E

C

/R Incorporated Providing Environmental Technical Support Since 1989

501 Eastowne Drive, Suite 250  Chapel Hill, North Carolina 27514

Telephone: (919)484-0222  Fax: (919) 484-0122

MEMORANDUM

DATE: July 28, 2011

SUBJECT: Oil and Natural Gas Production MACT and Natural Gas Transmission and 

Storage MACT – MACT Allowable Emissions and Risks

FROM: Heather Brown, P.E., EC/R Incorporated

Lesley Stobert, EC/R Incorporated

TO: Bruce Moore, EPA/OAQPS/SPPD/FIG

______________________________________________________________________________

The purpose of this memorandum is to present analyses related to “MACT allowable” 

emissions levels and risks for the Oil and Natural Gas Production and Natural Gas Transmission 

and Storage source categories that are being addressed under EPA’s Risk and Technology 

Review (RTR) program.

The RTR program is addressing the statutory requirements in section 112(f) and 

112(d)(6) of the Clean Air Act for federal air toxics regulations. The regulations are National 

Emission Standards for Hazardous Air Pollutants (NESHAP) contained in 40 CFR part 63. They 

are commonly referred to as Maximum Achievable Control Technology (MACT) standards. The 

emissions data being used for the RTR risk assessments for these categories consist of data 

representative of “actual” emission levels. In addition to the risks associated with these actual 

emission levels, EPA also considers the levels of HAP emissions that sources could emit and still 

be in compliance with the applicable MACT regulation. These emission levels are referred to as 

“MACT allowable” emissions. The purpose of this memorandum is to discuss these MACT

allowable emission levels and their impact on the baseline risks.

This memorandum is organized as follows. Section 1 presents the estimated maximum 

risk levels based on the actual emission levels for both source categories, and Section 2 discusses 

the basic approach to estimating the risks from the MACT allowable levels. This is followed by a 

discussion of the estimation of MACT allowable emission level, particularly as it relates to the 

actual emission levels used in the risk assessments. This is followed by a presentation of the 

estimated risks at these MACT allowable levels.

1.0 Risk Levels Based on Actual Emissions

The estimated maximum inhalation risks for the two source categories are summarized in 

Table 1. These risks are based on actual emission levels.
2

Table 1. Summary of Estimated Inhalation Risks for the Oil and Gas Source Categories 

Based On Actual Emissions Levels

Source Category

Maximum individual 

cancer risk (in a 

million)1

Maximum chronic 

noncancer TOSHI2

Oil and Natural Gas Production 40 0.1

Natural Gas Transmission and Storage 90 0.4

1 Maximum individual excess lifetime cancer risk.

2 Maximum target organ specific hazard index (TOSHI). Target organ system represented by the TOSHI varies 

across source categories. Maximum TOSHI is based on respiratory effects for oil and gas production and 

immunological effects for natural gas transmission and storage. 

2.0 Approach to Estimating Risks from MACT Allowable Emission Levels

Detailed emission point-specific MACT allowable emissions information is not available. 

Therefore, modeling was not conducted to estimate the risks from MACT allowable emission 

levels.

The basic approach to estimate the risks from MACT allowable emission levels was to 

first estimate the relationship between the actual and MACT allowable emission levels, and then 

to estimate the potential risk impacts from the differences between actual and MACT allowable 

emissions. In general, the risk impact was assumed to be proportional to the difference in 

emission levels. For example, if MACT allowable emissions were estimated to be three times as 

high as actual emissions, it was assumed that risks could be as much as three times as high as 

those estimated from the modeling conducted using actual emissions.

This assumption regarding the linear relationship between emissions and risks is 

generally reasonable for chronic cancer and noncancer risks. However, using this approach for 

acute risks would likely overestimate the impacts. The acute assessment already has numerous 

built in conservative assumptions. First, the acute assessment assumed a short-term emission rate 

up to 10 times that of the average longer term emission rate. Also, the maximum acute risks 

assume the simultaneous occurrence of independent factors that may vary greatly, such as hourly 

emissions rates, meteorology, and human activity patterns. In the assessment using actual 

emissions, EPA assumed that individuals remained for 1 hour at the point of maximum ambient 

concentration as determined by the co-occurrence of peak emissions and worst-case 

meteorological conditions. These assumptions would tend to overestimate actual exposures since 

it is unlikely that a person would be located at the point of maximum exposure during the time of 

worst-case impact. The addition of another factor to account for MACT allowable emissions 

level further increases the conservativeness of the estimated MACT allowable acute risks. 

Therefore, this analysis does not estimate acute risks for the MACT-allowable emissions level.
3

3.0 Results of Analysis

The Oil and Natural Gas Production NESHAP (40 CFR 63, subpart HH) addresses 

emissions from the following types of emission points: (1) glycol dehydration unit process vents, 

(2) storage vessels with the potential for flash emissions, and (3) equipment leaks at natural gas 

processing plants. The Natural Gas Transmission and Storage NESHAP (40 CFR 63, subpart 

HHH) addresses emissions from glycol dehydration unit process vents. Table 2 summarizes the 

formats of the standards for these emission points.

Table 2. Formats of Standards for Oil and Natural Gas Production and Natural Gas 

Transmission and Storage NESHAP

Emission Source Type Format of Primary Standard

Glycol Dehydrator Unit Process Vents Performance Standard (% reduction), 

Emissions Limit (tons per year benzene)

Storage Vessels Performance Standard (% reduction)

Equipment Leaks Equipment and Work Practice Standards

Oil and Natural Gas Production, Subpart HH

The ability to estimate MACT allowable emissions for specific emission points, or for 

specific emission point types, is largely dependent on the format of the standards. For equipment 

standards, sources subject to the regulation are required to install specific equipment. Assuming 

that the equipment is maintained properly and is in good working condition (as required), there 

would not be a difference in the actual emissions level and the level allowed by the standard. 

Similarly, there would be no difference between actual and MACT allowable emissions for 

emission sources subject to work practice requirements, provided that facilities are not 

conducting additional work practices proven to reduce emissions beyond those required in the 

rule. We are not aware of any such situations at oil and gas facilities. Therefore, for equipment 

leaks at natural gas processing plants, which are subject to equipment and work practice 

standards, we believe that the actual emission levels are a reasonable estimation of the levels 

allowed by the standard.

Subpart HH requires a 95 percent reduction in organic HAP emissions from storage 

vessels with the potential for flash emissions. This level of control was based on the use of vapor 

recovery units and combustion devices. These are the control devices that are currently being 

used, and we are not of aware control techniques being used that are more effective than these. 

Therefore, we conclude that actual emissions levels from facilities that are controlling their 

storage vessel emissions are representative of MACT allowable emission levels. If a facility 

installed controls on a storage vessel not subject to the performance standard in subpart HH, this 

would represent a situation where MACT allowable emissions would be greater than the actual 

emissions. We are not aware of any situations in which storage vessels not required to install 

controls However, for wastewater sources, we are not aware of any such controls on storage 

vessels not subject to the performance standard in subpart HH. Therefore, we believe that the 

actual storage vessel emission levels are a reasonable estimation of the levels allowed by the 

standard.
4

For glycol dehydrator unit process vents located at oil and natural gas production 

facilities, subpart HH includes the option to reduce organic HAP emissions by 95 percent or to 

reduce total benzene emissions to less than 1 ton/year. Condensers are the type of control device 

that the glycol dehydrators standards were based upon. Combustors are also widely used to 

control emissions from there units. As with storage vessels, these are the control devices that are 

currently being used, and we are not aware of control techniques being used that are more 

effective than these. However, many facilities do control the benzene emission to a level less 

than 1 tpy. In theory, they are allowed to increase their emissions to just below 1 tpy.

