(c) Any such request shall show that attainment of the secondary standards will require emission reductions exceeding those which can be achieved through the application of reasonably available control technology.

(d) Any such request for extension of the deadline with respect to any State's portion of an interstate region shall be submitted jointly with requests for such extensions from all other States within the region or shall show that all such States have been notified of such request.

(e) Any such request shall be submitted sufficiently early to permit development of a plan prior to the deadline in the event that such request is denied. § 51.32 Request for 1-year postpone

ment.

(a) Pursuant to section 110 (f) of the Act,1 the Governor of a State may request, with respect to any stationary source or class of moving sources, a postponement for not more than 1 year of the applicability of any portion of the control strategy.

(b) Any such request regarding sources located in an interstate region shall show that the Governor of each State in the region has been notified of such request.

(c) Any such request shall clearly identify the source(s) and portion(s) of the control strategy which are the subject of such request and shall include information relevant to the determinations required by section 110 (f) of the Act.

(d) A public hearing will be held, before the Administrator or his designee, on any such request. No such hearing will be held earlier than 1 year in advance of the prescribed date for compliance with any such portion (s) of the control strategy.

(e) No such request shall operate to stay the applicability of the portion (s) of the control strategy covered by such request.

(f) A State's determination to defer the applicability of any portion(s) of the control strategy with respect to such source(s) will not necessitate a request for postponement under this section unless such deferral will prevent attainment or maintenance of a national standard within the time specified in such plan: Provided, however, That any such determination will be deemed a revision of an applicable plan under § 51.6.

1 Defined term (Clean Air Act)--see definitions.

APPENDIX A-AIR QUALITY ESTIMATION Ambient pollutant levels may be estimated through the application of atmospheric diffusion models. These estimates are based primarily upon the pollutant emissions, meteorology, and topography that prevails within a region. Several procedures are available for estimating air quality based on atmospheric dispersion. The complexity and sophistication of these procedures range from a few simple calculations that may be made manually to thousands of calculations that require a computer. The procedures presented here are simple and require a minimum of calculations. The two procedures presented are referred to as an area model and a point model. The area model was used to classify regions not having air quality data where the air quality levels are the result of several pollutant sources distributed throughout the region. The point model was used where the air quality results from a single point source of pollutant.

Area model. The relationship presented in figure 1 is based on the concepts of the model developed by Miller and Holzworth.1 This model requires estimates of a region's average emission density, the "size" of the region, and the wind speed through the atmospheric mixing layer. A summary and description of how to use the procedure are presented here. For discussion purposes let:

X=Estimate concentration, micrograms/ cubic meter (μg/m3)

μ=Wind speed through mixing layer, meters/second (m/s)

Q=Emission density, micrograms/square

meter-second (μg/m2-s)

C=Urban size=1⁄2√√urban area, kilometers (km.)

Figure 1 is a plot of "normalized concentration" as a function of urban size and is defined to be the product of predicted concentration and wind speed divided by emission density. Concentrations are an increasing function of urban size and are directly proportional to emission density. The wind serves as a diluting agent and reduces expected pollutant concentrations.

As an example, the Standard Metropolitan Statistical Area (SMSA) of Chicago is used to compute the expected concentration of SO, from 1967 emissions in the Chicago area. The urban area of Chicago for computational purposes is 2,500 square km. The urban size, as defined is consequently 25 km. and thus from figure 1: Χμ

For Chicago:

230

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: 2

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 2 are available that may be used.

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.

1000

1

10

100

APPENDIX B-EXAMPLES OF EMISSION LIMITATIONS ATTAINABLE WITH REASONABLY AVAILABLE TECHNOLOGY

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.

"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, flue, 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.

be

The emission of visible air pollutants from gasoline-powered motor vehicles can 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/10° 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.

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 P0.16 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

oil-0.3 percent sulfur; bituminous coal0.7 percent sulfur. Availability of significant quantities of such low-sulfur fuels in any region where they do not naturally occur or have not been imported from other domestic or foreign sources will require planning for the timely development of new sources of such fuels. Because residual oil generally is obtained from overseas sources, its use ordinarily is restricted to areas accessible to waterborne transportation. There are limited tonnages of 0.7 percent sulfur coal produced at the present time, primarily in the western United States; large reserves of such coal exist but are not now being mined.

