachloride)) and chloroethanes ( e.g., dichloroethane, trichloroethane).
The results of the dispersion modeling analysis indicate that, at an emission rate of I g/s;·none of the
chemicals detected in the air sampling at the Lot 86 NPL Site will exceed the applicable regulatory limits
( e.g., OSHA PEL-TWA, OSHA PEL-C, NIOSH IDLH) within the 15-second time frame of a release.
Page 14
• •
TABLE 4-1
Comparison of Calculated Fenceline Concentrations with the NIOSH IDLH
Chemical
Chloromethane (Methyl Chloride)
Methylene Chloride (Dichloromethane)
Chloroform
1, 1, 1-Trichloroethane•
Benzene
Carbon Tetrachloride
Trichloroethene (Trichloroethylene)
Toluene
Tetrachloroethene (Perchloroethylene)
Chlorobenzene
Ethylbenzene
Xylenes
1,2,4-Trimethylbenzene
1,3,5-Trimethylbenzene
Freon-12 (Dichlorodifluoromethane)
Chloroethane (Ethyl Chloride)
1,2-Dichloropropane
Styrene
1,2-Dichlorobenzene
Carbon Disulfide
Methyl Ethyl Ketone
Nitric Acid
Ethylene Dibromide
Mean':
Median':
Fenceline Cone.
loom)'
1.82 3
1.00
0.55
0.50
1.50
0.30
0.50
1.00
0.35
0.80
0.70
0.80
0.70
0.70
0.30 3
0.98 3
0.70
0.90
0.15
1.40
1.80
2.00
0.12
0.84
0.80
IDLH'
loom)
2,000
2,300
500 -
500
200
1,000
500
150
1,000
800
900
--
--
15,000
3,800
--
700
150
500
--
25
100
1,674
600
Fenceline Cone.
% of IDLH
0.09%
0.04%'
0.11%
-
0.30%
0.15%
0.05%
0.20%
0.23%
0.08%
0.09%
0.09%
----
2.00E-03%
0.03%
--
0.13%
0.10%
0.28%
--
8.00%
0.12%
0.57%
0.12%
1. Fenceline concentrations were obtained from the SLAB model, using an emission rate of 100 g/s. The concentrations were
divided by 100 to estimate the fenceline concentrations for an emission rate of 1 g/s.
2. The IDLH (Immediately Dangerous to Life and Health) is an instantaneous exposure level which poses a hazard to human health.
3. Fenceline concentrations for these compounds was extrapolated from fenceline concentrations of other chloromethanes
and chloroethanes.
4. Used 1, 1,2-Trichloroethane in the model, as data for 1, 1, 1-was not available.
5. Mean and median values were calculated using chemicals With IDLH values.
"The lDLH concentrations were obtained from the NIOSH Chemical Listing and Documentation of Revised IDLH
IDLH Values (As of 3/1195). These values were posted on the NIOSH Home Page (www.cdc.gov/niosh/idlh/intrid4.html).
Page 15
• •
TABLE 4-2
Comparison of Calculated Fenceline Concentrations with the OSHA PEL-Ceiling
Chemical
Chloromethane (Methyl Chloride)
Methylene Chloride (Dichloromethane)
Chloroform
1, 1, 1-Trichloroethane'
Benzene
Carbon Tetrachloride
Trichloroethene (Trichloroethylene)
Toluene
Tetrachloroethene (Perchloroethylene)
Chlorobenzene
Ethyl benzene
Xylenes
1,2,4-Trimethylbenzene
1,3,5-Trimethylbenzene
Freon-12 (Dichlorodifluoromethane)
Chloroethane (Ethyl Chloride)
1,2-Dichloropropane
Styrene
1,2-Dichlorobenzene
Carbon Disulfide
Methyl Ethyl Ketone
Nitric Acid
Ethylene Dibromide
Mean 7:
Median':
Fenceline Cone.
lnnm)'
1.82 3
1.00
0.55
0.50
1.50
0.30
0.50
1.00
0.35
0.80
0.70
0.80
0.70
0.70
0.30 3
0.98 3
0.70
0.90
0.15
1.40
1.80
2.00
0.12
0.78
0.55
a
PEL-Ceiling'
loom)
200
???
50
-
5 (STEL)'
25
200
300
200
-·
..
..
..
·-..
..
..
200
50'
30
..
..
30
117
50
Fenceline Cone.
% of PEL-C
0.91%
..
