Approach to Developing
De_ Minimi's Values for the
Noncriteria Air Pollutants
June 1980
New Source Review Office
Standards Implementation Branch
Control Programs Development Division
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
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BACKGROUND
In the Alabama Power decision, the court indicated that emissions
from certain small modifications, and emissions of certain pollutants at
new sources, could be exempted from some or all PSD review requirements
on the grounds that such emissions would be de minimi's. In other words,
the Administrator may determine levels below which there is no practical
value in conducting an extensive PSD review. The September 5 proposal
incorporated the de minimi's concept and requested comments on the approach
taken. At that time, the Administrator noted that because of the urgency
associated with the proposal, the de minimi's numbers published were not
supported by extensive analysis, and that a more thorough analysis would
be undertaken prior to promulgation.
Accordingly, a reassessment of the de mini mis issue has been
undertaken. A significant part of the reassessment involved the use of
reasonable judgment, especially since this is an area in which not only
are data limited, but criteria for decision making are almost non-existent.
The first task was to identify the objectives to be met in selecting de_
minimi's values. A primary objective identified was to assure meaningful
permit reviews, i.e. obtaining useful air quality information or obtaining
greater emission reductions as a result of BACT analysis beyond what
would be expected from normal state permit or NSPS/NESHAPS processing.
There were three basic alternatives available for specifying de_
minimi's cutoffs--one based solely on air quality impact, one based
solely on emission rate, and one based on a combination of these, such
as was proposed on September 5. It is recommended that de minimis
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cutoffs be specified in terms of emission rate for applicability,
BACT and air quality analysis purposes, with no provisions for case-by-
case demonstration of a source's air quality impact. This approach is
recommended for several reasons. First, the Congress specified emission
rates, not projected air quality impacts, in the Clean Air Act as the
criteria for determining which sources are major and, therefore, subject
to PSD review. Moreover, the court, in the Alabama Power decision,
continually refers to emission rate rather than air quality concentration
in its discussion of the de minimis issue. Therefore, it seems inconsistent
with the existing guidance to abandon the emission rate concept.
Second, if applicability decisions depended on confirming a
demonstration by the source that its impact would be less than a given
air quality level, the review process would become excessively complex
and greatly increase the resources needed by reviewing authorities
to carry out the program. In addition, such an approval requirement would
create an atmosphere of uncertainty as to whether individual sources
needed to apply for a permit or not, and could lead to uneven application
of the regulations from state to state. Third, the task of establishing
de minimis air quality levels for noncriteria pollutants, with proper
consideration of threshold levels and factors of safety (if any), is
very complex and cannot be done in the time available.
Finally, given the inclusion of a de minimis exclusion for
monitoring, it serves little purpose to have a separate table to permit
an exclusion from the remaining air quality impact analysis requirement.
(A separate table would be required because monitoring capability and
concern for potential effects are unlikely to be associated with the
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same air quality concentrations.) Besides making the regulations more
complicated, the demonstration necessary to earn an exemption from air
quality impact analysis would in itself be_ an air quality impact analysis.
In analyzing the basis for de minimis emission rates, it is apparent
that two distinct classes of pollutants are involved. The first consists
of the criteria pollutants for which extensive health and welfare infor-
mation has been reviewed and criteria documents developed. The other
class, which is primarily addressed in this paper, consists of the
noncriteria pollutants for which no ambient air quality criteria documents
exist. Rather, these pollutants are only regulated within either the
New Source Performance Standards (NSPS) or the National Emission Standards
for Hazardous Air Pollutants (NESHAPs), both of which are based on a
national emissions standard, rather than an air quality management
appproach. The regulations developed under both these regulatory alter-
natives generally specify emission limitations and/or equipment performance
standards, rather than minimum air quality levels that must be achieved
as in the case of the criteria pollutants. Thus, it appears reasonable
to develop de minimis cutoffs from separate perspectives—that is, to
base criteria pollutant de minimis emission cutoffs on air quality
"design values" and to base the noncriteria pollutants de minimis values
on the emission rates embodied in the NSPS and NESHAPs.
