Draft Air Individual Permit Major Amendment

Draft Air Individual Permit Major Amendment 14700009-101 Permittee: Facility name: Northern Natural Gas Company - Owatonna Compressor Station Northern Natural Gas Company - Owatonna Compressor Station 8801 SW 88th Street Ellendale, MN 56026-2170 Steele County Operating permit issuance date: April 21, 1998 Expiration date: Non-expiring Permit * All Title I Conditions do not expire Major Amendment: [Action Issue Date] Permit characteristics: State; Limits to avoid Part 70/ True minor for NSR; True Minor for NSR The emission units, control equipment and emission stacks at the stationary source authorized in this permit amendment are as described in the submittals listed in the Permit Applications Table. This permit amendment supersedes Air Emission Permit No. 14700009-002 and authorizes the Permittee to operate and construct the stationary source at the address listed above unless otherwise noted in the permit. The Permittee must comply with all the conditions of the permit. Any changes or modifications to the stationary source must be performed in compliance with Minn. R. 7007.1150 to 7007.1500. Terms used in the permit are as defined in the state air pollution control rules unless the term is explicitly defined in the permit. Unless otherwise indicated, all the Minnesota rules cited as the origin of the permit terms are incorporated into the SIP under 40 CFR 52.1220 and as such are enforceable by the U.S. Environmental Protection Agency (EPA) Administrator or citizens under the Clean Air Act. Signature: [ ] For This document has been electronically signed. Don Smith, P.E., Manager Air Quality Permits Section Industrial Division for the Minnesota Pollution Control Agency

Table of Contents 1. Permit applications table... 3 2. Where to send submittals... 4 3. Facility description... 5 4. Summary of subject items... 6 5. Limits and other requirements... 7 6. Submittal/action requirements... 24 Page

Permit issued: [month day, year] 14700009-101 Permit expires: [month day, year] Page 3 of 27 1. Permit applications table Subsequent permit applications: Title description Application receipt date Action number Total Facility Operating Permit 09/15/1995 14700009-001 Administrative Amendment Not Applicable 14700009-002 Major Amendment 09/28/2018 14700009-101

Permit issued: [month day, year] 14700009-101 Permit expires: [month day, year] Page 4 of 27 2. Where to send submittals Send submittals that are required to be submitted to the EPA regional office to: Chief Air Enforcement Air and Radiation Branch EPA Region V 77 West Jackson Boulevard Chicago, Illinois 60604 Each submittal must be postmarked or received by the date specified in the applicable Table. Those submittals required by Minn. R. 7007.0100 to 7007.1850 must be certified by a responsible official, defined in Minn. R. 7007.0100, subp. 21. Other submittals shall be certified as appropriate if certification is required by an applicable rule or permit condition. Send submittals that are required by the Acid Rain Program to: U.S. Environmental Protection Agency Clean Air Markets Division 1200 Pennsylvania Avenue NW (6204N) Washington, D.C. 20460 Send any application for a permit or permit amendment to: Fiscal Services 6 th Floor Minnesota Pollution Control Agency 520 Lafayette Road North St. Paul, Minnesota 55155-4194 Also, where required by an applicable rule or permit condition, send to the Permit Document Coordinator notices of: a. Accumulated insignificant activities b. Installation of control equipment c. Replacement of an emissions unit, and d. Changes that contravene a permit term Unless another person is identified in the applicable Table, send all other submittals to: AQ Compliance Tracking Coordinator Industrial Division Minnesota Pollution Control Agency 520 Lafayette Road North St. Paul, Minnesota 55155-4194 Or Email a signed and scanned PDF copy to: submitstacktest.pca@state.mn.us (for submittals related to stack testing) AQRoutineReport.PCA@state.mn.us (for other compliance submittals) (See complete email instructions in Routine Air Report Instructions Letter at http://www.pca.state.mn.us/nwqh472.)

Permit issued: [month day, year] 14700009-101 Permit expires: [month day, year] Page 5 of 27 3. Facility description The Northern Natural Gas Company - Owatonna Compressor Station (Facility) is located at 8801 SW 88th Street in Ellendale, Steele County, Minnesota. The Northern Natural Gas Company - Owatonna Compressor Station is used to pressurize natural gas in order to facilitate its transmission through a pipeline system. The existing facility consists of one natural gas-fired turbine and a diesel-fired emergency generator. The existing facility is subject to New Source Performance Standards for the turbine, and National Emission Standard for Hazardous Air Pollutants for the emergency generator. This permit action authorizes installation and operation of one additional natural-gas fired turbine, two natural gasfired process heaters, and a new natural gas-fired four-stroke lean burn spark ignition emergency generator. The turbines' operating hours will be limited to ensure that site-wide CO emissions do not exceed 96 tons per year. The existing diesel-fired emergency generator will be removed and replaced with the natural gas-fired four-stroke lean burn spark ignition emergency generator. Flanges, valves and compressor seals are also added to the permit.

Permit issued: [month day, year] 14700009-101 Permit expires: [month day, year] Page 6 of 27 4. Summary of subject items SI ID: Relationshi Description p Type TFAC 1: Northern Natural Gas Co - Owatonna COMG 1: Turbine Hours has of Operation members EQUI 1: Stationary sends to Natural Gas-Fired Turbine EQUI 2: Emergency Generator EQUI 3: Natural Gas- Fired Turbine EQUI 4: Emergency Generator Related SI ID: Description EQUI 1, EQUI 3 STRU 1: Solar Mars Turbine 100-15000S Stack sends to STRU 2 sends to STRU 3: Solar Mars Turbine 100-16000S Stack sends to STRU 4: Cummins GTA38E Generator Stack EQUI 5: Heater sends to STRU 5: Process Heater EQUI 6: Heater sends to STRU 6: Process Heater SI ID: Description FUGI 1: Flanges FUGI 2: Compressor Seals FUGI 3: Valves STRU 1: Solar Mars Turbine 100-15000S Stack STRU 2: STRU 3: Solar Mars Turbine 100-16000S Stack STRU 4: Cummins GTA38E Generator Stack STRU 5: Process Heater STRU 6: Process Heater STRU 7: Compressor Building STRU 8: Compressor Building 2 STRU 9: Control Building STRU 10: Generator Building Relationshi p Type Related SI ID: Description