1.10%
-
30.00%
1.20%
0.25%
0.33%
0.18% ..
..
..
..
..
..
..
..
0.45%
0.30%
4.67%
..
..
0.40%
3.62%
0.45%
1. Fenceline concentrations were obtained from the SLAB model. using an emission rate of 100 g/s. The concentrations were
divided by 100 to estimate the fencefine concentrations for an emission rate of 1 g/s.
2. The PEL-C (Ceiling) is an exposure limit which is not to be exceeded at any time.
3. Fenceline concentrations for these compounds was extrapolated from fence!ine concentrations of other chloromethanes
and chloroethanes.
4. Used 1. 1,2-Trichloroethane in the model. as data for 1, 1, 1-was not available.
5. The Short-Term Exposure Limit (STEL) is a 15•minute average exposure limit.
6. The 50 ppm Ceiling Limit is for the ortho (O·) isomer of DichloFObenzene
7. Mean and median values were calculated using chemicals with PEL·C (or PEL·STEL) values.
• The OSHA PEL.Ceiling values were obtained from the 1998 edition of 29 CFR 1910.1000 (OSHA Standards for
Air Contaminants), which was last revised 8/4/97.
Page 16
• •
TABLE 4-3
Comparison of Calculated Fenceline Concentrations with the OSHA PEL-TWA
Chemical
Chloromethane (Methyl Chloride)
Methylene Chloride (Dichloromethane)
Chloroform
1, 1, 1-Trichloroethane'
Benzene
Carbon Tetrachloride
Trichloroethene (Trichloroethylene)
Toluene
Tetrachloroethene (Perchloroethylene)
Chlorobenzene
Ethylbenzene
Xylenes
1,2,4-Trimethylbenzene
1,3,5-Trimethylbenzene
Freon-12 (Dichlorodiftuoromethane)
Chloroethane (Ethyl Chloride)
1,2-Dichloropropane
Styrene
1,2-Dichlorobenzene
Carbon Disulfide
Methyl Ethyl Ketone
Nitric Acid
Ethylene Dibromide
Mean':
Median':
Fenceline Cone.
lnnm)'
1.82 3
1.00
0.55
0.50
1.50
0.30
0.50
1.00
0.35
0.80
0.70
0.80
0.70
0.70
0.30 3
0.98 3
0.70
0.90
0.15
1.40
1.80
2.00
0.12
0.87
0.80
PEL-TWA'
loom)
100
·-
--
350
1
10
100
200
100
75
100
100
--
--
1,000
1,000
75
100
75 5
20
200
2
20
191
100
Fenceline Cone.
% of PEL-TWA
1.82%
-
--
0.14%
150.00%
3.00%
0.50%
0.50%
0.35%
1.07%
0.70%
0.80%
--
--
0.03%
0.10%
0.93%
0.90%
0.20%
7.00%
0.90%
100.00%
0.60%
14.19%
0.80%
1. Fenceline concentrations were obtained from the SLAB model, using an emission rate of 100 g/s. The concentrations were
divided by 100 to estimate the fenceline concentrations for an emission rate of 1 g/s.
2. The PEL-TWA (Time-Weighted Average) is an eight-hour average exposure limit.
3. Fenceline concentrations for these compounds was extrapolated from fenceline concentrations of other chloromethanes
and chloroethanes.
4. Used 1, 1,2-Trichloroethane in the model, as data for 1, 1, 1-was not available.
5. The 75 ppm TWA is for the para (p-) isomer of Oichlorobenzene
6. Mean and median values were calculated using chemicals with PEL-TWA values.
* The OSHA PEL-TWA values were obtained from the 1998 edition of 29 CFR 1910.1000 (OSHA Standards for Air
Contaminants), which was last revised 8/4/97.
Page 17
S" f S'~ffifar t~ " .,_.,,L,,. , ..
>i •J!,..,!,j,,c -~It,:,'-'· :.,.~(~fafX!!J!f;,1~~-·~~~f; ·:. • ,,,-"'.-_. __ ~
lC, , e.
~~f!~;{~
~.\!\ . .Jlj\ 't"-1¥,,ru'".":r,f.: ;,;;I:"' :t!:J·,:1 ~~~ -,~~ • •';. ~:x ' ;,,l",,:::r~t'\;~ ,' ';',
; Ctib)( oionn
-_-\",-'~ l" •• ,. __ ,__ -;: ..... , ... ~.4,,,/-t-~-fu~ .