APPROACH
Recommended noncriteria pollutant emission rates were developed
from the existing emission standards (NSPS and NESHAPs) as found in 40
CFR Parts 60 and 61. In general, a fraction of the applicable standard
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was used to determine the noncriteria pollutant de mini mis emission
rates. Since the NSPS represents the best adequately demonstrated
control technology on a nationwide basis, and the NESHAPs are established
with an ample margin of safety to protect the public health from hazardous
pollutants, a small percentage of these standards would, for PSD purposes,
prevent a significant change from escaping review.
In this analysis emission levels representing 20 percent of an NSPS
emission standard and, because of their greater impact on health, 10
percent of an NESHAP emission standard were determined. These values are
believed to be stringent, but fair, criteria for defining insignificant
changes in the context of PSD review objectives. The air quality impacts
of the resulting de minjmis emission rates for NSPS pollutants were then
calculated using recommended EPA modeling methods, and the concentrations
were compared to available health and welfare data to assure that signi-
ficant adverse effects were avoided. In the case of fluorides, this
check resulted in a reduction of the emission rate originally indicated.
No adjustment based on resultant effect was made for the hazardous
pollutants since the NESHAP emission rate is, in itself, intended to protect
the public health with an ample margin of safety; therefore, ten percent
of such a value is believed to be sufficiently stringent for use as a de
mini mis value.
Other options were reviewed before using the approach mentioned
above. Some commenters to the September 5, 1979 proposal of PSD regula-
tions suggested the de minimi's emission rate should be based on existing
monitoring technology. Their argument was that if we could not reasonably
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measure the pollutant either in the stack gas or in the atmosphere by
accepted techniques, then the pollutant emission rate or concentration
was too small for PSD program review. However, this approach is not
recommended. Although such a criterion may be useful for determining
significance for monitoring purposes, it does not necessarily have a
relationship to environmental effects. Moreover, such an approach
creates the potential of having a changing basis for deriving de mini mis
values—as soon as EPA approved a more sensitive technique to measure a
pollutant, the regulatory decision-making process would be altered for
that pollutant. Since EPA is expecting to improve monitoring capabilities
over time, the constantly changing de minimi's values could prove to be
impractical.
Another approach considered was to evaluate the existing health and
welfare studies, assess thresholds and factors of safety (if any) and
decide upon de minimis air quality concentrations for each pollutant.
Then, using accepted modeling techniques, establish representative de_
minimis emission rates. In effect, this approach would be similar to
that for setting or revising a national ambient air quality standard.
It too was rejected, primarily for two reasons. First, the process
could be expected to be quite time consuming, given our experience in
developing the NAAQS, and certainly could not be done in the time available.
Second, standard setting, with extensive public input, has already been
undertaken for each of the noncriteria pollutants. Given the review
already performed on these pollutants, it is not clear what added insight
would be gained from an exhaustive analysis of impacts from emissions at
rates substantially smaller than those represented by the existing
standards. By making a check of the expected impact of the NSPS pollutant
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de minimi's emission rates, it is believed that unacceptable environmental
consequences can adequately be avoided.
The following portion of this paper discusses the results of the
recommended approach for defining the noncriteria pollutant de minimi's
emission rates. The NSPS pollutants are presented first and the NESHAPs
pollutants second.
NSPS POLLUTANTS
Fluorides. The EPA report Primary Aluminum: Guidelines for
Control of Fluoride Emissions from Existing Primary Aluminum Plants,
EPA-450/2-78-049b, indicates that the average primary aluminum plant
produces 157,000 tons of aluminum per year. The NSPS for primary aluminum
plants is set at about 2 pounds of fluoride emissions for each ton of
aluminum produced and reflects a well controlled plant. Applying the
2-pound-per-ton-of-aluminum emission rate to the average primary aluminum
plant production rate of 157,000 tons per year yields a fluoride emission
rate of 157 tons per year for the average well controlled plant. Twenty
percent of the average plant's fluoride emission rate equals about 30
tons per year.