Permit Expires: [month day, year] Page 7 of 27 5. Limits and other requirements TFAC 1 14700009 Northern Natural Gas Co - Owatonna 5.1.1 PERMIT SHIELD: Subject to the limitations in Minn. R. 7007.1800, compliance with the conditions of this permit shall be deemed compliance with the specific provision of the applicable requirement identified in the permit as the basis of each condition. Subject to the limitations of Minn. R. 7007.1800 and 7017.0100, subp. 2, notwithstanding the conditions of this permit specifying compliance practices for applicable requirements, any person (including the Permittee) may also use other credible evidence to establish compliance or noncompliance with applicable requirements. This permit shall not alter or affect the liability of the Permittee for any violation of applicable requirements prior to or at the time of permit issuance. [Minn. R. 7007.1800(A)(2)] 5.1.2 Circumvention: Do not install or use a device or means that conceals or dilutes emissions, which would otherwise violate a federal or state air pollution control rule, without reducing the total amount of pollutant emitted. [Minn. R. 7011.0020] 5.1.3 Air Pollution Control Equipment: Operate all pollution control equipment whenever the corresponding process equipment and emission units are operated. [Minn. R. 7007.0800, subp. 16(J), Minn. R. 7007.0800, subp. 2] 5.1.4 Operation and Maintenance Plan: Retain at the stationary source an operation and maintenance plan for all air pollution control equipment. At a minimum, the O & M plan shall identify all air pollution control equipment and control practices and shall include a preventative maintenance program for the equipment and practices, a description of (the minimum but not necessarily the only) corrective actions to be taken to restore the equipment and practices to proper operation to meet applicable permit conditions, a description of the employee training program for proper operation and maintenance of the control equipment and practices, and the records kept to demonstrate plan implementation. [Minn. R. 7007.0800, subp. 14, Minn. R. 7007.0800, subp. 16(J)] 5.1.5 Operation Changes: In any shutdown, breakdown, or deviation the Permittee shall immediately take all practical steps to modify operations to reduce the emission of any regulated air pollutant. The Commissioner may require feasible and practical modifications in the operation to reduce emissions of air pollutants. No emissions units that have an unreasonable shutdown or breakdown frequency of process or control equipment shall be permitted to operate. [Minn. R. 7019.1000, subp. 4] 5.1.6 Fugitive Emissions: Do not cause or permit the handling, use,

Permit Expires: [month day, year] Page 8 of 27 transporting, or storage of any material in a manner which may allow avoidable amounts of particulate matter to become airborne. Comply with all other requirements listed in Minn. R. 7011.0150. [Minn. R. 7011.0150] 5.1.7 Noise: The Permittee shall comply with the noise standards set forth in Minn. R. 7030.0010 to 7030.0080 at all times during the operation of any emission units. This is a state only requirement and is not enforceable by the EPA Administrator or citizens under the Clean Air Act. [Minn. R. 7030.0010-7030.0080] 5.1.8 Inspections: The Permittee shall comply with the inspection procedures and requirements as found in Minn. R. 7007.0800, subp. 9(A). [Minn. R. 7007.0800, subp. 9(A)] 5.1.9 The Permittee shall comply with the General Conditions listed in Minn. R. 7007.0800, subp. 16. [Minn. R. 7007.0800, subp. 16] 5.1.10 Performance Testing: Conduct all performance tests in accordance with Minn. R. ch. 7017 unless otherwise noted in this permit. [Minn. R. ch. 7017] 5.1.11 Performance Test Notifications and Submittals: Performance Test Notification and Plan: due 30 days before each Performance Test Performance Test Pre-test Meeting: due 7 days before each Performance Test Performance Test Report: due 45 days after each Performance Test The Notification, Test Plan, and Test Report must be submitted in a format specified by the commissioner. [Minn. R. 7017.2017, Minn. R. 7017.2030, subps. 1-4, Minn. R. 7017.2035, subps. 1-2] 5.1.12 Limits set as a result of a performance test (conducted before or after permit issuance) apply until superseded as stated in the MPCA's Notice of Compliance letter granting preliminary approval. Preliminary approval is based on formal review of a subsequent performance test on the same unit as specified by Minn. R. 7017.2025, subp. 3. The limit is final upon issuance of a permit amendment incorporating the change. [Minn. R. 7017.2025, subp. 3] 5.1.13 Monitoring Equipment Calibration - The Permittee shall either: 1. Calibrate or replace required monitoring equipment every 12 months; or 2. Calibrate at the frequency stated in the manufacturer's specifications. For each monitor, the Permittee shall maintain a record of all calibrations, including the date conducted, and any corrective action that resulted. The Permittee shall include the calibration frequencies, procedures, and manufacturer's specifications (if applicable) in the Operations and Maintenance Plan. Any requirements applying to continuous emission monitors are listed separately in this permit. [Minn. R. 7007.0800, subp. 4(D)] 5.1.14 Operation of Monitoring Equipment: Unless noted elsewhere in this permit, monitoring a process or control equipment connected to