. · ,. 781":'lF""' .. ~-.i1~ •-·
. ~--. -• J':i'<"--<::-,• ... ,, ·--~ "' ,, _<;.-.,'l;~~~;:-,r.n_-~~~~ .. ,,,;:, ~....,,,.,,,.,;:;::...JtJ.i;r~=~'!'~-s, __ .• -~~ __ ..=..;.. .... ;;.1~~c • ...._ • ~ _. ___ _, :f:'~,-,"l·:-t:,.·s,4'~,>",;:.~~i<::;"~ -e;'~~-:,a~~<l!~<'~'??,,::!· <-,'t,,:::,;: ~,~:";;':;,,;>• ''"'l4-'Z:> -I<--.,~ '7~ .. :,.,;;Jc>::,;~•,•;--t'-c>::'S"':""'-
(I
-~ ... i,~1Ytl!ic~'$iMitl;{f ·, ;,;.~ · .. :, :i:¼r!fu1"d~-~tt __ ,
• • Dichloromethane •
Distance(m) Concentration(eemJ
1. 0000, 1000000.000
1. 0000, 1000000.000
1. 0124, 1728.112
1.0264, 1334. 724
1.0421, 1152.953
1.0597, 1037.302
1.0795, 953.057
1.1018, 886.845
1.1268, 832.229
1.1550, 785.642
1.1866, 744.909
1.2221, 708. 613
1.2621, 675.779
1.3070, 645.706
1.3575, 617.874
1.4143, 591.880
1.4781, 567.404
1.5498, 544.183
1. 6304, 521.992
1. 7209, 500.628
1.8228, 479.898
1.9372, 459.603
2.0659, 439.518
2.2105, 419.350
2.3730, 398.649
2.5557, 376.525
2.7610, 350.003
2.9919, 307. 626
3.2Sl3, 295.866
3.5429, 236.883
3.8707, 2,9.208
4.2391, 2/2,287
4.6532, .265.849
5.116i, 259. 738
5.6419, 253.850
6.2300, 2~8 .116
6.891!, 2"2.484
7. 6341, 236.915
8.4692, 231.375
9.4080, 225.841
10.4631, 220.290
11.6492, 214.706
12.9823, 208.405
1'1.4486, 193.767
16.0283, ~35.058
17.7306, l:"6.932
19.5661, :63.885
21.5470, 100.712
23. 6869, '52.293
26.0017, !..JJ.556
28.5097, 134.482
31.2318, i;•5. 122
34.1923, '15.587
37.4194, 106.023
40.9455, 96.586
44.8081, 57.421
49.0508, 78.646
53.7236, 70.348
58.8848, 62.584
64.6019, 55.387
70.9530, 48.768
Chloroform
Distance(m)
l. 0000,
l. 0000,
1.0124,
1.0264,
1.0421,
1.0597,
l. 0795,
1.1018,
1.1268,
1.1550,
1.1866,
1.2221,
1.2621,
1.3070,
1.3575,
1.4143,
1.4781,
1.5498,
1. 6303,
1.7209,
1.8228,
1.9372,
2. 0659,
2.2105,
2.3730,
2.5557,
2.7610,
2.9918,
3.25i3,
3. 5429,
3.8707,
4 .2391,
4. 6532,
S.1187,
5.6419,
6.2300,
6.8911,
7.6341,
8.4692,
9.4080,
10.4631,
11.6492,
12.9823,
14.4807,
16.1293,
17.9057,
19.8193,
21.8808,
2-1.1023,
26.4972,
29.0811,
31.8716,
34.8891,
38.1570,
41.7024,
45.5564,
49. 7553,
54.3408,
59.3615,
64.8731,
70.9406,
Concentration(ppm)
1000000.000
1000000.000
346.636
338.279
329.909
321.547
313.215
304.932
296.714
288.577
280.531
272. 588
264.755
257.039
249.440
241. 960
234.595
227.342
220.192
213.135
206 .156
199.236
192.348
185.455
178.504
171.413
164. 041
156.083
146.535
127.624
123.905
120.750
117.914
115.276
112. 767
110. 343
107.974
105.638
103.318
101.000
98. 673
96. 328
93.957
91.261
85.543
82.066
78.806
75.577
72. 308
68.958
65. 4 97
61.905
58. 1 77
54.331
50. 4 03
46.446
,J 2. 520
38. 682
34.981
31.456
28.136
•
----~
0...