To determine the MACT allowable emission levels, we assumed that glycol dehydrators 

controlled to less than 1 tpy of benzene may increase emissions to the 1 tpy level. Using 

information in the NEI database, we identified each glycol dehydrator that had controlled 

benzene emissions below 1 tpy, and then scaled the emissions up to 1 tpy for each of these 

dehydrators. Of the controlled dehydrators with less than 1 tpy of benzene emissions, the average 

increase per dehydrator to make 1 tpy benzene emissions was 0.85 tpy, with an overall increase 

across the source category of 100 tpy, from 26 tpy to 126 tpy of benzene. To determine the 

difference in actual and MACT-allowable risk values, we performed three actions. First, we 

calculated the factor of difference between the emissions at each dehydrator and 1 tpy benzene

(i.e., 1/actual emissions). Next, we determined the contribution each of these dehydrators made 

to the oil and natural gas production risk for the facility at which they were located based on 

actual emissions. Then, we applied the factor of difference between actual benzene emissions 

and 1 tpy to each dehydrator’s risk contribution value and added this value to the remaining risk 

for the other portions of the facility to arrive at the MACT-allowable risk for the facility. The 

result is that the maximum oil and natural gas production facility cancer risk at the MACTallowable emissions level is 400-in-1 million and the maximum MACT-allowable TOSHI is 2.

Details of these calculations are provided in Attachment A.

Natural Gas Transmission and Storage, Subpart HHH

For glycol dehydrator unit process vents at natural gas transmission and storage facilities, 

subpart HHH includes the same options as subpart HH, to reduce organic HAP emissions by 95 

percent or to reduce total benzene emissions to less than 1 ton/year. Condensers and combustors

are also the types of control devices that these glycol dehydrators standards were based upon. As 

with subpart HH, these are the control devices that are currently being used, and we are not 

aware of control techniques being used that are more effective than these. However, many 

facilities do control the benzene emissions to a level less than 1 tpy. In theory, they are allowed 

to increase their emissions to just below 1 tpy. To determine the MACT allowable emission 

levels, we followed the same process as that described above for the Oil and Natural Gas 

Production source category. Of the controlled dehydrators with less than 1 tpy of benzene 

emissions, the average increase per dehydrator to make 1 tpy emissions was 0.9 tpy of benzene, 

with an overall increase across the source category of 24 tpy, from 3 tpy to 27 tpy of benzene. 

However, the facilities in the Natural Gas Transmission and Storage source category with glycol 

dehydrators controlled to less than 1 tpy of benzene were not the facilities with the highest risks 

for the source category. The highest cancer risk from these facilities at the actual emissions level 

is 1-in-1 million, while the highest cancer risk from facilities without glycol dehydrators 
5

controlled to less than 1 tpy of benzene in the source category is 90-in-1 million. Considering an

increase in emissions and risk if the controlled glycol dehydrators with less than 1tpy benzene 

emissions increase benzene emissions to 1 tpy, which would be the MACT-allowable emissions 

level, the maximum MIR from these facilities is 4-in-1 million. Therefore, the cancer risks of 

90-in-1 million from the actual emissions at other facilities exceed the MACT-allowable level at 

the subset of facilities that have controlled benzene emissions from glycol dehydrators of less 

than 1 tpy. Thus, the maximum MIR for the Natural Gas Transmission and Storage source 

category remains 90-in-1 million considering MACT-allowable emissions. 

Similarly to the cancer risks for the source category, the highest TOSHI from the subset 

of facilities with controlled glycol dehydrators emitting less than 1 tpy benzene at the actual 

emissions level was 0.003, while the highest TOSHI from other facilities in the source category 

is 0.4. Considering an increase in emissions and risk if the controlled glycol dehydrators with 

less than 1tpy benzene emissions increase benzene emissions to 1 tpy, which would be the 

MACT-allowable emissions level, the maximum TOSHI from these facilities is 0.02. Therefore, 

the TOSHI of 0.4 from the actual emissions at other facilities exceed the MACT-allowable level 

at the subset of facilities that have controlled benzene emissions from glycol dehydrators of less 

than 1 tpy. Thus, the maximum TOSHI for the Natural Gas Transmission and Storage source 

category remains 0.4 considering MACT-allowable emissions. 

Details of the MACT-allowable source category MIR and TOSHI calculations are 

provided in Attachment A.

Table 3. Summary of Estimated Inhalation Risks for the Oil and Gas Source Categories 

Based On MACT-Allowable Emissions Levels

Source Category

Maximum individual 

cancer risk (in a 

million)1

Maximum chronic 

noncancer TOSHI2

Oil and Natural Gas Production 400 2

Natural Gas Transmission and Storage 90 0.4
Attachment A
A B C D E F G H I J

Facility MIR

Cancer Risk 

from Source 

ID/HAP

Cancer Risk 

From Other 

Points

Controlled 

Dehydrator 

Benzene 

Emissions (tpy)

Factor for 1 tpy 

Benzene 

Adjustment

Adjusted Cancer 

Risk From 

Overcontrolled 

Point 

MACT Allowable 

MIR at Facility 

Due to Dehy 1 

tpy Limit

(from risk 

modeling 

results)

(from risk 

modeling 

results)

(Column D - 

Column E) (from NEI data) (1/Column G)

(Column E * 

Column H)

(Column F + 

Column I)

ONG_NEICA1115664 DN0022 Benzene 1.42E-05 1.39E-05 3.00E-07 0.2916 3.43 4.75E-05 4.78E-05

ONG_NEIOK2038 DN0001 Benzene 6.88E-06 4.37E-06 2.51E-06 0.8400 1.19 5.20E-06 7.71E-06

ONG_NEILA13789 DN0008 Benzene 6.12E-06 1.54E-07 5.97E-06 0.6128 1.63 2.50E-07 6.22E-06

ONG_NEI7410 DN0006 Benzene 2.98E-06 1.65E-06 1.33E-06 0.5160 1.94 3.20E-06 4.52E-06

ONG_NEICA0592118 DN0027 Benzene 2.23E-06 1.26E-06 9.75E-07 0.0744 13.45 1.69E-05 1.79E-05

ONG_NEIMIB9135 DN0005 Benzene 2.03E-06 1.19E-07 1.91E-06 0.1416 7.06 8.40E-07 2.75E-06

ONG_NEILA0770023 DN0004 Benzene 1.54E-06 1.32E-07 1.41E-06 0.1425 7.02 9.29E-07 2.34E-06

ONG_NEILA0450042 DN0004 Benzene 1.37E-06 3.96E-08 1.33E-06 0.0310 32.30 1.28E-06 2.61E-06

ONG_NEI2TX42343 DN0002 Benzene 1.19E-06 3.34E-07 8.58E-07 0.1032 9.69 3.23E-06 4.09E-06

ONG_NEIMIB9142 DN0009 Benzene 1.16E-06 1.05E-07 1.06E-06 0.0619 16.14 1.69E-06 2.75E-06

ONG_NEI8007 DN0051 Benzene 1.05E-06 2.99E-08 1.02E-06 0.0129 77.52 2.32E-06 3.56E-04

ONG_NEI8007 DN0005 Benzene 1.05E-06 1.53E-08 1.03E-06 0.00004 23071.24 3.53E-04

ONG_NEIMIB9160 DN0008 Benzene 8.61E-07 1.28E-07 7.33E-07 0.1310 7.64 9.79E-07 1.71E-06

ONG_NEICO1230184 DN0001 Benzene 8.13E-07 1.91E-07 6.23E-07 0.2240 4.46 8.51E-07 1.47E-06

ONG_NEIMIB9136 DN0005 Benzene 7.59E-07 1.74E-07 5.86E-07 0.2371 4.22 7.32E-07 1.32E-06

ONG_NEIAL10190 DN0002 Benzene 7.27E-07 4.97E-07 2.30E-07 0.5700 1.75 8.72E-07 1.10E-06

ONG_NEI12819 DN0001 Benzene 7.12E-07 6.06E-07 1.06E-07 0.6640 1.51 9.13E-07 1.02E-06