Permit Expires: [month day, year] Page 9 of 27 that process is not necessary during periods when the process is shutdown, or during checks of the monitoring systems, such as calibration checks and zero and span adjustments. If monitoring records are required, they should reflect any such periods of process shutdown or checks of the monitoring system. [Minn. R. 7007.0800, subp. 4(D)] 5.1.15 Recordkeeping: Retain all records at the stationary source, unless otherwise specified within this permit, for a period of five (5) years from the date of monitoring, sample, measurement, or report. Records which must be retained at this location include all calibration and maintenance records, all original recordings for continuous monitoring instrumentation, and copies of all reports required by the permit. Records must conform to the requirements listed in Minn. R. 7007.0800, subp. 5(A). [Minn. R. 7007.0800, subp. 5(C)] 5.1.16 Recordkeeping: Maintain records describing any insignificant modifications (as required by Minn. R. 7007.1250, subp. 3) or changes contravening permit terms (as required by Minn. R. 7007.1350, subp. 2), including records of the emissions resulting from those changes. [Minn. R. 7007.0800, subp. 5(B)] 5.1.17 If the Permittee determines that no permit amendment or notification is required prior to making a change, the Permittee must retain records of all calculations required under Minn. R. 7007.1200. For non-expiring permits, these records shall be kept for a period of five years from the date that the change was made. The records shall be kept at the stationary source for the current calendar year of operation and may be kept at the stationary source or office of the stationary source for all other years. The records may be maintained in either electronic or paper format. [Minn. R. 7007.1200, subp. 4] 5.1.18 Shutdown Notifications: Notify the Commissioner at least 24 hours in advance of a planned shutdown of any control equipment or process equipment if the shutdown would cause any increase in the emissions of any regulated air pollutant. If the owner or operator does not have advance knowledge of the shutdown, notification shall be made to the Commissioner as soon as possible after the shutdown. However, notification is not required in the circumstances outlined in Items A, B and C of Minn. R. 7019.1000, subp. 3. At the time of notification, the owner or operator shall inform the Commissioner of the cause of the shutdown and the estimated duration. The owner or operator shall notify the Commissioner when the shutdown is over. [Minn. R. 7019.1000, subp. 3] 5.1.19 Breakdown Notifications: Notify the Commissioner within 24 hours of a breakdown of more than one hour duration of any control equipment or process equipment if the breakdown causes any increase in the emissions of any regulated air pollutant. The 24- hour time period starts when the breakdown was discovered or reasonably should have been discovered by the owner or operator.

Permit Expires: [month day, year] Page 10 of 27 However, notification is not required in the circumstances outlined in Items A, B and C of Minn. R. 7019.1000, subp. 2. At the time of notification or as soon as possible thereafter, the owner or operator shall inform the Commissioner of the cause of the breakdown and the estimated duration. The owner or operator shall notify the Commissioner when the breakdown is over. [Minn. R. 7019.1000, subp. 2] 5.1.20 Notification of Deviations Endangering Human Health or the Environment: As soon as possible after discovery, notify the Commissioner or the state duty officer, either orally or by facsimile, of any deviation from permit conditions which could endanger human health or the environment. [Minn. R. 7019.1000, subp. 1] 5.1.21 Notification of Deviations Endangering Human Health or the Environment Report: Within 2 working days of discovery, notify the Commissioner in writing of any deviation from permit conditions which could endanger human health or the environment. Include the following information in this written description: 1. the cause of the deviation; 2. the exact dates of the period of the deviation, if the deviation has been corrected; 3. whether or not the deviation has been corrected; 4. the anticipated time by which the deviation is expected to be corrected, if not yet corrected; and 5. steps taken or planned to reduce, eliminate, and prevent reoccurrence of the deviation. [Minn. R. 7019.1000, subp. 1] 5.1.22 Application for Permit Amendment: If a permit amendment is needed, submit an application in accordance with the requirements of Minn. R. 7007.1150 through Minn. R. 7007.1500. Submittal dates vary, depending on the type of amendment needed. Upon adoption of a new or amended federal applicable requirement, and if there are 3 or more years remaining in the permit term, the Permittee shall file an application for an amendment within nine months of promulgation of the applicable requirement, pursuant to Minn. R. 7007.0400, subp. 3. [Minn. R. 7007.0400, subp. 3, Minn. R. 7007.1150-7007.1500] 5.1.23 Extension Requests: The Permittee may apply for an Administrative Amendment to extend a deadline in a permit by no more than 120 days, provided the proposed deadline extension meets the requirements of Minn. R. 7007.1400, subp. 1(H). Performance testing deadlines from the General Provisions of 40 CFR pt. 60 and pt. 63 are examples of deadlines for which the MPCA does not have authority to grant extensions and therefore do not meet the requirements of Minn. R. 7007.1400, subp. 1(H). [Minn. R. 7007.1400, subp. 1(H)] 5.1.24 Emission Inventory Report: due on or before April 1 of each calendar year following permit issuance. Submit in a format specified by the Commissioner. [Minn. R. 7019.3000-7019.3100] 5.1.25 Emission Fees: due 30 days after receipt of an MPCA bill. [Minn. R.

Permit Expires: [month day, year] Page 11 of 27 7002.0005-7002.0095] 5.1.26 The Permittee is authorized to install and operate EQUI3, EQUI4, EQUI5, EQUI6, FUGI1, FUGI2, FUGI3, STRU3, STRU4, STRU5, STRU6, STRU8, STRU9 and STRU10 as defined by the emissions unit information in Section 4 of this permit, within three years after issuance of permit 14700009-101. The units shall meet all the requirements of this permit. [Minn. R. 7007.0800, subp. 2] COMG 1 Turbine Hours of Operation 5.2.1 The Permittee shall limit Operating Hours <= 13,620 hours per year 12-month rolling sum of combined runtime hours of EQUI1 and EQUI3. [To avoid major source under 40 CFR 70.2 & Minn. R. 7007.0200] 5.2.2 Daily Recordkeeping: On each day of operation the Permittee shall record the daily hours of operation for both EQUI1 and EQUI3. Records shall be kept in a log at the facility. [Minn. R. 7007.0800, subps. 4-5, To avoid major source under 40 CFR 70.2 & Minn. R. 7007.0200] 5.2.3 Monthly Recordkeeping: Using the daily records, by the 15th day of each month, the Permittee shall calculate and record the following: 1. The total hours of operation for both EQUI1 and EQUI3 for the previous calendar month. 2. The 12-month rolling sum of hours of operation for both EQUI1 and EQUI3 for the previous 12-month period by summing the monthly hours data for the previous 12 months. [Minn. R. 7007.0800, subps. 4-5] EQUI 1 EU001 Stationary Natural Gas-Fired Turbine 5.3.1 The Permittee may replace the existing turbine with a similar turbine as described below. [Minn. R. 7007.0800, subp. 11] 5.3.2 If the Permittee replaces the existing turbine with a similar turbine, the Permittee shall meet the following conditions: 1. The maximum Brake horsepower (BHP) of the turbine may not exceed 16,000 BHP. 2. The turbine must be equipped with a low-nox burner and combust only pipeline-quality natural gas. 3. The Permittee shall calculate and keep a permanent record of the potential emission rates in lb/hr, of PM, PM10, PM2.5, SO2, NOx, and CO for the replacement turbine. 4. If the replacement turbine is a previously-operated unit that is an affected facility as defined in 40 CFR Section 60.330, and the Permittee has previously met all applicable requirements in 40 CFR Sections 60.7 and 60.8 for the replacement turbine, notify the MPCA of the replacement no later than 30 days after completion of installation of the replacement turbine. The notification shall

