[Code of Federal Regulations]
[Title 40, Volume 14]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR75.17]

[Page 223-225]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 75--CONTINUOUS EMISSION MONITORING--Table of Contents
 
                    Subpart B--Monitoring Provisions
 
Sec. 75.17  Specific provisions for monitoring emissions from common, bypass, 
and multiple stacks for NOx emission rate.

    Notwithstanding the provisions of paragraphs (a), (b), (c), and (d) 
of this section, the owner or operator of an affected unit that is using 
the procedures in this part to meet the monitoring and reporting 
requirements of a State or federal NOX mass emission 
reduction program must also meet the provisions for monitoring 
NOX emission rate in Secs. 75.71 and 75.72.
    (a) Unit utilizing common stack with other affected unit(s). When an 
affected unit utilizes a common stack with one or more affected units, 
but no nonaffected units, the owner or operator shall either:
    (1) Install, certify, operate, and maintain a NOx 
continuous emission monitoring system in the duct to the common stack 
from each affected unit; or
    (2) Install, certify, operate, and maintain a NOx 
continuous emission monitoring system in the common stack and follow the 
appropriate procedure in paragraphs (a)(2) (i) through (iii) of this 
section, depending on whether or not the units are required to comply 
with a NOx emission limitation (in lb/mmBtu, annual average 
basis) pursuant to section 407(b) of the Act (referred to hereafter as 
``NOx emission limitation'').
    (i) When each of the affected units has a NOx emission 
limitation, the designated representative shall submit a compliance plan 
to the Administrator that indicates:
    (A) Each unit will comply with the most stringent NOx 
emission limitation of any unit utilizing the common stack; or
    (B) Each unit will comply with the applicable NOX 
emission limitation by averaging its emissions with the other unit(s) 
utilizing the common stack, pursuant to the emissions averaging plan 
submitted under part 76 of this chapter; or
    (C) Each unit's compliance with the applicable NOX 
emission limit will be determined by a method satisfactory to the 
Administrator for apportioning to each of the units the combined 
NOX emission rate (in lb/mmBtu) measured in the common stack 
and for reporting the NOX emission rate, as provided in a 
petition submitted by the designated representative. The Administrator 
may approve such demonstrated substitute methods for apportioning and 
reporting NOX emission rate measured in a common stack 
whenever the demonstration ensures that there is a complete and accurate 
estimation of all emissions regulated under this part and, in 
particular, that the emissions from any unit with a NOX 
emission limitation are not underestimated.
    (ii) When none of the affected units has a NOx emission 
limitation, the owner or operator and the designated representative have 
no additional obligations pursuant to section 407 of the Act and may 
record and report a combined NOx emission rate (in lb/mmBtu) 
for the affected units utilizing the common stack.

[[Page 224]]

    (iii) When at least one of the affected units has a NOx 
emission limitation and at least one of the affected units does not have 
a NOx emission limitation, the owner or operator shall 
either:
    (A) Install, certify, operate, and maintain NOx and 
diluent monitors in the ducts from the affected units; or
    (B) Develop, demonstrate, and provide information satisfactory to 
the Administrator on methods for apportioning the combined 
NOx emission rate (in lb/mmBtu) measured in the common stack 
on each of the units. The Administrator may approve such demonstrated 
substitute methods for apportioning the combined NOx emission 
rate measured in a common stack whenever the demonstration ensures 
complete and accurate estimation of all emissions regulated under this 
part.
    (b) Unit utilizing common stack with nonaffected unit(s). When one 
or more affected units utilizes a common stack with one or more 
nonaffected units, the owner or operator shall either:
    (1) Install, certify, operate, and maintain a NOx-diluent 
continuous emission monitoring system in the duct from each affected 
unit; or
    (2) Develop, demonstrate, and provide information satisfactory to 
the Administrator on methods for apportioning the combined 
NOx emission rate (in lb/mmBtu) measured in the common stack 
for each of the units. The Administrator may approve such demonstrated 
substitute methods for apportioning the combined NOx emission 
rate measured in a common stack whenever the demonstration ensures 
complete and accurate estimation of all emissions regulated under this 
part.
    (c) Unit with multiple stacks or ducts. When the flue gases from an 
affected unit discharge to the atmosphere through two or more stacks or 
when flue gases from an affected unit utilize two or more ducts feeding 
into a single stack and the owner or operator chooses to monitor in the 
ducts rather than the stack, the owner or operator shall monitor the 
NOX emission rate in a way that is representative of each 
affected unit.Where another unit also exhausts flue gases to one or more 
of the stacks where monitoring systems are installed, the owner or 
operator shall also comply with the applicable common stack monitoring 
requirements of this section. The owner or operator shall either:
    (1) Install, certify, operate, and maintain a NOX-diluent 
continuous emission monitoring system and a flow monitoring system in 
each stack or duct and determine the NOX emission rate for 
the unit as the Btu-weighted average of the NOX emission 
rates measured in the stacks or ducts using the heat input estimation 
procedures in appendix F to this part. Alternatively, for units that are 
eligible to use the procedures of appendix D to this part, the owner or 
operator may monitor heat input and NOX emission rate at the 
unit level, in lieu of installing flow monitors on each stack or duct. 
If this alternative unit-level monitoring is performed, report, for each 
unit operating hour, the highest emission rate measured by any of the 
NOX-diluent monitoring systems installed on the individual 
stacks or ducts as the hourly NOX emission rate for the unit, 
and report the hourly unit heat input as determined under appendix D to 
this part. Also, when this alternative unit-level monitoring is 
performed, the applicable NOX missing data procedures in 
Secs. 75.31 or 75.33 shall be used for each unit operating hour in which 
a quality-assured NOX emission rate is not obtained for one 
or more of the individual stacks or ducts; or
    (2) Provided that the products of combustion are well-mixed, 
install, certify, operate, and maintain a NOX continuous 
emission monitoring system in one stack or duct from the affected unit 
and record the monitored value as the NOX emission rate for 
the unit. The owner or operator shall account for NOX 
emissions from the unit during all times when the unit combusts fuel. 
Therefore, this option shall not be used if the monitored stack or duct 
can be bypassed (e.g., by using dampers). Follow the procedure in 
Sec. 75.17(d) for units with bypass stacks. Further, this option shall 
not be used unless the monitored NOX emission rate truly 
represents the NOX emissions discharged to the atmosphere 
(e.g., the option is disallowed if there

[[Page 225]]

are any additional NOX emission controls downstream of the 
monitored location).
    (d) Unit with a main stack and bypass stack configuration. For an 
affected unit with a discharge configuration consisting of a main stack 
and a bypass stack, the owner or operator shall either:
    (1) Follow the procedures in paragraph (c)(1) of this section; or
    (2) Install, certify, operate, and maintain a NOX-diluent 
CEMS only on the main stack. If this option is chosen, it is not 
necessary to designate the exhaust configuration as a multiple stack 
configuration in the monitoring plan required under Sec. 75.53, with 
respect to NOX or any other parameter that is monitored only 
at the main stack. For each unit operating hour in which the bypass 
stack is used, report the maximum potential NOX emission rate 
(as defined in Sec. 72.2 of this chapter). The maximum potential 
NOX emission rate may be specific to the type of fuel 
combusted in the unit during the bypass (see Sec. 75.33(c)(8)).

[58 FR 3701, Jan. 11, 1993, as amended at 60 FR 26523, May 17, 1995; 63 
FR 57499, Oct. 27, 1998; 64 FR 28592, May 26, 1999; 67 FR 40424, June 
12, 2002]