ONG_NEI11191 DN0007 Benzene 6.30E-07 3.27E-07 3.03E-07 0.8500 1.18 3.85E-07 6.88E-07

ONG_NEI2CO0552 DN0001 Benzene 6.15E-07 6.53E-08 5.49E-07 0.5000 2.00 1.31E-07 6.80E-07

ONG_NEI12047 DN0005 Benzene 5.01E-07 3.33E-07 1.68E-07 0.2368 4.22 1.41E-06 1.57E-06

ONG_NEI7787 DN0002 Benzene 4.92E-07 9.99E-08 3.92E-07 0.9817 1.02 1.02E-07 4.93E-07

ONG_NEI11921 DN0003 Benzene 4.87E-07 1.50E-07 3.38E-07 0.0166 60.13 9.00E-06 9.34E-06

ONG_NEIOK2529 DN0015 Benzene 4.64E-07 6.75E-09 4.58E-07 0.0558 17.93 1.21E-07 5.79E-07

ONG_NEIAL0530007 DN0002 Benzene 4.60E-07 5.35E-08 4.06E-07 0.8600 1.16 6.22E-08 4.68E-07

ONG_NEI13271 DN0005 Benzene 4.56E-07 3.95E-07 6.16E-08 0.1580 6.33 2.50E-06 2.56E-06

ONG_NEICO1230048 DN0003 Benzene 4.42E-07 6.98E-08 3.72E-07 0.3060 3.27 2.28E-07 7.84E-07

ONG_NEICO1230048 DN0004 Benzene 4.42E-07 4.39E-08 3.98E-07 0.1925 5.19 2.28E-07

ONG_NEITXRUA0156 DN0004 Benzene 3.68E-07 1.90E-07 1.78E-07 0.2840 3.52 6.68E-07 8.46E-07

ONG_NEI2TX1520 DN0001 Benzene 2.70E-07 2.67E-07 3.10E-09 0.1324 7.55 2.01E-06 2.02E-06

ONG_NEI2CO045363 DN0003 Benzene 2.59E-07 2.26E-07 3.31E-08 0.2050 4.88 1.10E-06 1.19E-06

ONG_NEI2CO045363 DN0001 Benzene 2.59E-07 1.39E-08 2.45E-07 0.2050 4.88 6.79E-08

ONG_NEITX383004K DN0003 Benzene 1.96E-07 1.65E-08 1.79E-07 0.1100 9.09 1.50E-07 3.29E-07

ONG_NEITXRGJ0139 DN0003 Benzene 1.73E-07 2.97E-08 1.44E-07 0.0431 23.20 6.89E-07 8.33E-07

ONG_NEI2OK285 DN0004 Benzene 1.68E-07 6.69E-09 1.61E-07 0.0294 34.00 2.27E-07 3.88E-07

ONG_NEIMI14392 DN0009 Benzene 1.66E-07 9.18E-09 1.57E-07 0.0265 37.68 3.46E-07 5.03E-07

ONG_NEILA0070200$8 DN0001 Benzene 1.50E-07 4.57E-08 1.05E-07 0.0464 21.53 9.83E-07 1.09E-06

ONG_NEIMI055B915 DN0008 Benzene 1.28E-07 7.38E-08 5.42E-08 0.1416 7.06 5.21E-07 5.75E-07

ONG_NEI13316 DN0001 Benzene 1.25E-07 1.25E-07 -1.00E-15 0.0700 14.29 1.78E-06 1.78E-06

ONG_NEICO0186 DN0001 Benzene 1.15E-07 1.28E-13 1.15E-07 0.0005 2000.00 2.56E-10 1.15E-07

ONG_NEITX067CG00 DN0002 Benzene 1.06E-07 4.84E-08 5.73E-08 0.1007 9.93 4.80E-07 5.38E-07

ONG_NEILA0070200$6 DN0002 Benzene 1.05E-07 2.37E-08 8.14E-08 0.0155 64.60 1.53E-06 1.61E-06

ONG_NEIMIN6015 DN0015 Benzene 8.57E-08 2.97E-08 5.60E-08 0.1600 6.25 1.86E-07 4.07E-07

ONG_NEIMIN6015 DN0006 Benzene 8.57E-08 2.00E-08 6.56E-08 0.1080 9.26 1.86E-07

Table A-1. Oil and Natural Gas Production Facilities with Glycol Dehydrators Controlled to Less Than 1 TPY – MACT Allowable 

Cancer Risk

Facility ID Source ID HAP
A B C D E F G H I J

Facility MIR

Cancer Risk 

from Source 

ID/HAP

Cancer Risk 

From Other 

Points

Controlled 

Dehydrator 

Benzene 

Emissions (tpy)

Factor for 1 tpy 

Benzene 

Adjustment

Adjusted Cancer 

Risk From 

Overcontrolled 

Point 

MACT Allowable 

MIR at Facility 

Due to Dehy 1 

tpy Limit

(from risk 

modeling 

results)

(from risk 

modeling 

results)

(Column D - 

Column E) (from NEI data) (1/Column G)

(Column E * 

Column H)

(Column F + 

Facility ID Source ID HAP Column I)

ONG_NEI6456 DN0007 Benzene 8.41E-08 1.59E-13 8.41E-08 0.0009 1100.50 1.75E-10 8.44E-08

ONG_NEI6456 DN0016 Benzene 8.41E-08 1.10E-13 8.41E-08 0.0008 1214.28 1.34E-10

ONG_NEI2TX39520 DN0003 Benzene 7.89E-08 6.64E-08 1.25E-08 0.2868 3.49 2.31E-07 2.44E-07

ONG_NEITX42345 DN0001 Benzene 7.80E-08 1.17E-08 6.63E-08 0.0376 26.58 3.11E-07 3.77E-07

ONG_NEI2TX20371 DN0003 Benzene 7.56E-08 7.07E-08 4.94E-09 0.1328 7.53 5.32E-07 5.37E-07

ONG_NEI13085 DN0003 Benzene 6.12E-08 4.04E-08 2.08E-08 0.1622 6.17 2.49E-07 2.70E-07

ONG_NEI7785 DN0006 Benzene 4.87E-08 4.51E-10 4.82E-08 0.5000 2.00 9.02E-10 5.06E-08

ONG_NEI7785 DN0002 Benzene 4.87E-08 1.51E-10 4.85E-08 0.1670 5.99 9.02E-10

ONG_NEI7785 DN0005 Benzene 4.87E-08 1.51E-10 4.85E-08 0.1670 5.99 9.02E-10

ONG_NEI6453 DN0015 Benzene 4.27E-08 6.15E-11 4.27E-08 0.1633 6.12 3.76E-10 4.30E-08

ONG_NEIMIB5587 DN0005 Benzene 4.09E-08 1.93E-09 3.90E-08 0.0814 12.29 2.37E-08 6.26E-08

ONG_NEI11771 DN0004 Benzene 3.91E-08 2.25E-09 3.69E-08 0.0026 388.22 8.74E-07 9.10E-07

ONG_NEITX18630 DN0019 Benzene 3.75E-08 2.07E-10 3.73E-08 0.1685 5.93 1.23E-09 4.27E-08

ONG_NEITX18630 DN0017 Benzene 3.75E-08 1.81E-10 3.73E-08 0.0904 11.06 2.00E-09

ONG_NEITX18630 DN0018 Benzene 3.75E-08 1.72E-11 3.75E-08 0.9147 1.09 1.89E-11

ONG_NEITX18630 DN0016 Benzene 3.75E-08 9.25E-12 3.75E-08 0.0159 62.89 5.82E-10

ONG_NEITX18630 DN0011 Benzene 3.75E-08 3.14E-12 3.75E-08 0.0038 261.01 8.19E-10

ONG_NEITX18630 DN0009 Benzene 3.75E-08 6.82E-13 3.75E-08 0.0007 1410.47 9.62E-10

ONG_NEI7449 DN0008 Benzene 3.19E-08 1.58E-08 1.60E-08 0.0891 11.22 1.78E-07 1.94E-07