Permit Expires: [month day, year] Page 12 of 27 include a copy of all previously submitted notifications required by 40 CFR Section 60.7 and results of performance tests required by 40 CFR Section 60.8. 5. If the replacement turbine is a new unit that is an affected facility, complete all applicable notification and testing requirements in 40 CFR Sections 60.7 and 60.8. [Minn. R. 7007.0800, subp. 2] 5.3.3 Notification of Replacement: Postmarked within 60 days after making the replacement. Include the maximum BHP of the turbine and the potential emission rates in the notification. [Minn. R. 7007.0800, subp. 2] 5.3.4 The Permittee shall limit Nitrogen Oxides <= 0.0157 percent by volume at 15 percent oxygen and on a dry basis. [40 CFR 60.332(d), Minn. R. 7011.2350] 5.3.5 Opacity <= 20 percent opacity once operating temperatures have been attained. [Minn. R. 7011.2300, subp. 1] 5.3.6 Sulfur Dioxide <= 0.0015 pounds per million Btu heat input. The potential to emit from the unit is 0.00141 lb/mmbtu due to equipment design and allowable fuels. [Minn. R. 7011.2300, subp. 2(B)] 5.3.7 The Permittee shall limit Sulfur Content of Fuel <= 0.8 percent by weight. [40 CFR 60.333(b), Minn. R. 7011.2350] 5.3.8 Fuel type: Natural gas only by design. [Minn. R. 7005.0100, subp. 35a] 5.3.9 The Permittee shall keep records of fuel type and usage on a monthly basis. [Minn. R. 7007.0800, subp. 5] 5.3.10 See COMG1 for the annual hours of operation limit. [Minn. R. 7007.0800, subp. 2] 5.3.11 The Permittee may, but is not required to, for purposes of determining excess emissions, use a CEMS that meets the requirements of 40 CFR Section 60.334(b). Also, if the Permittee has previously submitted and received EPA, State, or local permitting authority approval of a procedure for monitoring compliance with the applicable NOx emission limit under 40 CFR Section 60.332, that approved procedure may continue to be used. [40 CFR 60.334(c), Minn. R. 7011.2350] 5.3.12 (1) The Permittee shall monitor the total sulfur content of the fuel being fired in the turbine, except as provided in 40 CFR Section 60.334(h)(3). The sulfur content of the fuel must be determined using total sulfur methods described in 40 CFR Section 60.335(b)(10). Alternatively, if the total sulfur content of the gaseous fuel during the most recent performance test was less than 0.4 weight percent (4000 ppmw), ASTM D4084-82, 94, D5504-01, D6228-98, or Gas Processors Association Standard 2377-86 (all of which are incorporated by reference, see 40 CFR Section 60.17), which measure the major sulfur compounds may be used; and (2) The Permittee shall monitor the nitrogen content of the fuel combusted in the turbine, if the Permittee claims an allowance for fuel bound nitrogen (i.e., if an F-value greater than zero is being or

Permit Expires: [month day, year] Page 13 of 27 will be used by the Permittee to calculate STD in 40 CFR Section 60.332). The nitrogen content of the fuel shall be determined using methods described in 40 CFR Section 60.335(b)(9) or an approved alternative. (3) Notwithstanding the provisions of 40 CFR Section 60.334(h)(1), the Permittee may elect not to monitor the total sulfur content of the gaseous fuel combusted in the turbine, if the gaseous fuel is demonstrated to meet the definition of natural gas in 40 CFR Section 60.331(u), regardless of whether an existing custom schedule approved by the administrator for 40 CFR pt. 60, subp. GG requires such monitoring. The Permittee shall use one of the following sources of information to make the required demonstration: (i) The gas quality characteristics in a current, valid purchase contract, tariff sheet or transportation contract for the gaseous fuel, specifying that the maximum total sulfur content of the fuel is 20.0 grains/100 scf or less; or (ii) Representative fuel sampling data which show that the sulfur content of the gaseous fuel does not exceed 20 grains/100 scf. At a minimum, the amount of fuel sampling data specified in section 2.3.1.4 or 2.3.2.4 of appendix D to 40 CFR pt. 75 is required. (4) For any turbine that commenced construction, reconstruction or modification after October 3, 1977, but before July 8, 2004, and for which a custom fuel monitoring schedule has previously been approved, the Permittee may, without submitting a special petition to the Administrator, continue monitoring on this schedule. [40 CFR 60.334(h), Minn. R. 7011.2350] 5.3.13 The frequency of determining the sulfur and nitrogen content of the fuel shall be as follows: (2) Gaseous fuel. Any applicable nitrogen content value of the gaseous fuel shall be determined and recorded once per unit operating day. For Permittees that elect not to demonstrate sulfur content using options in 40 CFR Section 60.334(h)(3), and for which the fuel is supplied without intermediate bulk storage, the sulfur content value of the gaseous fuel shall be determined and recorded once per unit operating day. (3) Custom schedules. Notwithstanding the requirements of 40 CFR Section 60.334(i)(2), operators or fuel vendors may develop custom schedules for determination of the total sulfur content of gaseous fuels, based on the design and operation of the affected facility and the characteristics of the fuel supply. Except as provided in 40 CFR Section 60.334(i)(3)(i) and (i)(3)(ii), custom schedules shall be substantiated with data and shall be approved by the Administrator before they can be used to comply with the standard in 40 CFR Section 60.333. (i) The two custom sulfur monitoring schedules set forth in 40 CFR Section 60.334(i)(3)(i)(A) through (D) and in 40 CFR Section 60.334(i)(3)(ii) are acceptable, without prior Administrative approval: (A) The Permittee shall obtain daily total sulfur content measurements for 30 consecutive unit operating days, using the