Low levels (about 1.0 microgram per cubic meter 24 hour average) of
floruides have been observed to produce effects on vegetation. See
Health Impacts, Emissions, and Emission Factors for Noncriteria Pollutants
Subject to^ De_ Minimis Guidelines and Emitted from Stationary Conventional
Combustion Processes, EPA-450/2-80-074. The possible impacts from a 30
ton per year de minimis emission rate were calculated using average
stack emission parameters as defined in the support document Impact of
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Proposed and Alternative De_ Mini mis Levels for Criteria Pollutants, EPA-
450/2-80-072. This report provides a ratio of an expected maximum air
quality concentration per ton of emissions for a variety of source
categories. The source data used was taken from the existing PSD permit
files. Using the population of sources making less than 100 ton per
year changes (i.e., those expected to be most affected by the de minimis
values), the resultant ratio is 0.325 micrograms per cubic meter (ug/m )
per ton of emissions. To calculate the maximum 24-hour concentration
expected under this average condition, the 30-ton-per-year fluoride
emission rate was multiplied by the impact factor of 0.325, giving a
maximum 24-hour impact of 10 micrograms per cubic meter (10 times the
concentration where effects have been observed). Thus, to protect
sensitive vegetation, it is recommended that the de minimis fluoride
emission rate be limited to 3 tons per year.
An alternative would be to base the emission rate on the NSPS
for phosphate fertilizer plants. Fertilizer plants typically emit much
less flourides than aluminum plants—a well controlled 500-ton-per-day
plant would emit 10 pounds of fluorides per day (about 2 tons per
year). See page 22, Background Information for Standards of
Performance: Phosphate Fertilizer Industry, EPA-450/2-74-019a, October
1974. A 20 percent de minimi's value would then be less than 0.5 ton,
which is unrealistic in view of both aluminum plants and coal fired
power plants. A well controlled coal fired power plant of 500 megawatt
capacity could emit 10 tons of fluorides per year. Minor changes at
such plants could trigger review with little prospect for meaningful
reduction in emissions or improvement in air quality. Moreover, changes
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at a fertilizer plant that resulted in an increase of 0.5 ton per year
would probably be reviewed under NSPS and/or State new source review
requirements.
Sulfuric Acid Mist. The only sources for sulfuric acid mist emissions
under NSPS are sulfuric acid plants. An average plant size is about
1300 tons of acid production per day, according to page 4-2 of the
report A Review of Standards of Performance for New Stationary Sources -
Sulfuric Acid Plants, EPA-450/3-79-003, January 1979. A well controlled
plant emits 0.15 pound of sulfuric acid mist per ton of acid produced;
therefore, the sulfuric acid mist emission rate for the average plant
equals 195 pounds per day (35 tons per year). Applying the 20 percent
factor to the 35 tons per year of acid mist emissions equals 7 tons per
year. Thus, the suggested sulfuric acid mist de minimi's emission rate
is 7 tons per year.
The associated air quality concentration that would occur downwind
from a sulfuric acid plant making such a de minimi's change was evaluated.
As for the fluoride calculations, the impact factor of 0.325 was
applied to the emission rate of 7 tons per year, yielding a 2 ug/m
maximum 24-hour concentration of sulfuric acid mist. This value is well
below concentrations known to produce any health or welfare effects.
See e.g., Health Impacts, Emissions, and Emission Factors for Noncriteria
Pollutants Subject tp_ De_ Minimi's Guidelines and Emitted from Stationary
Conventional Combustion Processes, EPA-450/2-80-074.
Total Reduced Sulfur. The total reduced sulfur compounds are
regulated for only the kraft pulp mill source category. A typical well
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controlled plant, from data on pages 2-3 and 8-5 of the Standards
Support and Environmental Impact Statement: Proposed Standards p_f_
Performance for Kraft Pulp Mills, EPA-450/2-76-014a, September 1976, has
a production rate of about 900 tons of pulp per day and emits 0.25 pound
of total reduced sulfur per ton of pulp produced. Thus, a typical pulp
mill will emit about 41 tons of total reduced sulfur to the atmosphere
each year. Twenty percent of the 41-ton-per-year figure equals a de
minimis emission rate of 8.3 tons per year. It is recommended that this
approximation be rounded to 10 tons for administrative purposes.
As for the other pollutants, the potential ambient impact was
checked, using a one hour averaging time because of a person's relatively
short-term sensitivity to odor effects. The calculated maximum impact
(8 micrograms per cubic meter, 1-hour average) from a 10 ton per year
emission rate is below nuisance levels. See page 9-2 of the above Standards
Support Document. The values shown estimate the level at which the presence
of the substance can be detected. Although the report shows odor thresholds
for some of the chemical components of total reduced sulfur to be in the
region of 8 ug/m , generally a multiple increase above the odor threshold
is necessary for the sulfur compound concentrations to become objectionable
in ambient air. See page 8-42 of Odors from Stationary and Mobile Sources,
National Academy of Sciences, Washington, D.C., January 1979.
