Regulatory Text: 
Louisiana Administrative Code, Title 33 ENVIRONMENTAL QUALITY, Part III Air (LAC 33:III)

Chapter 9. General Regulations on Control of Emissions and Emission Standards

Section 921. Stack Heights
Approved by EPA 03/08/89 (54 FR 09795) at 52.970(c)(49) effective 05/08/89.

   This regulation applies to all stacks in existence and all dispersion techniques implemented since December 31, 1970.

   A.  Definitions. For the purpose of this Section, the terms below will have the meaning herein given:

   Dispersion Technique-any technique which attempts to affect the concentration of a pollutant in the ambient air by:

      1.  using that portion of a stack which exceeds good engineering practice stack height;

      2.  varying the rate of emission of a pollutant according to atmospheric conditions or ambient concentrations of that pollutant; or

      3.  increasing final exhaust gas plume rise by manipulating source process parameters, exhaust gas parameters, stack parameters or combining exhaust gases from several existing stacks into one stack; or other selective handling of exhaust gas streams so as to increase the exhaust gas plume rise.

      LAC 33:III.921.A "dispersion technique 3" does not include:

           a.  the reheating of a gas stream, following use of a pollution control system, for the purpose of returning the gas to the temperature at which it was originally discharged from the facility generating the gas stream;

           b.  the merging of exhaust gas streams where:

              i.  the source owner or operator demonstrates that the facility was originally designed and constructed with such merged gas streams;

              ii.  after July 8, 1985, such merging is part of a change in operation at the facility that includes the installation of pollution controls and is accompanied by a net reduction in the allowable emissions of a pollutant.  This exclusion from the definition of “dispersion techniques” shall apply only to the emission limitation for the pollutant affected by such change in operation; or

              iii.  before July 8, 1985, such merging was part of a change in operation at the facility that included the installation of emissions control equipment or was carried out for sound economic or engineering reasons. Where there was an increase in the emission limitation or, in the event that no emission limitation was in existence prior to the merging, an increase in the quantity of pollutants actually emitted prior to the merging, the administrative authority shall presume that merging was significantly motivated by an intent to gain emissions credit for greater dispersion. Absent a demonstration by the source owner or operator that merging was not significantly motivated by such intent, the administrative authority shall deny credit for the effects of such merging in calculating the allowable emissions for the source;

           c.  smoke management in agricultural or silvicultural prescribed burning programs;

           d.  episodic restrictions on residential woodburning and open burning; or

           e.  techniques under LAC 33:III.921.A "dispersion technique 3." which increase final exhaust gas plume rise where the resulting allowable emissions of sulfur dioxide from the facility do not exceed 5,000 tons per year.

   Emission Limitation and Emission Standard-a requirement established by the administrative authority or administrator which limits the quantity, rate, or concentration of emissions of air pollutants on a continuous basis, including any requirements which limit the level of opacity, prescribe equipment, set fuel specifications, prescribe operation or maintenance procedures for a source to assure continuous emission reduction.

   Excessive Concentrations-is defined for the purpose of determining good engineering practice stack height under LAC 33:III.921.A.  "good engineering practice (GEP) stack height 3." and means:

       1.  for sources seeking credit for stack height exceeding that established under LAC 33:III.921.A "good engineering practice (GEP) stack height 2.", a maximum ground-level concentration due to emissions from a stack due in whole or part to downwash, wakes, and eddy effects produced by nearby structures or nearby terrain features which individually is at least 40 percent in excess of the maximum concentration experienced in the absence of such downwash, wakes, or eddy effects and which contributes to a total concentration due to emissions from all sources that is greater than an ambient air quality standard. For sources subject to the prevention of significant deterioration program (PSD), an excessive concentration alternatively means a maximum ground-level concentration due to emissions from a stack due in whole or part to downwash, wakes, or eddy effects produced by nearby structures or nearby terrain features which individually is at least 40 percent in excess of the maximum concentration experienced in the absence of the maximum concentration experienced in the absence of such downwash, wakes, or eddy effects and a greater than a prevention of significant deterioration increment. The allowable emission rate to be used in making demonstrations under this Section shall be prescribed by the new source performance standard that is applicable to the source category unless the owner or operator demonstrates that this emission rate is infeasible. Where such demonstrations are approved by the administrative authority, an alternative emission rate shall be established in consultation with the source owner or operator.

       2.  for sources seeking credit after October 11, 1983, for increases in existing stack heights up to the heights established under LAC 33:III.921.A "good engineering practice (GEP) stack height 2." either

           a.  a maximum ground-level concentration due in whole or part to downwash, wakes, or eddy effects as provided in 1. above, except that the emission rate specified by these regulations (or in the absence of such a limit, the actual emission rate) shall be used; or

           b.  the actual presence of a local nuisance caused by the existing stack, as determined by the administrative authority; and

       3.  for sources seeking credit after January 12, 1979 for a stack height determined under LAC 33:III.921.A "good engineering practice (GEP) stack height 2." where the administrative authority requires the use of a field study or fluid model to verify GEP stack height, for sources seeking stack height credit after November 9, 1984 based on the aerodynamic influence of cooling towers, and for sources seeking stack height credit after December 31, 1970 based on the aerodynamic influence of structures not adequately represented by the equations in LAC 33:III.921.A "good engineering practice (GEP) stack height 2.", a maximum ground-level concentration due in whole or part to downwash, wakes, or eddy effects that is at least 40 percent in excess of the maximum concentration experienced in the absence of such downwash, wakes, or eddy effects.