0... .__.,
C
0 +:;
('O .... -C
Q) u
C
0 u
SLAB Centerline Plot
100000 .....
10000
1000 -.. ·
100
10 ~-1··-·-··-·+ ·· •-··I··· · -·I· -
0 10 20
Fenceline I !
30 40
Chemical Name: Dichloromethane
Averaging Time: 15 s
Fenceline Distance: 39.62 m
·I· -·-·--1· ~--· I·
50 60 70
Downwind Distance (m)
•
80
•
1000000
,-.. ~ 100000
(l_
(l_
§ 10000 -ro .... -C Cl) u
C
0
0
1000
101--~--------I· ....
0 10
SLAB Centerline Plot
20
Fenceline I
30 40
Chemical Name: Chloroform
Averaging Time: 15 s
Fenceline Distance: 39.62 m
Toxic Endpoint: 100.42 PPM
50 60
Downwind Distance (m)
•
70 80
•
C
0 :.:, ro ,._ -C
Q) u
C
0
0
SLAB Centerline Plot
1000000
100000 ·
10000
1000 •
100
10 ---~t--·~ . I -1 . ·-I -
0 10 20
Fenceline \ \
Chemical Name: 1, 1,2-Trichloroethane
Averaging Time: 15 s
Fenceline Distance: 39.62 m
------·---,---
:50 m
30 40 50 60 70
Downwind Distance (m)
•
80
•
~
0....
0....
C
0 -rn L.. -C
Q)
(.)
C 0 0
SLAB Centerline Plot
1000000
100000
10000 -
1000 -·
101--1-----1--1 -· ·-···1-
0 10 20
Fenceline I
30
-·,·----------------,-·----~
' ' ' '
' ' ' '
Chemical Name: Benzene
Averaging Time: 15 s
Fenceline Distance: 39_62 m
---·-· --------,------·--------
• 1.',() rr"'
' ' . --,--. -. - - - --- - ----,------- - - - ----- -
I··· -----j---------1· ··---1----+----,----t----l
40 50 60 70 80
Downwind Distance (m)
•
•
-----2
0..
0.. ----C
0 :.:; ro '-+-' C
Q) u
C
0 u
1 000000 · · -----
100000 · -
10000
1000
SLAB Centerline Plot
i
: I
Fenceline l i
i
'
l
I ;
Chemical Name: Carbon Tetrachloride
Averaging Time: 15 s
Fenceline Distance: 39.62 m
1 :::_·-~t =.J. I-=--~I.~ .. ~.71~-=--~--~I -r-·:-11 ~10
~
11
:>m~I -:-1=--=··;:I. =··-=i-1 =-=··-·=-;:I=-·=-·+:~·-~· ~t~-=~-,.
0 10 20 30 40 50 60 70 80 90
Downwind Distance (m)
•
•
~
0...
0...
C
0
+-'
C'll L.. +-'
C
Q) u
C
0
0
SLAB Centerline Plot
1000000
100000
10000
1000
100
10 >--~f--·-· I -·--··I· -· ··-··I··-·
0 10 20
Fenceline I ·
: ,o
ll
30 40
-·,-----~-~------,---------------. . . . . . . .
Chemical Name: Trichloroethylene
Averaging Time: 15 s
Fenceline Distance: 39.62 m
--------· ---,-
-. . ' -
-.,. --- - - --,--
:
I ------1--·----1-.. --1
50 60 70 80
Downwind Distance (m)
•
•
C
0
+-' co L.. +-' C
Q)
(.)
C
0
0
SLAB Centerline Plot
1000000
100000 ·
10000
1000 -·
100
10,-~,---·-·I ·-t-· · -1--··· t
0 10 20
Fenceli11e I
30 40
Chemical Name: Toluene
Averaging Time: 15 s
Fenceline Distance: 39.62 m
. ;.
' '
I ·· ·-----1-----·-·t·· ·· · ---1----+----+>-----;•-----1
50 60 70 80
Dow11wind Distance (m)
•
•
1000000 ·
----2 100000
0...
0..
-----C
0 ~ m
L.. +-' C
Q)
(.)
C
0
0
10000
1000 · ..