Reduced Sulfur Compounds. Petroleum refineries are regulated for
their reduced sulfur compounds by the NSPS. A model refinery with a
sulfur recovery plant production rate of 100 long tons per day will emit
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about 47 tons of reduced sulfur compounds per year. This value is
calculated from data in the Standards Support; and Environmental impact
Statement: Proposed Standards of Performance for Petroleum Refinery
Sulfur Recovery Plants, EPA-450/2-76-016a, September 1976. The cte
minimis emission rate calculated using the 20 percent factor is 9.4
tons of reduced sulfur compounds per year. Using an emission rate
rounded to 10 tons per year (for consistency with TRS), the estimated 1-
hour maximum impact of 8 micrograms per cubic meter is below levels
where observed health and welfare effects have been observed. See Table
7.1 of the Standards Support document.
Hydrogen Sulfide. Like the other sulfur compounds, hydrogen sulfide
is specifically regulated by NSPS for only one source category. Under
Subpart J of 40 CFR 60, petroleum refineries are limited to 10 ppm of
hydrogen sulfide in the gases discharged into the atmosphere from a
Claus sulfur plant using a reduction control system not followed by
incineration. For an average facility of 100 long tons of sulfur produc-
tion per day, the NSPS emission limitation equates to 1.5 tons of hydrogen
sulfide emissions per year. At 20 percent, an emission rate of 0.3 ton
per year of hydrogen sulfide is indicated.
This emission rate is very low when compared to the other sulfur
compounds regulated only under the NSPS. The recommended reduced sulfur
compounds and the total reduced sulfur compounds de minimis emission
rates (which include hydrogen sulfide) is 10 tons per year. Since the
other sulfur species are regulated for similar potential welfare effects
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(odor) and the threshold values for odor are of the same magnitude, it
seems reasonable that the de minimi's rate for hydrogen sulfide be equal
to the other two sulfur compound de minimi's emission rates. Maximum one
hour concentrations from a 10-ton-per-year emission rate is estimated to
be 8 micrograms per cubic meter, below concentrations where perceptible
odors or other effects have been observed. See Table 7.1 of the Standards
Support Document for sulfur recovery plants. In view of the above, it is
recommended that a 10-ton-per-year de minimis emission rate for hydrogen
sulfide be used.
NESHAP POLLUTANTS
Mercury. The NESHAP limitation for mercury is given as an emission
rate, 2300 grams per day, which is approximately one ton per year. See
40 CFR 61.52(a). Using 10 percent of the regulated emission rate, the
calculated de minimis emission rate is 0.1 ton per year. To put this
emission rate into perspective, a well controlled 500 MW coal fired
power plant emits about 0.4 tons of mercury per year.
Beryllium. As in the case with mercury, the NESHAP limitation is
given as an emission rate of 10 grams of beryllium emitted per day. See
40 CFR 61.32(a). Ten percent of 10 grams per day equals 0.0004 ton per
year, the recommended de minimis emission rate for beryllium. The
example well controlled 500 MW boiler noted above would emit about
0.004 tons of beryllium per year.
For the hazardous air pollutants asbestos and vinyl chloride which
were regulated because they were found to be carcinogenic, no absolutely safe
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threshold of exposure can be identified. (Proposed policy for Regulation
of Airborne Carcinogens, 44 FR 60033, October 10, 1979.) Therefore,
no level of exposure can be presumed de minimi's from a health standpoint.
Based on this presumption, consideration was given to using a de minimi's
level of zero. However, setting de minimi's levels of zero would trigger
PSD reviews of sources emitting pollutants at levels well below the
level at which any NESHAP was set for that pollutant. This result seems
unnecessary given that the reviews are particularly resource intensive
and the NESHAP limit emissions of the subject pollutants to the extent
necessary to prevent unreasonable risk to the public. Therefore, as in
the case of mercury and beryllium, an attempt was made to establish de_
mini mis levels for asbestos and vinyl chloride that represent only a
small fraction of the estimated emissions allowable under the existing
standards.