Permit Expires: [month day, year] Page 14 of 27 applicable methods specified in 40 CFR pt. 60, subp. GG. Based on the results of the 30 daily samples, the required frequency for subsequent monitoring of the fuel's total sulfur content shall be as specified in 40 CFR Section 60.334(i)(3)(i)(B), (C), or (D), as applicable. (B) If none of the 30 daily measurements of the fuel's total sulfur content exceeds 0.4 weight percent (4000 ppmw), subsequent sulfur content monitoring may be performed at 12-month intervals. If any of the samples taken at 12-month intervals has a total sulfur content between 0.4 and 0.8 weight percent (4000 and 8000 ppmw), follow the procedures in 40 CFR Section 60.334(i)(3)(i)(C). If any measurement exceeds 0.8 weight percent (8000 ppmw), follow the procedures in 40 CFR Section 60.334(i)(3)(i)(D). (C) If at least one of the 30 daily measurements of the fuel's total sulfur content is between 0.4 and 0.8 weight percent (4000 and 8000 ppmw), but none exceeds 0.8 weight percent (8000 ppmw), then: (1) Collect and analyze a sample every 30 days for three months. If any sulfur content measurement exceeds 0.8 weight percent (8000 ppmw), follow the procedures in 40 CFR Section 60.334(i)(3)(i)(D). Otherwise, follow the procedures in 40 CFR Section 60.334(i)(3)(i)(C)(2). (2) Begin monitoring at 6-month intervals for 12 months. If any sulfur content measurement exceeds 0.8 weight percent (8000 ppmw), follow the procedures in 40 CFR Section 60.334(i)(3)(i)(D). Otherwise, follow the procedures in 40 CFR Section 60.334(i)(3)(i)(C)(3). (3) Begin monitoring at 12-month intervals. If any sulfur content measurement exceeds 0.8 weight percent (8000 ppmw), follow the procedures in 40 CFR Section 60.334(i)(3)(i)(D). Otherwise, continue to monitor at this frequency. (D) If a sulfur content measurement exceeds 0.8 weight percent (8000 ppmw), immediately begin daily monitoring according to 40 CFR Section 60.334(i)(3)(i)(A). Daily monitoring shall continue until 30 consecutive daily samples, each having a sulfur content no greater than 0.8 weight percent (8000 ppmw), are obtained. At that point, the applicable procedures of 40 CFR Section 60.334(i)(3)(i)(B) or (C) shall be followed. [40 CFR 60.334(i)(2)-(3)(i), Minn. R. 7011.2350] 5.3.14 (ii) The Permittee may use the data collected from the 720-hour sulfur sampling demonstration described in section 2.3.6 of appendix D to 40 CFR pt. 75 to determine a custom sulfur sampling schedule, as follows: (A) If the maximum fuel sulfur content obtained from the 720 hourly samples does not exceed 20 grains/100 scf (i.e., the maximum total sulfur content of natural gas as defined in 40 CFR Section 60.331(u)), no additional monitoring of the sulfur content of the gas is required, for the purposes of 40 CFR pt. 60, subp. GG. (B) If the maximum fuel sulfur content obtained from any of the 720 hourly samples exceeds 20 grains/100 scf, but none of the sulfur content values (when converted to weight percent sulfur) exceeds

Permit Expires: [month day, year] Page 15 of 27 0.4 weight percent (4000 ppmw), then the minimum required sampling frequency shall be one sample at 12 month intervals. (C) If any sample result exceeds 0.4 weight percent sulfur (4000 ppmw), but none exceeds 0.8 weight percent sulfur (8000 ppmw), follow the provisions 40 CFR Section 60.344(i)(3)(i)(C). (D) If the sulfur content of any of the 720 hourly samples exceeds 0.8 weight percent (8000 ppmw), follow the provisions of 40 CFR Section 60.344(i)(3)(i)(D). [40 CFR 60.334(i)(3)(ii), Minn. R. 7011.2350] 5.3.15 The Permittee shall submit reports of excess emissions and monitor downtime, in accordance with 40 CFR Section 60.7(c). Excess emissions shall be reported for all periods of unit operation, including startup, shutdown and malfunction. For the purpose of reports required under 40 CFR Section 60.7(c), periods of excess emissions and monitor downtime that shall be reported are defined as follows: (2) Sulfur dioxide. If the Permittee is required to monitor the sulfur content of the fuel under 40 CFR Section 60.334(h): (i) For samples of gaseous fuel obtained using daily sampling, flow proportional sampling, or sampling from the unit's storage tank, an excess emission occurs each unit operating hour included in the period beginning on the date and hour of any sample for which the sulfur content of the fuel being fired in the gas turbine exceeds 0.8 weight percent and ending on the date and hour that a subsequent sample is taken that demonstrates compliance with the sulfur limit. (iii) A period of monitor downtime begins when a required sample is not taken by its due date. A period of monitor downtime also begins on the date and hour of a required sample, if invalid results are obtained. The period of monitor downtime shall include only unit operating hours, and ends on the date and hour of the next valid sample. [40 CFR 60.334(j)(2), Minn. R. 7011.2350] 5.3.16 All reports required under 40 CFR Section 60.7(c) shall be postmarked by the 30th day following the end of each 6-month period. [40 CFR 60.334(j)(5), Minn. R. 7011.2350] EQUI 2 EU002 Emergency Generator 5.4.1 EQUI2 will be shut down and replaced by EQUI4 as authorized by permit no. 14700009-101. Simultaneous operation of EQUI2 and EQUI4 is prohibited. [Minn. R. 7007.0800, subp. 2] 5.4.2 Opacity <= 20 percent opacity once operating temperatures have been attained. [Minn. R. 7011.2300, subp. 1] 5.4.3 Sulfur Dioxide <= 0.0015 pounds per million Btu heat input. [Minn. R. 7011.2300, subp. 2] 5.4.4 The Permittee shall change oil and filter every 500 hours of operation or annually, whichever comes first. [40 CFR pt. 63, subp. ZZZZ(Table 2d), Minn. R. 7011.8150] 5.4.5 The Permittee shall inspect air cleaner every 1,000 hours of operation or annually, whichever comes first, and replace as