ONG_NEI12270 DN0006 Benzene 3.17E-08 1.48E-09 3.02E-08 0.0054 185.19 2.75E-07 3.05E-07

ONG_NEITXRHX1519 DN0001 Benzene 2.86E-08 2.76E-08 1.04E-09 0.0001 10000.00 2.76E-04 2.76E-04

ONG_NEI11924 DN0003 Benzene 2.69E-08 8.82E-10 2.60E-08 0.0088 113.64 1.00E-07 1.26E-07

ONG_NEI6483 DN0003 Benzene 2.62E-08 1.32E-08 1.30E-08 0.0093 107.01 1.41E-06 1.42E-06

ONG_NEILA0690006 DN0001 Benzene 2.53E-08 1.08E-08 1.46E-08 0.1075 9.30 1.00E-07 1.15E-07

ONG_NEITX161629 DN0004 Benzene 2.38E-08 6.21E-09 1.76E-08 0.0139 71.78 4.46E-07 8.68E-07

ONG_NEITX161629 DN0006 Benzene 2.38E-08 5.72E-09 1.81E-08 0.0139 71.78 4.11E-07

ONG_NEI7694 DN0006 Benzene 2.21E-08 1.81E-08 3.92E-09 0.0820 12.20 2.21E-07 2.25E-07

ONG_NEI6512 DN0004 Benzene 2.14E-08 1.38E-08 7.55E-09 0.0163 61.35 8.47E-07 8.55E-07

ONG_NEITX157312F DN0001 Benzene 1.76E-08 2.11E-10 1.74E-08 0.2916 3.43 7.24E-10 1.81E-08

ONG_NEILA0075 DN0001 Benzene 1.68E-08 2.38E-10 1.66E-08 0.7280 1.37 3.26E-10 1.72E-08

ONG_NEILA0075 DN0002 Benzene 1.68E-08 1.52E-11 1.68E-08 0.0464 21.53 3.26E-10

ONG_NEITX039692 DN0003 Benzene 1.64E-08 6.35E-09 1.00E-08 0.0161 62.11 3.94E-07 4.04E-07

ONG_NEI7998 DN0010 Benzene 1.63E-08 1.91E-09 1.44E-08 0.5200 1.92 3.66E-09 1.81E-08

ONG_NEILA0123 DN0001 Benzene 1.48E-08 5.70E-10 1.43E-08 0.4980 2.01 1.14E-09 1.65E-08

ONG_NEILA0123 DN0002 Benzene 1.48E-08 5.29E-11 1.48E-08 0.0464 21.53 1.14E-09

ONG_NEI13106 DN0003 Benzene 1.38E-08 7.77E-10 1.30E-08 0.0130 76.92 5.97E-08 7.28E-08

ONG_NEITX039674 DN0002 Benzene 1.33E-08 5.69E-09 7.64E-09 0.0156 64.27 3.66E-07 3.73E-07

ONG_NEITX039675 DN0002 Benzene 1.29E-08 5.69E-09 7.23E-09 0.0156 64.28 3.66E-07 3.73E-07

ONG_NEITX039676 DN0003 Benzene 1.29E-08 5.69E-09 7.20E-09 0.0156 64.27 3.66E-07 3.73E-07

ONG_NEI12503 DN0002 Benzene 1.21E-08 2.71E-09 9.41E-09 0.0600 16.67 4.52E-08 5.46E-08

ONG_NEI7375 DN0001 Benzene 1.20E-08 1.36E-12 1.20E-08 0.0005 2000.00 2.72E-09 1.48E-08

ONG_NEITX25152 DN0006 Benzene 9.01E-09 2.37E-09 6.64E-09 0.0143 70.12 1.66E-07 3.38E-07

ONG_NEITX25152 DN0004 Benzene 9.01E-09 5.92E-10 8.42E-09 0.0036 280.50 1.66E-07

ONG_NEITXRPE0106 DN0007 Benzene 6.91E-09 1.61E-13 6.91E-09 0.0008 1291.99 2.08E-10 7.12E-09

ONG_NEITX461006C DN0022 Benzene 6.42E-09 9.40E-12 6.42E-09 0.0431 23.22 2.18E-10 6.63E-09

ONG_NEI2TX39139 DN0002 Benzene 4.86E-09 1.11E-10 4.75E-09 0.1621 6.17 6.84E-10 5.43E-09
A B C D E F G H I J

Facility MIR

Cancer Risk 

from Source 

ID/HAP

Cancer Risk 

From Other 

Points

Controlled 

Dehydrator 

Benzene 

Emissions (tpy)

Factor for 1 tpy 

Benzene 

Adjustment

Adjusted Cancer 

Risk From 

Overcontrolled 

Point 

MACT Allowable 

MIR at Facility 

Due to Dehy 1 

tpy Limit

(from risk 

modeling 

results)

(from risk 

modeling 

results)

(Column D - 

Column E) (from NEI data) (1/Column G)

(Column E * 

Column H)

(Column F + 

Facility ID Source ID HAP Column I)

ONG_NEIOK2720 DN0003 Benzene 4.85E-09 8.63E-13 4.85E-09 0.0074 134.58 1.16E-10 4.96E-09

ONG_NEI6855 DN0004 Benzene 4.52E-09 8.73E-10 3.64E-09 0.0200 50.00 4.36E-08 4.73E-08

ONG_NEI2TX1619 DN0005 Benzene 4.51E-09 3.37E-09 1.14E-09 0.0600 16.67 5.61E-08 1.13E-07

ONG_NEI2TX1619 DN0015 Benzene 4.51E-09 2.62E-10 4.25E-09 0.0047 213.69 5.61E-08

ONG_NEITX215294O DN0001 Benzene 4.32E-09 1.49E-11 4.30E-09 0.2004 4.99 7.43E-11 4.38E-09

ONG_NEITXRSQ0088 DN0002 Benzene 4.24E-09 1.41E-10 4.10E-09 0.6009 1.66 2.34E-10 4.34E-09

ONG_NEILA1010013 DN0001 Benzene 4.07E-09 2.98E-11 4.05E-09 0.0825 12.12 3.61E-10 4.75E-09

ONG_NEILA1010013 DN0002 Benzene 4.07E-09 1.69E-11 4.06E-09 0.0470 21.28 3.60E-10

ONG_NEI7436 DN0002 Benzene 3.62E-09 5.83E-12 3.62E-09 0.0220 45.45 2.65E-10 4.40E-09

ONG_NEI7436 DN0010 Benzene 3.62E-09 3.84E-12 3.62E-09 0.0145 68.97 2.65E-10

ONG_NEI7436 DN0011 Benzene 3.62E-09 3.84E-12 3.62E-09 0.0145 68.97 2.65E-10

ONG_NEILA0750033 DN0002 Benzene 2.24E-09 1.27E-10 2.11E-09 0.2322 4.31 5.49E-10 3.08E-09

ONG_NEILA0750033 DN0003 Benzene 2.24E-09 1.27E-10 2.11E-09 0.2322 4.31 5.49E-10

ONG_NEITX371016P DN0003 Benzene 2.22E-09 9.23E-11 2.13E-09 0.0036 274.42 2.53E-08 2.75E-08

ONG_NEITXRCI0100 DN0005 Benzene 1.80E-09 2.87E-12 1.80E-09 0.0114 87.72 2.52E-10 2.05E-09

ONG_NEILA2210126$2 DN0001 Benzene 1.69E-09 1.21E-11 1.68E-09 0.0155 64.60 7.79E-10 2.46E-09

ONG_NEI6094 DN0001 Benzene 1.69E-09 2.85E-10 1.40E-09 0.1410 7.09 2.02E-09 5.36E-09