Asbestos. The NESHAP is expressed in terms of visible emissions
and work practice standards rather than in numerical terms. Therefore,
estimates had to be made of the allowable emissions of asbestos from
various sources. It is impossible to estimate asbestos emissions on an
industry wide basis because of the lack of data, but rough estimates for
several specific sources were made. The emissions were calculated from
a very limited data base, and involve assumptions concerning plant
parameters such as plant size, gas stream flow rate, and gas stream temperature.
They are, however, the best estimates available on asbestos emissions.
Three plant categories covered by the asbestos NESHAP were looked at
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(see 40 CFR 61.23). These included asbestos milling operations, manufacturing
operations using asbestos in the process, and asbestos asphalt operations.
The details of the emission calculations are described in a staff memorandum
from G. Wood to J. Weigold dated June 19, 1980. The emissions estimates
for the three plant categories, based on the use of a bag-house as candidate
best available control, was as follows: asbestos milling, 0.2 tons per
year (TRY); operations using asbestos manufacturing, 0.07 TRY; and
asbestos asphalt, 0.04 TRY.
An estimate of the asbestos emissions from rock crushing operations
(not regulated by a NESHAP) was also made. Rock crushing was selected
since it is a common industrial operation in which asbestos can be, in a
small number of cases, a trace constituent of the raw material. Emissions
of asbestos from such operations would be controlled as part of the
total particulate emission control effort. A typical rock crushing
plant at 150-ton-per-hour production rate would, after application of cjood
controls, emit about 60 tons per year of particulates. Using an estimated
asbestos content in the rock of 0.1 percent, asbestos emissions would be
0.06 TRY.
Given the variation in emissions from the different source categories
that were examined, the question arose as to which source category should
be used to establish a de minimi's emission rate. The staff recommendation
is based on two considerations: (1) in view of the carcinogenicity of
the pollutant, the de minimis value should be based on a small source
of asbestos, and (2) such source type should represent the bulk of the
asbestos emitting facilities. Manufacturing operations using asbestos
fit these criteria. As noted above, they emit about the same as the
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asbestos asphalt and rock crushing operations, and considerably less
than an asbestos milling source. Further, these plants are by far the
most numerous of any of the categories examined. Therefore, it is
recommended that the asbestos de minimis emission rate be set at ten
percent of the calculated emissions from manufacturing operations using
asbestos -- i.e., 0.007 tons per year.
Vinyl Chloride. Unlike mercury and beryllium, the NESHAP standard
is expressed in parts per million of the stack gas. This concentration
limit must be combined with volume data to arrive at an emission rate.
It was therefore necessary to assume model plant characteristics in order
to develop expected emissions. Because vinyl chloride is a carcinogen
and because it is desired to establish a de minimis level representing a
small fraction of emissions allowed by the NESHAPs, these calculations
were based on a small regulated plant. In the Standard Support and
Environmental Impact Statement: Emission Standard for Vinyl Chloride,
EPA-450/2-75-009, October 1975, the Agency addressed the various sources
of vinyl chloride and the size range for the predominant source categories.
The Standard Support Document lists the existing (1975) polyvinyl chloride
plants on page 3-32, showing a range of plant production of 2 to 135
million kilograms per year. Capacity of small plants listed varies
from 2-15 million kilograms. Assuming that the smallest plant can apply
controls as effective as the typical plant mentioned above, the corresponding
controlled emission rate is about 6 tons of vinyl chloride per year.
Similarly, as shown on page 3-30 of the Standard Support Document,
the smallest ethylene-dichloride-to-vinyl-chloride plant manufactures 70
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million kilograms per year of products, and a well controlled plant
would emit about 17 tons per year of vinyl chloride. These two source
categories account for about 96 percent of all the vinyl chloride emissions,
Therefore, controlled emissions from a small plant appear to be roughly
10 tons per year for the above mix of sources. The recommended de_
minimis emission rate (10 percent of the small source emissions) is 1
ton of vinyl chloride emissions per year.
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Appendix
Example Calculations
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FLOURIDES
Regulations Governing Emissions:
New Source Performance Standards (NSPS), 40 CFR 60.192, 202, 212,
222, 232, 242.