Permit Expires: [month day, year] Page 16 of 27 necessary. [40 CFR pt. 63, subp. ZZZZ(Table 2d), Minn. R. 7011.8150] 5.4.6 The Permittee shall inspect all hoses and belts every 500 hours of operation or annually, whichever comes first, and replace as necessary. [40 CFR pt. 63, subp. ZZZZ(Table 2d), Minn. R. 7011.8150] EQUI 3 Natural Gas-Fired Turbine 5.5.1 The Permittee shall limit Nitrogen Oxides <= 25 parts per million at 15 percent oxygen, or 150 ng/j of useful output (1.2 lb/mwh). [40 CFR 60.4320(a), 40 CFR pt. 60, subp. KKKK(Table 1), Minn. R. 7011.2375] 5.5.2 The Permittee shall limit Sulfur Dioxide <= 110 nanograms per joule (0.90 pounds per megawatt-hour (lb/mwh)) gross output. [40 CFR 60.4330(a)(1), Minn. R. 7011.2375] 5.5.3 Opacity <= 20 percent opacity once operating temperatures have been attained. [Minn. R. 7011.2300, subp. 1] 5.5.4 Sulfur Dioxide <= 0.0015 pounds per million Btu heat input. The potential to emit from the unit is 0.00141 lb/mmbtu due to equipment design and allowable fuels. [Minn. R. 7011.2300, subp. 2(B)] 5.5.5 Fuel type: Natural gas only by design. [Minn. R. 7005.0100, subp. 35a] 5.5.6 The Permittee shall keep records of fuel type and usage on a monthly basis. [Minn. R. 7007.0800, subp. 5] 5.5.7 See COMG1 for the annual hours of operation limit. [Minn. R. 7007.0800, subp. 2] 5.5.8 The Permittee must operate and maintain EQUI3, air pollution control equipment, and monitoring equipment in a manner consistent with good air pollution control practices for minimizing emissions at all times including during startup, shutdown, and malfunction. [40 CFR 60.4333, Minn. R. 7011.2375] 5.5.9 The Permittee must perform annual performance tests in accordance with 40 CFR Section 60.4400 to demonstrate continuous compliance. If the NOx emission result from the performance test is less than or equal to 75 percent of the NOx emission limit for the turbine, the Permittee may reduce the frequency of subsequent performance tests to once every 2 years (no more than 26 calendar months following the previous performance test). If the results of any subsequent performance test exceed 75 percent of the NOx emission limit for the turbine, the Permittee must resume annual performance tests. [40 CFR 60.4340(a), Minn. R. 7011.2375] 5.5.10 The Permittee must submit reports of excess emissions and monitor downtime, in accordance with 40 CFR Section 60.7(c). Excess emissions must be reported for all periods of unit operation, including startup, shutdown, and malfunction. [40 CFR 60.4375(a),

Permit Expires: [month day, year] Page 17 of 27 Minn. R. 7011.2375] 5.5.11 The Permittee must submit a written report of the results of each performance test to the Agency before the close of business on the 60th day following the completion of the performance test. [40 CFR 60.4375(b), Minn. R. 7011.2375] 5.5.12 For samples of gaseous fuel and for oil samples obtained using daily sampling, flow proportional sampling, or sampling from the unit's storage tank, an excess emission occurs each unit operating hour included in the period beginning on the date and hour of any sample for which the sulfur content of the fuel being fired in the combustion turbine exceeds the applicable limit and ending on the date and hour that a subsequent sample is taken that demonstrates compliance with the sulfur limit. [40 CFR 60.4385(a), Minn. R. 7011.2375] 5.5.13 The NOx performance test must be done at any load condition within plus or minus 25 percent of 100 percent of peak load. The Permittee may perform testing at the highest achievable load point, if at least 75 percent of peak load cannot be achieved in practice. The Permittee must conduct three separate test runs for each performance test. The minimum time per run is 20 minutes. [40 CFR 60.4400(b), Minn. R. 7011.2375] 5.5.14 Compliance with the applicable NOx emission limit in 40 CFR Section 60.4320 must be demonstrated at each tested load level. Compliance is achieved if the three-run arithmetic average NOx emission rate at each tested level meets the applicable emission limit in 40 CFR Section 60.4320. [40 CFR 60.4400(b)(4), Minn. R. 7011.2375] 5.5.15 The ambient temperature must be greater than 0 degrees F during the NOx performance test. [40 CFR 60.4400(b)(6), Minn. R. 7011.2375] 5.5.16 The Permittee must conduct an initial performance test, as required in 40 CFR Section 60.8 for SO2. Subsequent SO2 performance tests shall be conducted on an annual basis (no more than 14 calendar months following the previous performance test). (1) The Permittee shall periodically determine the sulfur content of the fuel combusted in the turbine, a representative fuel sample would be collected following ASTM D4177 (incorporated by reference, see 40 CFR Section 60.17) for oil. Alternatively, for oil, the Permittee may follow the procedures for manual pipeline sampling in section 14 of ASTM D4057 (incorporated by reference, see 40 CFR Section 60.17). The fuel analyses of 40 CFR Section 60.4415 may be performed either by the Permittee, a service contractor retained by the Permittee, the fuel vendor, or any other qualified agency. Analyze the samples for the total sulfur content of the fuel using: (ii) For gaseous fuels, ASTM D1072, or alternatively D3246, D4084, D4468, D4810, D6228, D6667 or Gas Processors Association Standard 2377 (all of which are incorporated by reference, see 40 CFR Section 60.17.). [40 CFR 60.4415(a)(1)(ii), Minn. R. 7011.2375] 5.5.17 The Permittee shall submit a notification of any physical or

