§ 75.16 Special provisions for monitoring emissions from common, bypass, and multiple stacks for SO2 emissions and heat input determinations.
(a) [Reserved]
(b) Common stack procedures. The following procedures shall be used when more than one unit uses a common stack:
(1) Unit utilizing common stack with other affected unit(s). When a Phase I or Phase II affected unit utilizes a common stack with one or more other Phase I or Phase II affected units, but no nonaffected units, the owner or operator shall either:
(i) Install, certify, operate, and maintain an SO2 continuous emission monitoring system and flow monitoring system in the duct to the common stack from each affected unit; or
(ii) Install, certify, operate, and maintain an SO2 continuous emission monitoring system and flow monitoring system in the common stack and combine emissions for the affected units for recordkeeping and compliance purposes.
(2) Unit utilizing common stack with nonaffected unit(s). When one or more Phase I or Phase II affected units utilizes a common stack with one or more nonaffected units, the owner or operator shall either:
(i) Install, certify, operate, and maintain an SO2 continuous emission monitoring system and flow monitoring system in the duct to the common stack from each Phase I and Phase II unit; or
(ii) Install, certify, operate, and maintain an SO2 continuous emission monitoring system and flow monitoring system in the common stack; and
(A) Designate the nonaffected units as opt-in units in accordance with part 74 of this chapter and combine emissions for recordkeeping and compliance purposes; or
(B) Install, certify, operate, and maintain an SO2 continuous emission monitoring system and flow monitoring system in the duct from each nonaffected unit; determine SO2 mass emissions from the affected units as the difference between SO2 mass emissions measured in the common stack and SO2 mass emissions measured in the ducts of the nonaffected units, not to be reported as an hourly average value less than zero; combine emissions for the Phase I and Phase II affected units for recordkeeping and compliance purposes; and calculate and report SO2 mass emissions from the Phase I and Phase II affected units, pursuant to an approach approved by the Administrator, such that these emissions are not underestimated; or