Page 53 - Wastewater Solids Incineration Systems

22 Wastewater Solids Incineration Systems

2.3 Potential Emissions

Potential emissions are the emissions that would occur on an annual basis if the
facility was operated at its design capacity continuously. Potential emissions can be
reduced if there is a physical limitation that constrains the process from operating at
its design capacity on a continuous basis or a federally enforceable operational limi-
tation was adopted which limits operation (for example, the total quantity of solids
to be processed on an annual basis). If the potential emissions from a new source are
greater than the emission thresholds for federal permit review, as presented in Table
3.1, then the facility is a new major emission source. A facility with emissions less
than major emission source thresholds are considered a minor source and are subject
to state permit review requirements.
If the proposed action is a modification to an existing facility, then emissions
from the existing facility need to be quantified to determine whether the existing
source is a major or minor air emissions source and whether the proposed change
will result in a net increase or decrease in air emissions. If the net change in emissions
is greater than the emission thresholds for a modification, then the proposed action is
a major modification. The process of determining what emission credits apply when
calculating a net change can be rather involved and may require emission offset
credits. Consultation with the governing regulatory authority may be needed to be
sure that changes in net emissions are being calculated appropriately.
In the planning phase, the details associated with the proposed action may not
be fully developed. Yet estimating potential emissions is a key to determining future
regulatory review. A preliminary estimate of emissions for a multiple-hearth or fluid
bed incinerator can be made using emission factors. Emission rates based on generic
emission factors should not be the sole method for determining emission limitations.
Source specific emission testing and vendor performance guarantees are preferred
methods for setting emission limits.
State and local regulatory agencies also have established emission thresholds that
determine whether a facility is subject to regulatory review. These thresholds are
lower than the major source and major modification thresholds defined in Table 3.1.
Facilities should consult with the appropriate regulatory authority to determine what
the emission thresholds are and what information is needed to meet the state and
local permit review requirements.
Emission factors that can be used to estimate emission rates from a proposed
incinerator or to identify applicable emission limits can be found in the U.S. EPA’s