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(c) Any such request shall show that APPENDIX A-AIR QUALITY ESTIMATION attainment of the secondary standards Ambient pollutant levels may be estimated will require emission reductions exceed through the application of atmospheric dif

fusion models. These estimates are based priing those which can be achieved through

marily upon the pollutant emissions, meteorthe application of reasonably available

ology, and topography that prevails within control technology.

a region. Several procedures are available for (d) Any such request for extension of

estimating air quality based on atmospheric the deadline with respect to any State's

dispersion. The complexity and sophisticaportion of an interstate region shall be tion of these procedures range from a few

tion of these proc submitted jointly with requests for such simple calculations that may be made manuextensions from all other States within ally to thousands of calculations that require the region or shall show that all such a computer. The procedures presented here States have been notified of such request.

are simple and require a minimum of calcula

tions. The two procedures presented are re(e) Any such request shall be sub

ferred to as an area model and a point model. mitted sufficiently early to permit devel

The area model was used to classify regions opment of a plan prior to the deadline in

not having air quality data where the air the event that such request is denied. quality levels are the result of several pollu

tant sources distributed throughout the re§ 51.32 Request for 1-year postpone

gion. The point model was used where the air ment.

quality results from a single point source of (a) Pursuant to section 110(f) of the pollutant. Act, the Governor of a State may re

Area model. The relationship presented in

figure 1 is based on the concepts of the model quest, with respect to any stationary

developed by Miller and Holzworth. This source or class of moving sources, a post

model requires estimates of a region's average ponement for not more than 1 year of emission density, the "size" of the region, the applicability of any portion of the and the wind speed through the atmospheric control strategy.

mixing layer. A summary and description of (b) Any such request regarding sources how to use the procedure are presented here. located in an interstate region shall show

For discussion purposes let: that the Governor of each State in the X=Estimate concentration, micrograms/ region has been notified of such request.

cubic meter (ug/m3) (c) Any such request shall clearly

u=Wind speed through mixing layer, identify the source(s) and portion(s) of

meters/second (m/s) the control strategy which are the sub

Q=Emission density, micrograms/square

meter-second (ug/m2-s) ject of such request and shall include in

C=Urban size=12 Vurban area, kilometers formation relevant to the determinations

(km.) required by section 110(f) of the Act. (d) A public hearing will be held, be

Figure 1 is a plot of “normalized concen

tration" as a function of urban size and is fore the Administrator or his designee,

defined to be the product of predicted conon any such request. No such hearing

centration and wind speed divided by will be held earlier than 1 year in ad

emission density. Concentrations are an invance of the prescribed date for com creasing function of urban size and are dipliance with any such portion (s) of the rectly proportional to emission density. The control strategy.

wind serves as a diluting agent and reduces (e) No such request shall operate to

expected pollutant concentrations. stay the applicability of the portion(s)

As an example, the Standard Metropolitan

Statistical Area (SMSA) of Chicago is used of the control strategy covered by such

to compute the expected concentration of request.

So, from 1967 emissions in the Chicago area. (f) A State's determination to defer The urban area of Chicago for computational the applicability of any portion(s) of the purposes is 2,500 square km. The urban size, control strategy with respect to such as defined is consequently 25 km. and thus source(s) will not necessitate a request

from figure 1:

Хи for postponement under this section unless such deferral will prevent attainment or maintenance of a national

For Chicago: standard within the time specified in such plan: Provided, however, That any

6.0 meter such determination will be deemed a re

d=7.3 meters/sec vision of an applicable plan under $ 51.6.

1 Miller, M.E., and Holzworth, G.C., "An

Atmospheric Diffusion Model for Metropoli1 Defined term (Clean Air Act)--see defini tan Areas”, Jour. Air Poll. Cont. Assoc., 17: tions.

46–50; Jan. 1967.

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Using this procedure, concentration estimates for both so, and particulate matter may be made on a regional basis. These predicted air quality concentrations may be used to establish region classification.

Point Model. The ambient air quality concentrations that result from the emissions of a single point source have a large degree of variability depending upon the meteorological conditions. Because of this, the shortterm air quality concentrations are of more concern than the long-term. In many cases, the short-term maximum concentrations occur when the plume is trapped in a mixing layer of limited depth. In these cases, the 1-hour ground level concentration from a single point source may be estimated from the following equation: 3

The values of the meteorological parameters must be based on the meteorological conditions in the vicinity of the source. Multiplying the estimated maximum 1-hour concentration by 0.25 may be used to estimate a maximum 24-hour concentration. This factor is deemed appropriate for the meteorological conditions to which the above equation applies. The factor implies that the meteorological conditions persist 6 hours of a 24-hour period. During the remaining 18 hours, wind direction and other meteorological parameters are such that the source has no impact upon the location subjected to contamination during the 6-hour period. The estimated maximum 24-hour concentration may be compared to the maximum 24-hour national standards. This procedure may be used in Priority 1A regions to estimate the existing air quality levels for developing a control strategy.