Permit Expires: [month day, year] Page 18 of 27 operational change which increases emission rate: due 60 days (or as soon as practical) before the change is commenced. [40 CFR 60.7(a)(4), Minn. R. 7019.0100, subp. 1] 5.5.18 Recordkeeping: The Permittee shall maintain records of the occurrence and duration of any startup, shutdown, or malfunction in the operation of the facility including; any malfunction of the air pollution control equipment; or any periods during which a continuous monitoring system or monitoring device is inoperative. [40 CFR 60.7(b), Minn. R. 7019.0100, subp. 1] 5.5.19 Recordkeeping: The Permittee shall maintain a file of all measurements, maintenance, reports and records for at least five years. This requirement is more stringent than 40 CFR Section 60.7(f), which specifies two years. [40 CFR 60.7(f), Minn. R. 7007.0800, subp. 5(C), Minn. R. 7019.0100, subp. 1] 5.5.20 No owner or operator shall build, erect, install, or use any article, machine, equipment or process, the use of which conceals an emission which would otherwise constitute a violation of an applicable standard. [40 CFR 60.12, Minn. R. 7011.0050] 5.5.21 Operations during periods of startup, shutdown, and malfunction shall not constitute representative conditions for the purpose of a performance test nor shall emissions in excess of the level of the applicable emission limit during periods of startup, shutdown, and malfunction be considered a violation of the applicable emission limit unless otherwise specified in the applicable standards. [40 CFR 60.8(c), Minn. R. 7017.2015, subp. 2(A)] EQUI 4 Emergency Generator 5.6.1 The Permittee shall limit Nitrogen Oxides <= 2.0 grams per horsepower-hour (160 ppmvd at 15% O2). [40 CFR 60.4233(e), 40 CFR 63.6590(c), 40 CFR pt. 60, subp. JJJJ(Table 1), Minn. R. 7011.2310, Minn. R. 7011.8150] 5.6.2 The Permittee shall limit Carbon Monoxide <= 4.0 grams per horsepower-hour (540 ppmvd at 15% O2). [40 CFR 60.4233(e), 40 CFR 63.6590(c), 40 CFR pt. 60, subp. JJJJ(Table 1), Minn. R. 7011.2310, Minn. R. 7011.8150] 5.6.3 The Permittee shall limit Volatile Organic Compounds <= 1.0 grams per horsepower-hour (86 ppmvd at 15% O2). [40 CFR 60.4233(e), 40 CFR 63.6590(c), 40 CFR pt. 60, subp. JJJJ(Table 1), Minn. R. 7011.2310, Minn. R. 7011.8150] 5.6.4 Opacity <= 20 percent opacity once operating temperatures have been attained. [Minn. R. 7011.2300, subp. 1] 5.6.5 Sulfur Dioxide <= 0.0015 pounds per million Btu heat input. The potential to emit from the unit is 0.000588 lb/mmbtu due to equipment design and allowable fuels. [Minn. R. 7011.2300, subp. 2(B)] 5.6.6 Fuel type: Natural gas only by design. [Minn. R. 7005.0100, subp. 35a]

Permit Expires: [month day, year] Page 19 of 27 5.6.7 Hours of Operation: The Permittee shall maintain documentation on site that the unit is an emergency generator by design that qualifies under the U.S. EPA memorandum entitled "Calculating Potential to Emit (PTE) for Emergency Generators" dated September 6, 1995, limiting operation to 500 hours per year. [Minn. R. 7007.0800, subps. 4-5] 5.6.8 The Permittee shall keep records of fuel type and usage on a monthly basis. [Minn. R. 7007.0800, subp. 5] 5.6.9 EQUI4 is a new stationary RICE located at an area source and the Permittee must meet the requirements of 40 CFR pt. 63, subp. ZZZZ by meeting the requirements of 40 CFR pt. 60, subp. JJJJ for spark ignition engines. No further requirements apply for such engines under 40 CFR pt. 63, subp. ZZZZ. [40 CFR 63.6590(c)(1), Minn. R. 7011.8150] 5.6.10 The Permittee is an owner and operator of an emergency stationary SI ICE that commenced construction after June 12, 2006, where the stationary SI ICE was manufactured on or after January 1, 2009, for emergency engines with a maximum engine power greater than 19 KW (25 HP). [40 CFR 60.4230(a)(4)(iv), 40 CFR 63.6590(c), Minn. R. 7011.2310, Minn. R. 7011.8150] 5.6.11 The Permittee must operate and maintain EQUI4 that achieves the emission standards as required in 40 CFR Section 60.4233 over the entire life of the engine. [40 CFR 60.4234, 40 CFR 63.6590(c), Minn. R. 7011.2310, Minn. R. 7011.8150] 5.6.12 The Permittee may not install engines that do not meet the applicable requirements in 40 CFR Section 60.4233 after January 1, 2011. [40 CFR 60.4236(c), 40 CFR 63.6590(c), Minn. R. 7011.2310, Minn. R. 7011.8150] 5.6.13 The Permittee is purchasing an engine certified according to procedures specified in 40 CFR pt. 60, subp. JJJJ, for the same model year and demonstrating compliance according to one of the methods specified in 40 CFR Section 60.4243(a). The Permittee must keep a maintenance plan and records of conducted maintenance and must, to the extent practicable, maintain and operate the engine in a manner consistent with good air pollution control practice for minimizing emissions. In addition, the Permittee must conduct an initial performance test and conduct subsequent performance testing every 8,760 hours or 3 years, whichever comes first, thereafter to demonstrate compliance. [40 CFR 60.4243(b)(1)(ii), 40 CFR 63.6590(c), Minn. R. 7011.2310, Minn. R. 7011.8150] 5.6.14 The Permittee must operate EQUI4 according to the requirements in 40 CFR Section 60.4243(d)(1) through (3). In order for the engine to be considered an emergency stationary ICE under 40 CFR pt. 60, subp. JJJJ, any operation other than emergency operation, maintenance and testing, emergency demand response, and operation in non-emergency situations for 50 hours per year, as described in 40 CFR Section 60.4243(d)(1) through (3), is prohibited. If the Permittee does not operate the engine according to the requirements in 40 CFR Section 60.4243(d)(1) through (3), the