   Good Engineering Practice (GEP) Stack Height-the greater of:

       1.  65 meters, measured from the ground-level elevation at the base of the stack;

       2.  a. for stacks in existence on January 12, 1979, and for which the owner or operator had obtained all applicable permits or approvals required under state or federal regulations,

                      Hg = 2.5H

provided the owner or operator produces evidence that this equation was actually relied on in establishing an emission limitation;

           b.  for all other stacks,

                  Hg = H + 1.5L

              where:

         Hg = good engineering practice stack height, measured from the ground-level elevation of the base of the stack;

         H = height of nearby structure(s) measured from the ground-level elevation at the base of the stack;

         L = lesser dimension, height or projected width, of nearby structure(s);

provided that EPA or the administrative authority may require the use of a field study or fluid model to verify GEP stack height for the source; or

       3.  the height demonstrated by a fluid model or a field study approved by EPA or the administrative authority, which ensures that the emissions from a stack do not result in excessive concentrations of any air pollutant as a result of atmospheric downwash, wakes, or eddy effects created by the source itself, nearby structures, or nearby terrain features.

   Nearby-as used in LAC 33:III.921.A "good engineering practice (GEP) stack height" of this section is defined for a specific structure or terrain feature and
       1.  for purposes of applying the formulae provided in LAC 33:III.921.A. "good engineering practice (GEP) stack height 2.b" means that distance up to five times the lesser of the height or the width dimension of a structure, but not greater than 0.8 km   (1/2 mile), and
       2.  for conducting the demonstrations under LAC 33:III.921.A "good engineering practice (GEP) stack height 3." means not greater than 0.8 km (1/2 mile), except that the portion of a terrain feature may be considered to be nearby which falls within a distance of up to 10 times the maximum height (Ht) of the feature, not to exceed two miles if such feature achieves a height (Ht) 0.8 km from the stack that is at least 40 percent of the GEP stack height determined by the formulae provided in LAC 33:III.921.A "good engineering practice (GEP) stack height 2" or 26 meters, whichever is greater, as measured from the ground-level elevation at the base of the stack. The height of the structure or terrain feature is measured from the ground-level elevation at the base of the stack.

   Stack-any point in a source designed to emit solids, liquids, or gases into the air, including a pipe or duct but not including flares.

   A Stack in Existence-the owner or operator had (1) begun, or caused to begin, a continuous program of physical on-site construction of the stack or (2) entered into binding agreements or contractual obligations, which could not be cancelled or modified without substantial loss to the owner or operator, to undertake a program of construction of the stack to be completed in a reasonable time.


   B.  Degree of Emission Limitation

       1.  The degree of emission limitation required of any source for control of any air pollutant must not be affected by so much of any source's stack height that exceeds good engineering practice (GEP) or by any other dispersion technique, except as provided herein. The administrative authority will notify the public of the availability of any stack height demonstration study and will provide opportunity for public hearing on it. This Section does not restrict, in any manner, the actual stack height of any source.

       2.  The provisions of LAC 33:III.921.B shall not apply to (a) stack heights in existence, or dispersion techniques implemented prior to December 31, 1970, except where pollutants are being emitted from such stacks or using such dispersion techniques by sources, as defined in Section 111(a)(3) of the Clean Air Act, which were constructed or reconstructed, or for which major modifications, as defined in LAC 33:III.509.B "major modification," were carried out after December 31, 1970; or (b) coal-fired steam electric generating units, subject to the provisions of Section 118 of the Clean Air Act, which commenced operation before July 1, 1957, and whose stacks were constructed under a construction contract awarded before February 8, 1974.


   C.  Review of New Sources and Modifications. The degree of emission limitation required of any source for control of any air pollutant must not be affected so much by any source's stack height that exceeds good engineering practice or by any other dispersion technique, except as provided in LAC 33:III.921.B. When the administrative authority proposes to issue a permit to a source based on a good engineering practice stack height that exceeds the height allowed by LAC 33:III.921.A. “good engineering practice (GEP) stack height 1 or 2,” the administrative authority will notify the public of the availability of the demonstration study and will provide opportunity for public hearing on it. This Section does not restrict, in any manner, the actual stack height of any source.

   AUTHORITY NOTE:  Promulgated in accordance with R.S. 30:1084.
   HISTORICAL NOTE:  Promulgated by the Department of Environmental Quality, Office of Air Quality and Nuclear Energy, Air Quality Division in LR 13:741 (December 1987).

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