100
SLAB Centerline Plot
Fenceli11e I
-. ' ---------·--·-·,----------
' ' ' '
Chemical Name: Tetrachloroethylene
Averaging Time: 15 s
Fenceline Distance: 39.62 m
10 >-~+-~1··----·--l----··--I·--· -•-I
0 10 20 30 40 50 60 70
Downwind Distance (m)
•
80
•
1000000
------'.:2: 100000
D...
D... ---C 10000 0 :;:; ro I--1000 C
(1) u
C
0 100 0
10
SLAB Centerline Plot
...
----
1------1·-----·--+· .... ·\··· .. · -1 --·
0 10 20
Fenceline) )
30 40
Chemical Name: Chlorobenzene
Averaging Time: 15 s
Fenceline Distance: 39.62 m
:
50 60 70
Downwind Distance (m)
•
80
•
C
0 :;::;
Cl]
L--C
Q) u
C 0
0
SLAB Centerline Plot
1000000 ---
100000
10000
1000 •
Fenceline I
Chemical Name: Ethylbenzene
Averaging Time: 15 s
Fenceline Distance: 39.62 m
,. "•-
-' --
100 ---~--~ ... :--. -::-~--~------r-70...:.:,ff_j;l~~~---..i··,-.:...· -~---~·-·:.:.:··-~---[,---~--
10 ~--1------i --· i ---·t· -· ·I
0 10 20 30 40 50 60 70
Downwind Distance (m)
•
80
•
~
0..
0..
C 0 -~ -C
Q)
(.)
C
0
0
1000000
100000
10000 ·
1000 · .... ,.
10·----1---1
0 10
SLAB Centerline Plot
. . 1-
20
' ' ' '
I Fenceline I :
. I
30 40
Chemical Name: M-Xylene
Averaging Time: 15 s
Fenceline Distance: 39.62 m
···,·-· ------------,
-
-
1
-
----
-
-
-------"i -
-
-
-
-
---
-
-
·· + ·--·· I -------\1----i----+----t--
50 60 70 80
Downwind Distance (m)
•
•
~
Q_
Q_
C
0 :;::; ro ._
+-' C
Q) u
C
0
0
SLAB Centerline Plot
1000000·--
100000
10000
1000 _-
100 ;--------
1 O>--~ ------·-! ------1-------1--------I
0 10 20
F~nceline I :
Chemical Name: O-Xylene
Averaging Time: 15 s
Fenceline Distance: 39.62 m
;
-. -
-
-
--,---
-
-
-
-
-
-
-
-
-
-
-
-,--
-
-
-
-
-
-
-
-
-
-
-
--
-
I· -1-------\------1-------f---f---+---t--~
30 40 50 60 70 80
Downwind Distance (m)
•
•
1000000
,......._ 100000 ~
0..
0..
~
C 10000 0 --co L---1000 · C
Q) u
C
0 100 · u
10
0 10
SLAB Centerline Plot
20
I Fenceline I :
Chemical Name: 1,2,4-Trimethylbenzene
Averaging Time: 15 s
Fenceline Distance: 39.62 m
: 7lJ pffY1
----~--L
-I-------!----------t · ------!-·---f--,---+:-------1
30 40 50 60 70 80
Downwind Distance (m)
•
•
C
0 -~ -C a.> (.)
C
0
0
SLAB Centerline Plot
1000000
100000
10000
1000
100 ----
1 0 l--+------1-------1-------1-----·-·· I ·
0 10 20
Fenceli11e [ \
30 40
Chemical Name: 1,3,5-Trimethylbenzene
Averaging Time: 15 s
Fenceline Distance: 39.62 m
., .
----,-------------,----------------
1----l--·-··---1----+--'
0 ---+--+, -~---'
50 60 70 80
Downwind Distance (m)
•
•
~
0..
0..
C
0 ·..:; cu '--C
(l) u
C
0
0
SLAB Centerline Plot
1000000
100000.
I Fenceline I :
10000 · ..
1000 C ••••
' ---··--·-----·,-·----.
' ' ' ' ' '
' '
Chemical Name: 1,2-Dichloropropane
Averaging Time: 15 s
Fenceline Distance: 39.62 m
------,--
100 .. ~--:-:---~---------f: "1i~v1irrf1!' ~··.:.i· -~··-~· ~----===l···--· ·---·--·--·
10 --1---·-----!--· --\--·--·1--·-· I .. 1------·-l------1 ------f----+--t---t---j
0 10 20 30 40 50 60 70 80
Downwind Distance (m)
•
•
C
0 :;::. ro ,_
+J
C
Q) u
C
0
0
1000000 --....