ONG_NEI6094 DN0002 Benzene 1.69E-09 3.05E-11 1.66E-09 0.0155 64.60 1.97E-09

ONG_NEITX461002K DN0006 Benzene 1.64E-09 2.52E-12 1.64E-09 0.0079 126.58 3.19E-10 1.95E-09

ONG_NEITXRPE0042 DN0005 Benzene 1.37E-09 1.07E-10 1.27E-09 0.1000 10.00 1.07E-09 2.33E-09

ONG_NEILA0098 DN0003 Benzene 1.37E-09 4.13E-10 9.53E-10 0.0020 500.00 2.07E-07 2.07E-07

ONG_NEI11929 DN0004 Benzene 1.18E-09 1.03E-11 1.17E-09 0.0116 86.21 8.89E-10 2.94E-09

ONG_NEI11929 DN0005 Benzene 1.18E-09 1.02E-11 1.17E-09 0.0115 86.96 8.89E-10

ONG_NEI2TX07156 DN0001 Benzene 1.16E-09 4.10E-14 1.16E-09 0.0001 10000.00 4.10E-10 1.57E-09

ONG_NEILA1090032 DN0001 Benzene 6.54E-10 5.08E-11 6.04E-10 0.0619 16.15 8.21E-10 1.42E-09

ONG_NEITX461001M DN0006 Benzene 5.50E-10 1.65E-12 5.49E-10 0.0256 39.01 6.42E-11 6.13E-10

ONG_NEI2TX07186 DN0006 Benzene 5.37E-10 1.14E-11 5.25E-10 0.0278 35.97 4.11E-10 9.37E-10

ONG_NEI12470 DN0002 Benzene 4.52E-10 1.10E-10 3.42E-10 0.0055 182.43 2.00E-08 2.04E-08

ONG_NEI7500 DN0001 Benzene 7.09E-11 5.37E-11 1.72E-11 0.0001 10000.00 5.37E-07 5.37E-07

* shading incidates facilities with more than one glycol dehdrator controlled to less than 1 tpy benzene
A B C D E F G H I J

Immunological 

HI

Immunologic

al System HI 

from Source 

ID/HAP

Immunologic

al System HI 

from Other 

Points

Controlled 

Dehydrator 

Benzene 

Emissions 

(tpy)

Factor for 1 

tpy Benzene 

Adjustment

Adjusted HI 

From 

Overcontroll

ed Point 

MACT 

Allowable 

Immunologi

cal HI at 

Facility Due 

ot Dehy 1 

TPY Limit

(from risk 

modeling 

results)

(from risk 

modeling 

results)

(Column D - 

Column E)

(from NEI 

data)

 (1/Column 

G)

(Column E * 

Column H)

(Column F + 

Column I)

ONG_NEI11191 DN0007 Benzene 2.54E-03 1.40E-03 1.14E-03 0.8500 1.18 1.64E-03 2.79E-03

ONG_NEI11771 DN0004 Benzene 1.52E-04 9.62E-06 1.42E-04 0.0026 388.22 3.73E-03 3.88E-03

ONG_NEI11921 DN0003 Benzene 1.88E-03 6.40E-04 1.24E-03 0.0166 60.13 3.85E-02 3.97E-02

ONG_NEI11929 DN0004 Benzene 4.54E-06 4.41E-08 4.46E-06 0.0116 86.21 3.80E-06 1.21E-05

ONG_NEI11929 DN0005 Benzene 4.54E-06 4.37E-08 0.0115 86.96 3.80E-06

ONG_NEI12047 DN0005 Benzene 2.13E-03 1.42E-03 7.11E-04 0.2368 4.22 6.01E-03 6.72E-03

ONG_NEI12470 DN0002 Benzene 1.77E-06 4.69E-07 1.30E-06 0.0055 182.43 8.55E-05 8.68E-05

ONG_NEI12503 DN0002 Benzene 4.93E-05 1.16E-05 3.77E-05 0.0600 16.67 1.93E-04 2.31E-04

ONG_NEI12819 DN0001 Benzene 3.00E-03 2.59E-03 4.06E-04 0.6640 1.51 3.90E-03 4.31E-03

ONG_NEI13085 DN0003 Benzene 2.52E-04 1.73E-04 7.99E-05 0.1622 6.17 1.06E-03 1.14E-03

ONG_NEI13271 DN0005 Benzene 1.90E-03 1.69E-03 2.13E-04 0.1580 6.33 1.07E-02 1.09E-02

ONG_NEI13316 DN0001 Benzene 5.33E-04 5.33E-04 0.00E+00 0.0700 14.29 7.61E-03 7.61E-03

ONG_NEI2CO045363 DN0003 Benzene 1.10E-03 9.65E-04 7.98E-05 0.2050 4.88 4.71E-03 5.08E-03

ONG_NEI2CO045363 DN0001 Benzene 1.10E-03 5.95E-05 0.2050 4.88 2.90E-04

ONG_NEI2CO0552 DN0001 Benzene 2.41E-03 2.79E-04 2.13E-03 0.5000 2.00 5.58E-04 2.69E-03

ONG_NEI2TX07156 DN0001 Benzene 4.56E-06 1.76E-10 4.56E-06 0.0001 10000.00 1.76E-06 6.32E-06

ONG_NEI2TX07186 DN0006 Benzene 2.26E-06 4.89E-08 2.21E-06 0.0278 35.97 1.76E-06 3.97E-06

ONG_NEI2TX1520 DN0001 Benzene 1.14E-03 1.14E-03 0.00E+00 0.1324 7.55 8.60E-03 8.60E-03

ONG_NEI2TX1619 DN0005 Benzene 1.88E-05 1.44E-05 3.28E-06 0.0600 16.67 2.40E-04 4.83E-04

ONG_NEI2TX1619 DN0015 Benzene 1.88E-05 1.12E-06 0.0047 213.69 2.40E-04

ONG_NEI2TX20371 DN0003 Benzene 3.21E-04 3.02E-04 1.88E-05 0.1328 7.53 2.27E-03 2.29E-03

ONG_NEI2TX39139 DN0002 Benzene 1.84E-05 4.74E-07 1.79E-05 0.1621 6.17 2.92E-06 2.09E-05

ONG_NEI2TX39520 DN0003 Benzene 3.31E-04 2.84E-04 4.72E-05 0.2868 3.49 9.89E-04 1.04E-03

ONG_NEI2TX42343 DN0002 Benzene 4.93E-03 1.43E-03 3.50E-03 0.1032 9.69 1.38E-02 1.73E-02

ONG_NEI6094 DN0001 Benzene 6.71E-06 1.22E-06 5.37E-06 0.1410 7.09 8.63E-06 2.24E-05

ONG_NEI6094 DN0002 Benzene 6.71E-06 1.30E-07 0.0155 64.60 8.41E-06

ONG_NEI6453 DN0015 Benzene 1.71E-04 2.63E-07 1.71E-04 0.1633 6.12 1.61E-06 1.72E-04

ONG_NEI6456 DN0007 Benzene 3.50E-04 6.81E-10 3.50E-04 0.0009 1100.50 7.49E-07 3.52E-04

ONG_NEI6456 DN0016 Benzene 3.50E-04 4.72E-10 0.0008 1214.28 5.73E-07

ONG_NEI6483 DN0003 Benzene 1.07E-04 5.63E-05 5.05E-05 0.0093 107.01 6.03E-03 6.08E-03

ONG_NEI6512 DN0004 Benzene 8.82E-05 5.90E-05 2.92E-05 0.0163 61.35 3.62E-03 3.65E-03

ONG_NEI6855 DN0004 Benzene 1.78E-05 3.73E-06 1.41E-05 0.0200 50.00 1.86E-04 2.01E-04

ONG_NEI7375 DN0001 Benzene 4.97E-05 5.82E-09 4.97E-05 0.0005 2000.00 1.16E-05 6.13E-05

