Authority: IC 13-14-8; IC 13-17-3-4; IC 13-17-3-11

Affected: IC 13-15; IC 13-17

Sec. 14. (a) NIPSCO Dean H. Mitchell Generating Station, Source Identification Number 00117, shall comply with the sulfur dioxide emission limits for Boilers 4, 5, 6, and 11 in pounds per million British thermal units (MMBtu), pounds per hour, and other requirements as follows:

1. (1) Operation under either subdivision (2)(B) or (2)(C) shall only be allowed provided that a nozzle is in the stack serving Boilers 4 and 5 such that the stack diameter is restricted to eight and three-tenths (8.3) feet.

2. (2) Sulfur dioxide emissions for boilers operating under the scenarios listed in this subdivision shall be measured as a daily weighted average by the continuous emissions monitoring systems (CEMS) required in subsection (b)(2). NIPSCO Dean H. Mitchell Generating Station may operate under any one (1) of the following scenarios:

   1. (A) Boilers 4, 5, 6, and 11 may operate simultaneously under the following conditions:

      1. (i) One (1) of Boiler 4 or 5 may operate on coal if the other boiler is operated on natural gas or is not operating. Sulfur dioxide emissions from the stack serving Boilers 4 and 5 shall be limited to one and five-hundredths (1.05) pounds per MMBtu and one thousand three hundred thirteen (1,313.0) pounds per hour.
      2. (ii) Boilers 6 and 11 may operate simultaneously on coal. Sulfur dioxide emissions from the stack serving Boilers 6 and 11 shall be limited to one and five-hundredths (1.05) pound per MMBtu and two thousand four hundred seventy-five (2,475.0) pounds per hour.

   2. (B) Boilers 4, 5, 6, and 11 may operate simultaneously on coal subject to the following conditions:

      1. (i) Sulfur dioxide emissions from the stack serving Boilers 4 and 5 shall be limited to seventy-seven hundredths (0.77) pound per MMBtu and one thousand nine hundred twenty-five (1,925.0) pounds per hour.
      2. (ii) Sulfur dioxide emissions from the stack serving Boilers 6 and 11 shall be limited to seventy-seven hundredths (0.77) pound per MMBtu and one thousand eight hundred fifteen (1,815.0) pounds per hour.

   3. (C) One (1) set of either Boilers 4 and 5 or 6 and 11 may operate on coal if the other set is not operating, subject to the following conditions:

      1. (i) Sulfur dioxide emissions from the stack serving Boilers 4 and 5 shall be limited to one and five-hundredths (1.05) pounds per MMBtu and two thousand six hundred twenty-five (2,625.0) pounds per hour.
      2. (ii) Sulfur dioxide emissions from the stack serving Boilers 6 and 11 shall be limited to one and five-hundredths (1.05) pounds per MMBtu and two thousand four hundred seventy-five (2,475.0) pounds per hour.

3. (3) NIPSCO Dean H. Mitchell Generating Station shall maintain a daily log of the following for Boilers 4, 5, 6, and 11:

   1. (A) Fuel type.
   2. (B) Transition time of changes between or within operating scenarios.
4. The log shall be maintained for a minimum of five (5) years and shall be made available to the department and U.S. EPA upon request.
5. (4) Emission limits shall be maintained during transition periods within or between operating scenarios.

(b) NIPSCO Dean H. Mitchell Generating Station shall comply with the following:

1. (1) The diameter of the stack serving Boilers 6 and 11 shall be restricted to eight and three-tenths (8.3) feet.

2. (2) Beginning May 31, 1992, NIPSCO Dean H. Mitchell Generating Station shall maintain and operate CEMS in the stacks serving Boilers 4, 5, 6, and 11. The CEMS shall be operated in accordance with the procedures specified in 326 IAC 3-4 and 326 IAC 3-5, with the exception of the three (3) hour block period reporting requirements under 326 IAC 3-5-7. Records of daily average emissions data shall be:

   1. (A) maintained for a minimum of five (5) years; and
   2. (B) made available to the department and U.S. EPA upon request.

3. (3) NIPSCO Dean H. Mitchell Generating Station shall submit a written report to the department within thirty (30) days after the end of each calendar quarter. The report shall contain the daily weighted average emission rate in units of pounds per MMBtu as measured by the CEMS for each stack venting emissions from those boilers specified in subdivision (2). The hourly gross megawatt power production from the units connected to each stack may be used as the weighting factor in determining the daily weighted average. Records of the hourly gross megawatt power production shall be:

   1. (A) maintained for a minimum of five (5) years; and
   2. (B) made available to the department and U.S. EPA upon request.

(Air Pollution Control Division; 326 IAC 7-4.1-14; filed May 25, 2005, 10:50 a.m.: 28 IR 2960; readopted filed Oct 18, 2024, 2:09 p.m.: 20241113-IR-326230809RFA)