Under certain source and meteorological conditions, the above equation may not be appropriate; however, other equations are available that may be used.

X =

V2m0yLu where:

X=concentration, gm/meter 3.
Q=source emission rate, gm/sec.
Dy=the standard deviation in the cross-

wind direction of the plume concen

tration distribution, meters. L=height of the mixing layer, meters. u=wind speed, meters/sec.

2 Turner, D. B., "Workbook of Atmospheric Dispersion Estimates”, Public Health Service Publication No. 999–AP-26, U.S. Department of Health, Education, and Welfare, Public Health Service, Consumer Protection and Environmental Health Service, National Air Pollution Control Administration, Cincinnati, Ohio. Revised 1969.

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This appendix sets forth emission limitations which, in the Administrator's judgment, are attainable through the application of reasonable available emission control technology. The statements presented herein are not intended, and should not be construed, to require or encourage State agencies to adopt such emission limitations without consideration of (1) the necessity of imposing such emission limitations in order to attain and maintain a national standard, (2) the social and economic impact of such emission limitations, and (3) alternative means of providing for attainment and maintenance of a national standard. Failure of a State agency to adopt any or all of the emission limitations set forth herein will not be grounds for rejecting a State implementation plan if that implementation plan provides for attainment and maintenance of the National Ambient Air Quality Standards within the time prescribed by the Clean Air Act. Nor will State adoption of any or all of these emission limitations be grounds for approval of an implementation plan that does not provide for timely attainment and maintenance of the national standards. In preparing implementation plans, State agencies should tailor their control strategies to deal with the particular problems and meet the particular needs of their own States.

1.0 DEFINITIONS "Air pollutant” means dust, fumes, mist, smoke, other particulate matter, vapor, gas, odorous substances, or any combination thereof.

"Effluent water separator" means any tank, box, sump, or other container in which any volatile organic compound floating on or entrained or contained in water entering such tank, box, sump, or other container is physically separated and removed from such water prior to outfall, drainage, or recovery of such water.

“Emission” means the act of releasing or discharging air pollutants into the ambient air from any source.

"Fuel-burning equipment” means any furnace, boiler, apparatus, stack, and all appurtenances thereto, used in the process of burning fuel for the primary purpose of producing heat or power by indirect heat transfer.

"Fugitive dust” means solid, airborne particulate matter emitted from any source other than through a stack.

“Opacity" means a state which renders material partially or wholly impervious to rays of light and causes obstruction of an observer's view.

"Particulate matter” means any material, except water in uncombined form, that is or

has been airborne and exists as a liquid or a solid at standard conditions

"Ringelmann chart” means the chart published and described in the U.S. Bureau of Mines Information Circular 8333.

"Source" means any property, real or personal, which emits or may emit any air pollutant.

"Stack" means any chimney, fiue, conduit, or duct arranged to conduct emissions to the ambient air.

"Standard conditions” mean a dry gas temperature of 70° Fahrenheit and a gas pressure of 14.7 pounds per square inch absolute.

"Submerged fill pipe" means any fill pipe the discharge opening of which is entirely submerged when the liquid level is 6 inches (15 cm.) above the bottom of the tank; or when applied to a tank which is loaded from the side, means any fill pipe the discharge opening of which is entirely submerged when the liquid level is 18 inches (45 cm.) above the bottom of the tank.

“Volatile organic compounds" means any compound containing carbon and hydrogen or containing carbon and hydrogen in combination with any other element which has a vapor pressure of 1.5 pounds per square inch absolute (77.6 mm. Hg) or greater under actual storage conditions.

2.0 CONTROL OF PARTICULATE EMISSIONS 2.1 Visible emissions. The emission of visible air pollutants can be limited to a shade or density equal to but not darker than that designated as No. 1 on the Ringelmann chart or 20 percent opacity except for brief periods during such operations as soot blowing and startup. This limitation would generally eliminate visible pollutant emissions from stationary sources.

The emission of visible air pollutants from gasoline-powered motor vehicles can be eliminated except for periods not exceeding 5 consecutive seconds. The emission of visible air pollutants from diesel-powered motor vehicles can be limited to a shade or density equal to but not darker than that designated as No. 1 on the Ringelmann chart or 20 percent opacity except for periods not exceeding 5 consecutive seconds.

