Authority: IC 13-14-8; IC 13-17-3

Affected: IC 13-15; IC 13-17; IC 13-22

Sec. 10. (a) The following sources and facilities located in Warrick County shall comply with the sulfur dioxide emission limitations in pounds per million Btu, unless otherwise specified, and other requirements:

1. (1) Southern Indiana Gas and Electric Company (SIGECO)

   	Facility Description		Emission Limitations
   	(A) Culley Units 1, 2, and 3
   		Beginning December 31, 1989	5.41 each
   		Beginning August 1, 1991 (Units 1 and 2 only)	2.79 each

   1. (B) As an alternative to the emission limitations specified in clause (A), beginning August 1, 1991, sulfur dioxide emissions from Culley Units 1 and 2 shall be limited as follows:

      	Facility Description	Emission Limitations
      	Unit 1	0.0006
      	Unit 2	4.40

   2. (C) SIGECO shall notify the department and the U.S. EPA via certified mail at least fourteen (14) days prior to its intention to rely on the set of limits in clause (B) or to switch between sets of limits listed in clauses (A) and (B).
   3. (D) For the purposes of 326 IAC 7-2-1(e)(1), during thirty (30) day periods in which SIGECO relies on more than one (1) set of limits contained in clauses (A) and (B), a separate thirty (30) day rolling weighted average for each set of limits shall be determined. Each thirty (30) day rolling weighted average shall be based on data from the previous thirty (30) operational days within the last ninety (90) days for that set of limits. If SIGECO does not operate thirty (30) days under any one (1) set of limits within the last ninety (90) days, the rolling weighted average shall be based on all operational days within the last ninety (90) days for that set of limits.
   4. (E) Units 2 and 3 shall maintain a thirty (30) day rolling average sulfur dioxide (SO2) removal efficiency of at least ninety-five percent (95%) using continuous emissions monitoring system (CEMS) data from both the inlet and outlet of the control device determined in accordance with 40 CFR 75*. A thirty (30) day rolling average sulfur dioxide (SO2) removal efficiency means the percent reduction in the mass of a pollutant achieved by a unit's pollution control device over a thirty (30) day period using the thirty (30) day rolling average emission rate. A thirty (30) day rolling average emission rate shall be determined by calculating an arithmetic average of all hourly emission rates in lb/MMBtu for the current day and the previous twenty-nine (29) operating days. A new thirty (30) day rolling average emission rate shall be calculated for each new operating day. Each thirty (30) day rolling average emission rate shall include all startup, shutdown, and malfunction periods within an operating day.
   5. (F) SIGECO shall continuously operate the flue gas desulfurization system (FGD) serving Units 2 and 3 at all times the units are in operation. Following startup of the units, SIGECO need not operate the FGD until either unit is fired with any coal. In the event of a planned FGD outage, SIGECO may continue to operate Unit 2, but shall burn down the coal existing in the Unit 2 bunker to the extent practicable, and, prior to shutting down the FGD, load compliance coal into the bunker for use until such time as the FGD resumes operation. In the event of an unplanned FGD outage, SIGECO shall feed compliance coal to the Unit 2 bunker until such time as the FGD resumes operation. Compliance coal is defined as two (2.0) lb/MMBtu SO2, as demonstrated by a four (4) hour composite sample of the feed stock.

2. (2) Aluminum Company of America (ALCOA) Warrick Power Plant

   	Facility Description	Emission Limitations
   	Units 1, 2, 3, and 4	5.11 each

3. Unit 4 is jointly owned by ALCOA and SIGECO.

4. (3) ALCOA-Warrick Smelter Operations shall comply with the sulfur dioxide emission limitations in pounds per hour, unless otherwise specified, and other requirements as follows:

   	Facility Description	Emission Limitations
   	(A) Potline 1:
   	All stacks associated with scrubber	176.3
   	Roof monitors associated with Potline 1	19.6
   	(B) Potline 2:
   	All stacks associated with scrubber	195.2
   	Roof monitors associated with Potline 2	21.7
   	(C) Potline 3:
   	All vents or stacks associated with scrubber	195.2
   	Roof monitors associated with Potline 3	21.7
   	(D) Potline 4:
   	All vents associated with scrubber	195.2
   	Roof monitors associated with Potline 4	21.7
   	(E) Potline 5:
   	All stacks associated with scrubber	195.2
   	Roof monitors associated with Potline 5	21.7
   	(F) Potline 6:
   	All stacks associated with scrubber	195.2
   	Roof monitors associated with Potline 6	21.7
   	(G) Potlines 1, 2, 3, 4, 5, and 6	5,608 tons per year total
   	(H) Anode Bake Ring Furnace	94.1
   		(412 tons per year)

5. Any sulfur dioxide emission limitation established in a permit issued in conformance with the prevention of significant deterioration rules under 326 IAC 2-2 or 40 CFR 52*, if more stringent, shall supersede the requirements in this subdivision.

(b) Compliance with the pounds per hour limitations specified in subsection (a)(4) shall be based on a stack test under 326 IAC 7-2-1(d).

(c) Compliance with the tons per year limitations specified in subsection (a)(4) shall be based on a rolling twelve (12) consecutive month emission total. Monthly sulfur dioxide emissions shall be determined from calendar month material balances using actual average sulfur content and material throughput. Quarterly reports shall be submitted to the department containing the calendar month and rolling twelve (12) month sulfur dioxide emissions from the smelter operations (potline scrubber stacks, roof monitors, and anode bake ring furnace). The report shall:

1. (1) include documentation of the data and methodology used to calculate the monthly sulfur dioxide emissions; and
2. (2) be submitted by the end of the month following the end of the quarter.

*These documents are incorporated by reference. Copies may be obtained from the Government Printing Office, 732 North Capitol Street NW, Washington, D.C. 20401 or are available for review and copying at the Indiana Department of Environmental Management, Office of Air Quality, Indiana Government Center-North, Tenth Floor, 100 North Senate Avenue, Indianapolis, Indiana 46204.

(Air Pollution Control Division; 326 IAC 7-4-10; filed Aug 28, 1990, 4:50 p.m.: 14 IR 75; readopted filed Jan 10, 2001, 3:20 p.m.: 24 IR 1477; errata filed Dec 12, 2002, 3:35 p.m.: 26 IR 1568; filed Aug 26, 2004, 11:30 a.m.: 28 IR 43; filed Jul 31, 2008, 4:00 p.m.: 20080827-IR-326070309FRA; readopted filed Oct 18, 2024, 2:09 p.m.: 20241113-IR-326230809RFA)