Sources regulated:
Primary aluminum reduction plant, -^ 2 pounds per ton aluminum , wet
process phosphoric acid plants - 0.02 pound per tons of PO^B' suPer~'
phosphoric acid plants - 0.01, diammonium phosphate plants - 0.06,
triple superphosphate plants j 0.2, grannular triple superphosphate
storage facilities - 5.0 X 10 pounds per hour per ton PO,- stored.
Calculations:
According to the reference, "Background Information for Standards of
Performance: Phosphate Fertilizer Industry," EPA-450/2- 74-01 9a,
page 22, a typical 500 tons of P^O,- per day, well -controlled, would
emit (assuming continuous operation)
* 1
500 tons/day X 0.02 pound /ton X 365 days/year X 20QQ ton/pound
= 1.8 tons/year (20% = 0.36 ton/year)
For the superphosphoric acid plants, typically about 200 tons per day
P-Or production (see page 30) would emit:
200 tons/day X 0.01 pound /ton X 365 days/year
1
ton/pound =0.4 ton/year (20% = 0.08 ton/year)
2000
In the "Primary Aluminum: Guidelines for Control of Fluoride Emissions
from Existing Primary Aluminum Plants," EPA-450/2*78-049b, December 1979,
page 3-12, the average plant capacity is 157 X 10 tons per year. The
controlled emission rate would equal:
* NSPS omission limitation
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3 * 1
157 X 10 tons/year X 2 pounds /ton X O— ton/pound =
157 tons/year
**twenty percent would then equal:
20% X 157 tons/year = 32 tons/year
The air quality impact from a 30-ton per year source can be estimated.
From the PEDCo report, "Impact of Proposed and Alternative De Minimi's
Levels for Criteria Pollutants," EPA-450/2-80-072, 1980, page 4-31,
there is a factor that can be used to calculate an approximate 24 hour
impact from a tons per year emission rate:
30 tons/year X 0-325 ^7r^ararm/cubl'c meter
9.7 micrograms/cubic meter (24 hour average)
A tenfold reduction in emissions would give a tenfold reduction in the
air quality impact.
3 tons/year X 0.325 'nlcroqram/cublc meter __ Q^ microgram/cubic meter
ton/year (24 hour average)
A 500 MW pulverized dry bottom boiler operating at 60 percent capacity
and 40 percent overall efficiency burning typical bituminous coal and
controlled to meet the NSPS would emit 10 metric tons of fluorides per
year - EPA-450/2-80-074 "Health Impacts, Emissions, and Emission Factors
for Noncriteria Pollutants Subject to De Minimi's Guidelines and Emitted
from Stationary Conventional Combustion Process," June 1980, page 54.
10 metric tons/year X tons^ = n tons/year
* NSPS emission limitation
** See main text for explanation of twenty percent factor
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SULFURIC ACID MIST
Regulations Governing Emissions:
NSPS, 40 CFR 60.83
Sources regulated:
Sulfuric Acid Plants - 0.15 pound per ton acid produced.
Calculation:
The reference, "A Review of Standards of Performance for New Stationary
Sources - Sulfuric Acid Plants," EPA-450/3-79-003, January 1979, labels
a 1300-ton per day plant as typical for this source category. Emissions
from a typical well controlled plant operating continuously would be:
1300 tons acid/day X 0.15 pound*/ton acid X 365 days/year
X ton/pound = 35 tons/year
Twenty percent of that emission rate:
20% X 35 tons/year = 7 tons/year
The resulting air quality impact may be calculated by multiplying the
emission rate in tons per year by a correction factor as given in the
PEDCo report, "Impact of Proposed and Alternative De Minimis Levels for
Criteria Pollutants," EPA-450/2-80-072, page 4-31:
7 tons/year X 0.325 ^gram/cubic meter = 2.3 micrograms/cubic meter
*NSPS emission limitation
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TOTAL REDUCED SULFUR
Regulations Governing Emissions:
NSPS, 40 CFR 60.283
Source regulated:
Kraft pulp mills
Emission rate:
Varies for different processing units within the mill, but most
rates given in parts per million of gas stream.