ONG_NEI7410 DN0006 Benzene 1.22E-02 7.05E-03 5.10E-03 0.5160 1.94 1.37E-02 1.88E-02

ONG_NEI7436 DN0002 Benzene 1.44E-05 2.49E-08 1.43E-05 0.0220 45.45 1.13E-06 1.77E-05

ONG_NEI7436 DN0010 Benzene 1.44E-05 1.64E-08 0.0145 68.97 1.13E-06

ONG_NEI7436 DN0011 Benzene 1.44E-05 1.64E-08 0.0145 68.97 1.13E-06

ONG_NEI7449 DN0008 Benzene 1.25E-04 6.77E-05 5.75E-05 0.0891 11.22 7.60E-04 8.17E-04

ONG_NEI7500 DN0001 Benzene 2.29E-07 2.29E-07 0.00E+00 0.0001 10000.00 2.29E-03 2.29E-03

ONG_NEI7694 DN0006 Benzene 9.34E-05 7.75E-05 1.58E-05 0.0820 12.20 9.46E-04 9.61E-04

ONG_NEI7785 DN0006 Benzene 1.86E-04 1.93E-06 1.83E-04 0.5000 2.00 3.86E-06 1.94E-04

ONG_NEI7785 DN0002 Benzene 1.86E-04 6.44E-07 0.1670 5.99 3.86E-06

ONG_NEI7785 DN0005 Benzene 1.86E-04 6.44E-07 0.1670 5.99 3.86E-06

ONG_NEI7787 DN0002 Benzene 2.07E-03 4.27E-04 1.64E-03 0.9817 1.02 4.35E-04 2.08E-03

ONG_NEI7998 DN0010 Benzene 6.57E-05 8.14E-06 5.76E-05 0.5200 1.92 1.57E-05 7.32E-05

Facility ID Source ID HAP

Table A-2. Oil and Natural Gas Production Facilities with Glycol Dehydrators Controlled to Less Than 1 TPY – MACT 

Allowable Non-Cancer TOSHI
A B C D E F G H I J

Immunological 

HI

Immunologic

al System HI 

from Source 

ID/HAP

Immunologic

al System HI 

from Other 

Points

Controlled 

Dehydrator 

Benzene 

Emissions 

(tpy)

Factor for 1 

tpy Benzene 

Adjustment

Adjusted HI 

From 

Overcontroll

ed Point 

MACT 

Allowable 

Immunologi

cal HI at 

Facility Due 

ot Dehy 1 

TPY Limit

(from risk 

modeling 

results)

(from risk 

modeling 

results)

(Column D - 

Column E)

(from NEI 

data)

 (1/Column 

G)

(Column E * 

Column H)

(Column F + 

Facility ID Source ID HAP Column I)

ONG_NEI8007 DN0051 Benzene 4.08E-03 1.28E-04 3.89E-03 0.0129 77.52 9.90E-03 1.52E+00

ONG_NEI8007 DN0005 Benzene 4.08E-03 6.53E-05 0.00004 23071.24 1.51E+00

ONG_NEIAL0530007 DN0002 Benzene 1.96E-03 2.29E-04 1.73E-03 0.8600 1.16 2.66E-04 2.00E-03

ONG_NEIAL10190 DN0002 Benzene 3.07E-03 2.13E-03 9.43E-04 0.5700 1.75 3.73E-03 4.67E-03

ONG_NEICA0592118 DN0027 Benzene 9.52E-03 5.37E-03 4.15E-03 0.0744 13.45 7.23E-02 7.64E-02

ONG_NEICA1115664 DN0022 Benzene 6.02E-02 5.92E-02 1.02E-03 0.2916 3.43 2.03E-01 2.04E-01

ONG_NEICO0186 DN0001 Benzene 3.09E-04 5.46E-10 3.09E-04 0.0005 2000.00 1.09E-06 3.10E-04

ONG_NEICO1230048 DN0003 Benzene 8.36E-04 2.98E-04 3.50E-04 0.3060 3.27 9.75E-04 2.30E-03

ONG_NEICO1230048 DN0004 Benzene 8.36E-04 1.88E-04 0.1925 5.19 9.75E-04

ONG_NEICO1230184 DN0001 Benzene 2.03E-03 8.15E-04 1.21E-03 0.2240 4.46 3.64E-03 4.85E-03

ONG_NEILA0070200$6 DN0002 Benzene 4.05E-04 1.01E-04 3.04E-04 0.0155 64.60 6.53E-03 6.84E-03

ONG_NEILA0070200$8 DN0001 Benzene 5.80E-04 1.95E-04 3.84E-04 0.0464 21.53 4.20E-03 4.59E-03

ONG_NEILA0075 DN0001 Benzene 6.74E-05 1.02E-06 6.63E-05 0.7280 1.37 1.39E-06 6.91E-05

ONG_NEILA0075 DN0002 Benzene 6.74E-05 6.48E-08 0.0464 21.53 1.39E-06

ONG_NEILA0098 DN0003 Benzene 5.84E-06 1.76E-06 4.07E-06 0.0020 500.00 8.82E-04 8.87E-04

ONG_NEILA0123 DN0001 Benzene 5.97E-05 2.44E-06 5.70E-05 0.4980 2.01 4.89E-06 6.68E-05

ONG_NEILA0123 DN0002 Benzene 5.97E-05 2.26E-07 0.0464 21.53 4.87E-06

ONG_NEILA0450042 DN0004 Benzene 5.66E-03 1.69E-04 5.49E-03 0.0310 32.30 5.47E-03 1.10E-02

ONG_NEILA0690006 DN0001 Benzene 1.02E-04 4.60E-05 5.64E-05 0.1075 9.30 4.28E-04 4.84E-04

ONG_NEILA0750033 DN0002 Benzene 8.71E-06 5.45E-07 7.62E-06 0.2322 4.31 2.35E-06 1.23E-05

ONG_NEILA0750033 DN0003 Benzene 8.71E-06 5.45E-07 0.2322 4.31 2.35E-06

ONG_NEILA0770023 DN0004 Benzene 6.33E-03 5.66E-04 5.76E-03 0.1425 7.02 3.97E-03 9.73E-03

ONG_NEILA1010013 DN0001 Benzene 1.62E-05 1.27E-07 1.60E-05 0.0825 12.12 1.54E-06 1.91E-05

ONG_NEILA1010013 DN0002 Benzene 1.62E-05 7.24E-08 0.0470 21.28 1.54E-06

ONG_NEILA1090032 DN0001 Benzene 2.53E-06 2.17E-07 2.31E-06 0.0619 16.15 3.51E-06 5.82E-06

ONG_NEILA2210126$2 DN0001 Benzene 6.53E-06 5.15E-08 6.47E-06 0.0155 64.60 3.33E-06 9.80E-06

ONG_NEIMI055B915 DN0008 Benzene 5.26E-04 3.15E-04 2.11E-04 0.1416 7.06 2.23E-03 2.44E-03

ONG_NEIMI14392 DN0009 Benzene 6.81E-04 3.92E-05 6.42E-04 0.0265 37.68 1.48E-03 2.12E-03

ONG_NEIMIB9135 DN0005 Benzene 8.43E-03 5.08E-04 7.93E-03 0.1416 7.06 3.59E-03 1.15E-02

ONG_NEIMIB9136 DN0005 Benzene 3.14E-03 7.42E-04 2.40E-03 0.2371 4.22 3.13E-03 5.53E-03

ONG_NEIMIB9142 DN0009 Benzene 4.83E-03 4.47E-04 4.38E-03 0.0619 16.14 7.21E-03 1.16E-02

ONG_NEIMIB9160 DN0008 Benzene 3.57E-03 5.48E-04 3.02E-03 0.1310 7.64 4.18E-03 7.21E-03