100000 ·
10000
1000
100
10 ---I ~ ··I
0 10
SLAB Centerline Plot
j Fenceline I ;
Chemical Name: Styrene
Averaging Time: 15 s
Fenceline Distance: 39.62 m
---·--,--------· ------
.'
. . -. -. -. '
20 30 40 50 60 70 80
Downwind Distance (m)
•
•
,-..
~
(L
(L
C
0 :;:; ro '--C
Q) u
C 0
0
1000000 -·-· I
100000
10000
1000
.... 100 -
10
0 10
SLAB Centerline Plot
--1-----1-----I·
20 30
:\ Fenceline \
: 15 ff'"
Chemical Name: O-Dichlorobenzene
Averaging Time: 15 s
Fenceline Distance: 39.62 m
-
-
. -·, -
-
-
-
--
-
-. -
-
'. -
-
' ' I -----l-----1-----+------1---i.---+---t----+-----l
40 50 60 70 80 90 100
Downwind Distance (m)
•
•
~
Cl.
Cl.
C
0 -cu '--C
Q)
(.)
C
0
0
SLAB Centerline Plot
1000000
100000
10000
1000 , ·
1 0 ---1----·I--· · --1------1--· · I
0 10 20
Fenceline I i
30 40
. ·----,---------------,·----------·
' ' ' ' ' ' ' '
Chemical Name: Carbon Disulfide
Averaging Time: 15 s
Fenceline Distance: 39.62 m
50 60 70 80
Downwind Distance (m)
•
•
1000000. C •••• -
--~ 100000-.·
0...
0...
C
0 -ro '--
10000 ·
SLAB Centerline Plot
[ Fenceline I [
Chemical Name: Methyl Ethyl Ketone
Averaging Time: 15 s
Fenceline Distance: 39.62 m
C
Q)
(.)
C
0
0
1000 -
100 .... -.. --.---------~•Jl®'Jf,'._ ___ ~··~···c;··c.···..:··c.···-··•..:· ·..:· ---
10 ···-· ·I
0
· I· ··I······· I
10 20
I· ... ·· I .. ·-I . ·----1~--1-----+----'-----l
30 40 50 60 70 80
Downwind Distance (m)
•
•
SLAB Centerline Plot
1000000
,-... ~ 100000
0..
0..
§ 10000
.....,
Cll L-
Fenceli11e I
Chemical Name: Nitric Acid
Averaging Time: 15 s
Fenceline Distance: 39.62 m
Toxic Endpoint: 10.1 PPM
J 1 :::-. _-_-_ -r-----~---t: Jiv'!"l'E.__~--r=-:--:· ·c.;· ·;..· ---: ·::.· ·c.· --,,-·,;;· ·;.· ·;:· ---:•::. ·· ·::.· -------. -----.
[I~~ic E~dpoint
10-----1-----1-----I----··· I -----I -I ------1---l-------1~L1-----+---l----+--l
0 10 20 30 40 50 60 70 80 90
Downwind Distance (m)
•
•
2
0...
0... ----C
0 -~ -C
Q) u
C
0
0
SLAB Centerline Plot
1000000 ,. --
-
100000 -
10000 •
1000
100 -
1 1~-1----·· I -•-·--1 -----!
0 10 20
Fenceline I :
Chemical Name: Ethylene Dibromide
Averaging Time: 15 s
Fenceline Distance: 39.62 m '----------------
--
-
---: --
. . .. 1-------1-------1----.----~•--1
30 40 50 60 70
Downwind Distance (m)
•
•
~
0..
0..
C
0 :;::; co L.. +-' C
Q)
(.)
C
0
0
SLAB Centerline Plot
.v, ~-~,!/ 0,1/i, }o l(;/rqt,J~~ IMatNe
Co,t, d-{,/1{1),'Je{(,m~
1000000 -·-
100000 ·
10000
1000.
100·· - - -. ---' -
10 J __ ~-<··----·--·1--··-···-1··---·· - I
0 10 20
[ Fenceline [ i
30 40
Chemical Name: 1, 1-Dichloroethane
Averaging Time: 15 s
Fenceline Distance: 39.62 m
• 1 • - - • -
' ' . . -- --,-- ---- - - - -- - - - --,-. - - - - -- - ---
' ' ' '
· I -----1-----1----f---t----+---t---1
50 60 70 80
Downwind Distance (m)
•
•