Ariz. Admin. Code § 18-2-332

Current through Register Vol. 30, No. 50, December 13, 2024

Section R18-2-332 - Stack Height Limitation

A. The degree of emission limitation required of any source for control of any pollutant shall not be affected by so much of the source's stack height that exceeds good engineering practice or by any other dispersion technique, except as provided in subsection (B). This section does not require the plan to restrict, in any manner, the actual stack height of any source.

B. Subsection (A) shall not apply to:

Stacks in existence, or dispersion techniques implemented, on or before December 31, 1970, unless the stationary source or emission unit emitting pollutants through the stack, or employing the dispersion technique, was constructed, reconstructed or underwent a major modification after December 31, 1970; or

2. Coal-fired steam electric generating units, subject to the provisions of Section 118 of the Act which commenced operation before July 1, 1957, with stacks constructed under a construction contract awarded before February 8, 1974.

C. Good engineering practice stack height is the greater of the following heights:

1. 213.25 feet (65 meters) measured from the ground-level elevation at the base of the stack;

2. The result of one of the following equations, where "Hg" = good engineering practice stack height measured from the ground-level elevation at the base of the stack; "H" = height of nearby structures measured from the ground-level elevation at the base of the stack; and "L" = lesser dimension (height or projected width) of nearby structures:

a. For stacks in existence on January 12, 1979, and for which the owner or operator had obtained all applicable preconstruction permits or approvals required under 40 CFR 51 and 52, Hg = 2.5H, provided the owner or operator produces evidence that this equation was actually relied on in establishing an emission limitation; or

b. For all other stacks, Hg = H + 1.5L,

provided that EPA, the Director, or local control agency may require the use of a field study or fluid model to verify good engineering practice stack height for the source;

3. The height demonstrated by a fluid model or a field study approved by the reviewing agency, 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.

D. As used in this Section:

1. For a specific structure or terrain feature, "nearby" means:

a. For purposes of applying the formulae in subsection (C)(2), 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).

b. For conducting demonstrations under subsection (C)(3), not greater than 0.8 km (1/2 mile). An exception is 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 2 miles if such feature achieved a height (Ht) 0.8 km from the stack that is at least 40% of the good engineering practice stack height determined by the formula provided in subsection (C)(2)(b), or 85 feet (26 meters), whichever is greater, as measured from the ground-level elevation at the base of the stack.

2. "Excessive concentrations" means:

a. For sources seeking credit for stack height exceeding that established under subsection (C)(2), a maximum ground-level concentration due to emissions from a stack due in whole or in part to downwash, wakes, and eddy effects produced by nearby structures or nearby terrain features which individually is at least 40% 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 a national ambient air quality standard. For sources subject to R18-2-406, 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% in excess of the maximum concentration experienced in the absence of such downwash, wakes, or eddy effects and greater than the applicable maximum allowable increase contained in R18-2-218. The allowable emission rate to be used in making demonstrations under subsection (C)(3) shall be prescribed by the new source performance standard which 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 Director, an alternative emission rate shall be established in consultation with the source owner or operator;

b. For sources seeking credit after October 11, 1983, for increases in existing stack heights up to the heights established under subsection (C)(2), either:

i. A maximum ground-level concentration due in whole or in part to downwash, wakes, or eddy effects as provided in subsection (D)(2)(a), except that emission rate specified by any applicable SIP (or, in the absence of such a limit, the actual emission rate) shall be used; or

ii. The actual presence of a local nuisance caused by the existing stack, as determined by the Director; and

c. For sources seeking credit after January 12, 1979, for a stack height determined under subsection (C)(2), where the Director requires the use of a field study or fluid model to verify good engineering practice 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 subsection (C)(2), a maximum ground-level concentration due in whole or in part to downwash, wakes, or eddy effects that is at least 40% in excess of the maximum concentration experienced in the absence of such downwash, wakes, or eddy effects.

E. Before the Director issues a permit or permit revision under R18-2-334 or Article 4 to a source based on a good engineering practice stack height that exceeds the height allowed by subsection (B)(1) or (2), the Director shall notify the public of the availability of the demonstration study and provide opportunity for a public hearing in accordance with the requirements of R18-2-330.

Ariz. Admin. Code § R18-2-332

Adopted effective November 15, 1993 (Supp. 93-4). Amended by final rulemaking at 23 A.A.R. 333, effective 3/21/2017.