Calculation:
The reference, "Standards Support and Environmental Impact Statement:
Proposed Standards of Performance for Kraft Pulp Mills," EPA-450/2-
76-014a, September 1976 defines a 900-ton per day pulp mill as typical
on page 8-4. On page 2-3, a well controlled mill emits 0.25 pounts
of TRS per ton of pulp produced. Assuming continuous operation, a
900-ton per day plant would emit:
900 tons/day X 0.25 pound/ton X 365 days/year X „.!-„ ton/pound
= 41 tons/year of TRS
Twenty percent of this rate would equal:
41 tons/day X 20% = 8.3 tons/year
The air quality impact from this emission rate is calculated by
applying the PEDCo factor from "Impact of Proposed and Alternative
De Minimis Levels for Criteria Pollutants," EPA-450/2-80-072, 1980
page 4-31:
8.3 tons/year X 0.325 meter = 2.7 micrograms/cutic meter
(24 hour average)
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Since odors are of concern, a shorter averaging time of 1 hour should
be considered. From page 4-21 of "Procedures for Evaluating Air Quality
Impact of New Stationary Sources," EPA-450/4-77-001, October 1977,
another correction factor can be used to estimate the 1-hour impact
from the 24-hour impact:
2.7 micrograms/cubic meter X «—j - 6.7 micrograms/cubic meter
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HYDROGEN SULFIDE
Regulations Governing Emissions:
NSPS, 40 CFR 60.104
Sources regulated:
Sulfur recovery plants at petroleum refineries
Emission rate:
0.001 percent by volume in discharge gases (10 ppmv)
Calculations:
Same references used as seen in "REDUCED SULFUR COMPOUNDS." From
the table 4-2 on page 4.24 of the Standards Support Document -
a 6000 ppmv equals 200 pounds per hour of hUS emissions; therefore,
a 100-long ton per day source meeting NSPS at 10 ppmv must equal:
10 parts per million-volume X = 0.33 pound/hour
assuming continuous operation. This rate in tons per year equals:
0.33 pound/hour X 8760 hours/year X ^^— ton/pound = 1.5 tons/year
2000
Twenty percent equals:
1.5 tons/year X 20% = 0.3 ton/year
See June 19, 1980 memo, G. H. Wood to J.B. Weigold, "Rough Estimates
of Asbestos Emission Levels."
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REDUCED SULFUR COMPOUNDS
Regulations Governing Emissions:
NSPS, 40 CFR 60.104(a)(2)
Sources regulated:
Sulfur recovery plants in petroleum refineries
Emission rate:
0.030 percent by volume of discharge gases
Calculation:
A typical well controlled refinery of 100 long tons per day (see
"Standards Support and Environmental Impact Statement: Proposed
Standards of Performance for Petroleum Refinery Sulfur Recovery
Plants," EPA-450/2-76-016a, September 1976 page 4.24,) puts out about
8 pounds per hour of total reduced sulfur:
8 pounds/hour X 8760 hours/year X pQQQ ton/pound = 35 tons/year
assuming continuous operation. However the emission rate is based
on 225 ppmv of total reduced sulfur in gas stream. The NSPS calls
for 300 ppmv; thus, a 100-long ton per day refinery meeting NSPS would
put out:
35 tons/day X = 47 tons/year
Twenty percent of this emission rate equals
47 X 20% = 9.4 tons/year
Applying the PEDCo correction factor, which gives a concentration
based on a 24-hour average, and the 24-hour to 1-hour averging time
correction as seen under "TOTAL REDUCED SULFUR" elsewhere in these
calculations, one finds the hourly impact of:
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9.4 tons/year X 0.325 ^rograrn/cubic meter x _1_ = ?>6 micrograms/cubic
meter
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BERYLLIUM
Regulations Governing Emissions:
NESHAP, 40 CFR 61.30-44
Sources Subject:
Extraction plants, ceramic plants, foundries, incinerators, and
propel 1 ant plants which process beryllium ore, beryllium, beryllium
oxide, beryllium alloys or beryllium containing waste, machine shops
which process beryllium, beryllium oxides or any alloy (more than
5% beryllium) and rocket motor test sites.