Permit Expires: [month day, year] Page 20 of 27 engine will not be considered an emergency engine under 40 CFR pt. 60, subp. JJJJ and must meet all requirements for nonemergency engines. (1) There is no time limit on the use of emergency stationary ICE in emergency situations. (2) The Permittee may operate EQUI4 for any combination of the purposes specified in 40 CFR Section 60.4243(d)(2)(i) for a maximum of 100 hours per calendar year. Any operation for nonemergency situations as allowed by 40 CFR Section 60.4243(d)(3) counts as part of the 100 hours per calendar year allowed by 40 CFR Section 60.4243(d)(2). (i) EQUI4 may be operated for maintenance checks and readiness testing, provided that the tests are recommended by federal, state or local government, the manufacturer, the vendor, the regional transmission organization or equivalent balancing authority and transmission operator, or the insurance company associated with the engine. The Permittee may petition the Administrator for approval of additional hours to be used for maintenance checks and readiness testing, but a petition is not required if the Permittee maintains records indicating that federal, state, or local standards require maintenance and testing of emergency ICE beyond 100 hours per calendar year. (3) EQUI4 may be operated for up to 50 hours per calendar year in non-emergency situations. The 50 hours of operation in nonemergency situations are counted as part of the 100 hours per calendar year for maintenance and testing and emergency demand response provided in 40 CFR Section 60.4243(d)(2). Except as provided in 40 CFR Section 60.4243(d)(3)(i), the 50 hours per year for non-emergency situations cannot be used for peak shaving or non-emergency demand response, or to generate income for a facility to an electric grid or otherwise supply power as part of a financial arrangement with another entity. (i) The 50 hours per year for non-emergency situations can be used to supply power as part of a financial arrangement with another entity if all of the following conditions are met: (A) The engine is dispatched by the local balancing authority or local transmission and distribution system operator; (B) The dispatch is intended to mitigate local transmission and/or distribution limitations so as to avert potential voltage collapse or line overloads that could lead to the interruption of power supply in a local area or region. (C) The dispatch follows reliability, emergency operation or similar protocols that follow specific NERC, regional, state, public utility commission or local standards or guidelines. (D) The power is provided only to the facility itself or to support the local transmission and distribution system. (E) The Permittee identifies and records the entity that dispatches the engine and the specific NERC, regional, state, public utility commission or local standards or guidelines that are being followed for dispatching the engine. The local balancing authority or local transmission and distribution system operator may keep these records on behalf of the engine owner or operator. [40 CFR

Permit Expires: [month day, year] Page 21 of 27 60.4243(d), 40 CFR 63.6590(c), Minn. R. 7011.2310, Minn. R. 7011.8150] 5.6.15 (a) Each performance test must be conducted within 10 percent of 100 percent peak (or the highest achievable) load and according to the requirements in 40 CFR Section 60.8 and under the specific conditions that are specified in 40 CFR pt. 60, subp. JJJJ, Table 2. (b) The Permittee may not conduct performance tests during periods of startup, shutdown, or malfunction, as specified in 40 CFR Section 60.8(c). If EQUI4 is non-operational, the Permittee does not need to startup the engine solely to conduct a performance test; however, the Permittee must conduct the performance test immediately upon startup of the engine. (c) The Permittee must conduct three separate test runs for each performance test required in 40 CFR Section 60.4244, as specified in 40 CFR Section 60.8(f). Each test run must be conducted within 10 percent of 100 percent peak (or the highest achievable) load and last at least 1 hour. (d) To determine compliance with the NOx mass per unit output emission limitation, convert the concentration of NOx in the engine exhaust using the following equation: ER = Cd * 1.912 x 10^-3 * Q * T / HP-hr Where: ER = Emission rate of NOx in g/hp-hr Cd = Measured NOx concentration in parts per million by volume (ppmv) 1.912 x 10^-3 = Conversion constant for ppm NOx to grams per standard cubic meter at 20 degrees Celsius Q = Stack gas volumetric flow rate, in standard cubic meter per hour, dry basis T = Time of test run, in hours HP-hr = Brake work of the engine, horsepower-hour (HP-hr). (e) To determine compliance with the CO mass per unit output emission limitation, convert the concentration of CO in the engine exhaust using the following equation: ER = Cd * 1.164 x 10^-3 * Q * T / HP-hr Where: ER = Emission rate of CO in g/hp-hr Cd = Measured CO concentration in ppmv 1.164 x 10^-3 = Conversion constant for ppm CO to grams per standard cubic meter at 20 degrees Celsius Q = Stack gas volumetric flow rate, in standard cubic meters per hour, dry basis T = Time of test run, in hours HP-hr = Brake work of the engine in HP-hr. (f) For purposes of 40 CFR pt. 60, subp. JJJJ, when calculating emissions of VOC, emissions of formaldehyde should not be included. To determine compliance with the VOC mass per unit

Permit Expires: [month day, year] Page 22 of 27 output emission limitation, convert the concentration of VOC in the engine exhaust using the following equation: ER = Cd * 1.833 x 10^-3 * Q * T / HP-hr Where: ER = Emission rate of VOC in g/hp-hr Cd = VOC concentration measured as propane in ppmv 1.833 x 10^-3 = Conversion constant for ppm VOC measured as propane, to grams per standard cubic meter at 20 degrees Celsius Q = Stack gas volumetric flow rate, in standard cubic meters per hour, dry basis T = Time of test run, in hours HP-hr = Brake work of the engine, in HP-hr. (g) If the Permittee chooses to measure VOC emissions using either Method 18 of 40 CFR part 60, appendix A, or Method 320 of 40 CFR part 63, appendix A, then the Permittee has the option of correcting the measured VOC emissions to account for the potential differences in measured values between these methods and Method 25A. The results from Method 18 and Method 320 can be corrected for response factor differences using the following two equations. RFi = CMi / CAi Where: RFi = Response factor of compound i when measured with EPA Method 25A CMi = Measured concentration of compound i in ppmv as carbon CAi = True concentration of compound i in ppmv as carbon Cicorr = RFi * Cmeas Where: Cicorr = Concentration of compound i corrected to the value that would have been measured by EPA Method 25A, ppmv as carbon Cimeas = Concentration of compound i measured by EPA Method 320, ppmv as carbon The corrected VOC concentration can then be placed on a propane basis using the following equation: CPeq = 0.6098 * Cicorr Where: CPeq = Concentration of compound i in mg of propane equivalent per DSCM. [40 CFR 60.4244, 40 CFR 63.6590(c), Minn. R. 7011.2310, Minn. R. 7011.8150] 5.6.16 The Permittee must keep the following records of the information: 1. All notifications submitted to comply with 40 CFR pt. 60, subp. JJJJ and all documentation supporting any notification. 2. Maintenance conducted on the engine.