ONG_NEIMIN6015 DN0015 Benzene 3.45E-04 1.27E-04 1.32E-04 0.1600 6.25 7.93E-04 1.72E-03

ONG_NEIMIN6015 DN0006 Benzene 3.45E-04 8.57E-05 0.1080 9.26 7.93E-04

ONG_NEIOK2038 DN0001 Benzene 2.61E-02 1.87E-02 7.47E-03 0.8400 1.19 2.22E-02 2.97E-02

ONG_NEIOK2720 DN0003 Benzene 1.90E-05 3.69E-09 1.90E-05 0.0074 134.58 4.96E-07 1.95E-05

ONG_NEITX039674 DN0002 Benzene 5.12E-05 2.43E-05 2.69E-05 0.0156 64.27 1.56E-03 1.59E-03

ONG_NEITX039675 DN0002 Benzene 4.96E-05 2.43E-05 2.53E-05 0.0156 64.28 1.56E-03 1.59E-03

ONG_NEITX039676 DN0003 Benzene 4.95E-05 2.43E-05 2.52E-05 0.0156 64.27 1.56E-03 1.59E-03

ONG_NEITX039692 DN0003 Benzene 6.30E-05 2.71E-05 3.58E-05 0.0161 62.11 1.68E-03 1.72E-03

ONG_NEITX067CG00 DN0002 Benzene 4.52E-04 2.07E-04 2.45E-04 0.1007 9.93 2.05E-03 2.30E-03

ONG_NEITX157312F DN0001 Benzene 6.36E-05 9.03E-07 6.27E-05 0.2916 3.43 3.10E-06 6.58E-05

ONG_NEITX161629 DN0004 Benzene 9.12E-05 2.65E-05 4.02E-05 0.0139 71.78 1.91E-03 3.70E-03

ONG_NEITX161629 DN0006 Benzene 9.12E-05 2.44E-05 0.0139 71.78 1.75E-03

ONG_NEITX18630 DN0019 Benzene 1.45E-04 2.92E-09 1.44E-04 0.1685 5.93 1.73E-08 1.62E-04

ONG_NEITX18630 DN0017 Benzene 1.45E-04 7.72E-07 0.0904 11.06 8.53E-06

ONG_NEITX18630 DN0018 Benzene 1.45E-04 7.37E-08 0.9147 1.09 8.06E-08

ONG_NEITX18630 DN0016 Benzene 1.45E-04 3.95E-08 0.0159 62.89 2.49E-06

ONG_NEITX18630 DN0011 Benzene 1.45E-04 1.34E-08 0.0038 261.01 3.50E-06

ONG_NEITX18630 DN0009 Benzene 1.45E-04 2.92E-09 0.0007 1410.47 4.11E-06

ONG_NEITX215294O DN0001 Benzene 1.78E-05 6.36E-08 1.78E-05 0.2004 4.99 3.18E-07 1.81E-05
A B C D E F G H I J

Immunological 

HI

Immunologic

al System HI 

from Source 

ID/HAP

Immunologic

al System HI 

from Other 

Points

Controlled 

Dehydrator 

Benzene 

Emissions 

(tpy)

Factor for 1 

tpy Benzene 

Adjustment

Adjusted HI 

From 

Overcontroll

ed Point 

MACT 

Allowable 

Immunologi

cal HI at 

Facility Due 

ot Dehy 1 

TPY Limit

(from risk 

modeling 

results)

(from risk 

modeling 

results)

(Column D - 

Column E)

(from NEI 

data)

 (1/Column 

G)

(Column E * 

Column H)

(Column F + 

Facility ID Source ID HAP Column I)

ONG_NEITX25152 DN0006 Benzene 3.47E-05 1.01E-05 2.46E-05 0.0143 70.12 7.09E-04 7.34E-04

ONG_NEITX42345 DN0001 Benzene 3.01E-04 5.00E-05 2.51E-04 0.0376 26.58 1.33E-03 1.58E-03

ONG_NEITX461001M DN0006 Benzene 2.13E-06 7.03E-09 2.12E-06 0.0256 39.01 2.74E-07 2.40E-06

ONG_NEITX461002K DN0006 Benzene 6.51E-06 1.08E-08 6.50E-06 0.0079 126.58 1.36E-06 7.86E-06

ONG_NEITX461006C DN0022 Benzene 2.49E-05 4.02E-08 2.48E-05 0.0431 23.22 9.33E-07 2.57E-05

ONG_NEITXRCI0100 DN0005 Benzene 7.54E-06 1.23E-08 7.53E-06 0.0114 87.72 1.08E-06 8.60E-06

ONG_NEITXRGJ0139 DN0003 Benzene 6.73E-04 1.27E-04 5.46E-04 0.0431 23.20 2.94E-03 3.49E-03

ONG_NEITXRHX1519 DN0001 Benzene 1.18E-04 1.18E-04 0.00E+00 0.0001 10000.00 1.18E+00 1.18E+00

ONG_NEITXRPE0042 DN0005 Benzene 5.10E-06 4.55E-07 4.65E-06 0.1000 10.00 4.55E-06 9.20E-06

ONG_NEITXRPE0106 DN0007 Benzene 2.68E-05 6.89E-10 2.68E-05 0.0008 1291.99 8.90E-07 2.77E-05

ONG_NEITXRSQ0088 DN0002 Benzene 1.81E-05 6.01E-07 1.75E-05 0.6009 1.66 1.00E-06 1.85E-05

ONG_NEITXRUA0156 DN0004 Benzene 1.50E-03 8.11E-04 6.89E-04 0.2840 3.52 2.86E-03 3.55E-03
A B C D E F G H I J

Facility MIR

Cancer Risk 

from Source 

ID/HAP

Cancer Risk 

From Other 

Points

Controlled 

Dehydrator 

Benzene 

Emissions 

(tpy)

Factor for 1 

tpy Benzene 

Adjustment

Adjusted 

Cancer Risk 

From 

Overcontroll

ed Point 

MACT 

Allowable 

MIR at 

Facility Due 

to Dehy 1 

tpy Limit

(from risk 

modeling 

results)

(from risk 

modeling 

results)

(Column D - 

Column E)

(from NEI 

data)

 (1/Column 

G)

(Column E * 

Column H)

(Column F + 

Column I)

NGT_NEI11118 DN0001 Benzene 2.89E-08 2.04E-08 8.47E-09 0.10 10.13 2.07E-07 4.17E-07

NGT_NEI11118 DN0002 Benzene 2.89E-08 5.86E-09 2.30E-08 0.03 35.34 2.07E-07

NGT_NEI12421 DN0011 Benzene 8.81E-08 5.01E-08 3.80E-08 0.32 3.08 1.54E-07 3.37E-07

NGT_NEI12421 DN0012 Benzene 8.81E-08 9.54E-09 7.85E-08 0.06 16.18 1.54E-07

NGT_NEI12805 DN0003 Benzene 5.04E-09 6.50E-11 4.97E-09 0.47 2.13 1.38E-10 5.11E-09

NGT_NEI13099 DN0006 Benzene 5.98E-08 1.18E-09 5.87E-08 0.01 113.64 1.34E-07 1.92E-07

NGT_NEI13136 DN0005 Benzene 1.29E-07 6.23E-09 1.23E-07 0.01 153.85 9.58E-07 1.08E-06

NGT_NEI13256 DN0007 Benzene 8.08E-10 6.00E-11 7.48E-10 0.001 785.88 4.71E-08 9.50E-08

NGT_NEI13256 DN0009 Benzene 8.08E-10 6.00E-11 7.48E-10 0.001 785.88 4.71E-08

NGT_NEI2OK3163 DN0010 Benzene 7.03E-08 2.27E-09 6.80E-08 0.02 56.37 1.28E-07 1.96E-07

NGT_NEI2TX21310 DN0001 Benzene 3.89E-08 1.06E-08 2.82E-08 0.09 10.98 1.17E-07 1.45E-07