2.2 Fugitive dust. Reasonable precautions can be taken to prevent particulate matter from becoming airborne. Some of these reasonable precautions include the following:

(a) Use, where possible, of water or chemicals for control of dust in the demolition of existing buildings or structures, construction operations, the grading of roads or the clearing of land;

(b) Application of asphalt, oil, water, or suitable chemicals on dirt roads, materials stockpiles, and other surfaces which can give rise to airborne dusts;

(c) Installation and use of hoods, fans, and fabric filters to enclose and vent the handling of dusty materials. Adequate containment methods can be employed during sandblasting or other similar operations;

(d) Covering, at all times when in motion, open bodied trucks, transporting materials likely to give rise to airborne dusts;

(e) Conduct of agricultural practices such as tilling of land, application of fertilizers, etc., in such manner as to prevent dust from becoming airborne;

(f) The paving of roadways and their maintenance in a clean condition;

(g) The prompt removal of earth or other material from paved streets onto which earth or other material has been transported by trucking or earth moving equipment, erosion by water, or other means.

2.3 Incineration. The emission of particulate matter from any incinerator can be limited to 0.20 pound per 100 pounds (2 gm/kg.) of refuse charged. This emission limitation is based on the source test method for stationary sources of particulate emissions which will be published by the Administrator. This method includes both a dry filter and wet impingers and represents particulate matter of 70° F. and 1.0 atmosphere pressure.

2.4 Fuel burning equipment. The emission of particulate matter from fuel burning equipment burning solid fuel can be limited to 0.30 pound per million B.t.u. (0.54 gm/106 gm-cal) of heat input. This emission limitation is based on the source test method for stationary sources of particulate emissions which will be published by the Administrator. This method includes both a dry filter and wet impingers and represents particulate matter of 70° F. and 1.0 atmosphere pressure.

2.5 Process industries-general. The emission of particulate matter for any process source can be limited in a manner such as in table I. Process weight per hour means the total weight of all materials introduced into any specific process that may cause any emission of particulate matter. Solid fuels charged are considered as part of the process weight, but liquid and gaseous fuels and combustion air are not. For a cyclical or batch operation, the process weight per hour is derived by dividing the total process weight by the number of hours in one complete operation from the beginning of any given process to the completion thereof, excluding any time during which the equipment is idle. For a continuous operation, the process weight per hour is derived by dividing the process weight for a typical period of time.


weight rate

rate (lbs./hr.)

(lbs./hr.) 50

0.36 100


1,000 -
5.000 --

6. 34
10,000 ---

9. 73

TABLE I-Continued

weight rate

rate (lbs./hr.)

(lbs./hr.) 20,000

14. 99 60,000

29. 60 80,000

31. 19 120,000

33. 28 160,000

34. 85 200,000

36. 11 400,000

40. 35 1,000,000

46. 72 Interpolation of the data in table I for the process weight rates up to 60,000 lbs./hr. shall be accomplished by the use of the equation:

E=3.59 p0.62 P<30 tons/hr. and interpolation and extrapolation of the data for process weight rates in excess of 60,000 lbs./hr. shall be accomplished by use of the equation:

E=17.31 po.16 P>30 tons/hr. Where: E=Emissions in pounds per hour.

P=Process weight rate in tons per

hour. Application of mass emission limitations on the basis of all similar units at a plant is recommended in order to avoid unequal application of this type of limitation to plants with the same total emission potential but different size units. 3.0 CONTROL OF SULFUR COMPOUND

EMISSIONS 3.1 Fuel combustion. It is not possible to make nationally applicable generalizations about attainable degrees of control of sulfur oxides emissions from combustion sources. Availability of low-sulfur fuels varies from one area to another. In some areas, severe restrictions on the sulfur content of fuels could have a significant impact on fuel-supply patterns; accordingly, where such restrictions are necessary for attainment of national ambient air quality standards, adoption of phased schedules of sulfur-in-fuel limitations is recommended. Stack gas cleaning is feasible at large industrial combustion sources and steam electric power plants. Technology has been demonstrated which will allow 70 percent removal of sulfur oxides from combustion gases of most existing fuel burning units.

Alternative means of meeting requirements for the control of sulfur oxides emissions from fuel combustion sources include: Use of natural gas, distillate oil, low-sulfur coal, and low-sulfur residual oil; desulfurization of oil or coal; stack gas desulfurization; and restricted use, shutdown, or relocation of large existing sources.