The flaring or combustion of any refinery process gas stream or any other process gas stream that contains sulfur compounds measured as hydrogen sulfide can be limited to a concentration of 10 grains per 100 standard cubic feet (23 gm/100scm) of gas. This limitation on combustion of process gas relates to the control of sulfur oxide emissions that would result from burning untreated process gas from refinery operations or coke ovens containing hydrogen sulfide and other sulfur compounds. Hydrogen sulfide emissions can be controlled by requiring incineration or other equally effective means for all process units. Approximately 95 to 99 percent of the sulfur compounds must be removed from the process gas stream to meet this emission limitation. It may be appropriate to consider exemption of very small units which economically may not be able to achieve this level of control.

3.2 Sulfuric acid plants. The emissions of sulfur dioxide from sulfuric acid plants can be limited to 6.5 pounds per ton (3.25 kg./metric ton) of 100 percent acid produced. This emission limitation is equivalent to an overall SO, to SO, conversion efficiency of 99.5 percent or a stack gas concentation of about 250 to 550 p.p.m. of sulfur dioxide, by volume, depending on the strength of the feed gas.

3.3 Sulfur recovery plants. The emission of sulfur oxides, calculated as sulfur dioxide, from a sulfur recovery plant can be limited to 0.01 pound (kg.) per pound (kg.) of sulfur processed. Approximately 99.5 percent of the sulfur processed must be recovered to meet this limitation. Existing plants typically recover 90 to 97 percent of the sulfur. This emission limitation corresponds to a sulfur dioxide concentration of about 1,300 p.p.m., by volume.

3.4 Nonferrous smelters. Technology is available to limit emission of sulfur oxides, calculated as sulfur dioxide, from primary nonferrous smelters according to the following equations:

Copper smelters: Y=0.2X.
Zinc smelters: Y=0.564X0.85.
Lead smelters: Y=0.98X0.77.

Where:

X=Total sulfur fed to smelter (lb./hr.). Y=Sulfur Dioxide Emissions (lb./hr.). These emission limitations are equivalent to removal of about 90 percent of the input-sul

fur to the smelter for most copper smelters and somewhat higher for most lead and zinc smelters. Technology capable of achieving such emission limitations may not be applicable to all existing smelters. In such cases, less restrictive control can be coupled with restricted operations to achieve air quality standards.

3.5 Sulfite pulp mills. The total sulfite pulp mill emissions of sulfur oxides, calculated as sulfur dioxide, from blow pits, washer vents, storage tanks, digester relief, and recovery system, can be reduced to 9 pounds per air-dried ton (4.5 kg./metric ton) of pulp produced. This emission limitation has application only to those sulfite mills that install waste liquor recovery systems for water pollution control or other purposes. The installation of a recovery system can result in significant sulfur oxides emissions if not properly designed. For sulfite mills with existing recovery systems, a sulfur oxides emission limitation of 20 pounds per air-dried ton (9 kg./metric ton) of pulp may be more reasonable due to economic considerations.

are

The following emission limitations applicable to the principal stationary source of organic compound emissions. Reducing total organic compound emissions will reduce photochemical oxidant formation. Such control of organic compound emissions may appropriately be considered in areas where application of the Federal motor vehicle emission standards will not produce the emission reductions necessary for attainment and maintenance of the national ambient air quality standards for photochemical oxidants. These emission limitations emphasize reduction of total organic compound emissions, rather than substitution of "nonreactive" or "less reactive" organic compounds for those already in use, because there is evidence that very few organic compounds are photochemically nonreactive. Substitution may be useful, however, where it would result in a clearly evident decrease in reactivity and thus tend to reduce photochemical oxidant formation. The extent to which application of these emission limitations would reduce photochemical oxidant formation in a given air quality control region will depend on the "mix" of emission sources in the region. These limitations are separable, i.e., one or more portions can be considered, as necessary. 4.1

Storage of volatile organic compounds. The storage of volatile organic compounds in any stationary tank, reservoir or other container of more than 40,000 gallons (150,000 liters) can be in a pressure tank capable of maintaining working pressures sufficient at all times to prevent vapor or gas loss to the atmosphere. If this cannot be done, the tank can be equipped with a vapor loss control device such as:

(a) A floating roof, consisting of a pontoon type, double deck type roof or internal