NGT_NEI7244 DN0004 Benzene 1.43E-08 7.38E-09 6.89E-09 0.05 20.62 1.52E-07 1.59E-07

NGT_NEI7431 DN0001 Benzene 1.07E-08 9.61E-10 9.77E-09 0.01 90.91 8.74E-08 9.72E-08

NGT_NEI8351 DN0017 Benzene 1.20E-09 1.65E-10 1.04E-09 0.002 434.78 7.17E-08 7.27E-08

NGT_NEILA0010059 DN0004 Benzene 1.41E-07 9.19E-09 1.32E-07 0.02 64.60 5.94E-07 7.25E-07

NGT_NEILA1010014 DN0002 Benzene 9.23E-07 5.32E-07 3.91E-07 0.14 7.18 3.82E-06 4.21E-06

NGT_NEILA13384 DN0003 Benzene 1.04E-07 3.59E-08 6.81E-08 0.14 7.17 2.58E-07 5.52E-07

NGT_NEILA13384 DN0004 Benzene 1.04E-07 3.13E-08 7.27E-08 0.12 8.23 2.58E-07

NGT_NEIOK1056 DN0003 Benzene 1.24E-08 2.06E-09 1.03E-08 0.07 14.50 2.99E-08 4.03E-08

NGT_NEIOK2226 DN0005 Benzene 4.24E-08 1.00E-08 3.24E-08 0.08 13.16 1.32E-07 1.64E-07

NGT_NEIOK2372 DN0002 Benzene 2.58E-07 2.57E-08 2.32E-07 0.27 3.68 9.45E-08 3.26E-07

NGT_NEIOK401491548DN0010 Benzene 8.18E-07 5.65E-08 7.62E-07 0.20 5.11 2.89E-07 1.05E-06

NGT_NEITX065094I DN0009 Benzene 3.27E-09 6.94E-11 3.20E-09 0.36 2.77 1.92E-10 3.40E-09

NGT_NEITX157266K DN0004 Benzene 3.70E-07 1.96E-08 3.50E-07 0.01 100.00 1.96E-06 2.31E-06

NGT_NEITX161FI01 DN0002 Benzene 9.80E-09 1.19E-09 8.61E-09 0.005 203.14 2.43E-07 2.51E-07

NGT_NEITX36562 DN0001 Benzene 1.30E-08 4.75E-09 8.28E-09 0.03 36.91 1.75E-07 1.84E-07

NGT_NEITXRJE0157 DN0001 Benzene 5.73E-08 2.44E-08 3.29E-08 0.14 7.36 1.80E-07 2.13E-07

Facility ID Source ID HAP

* shading incidates facilities with more than one glycol dehdrator controlled to less than 1 tpy benzene

Table A-3. Natural Gas Transmission Facilities with Glycol Dehydrators Controlled to Less Than 1 TPY – MACT 

Allowable Cancer Risk
A B C D E F G H I J

Immunological HI

Immunological 

System HI from 

Source ID/HAP

Immunological 

System HI from 

Other Points

Controlled 

Dehydrator 

Benzene 

Emissions 

(tpy)

Factor for 1 

tpy Benzene 

Adjustment

Adjusted HI 

From 

Overcontroll

ed Point 

Adjusted 

Immunological 

HI

(from risk 

modeling results)

(from risk 

modeling 

results)

(Column D - 

Column E)

(from NEI 

data)

 (1/Column 

G)

(Column E * 

Column H)

(Column F + 

Column I)

NGT_NEI11118 DN0001 Benzene 1.12E-04 8.73E-05 0.00E+00 0.098700002 10.1 8.85E-04 1.77E-03

NGT_NEI11118 DN0002 Benzene 1.12E-04 2.50E-05 0.0283 35.3 8.85E-04

NGT_NEI12421 DN0011 Benzene 3.63E-04 2.14E-04 1.08E-04 0.324699998 3.1 6.60E-04 1.43E-03

NGT_NEI12421 DN0012 Benzene 3.63E-04 4.08E-05 0.061799999 16.2 6.60E-04

NGT_NEI12805 DN0003 Benzene 2.05E-05 2.78E-07 2.02E-05 0.469999999 2.1 5.91E-07 2.08E-05

NGT_NEI13136 DN0005 Benzene 5.00E-04 2.66E-05 4.73E-04 0.0065 153.8 4.10E-03 4.57E-03

NGT_NEI13256 DN0007 Benzene 3.12E-06 2.56E-07 2.61E-06 0.001272456 785.9 2.01E-04 4.06E-04

NGT_NEI13256 DN0009 Benzene 3.12E-06 2.56E-07 0.001272456 785.9 2.01E-04

NGT_NEI2OK3163 DN0010 Benzene 2.78E-04 9.70E-06 2.69E-04 0.01774008 56.4 5.47E-04 8.15E-04

NGT_NEI2TX21310 DN0001 Benzene 1.47E-04 4.55E-05 1.02E-04 0.0911 11.0 4.99E-04 6.01E-04

NGT_NEI7244 DN0004 Benzene 5.45E-05 3.16E-05 2.30E-05 0.048508128 20.6 6.50E-04 6.73E-04

NGT_NEI7431 DN0001 Benzene 4.13E-05 4.11E-06 3.72E-05 0.011 90.9 3.74E-04 4.11E-04

NGT_NEI8351 DN0017 Benzene 4.58E-06 7.04E-07 3.88E-06 0.0023 434.8 3.06E-04 3.10E-04

NGT_NEILA0010059 DN0004 Benzene 5.45E-04 3.93E-05 5.06E-04 0.01548 64.6 2.54E-03 3.04E-03

NGT_NEILA1010014 DN0002 Benzene 3.53E-03 2.27E-03 1.26E-03 0.139319998 7.2 1.63E-02 1.76E-02

NGT_NEILA13384 DN0003 Benzene 4.38E-04 1.54E-04 1.51E-04 0.1395 7.2 1.10E-03 2.35E-03

NGT_NEILA13384 DN0004 Benzene 4.38E-04 1.34E-04 0.1215 8.2 1.10E-03

NGT_NEIOK1056 DN0003 Benzene 4.96E-05 8.82E-06 4.07E-05 0.06894792 14.5 1.28E-04 1.69E-04

NGT_NEIOK2226 DN0005 Benzene 1.57E-04 4.28E-05 1.15E-04 0.076 13.2 5.63E-04 6.78E-04

NGT_NEIOK2372 DN0002 Benzene 7.87E-04 1.10E-04 6.77E-04 0.2715192 3.7 4.04E-04 1.08E-03

NGT_NEIOK401491548 DN0010 Benzene 3.17E-03 2.42E-04 2.92E-03 0.195729117 5.1 1.23E-03 4.16E-03

NGT_NEITX065094I DN0009 Benzene 1.37E-05 2.97E-07 1.34E-05 0.360599995 2.8 8.23E-07 1.42E-05

NGT_NEITX157266K DN0004 Benzene 1.44E-03 8.37E-05 1.36E-03 0.01 100.0 8.37E-03 9.73E-03

NGT_NEITX161FI01 DN0002 Benzene 3.78E-05 5.10E-06 3.27E-05 0.00492264 203.1 1.04E-03 1.07E-03

NGT_NEITX36562 DN0001 Benzene 5.01E-05 2.03E-05 2.98E-05 0.02709 36.9 7.49E-04 7.79E-04

NGT_NEITXRJE0157 DN0001 Benzene 2.45E-04 1.04E-04 1.41E-04 0.135800004 7.4 7.68E-04 9.09E-04

Facility ID Source ID HAP

* shading incidates facilities with more than one glycol dehdrator controlled to less than 1 tpy benzene

Table A-4. Natural Gas Transmission Facilities with Glycol Dehydrators Controlled to Less Than 1 TPY – MACT Allowable Non-Cancer 

TOSHI