It is technically feasible to produce or desulfurize fuels to meet the following specifications: Distillate oil-0.1 percent sulfur (though it should be noted that distillate oil containing less than 0.2 percent sulfur is not generally available at this time); residual

2. 25

oil—0.3 percent sulfur; bituminous coal fur to the smelter for most copper smelters 0.7 percent sulfur. Availability of significant and somewhat higher for most lead and zinc quantities of such low-sulfur fuels in any smelters. Technology capable of achieving region where they do not naturally occur such emission limitations may not be apor have not been imported from other domes plicable to all existing smelters. In such cases, tic or foreign sources will require planning less restrictive control can be coupled with for the timely development of new sources restricted operations to achieve air quality of such fuels. Because residual oil generally standards. is obtained from overseas sources, its use 3.5 Sulfite pulp mills. The total sulfite ordinarily is restricted to areas accessible to pulp mill emissions of sulfur oxides. calcu. waterborne transportation. There are limited lated as sulfur dioxide, from blow pits, washer tonnages of 0.7 percent sulfur coal produced vents, storage tanks, digester relief, and at the present time, primarily in the western recovery system, can be reduced to 9 pounds United States; large reserves of such coal per air-dried ton (4.5 kg./metric ton) of pulp exist but are not now being mined.

produced. This emission limitation has appliThe ilaring or combustion of any refinery cation only to those sulfite mills that install process gas stream or any other process gas waste liquor recovery systems for water pollustream that contains sulfur compounds tion control or other purposes. The installameasured as hydrogen sulfide can be limited tion of a recovery system can result in signifito a concentration of 10 grains per 100 stand cant sulfur oxides emissions if not properly ard cubic feet (23 gm/100scm) of gas. This designed. For sulfite mills with existing limitation on combustion of process gas re

recovery systems, a sulfur oxides emission lates to the control of sulfur oxide emissions

limitation of 20 pounds per air-dried ton (9

kg./metric ton) of pulp may be more reasonthat would result from burning untreated process gas from refinery operations or coke able due to economic considerations. ovens containing hydrogen sulfide and other

4.0 CONTROL OF ORGANIC COMPOUNDS sulfur compounds. Hydrogen sulfide emis

EMISSIONS sions can be controlled by requiring incineration or other equally effective means for all

The following emission limitations are process units. Approximately 95 to 99 percent applicable to the principal stationary source of the sulfur compounds must be removed of organic compound emissions. Reducing from the process gas stream to meet this total organic compound emissions will reduce emission limitation. It may be appropriate photochemical oxidant formation. Such conto consider exemption of very small units trol of organic compound emissions may which economically may not be able to appropriately be considered in areas where achieve this level of control.

application of the Federal motor vehicle 3.2 Sulfuric acid plants. The emissions of emission standards will not produce the sulfur dioxide from sulfuric acid plants can emission reductions necessary for attainment be limited to 6.5 pounds per ton (3.25

(3.25 and maintenance of the national ambient kg./metric ton) of 100 percent acid produced

oduced. air quality standards for photochemical oxi

dants. These emission limitations emphasize This emission limitation is equivalent to an

reduction of total organic compound emisoverall so, to so, conversion efficiency of 99.5

sions, rather than substitution of “nonpercent or a stack gas concentation of about

reactive" or "less reactive” organic com250 to 550 p.p.m. of sulfur dioxide, by volume,

pounds for those already in use, because there depending on the strength of the feed gas.

is evidence that very few organic compounds 3.3 Sulfur recovery plants. The emission of

are photochemically nonreactive. Substitusulfur oxides, calculated as sulfur dioxide,

tion may be useful, however, where it would from a sulfur recovery plant can be limited

result in a clearly evident decrease in reactivto 0.01 pound (kg.) per pound (kg.) of sul

ity and thus tend to reduce photochemical fur processed. Approximately 99.5 percent of

oxidant formation. The extent to which the sulfur processed must be recovered to

application of these emission limitations meet this limitation. Existing plants typi

would reduce photochemical oxidant formacally recover 90 to 97 percent of the sulfur. This emission limitation corresponds to a

tion in a given air quality control region will

depend on the “mix” of emission sources in sulfur dioxide concentration of about 1,300

the region. These limitations are separable, p.p.m., by volume.

i.e., one or more portions can be considered, 3.4 Nonferrous smelters. Technology is available to limit emission of sulfur oxides,

as necessary. calculated as sulfur dioxide, from primary

4.1 Storage of volatile organic compounds.

The storage of volatile organic compounds nonferrous smelters according to the follow

in any stationary tank, reservoir or other ing equations:

container of more than 40,000 gallons (150,000 Copper smelters: Y=0.2X.

liters) can be in a pressure tank capable of Zinc smelters: Y=0.564X0.85.

maintaining working pressures sufficient at Lead smelters: Y=0.98X0.77.

all times to prevent vapor or gas loss to the Where:

atmosphere. If this cannot be done, the tank X=Total sulfur fed to smelter (lb./hr.). can be equipped with a vapor loss control

Y=Sulfur Dioxide Emissions (lb./hr.). device such as: These emission limitations are equivalent to (a) A floating roof, consisting of a ponremoval of about 90 percent of the input-sul- toon type, double deck type roof or internal

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