# ~~ NORTH DAKOTA

# ~J DEPARTMENT

## a! HEALTH

March 11, 2005



### Mr. John Graves Environmental Manager Minnkota Power Cooperative 1822 Mill Road P.O. Box 13200 Grand Forks, NO 58208-3200 ENVIRONMENTAL HEALTH SECTION 1200 Missouri Avenue, Bismarck, NO 58504·5264 P.O. Box 5520, Bismarck, NO 58506·5520 701.328.5200 (fax) www.ndhealth.gov



### Re: PSO Applicability Determination M.R. Young Station 

### Unit 1 Turbine Upgrade
Dear Mr. Graves: 

### We have reviewed your letters of August 9, 2004 and March 7, 2005 regarding the proposed upgrade to the Unit 1 turbine at the Milton R. Young Station near Center, North Dakota. Your proposed changes appear to be very similar to those proposed by the Detroit Edison Company at the Monroe Power Plant in 2000 (i.e., Dense Pack 

### Project). The Detroit Edison project was reviewed by U.S. Environmental Protection Agency (EPA) and a determination was provided on May 23, 2000. The EPA determined that the dense pack project at the Monroe Power Plant was not routine maintenance and repair. The EPA also outlined the steps that were necessary in order to prove that the dense pack project was not a major modification under the Prevention of Significant Deterioration (PSD) Program. In summary. Detroit Edison was required to prepare calculations that show the modification would not have a significant increase in emissions and was required to track annual emissions from the facility. Based on the Detroit Edison interpretation, the Department believes your turbine upgrade at Unit 1 does not qualify as routine maintenance or repair. Therefore. it is incumbent upon Minnkota Power Cooperative to demonstrate that the proposed changes are not a major modification under PSD. You have proposed testing of the turbine and generator set to determine maximum short-term input and output conditions before and after the change. These tests are acceptable to prove that a modification has not taken place under the New Source Performance Standards. However. these types of tests do not address annual

Environmental Health section Chiefs Office 701.328.5150 A>- Qua"", 701.328.5188 Municipal Facilities 701.328.521' Printedon recyCledpaper. Waste Management 701.328.5166 Water Quality 701.328.5210

### Mr. Graves 2 March 11, 2005



### operation of the facility. The Department is concerned that the proposed changes could allow Minnkota Power to operate the unit at a higher level of utilization after the proposed changes are made. Therefore, there is a potential to increase emissions on an annual basis. Minnkota must follow the procedures outlined in the North Dakota Air Pollution Controls to demonstrate that a major modification will not occur. The rules (commonly known as the WEPCO rule

- NDAC §33-l5-l5-01.l. a (4)) require Minnkota to compute baseline actual emissions (or other parameter such as heat input) and project the future actual emissions from the modified unit for a two year period after the physical change, or another two year period that is more representative of normal operations.
In addition, Minnkota must maintain and submit to the Department on an annual basis for a period of ten years from the date the unit resumed regular operations information demonstrating that the renovation did not result in a significant emissions increase. This period of time may be reduced by the Department to a period of not less than five years if Minnkota can provide adequate demonstration that the changes have not resulted in a significant increase of emissions. The calculation of the baseline emission rates (or other parameter) and the projected future emissions must be submitted to the Department. The method of calculating the baseline and the monitoring methods to track emissions should also be included. If you have any questions regarding this issue, please feel free to contact Tom Bachman of my staff at 701.328.5188. Respectfully, 

### /I**.:~** 

### Terry L. O'Clair, P.E. Director Division of Air Quality TLO/TB:csc xc: Lyle Witham, Assistant Attorney General Kathleen Paser, EPA

- Region VIII Dave Glatt, EHSTo 

### be inserted in email when I get it back! August23, 2004
Discussion ofMimtkotalMilton R. Young turbine upgrade project
In regardto facsimile sent to Kathleen Paserby Tom Bachman: An August 9, 2004, letter from John T. Graves, Envrionmental ManagerofMinnkota PowerCooperativeto Teny O'Clair, Air Program Director, North Dakota DepartmentofHealth.
Minnkota is considering retrofitting the main stearn turbine atthe Milton R. Young Station. This rotrofit is aturbine upgrade, the goal ofwhich is to increase the electrical outputof Unit I, by increasing the efficiency ofthe High PressurelIntennediate Pressure (HPIIP) turbine.
Based onthe informationprovided in August 9, 2004 letter, and determinations madeby bothEPA Region 8 and NorthDakotawithregard to otherturbine upgrade projects in North Dakota1

, this modification to the plant should notbe considered routine maintenance, repair, and replacement.
SinceMinnkotamaintains thatthere will be no design change ofthe heatinputto the boilerand no significantemission increases, then the project would not 

### be subjectto PSD pennittingrequirements by this virtue. However, asNorth Dakota required with Basin Electric's Leland Olds' turbine upgrade, the emissions should be tracked as required by the WEPCO rules.