Emission rate:
10 grams per day
Calculations:
A source meeting the NESHAP emission limit of 10 grams per day would
equal a certain number of tons per year (assuming continuous operation of
the source):
10 grams/day X 365 days/year X ^54 pound/gram
X U- ton/pound = 0.004 ton/year
*
Ten percent of this result equals:
0.004 ton/year X 10% = 0.0004 ton/year
A 500 MW pulverized dry bottom boiler operating at 60 percent capacity
and 40 percent overall efficiency burning typical bituminous coal and
controlled to meet the NSPS would emit 0.004 metric tons per year of
beryllium, "Health Impacts, Emissions, and Emission Factors for
Noncriteria Pollutants Subject to De Minimis Guidelines and Emitted
from Stationary Conventional Combustion Sources Processes," - EPA-450/2-
80-074, June 1980.
0.004 metric ton X 1c tons = 0.0044 ton/year
* See main text for explanation of use at 10%.
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VINYL CHLORIDE
Regulations Governing Emissions:
NESHAP, 40 CFR 61.60-71
Sources subject:
1) Ethylene dichloride plant;
2) Vinyl chloride plant;
3) Polyvinyl chloride plant;
Emission limit:
Generally 10 ppm in the exhaust gases.
Calculations:
From the "Standard Support Document and Environmental Impact Statement:
Emissions Standard for Vinyl Chloride," EPA-450/2-75-009, October 1975,
pages 4-80, 81, 82, a typical polyvinyl chloride plant of 68 million
kilograms per year would put out 705 pounds per hour uncontrolled
emissions. The control efficiency for this controlled plant would
equal:
Contro, efficiency „ - 1-
n = 0.94 or 94%
Rounding offf 94% gives good control efficiency of 95%
For the example above 68 million kilograms per year production emits
45.6 pounds of vinyl chloride per hour or:
45.6 pounds/hour X 8760 hours/year X on P°und/ton = 200 tons/year
assuming continuous operation. From page 3-32 of the above document,
PVC plants range from 2-135 million kilograms per year. Assuming a smaller
source can apply the same control efficiency as a larger source (95%
efficiency), 2 thru 15 million kilograms per year plant would proportionately
emit:
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15 X 106 kilograms/year X 20° tons/year = 44 tons/year
68 X 10 kilograms/year
Thus, smaller plant emissions range from 6 to 44 tons per year. Ten
percent of this range of smaller source equals
10% X 44 tons/year =4.4 tons/year
10% X 6 tons/year =0.6 ton/year
Assume 1 ton per year is representative of this range. Ethylene
dichloride plants are also considered. The range of plant equals
70-590 million kilograms of production per year (page 3-28). A
small plant, uncontrolled, 70 million kilograms per year would emit
when operating continuously:
70 X 10 kilograms production/year X (see page 3-37) 0.4479 kilograms VC
100 kilograms
production
3.15 X 10 kilograms/year X 2.2 pounds/kilogram X onnn" ton/pound
= 346 tons/year (Uncontrolled emissions)
Assuming again a 95% control efficiency:
Uncontrolled rate X (1-control efficiency) = Controlled emission rate
346 tons/year X (1-0.95) = 17.3 tons/year (Controlled emissions)
Ten percent of this estimated emission rate equals:
17.3 tons/year X 10% = 1.7 tons/year
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MERCURY
Regulations Governing Emissions:
National Emissions Standards for Hazardous Pollutants (NESHAP),
40 CFR 61.50-55
Sources subject:
1) Mercury ore processing plants - 2300 grams/day
2) Mercury chlor-alkali cells - 2300 grams/day
3) Incinerator or dry waste water treatment plant sludge - 3200 - grams/day
Calculations:
A source meeting the NESHAP emission of 2300 grams per day limit would
equal a certain number of tons per year of emissions (assuming continuous
operation of the source).
2300 grams/day X 365 days/year X J^T pound/gram
X n ton/pound = 0.93 ton/year
Rounding off the result to 1.0 tons per year and taking 10% gives:
1.0 ton/year X 10% = 0.1 ton/year
A 500 MW pulverized dry bottom boiler operating at 60 percent capacity
and 40 percent overall efficiency burning typical bituminous coal and
controlled to meet the NSPS would emit 0.4 metric tons of mercury
per year - EPA-450/2-80-074, "Health Impacts, Emissions and Emission
Factors for Noncriteria Pollutants Subject to De Minimi's Guidelines
and Emitted from Stationary Conventional Combustion Process," June 1980,
page 54.
0.4 metric tons/year X *?03 tons^ ^ = p.44 ton/year
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