Current through Register Vol. 24-06, March 15, 2024
(1) Applicability. These provisions shall
apply to all sources except:
(a) Stacks for
which construction had commenced on or before December 31, 1970, except where
pollutants are being emitted from such stacks used by sources which were
constructed, or reconstructed, or for which major modifications were carried
out after December 31, 1970;
(b)
Coal-fired steam electric generating units subject to the provisions of Section
118 of the Federal Clean Air Act, which commenced operation before July 1,
1957, and for whose stacks construction commenced before February 8,
1974;
(c) Flares;
(d) Outdoor burning for agricultural or
silvicultural purposes as covered under the smoke management plan;
(e) Residential wood combustion and open
burning for which episodic restrictions apply.
These provisions shall not be construed to limit the actual
stack height.
(2) Prohibitions. No source may use
dispersion techniques or excess stack height to meet ambient air quality
standards or PSD increment limitations.
(a)
Excess stack height. Excess stack height is that portion of a stack which
exceeds the greater of:
(i) Sixty-five
meters, measured from the ground level elevation at the base of the stack;
or
(ii) Hg =
H + 1.5L
where: Hg = "good engineering practice"
(GEP) stack height, measured from the ground level elevation at 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), subject to the proviso below.
"Nearby," as used in this subsection for purposes of applying
the GEP formula 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 kilometer (1/2
mile).
(b)
Dispersion techniques. 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. This does not include:
(i) The
reheating of a gas stream, following the 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;
(ii) The merging of gas streams where:
(A) The source was originally designed and
constructed with such merged gas streams, as demonstrated by the source
owner(s) or operator(s).
(B) 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 shall apply only to the
emission limitation for the pollutant affected by such change in
operation.
(C) 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, and not primarily motivated by an intent to
gain emissions credit for greater dispersion.
(3) Exception. EPA, ecology, or a
permitting authority may require the use of a field study or fluid model to
verify the creditable stack height for the source. This also applies to a
source seeking credit after the effective date of this rule for an increase in
existing stack height up to that established by the GEP formula. A fluid model
or field study shall be performed according to the procedures described in the
EPA Guideline for Determination of Good Engineering Practice Height (Technical
Support Document of the Stack Height Regulations). The creditable height
demonstrated by a fluid model or field study shall ensure 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.
(a) "Nearby," as used in this subsection for
conducting a field study or fluid model, means not greater than 0.8 km, except
that the portion of a terrain feature may be considered to be nearby which
falls within a distance of up to ten times the maximum height of the feature,
not to exceed two miles if such feature achieves a height 0.8 km from the stack
that is at least forty percent of the GEP stack height or twenty-six 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.
(b) "Excessive concentration" is defined for
the purpose of determining creditable stack height under this subsection and
means a maximum ground-level concentration owing to a significant downwash
effect which contributes to excursion over an ambient air quality standard. For
sources subject to PSD review (WAC
173-400-720 and
40 C.F.R.
52.21 ) an excessive concentration
alternatively means a maximum ground-level concentration owing to a significant
downwash effect which contributes to excursion over a PSD increment. The
emission rate used in this demonstration shall be the emission rate specified
in the state implementation plan, or in the absence of such, the actual
emission rate of the source. "Significant downwash effect" means 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 forty percent in excess
of the maximum concentration experienced in the absence of such downwash,
wakes, or eddy effects.
Statutory Authority:
RCW
70.94.152. 05-03-033 (Order 03-07), §
173-400-200, filed 1/10/05, effective 2/10/05. Statutory Authority:
Chapter
70.94 RCW. 91-05-064
(Order 90-06), § 173-400-200, filed 2/19/91, effective
3/22/91.