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.
A
B.
Subsection (A) shall not apply to:
1.
Begun, or caused to begin, a continuous program of
physical on-site construction of the stack;
2.
Entered into building 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 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
3
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.
B
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
3
b. For all other stacks, Hg = H + 1.5L,
where
Hg = good engineering practice
stack height, measured from the ground-level elevation at the base of the
stack;
H = height of nearby structure
measured from the ground-level elevation at the base of the stack;
L = lesser dimension (height or
projected width) of nearby structure; 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;
4
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:
5
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.
6
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.
C.
The degree of emission limitation required of any
source after the respective date given in subsection (A) above for control of
any pollutant shall not be affected by so much of any source's stack height
that exceeds good engineering practice or by any other dispersion
technique.
D.
The good engineering practice (GEP) stack height for
any source seeking credit because of plume impaction which results in
concentrations in violation of national ambient air quality standards or
applicable maximum allowable increases under R18-2-218 can be adjusted by
determining the stack height necessary to predict the same maximum air
pollutant concentration on any elevated terrain feature as the maximum
concentration associated with the emission limit which results from modelling
the source using the GEP stack height as determined herein and assuming the
elevated terrain features to be equal in elevation to the GEP stack height. If
this adjusted GEP stack height is greater than stack height the source proposes
to use, the source's emission limitation and air quality impact shall be
determined using the proposed stack height and the actual terrain
heights.
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.
Notes
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.