IOttertailPower's Coyote Station, April 2001. GreatRiverEnergy's Coal Creek Station, October 1998. Basin Electric PowerCooperative's Leland Olds Station, April 2003.Ul)/&'.J/V'I.I..I. .•"



### NORTH DAKOTA DEPARTMENT OF HEALTH Environmental Health Section Locatlon: 1200 Missouri Avenue Bismarck, NO 58504·5264 

### Fax': 701-321>-5200 

### Maili"g Addr"ss: P.O. Box 5520 Bismarck, NO 58506-5520



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# MinnkotaPower Mpcj COOPERATIVE, INC.

\822 Mil Raad • P.O. 80x 13200' Gnnd forts. NO 5020.&-3200 • Phllll8 (701)**795~OOO** August 9, 2004

: Mr. TeTTY O'Clair Division ofAir Quality North Dakota Departmentof Health P.O. Box 5520 Bismarck. ND 58506-5520



### . .'. Subject: PSD Applicability Determination Milton 

### R. Young Station, Unit 1

.Turbine Upgrade

.Dear Mr. O'Clair: 

## • , YourTouchstone EneriY· Parmer ".



# -

Minnkota Is considering the retrofitting the main steam turbine at Milton 

### R. Young Station,**Un~** 1. This retrofit is similarto turbine upgrades that have taken place at other power plants in the nation. In North Dakota, turbine upgrades were accomplished at Coal Creek Station near Underwood, North Dakota. (The turbine retrofit Minnkota is considering is not mechanicallyjdentical to the Advanced Design Steam Path upgrade accomplished at Coal Creek Station, but rather similar in that they both increase the t"rbine cycle efficiency.) The project is currently scheduled to be**in~iated** in October 2004 with a request for bids, and be completed in the year2006

.



# . The goal ofthe project is to increase the electrical output of Unit 1, by increasing the efficiency ofthe High p'ressurellnterrnediate Pressure (HPIIP) turbine. The project would :n

..**·c~vG. rep!~dng** **~!I** clt.'le HP/:P C',1iiica;" internals.**So~e** ofthe mair. rtems**t';c;~** would be replaced include the HPIIP rotorwith associated buckets, the HP/IP diaphragms. and the inner cylindershell. Items not currently being considered for replacement include the HPIIP outercylinder, the associated outercylinder equipment, the control valves, and the #1 

### & #2 bearings. General Electric refers to this retrofit as a "Dense Pack". Othervendors have different names forthis type 

### ofturbine retrofrt. The North Dakota Air Pollution Control RegUlations, Section 33-15-1 &-01, defines a "Major Modification" as •... any physical change in, orchange in the method of operation of a majorstationary source that would result in a significantnetemissions increase of any air contaminant subject to regulation under North Dakota Century Code chapter23-25." (Emphasis added.) The regulations also indicate that "A physical change orchange in the method of operation does not include: (a) Routinemaintenance, repair, and replacement..:. Section 33-15-15-01 ofthe Reguiations indicates that any majorstationary source undergoing a major modification is subjectto regulation underSection 33-15-15-01, commonly referred to as the Prevention of Significant Deterioration, PSD, regGlation. This turbine retrofitwjll be designed specificallyso as notto impactthe operation or capacities ofthe boiler. The below described approach illustrates how this can be accomplished. The drawing below illustrates the Milton R. Young Unit 1 energy cycle. The bolle, cycle converts heat input in the fonn offuiilto heat output in the fonn ofsteam. The turbine cycle accepts this heat inpu1 in the fonn ofsteam and converts it into heat output in the fonn ofelectrical energy. '.

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, Ifthe turbine cycle heat input remains unchanged, the boiler cycle heat ou1put will remain unchanged. Correspondingly, the boiler cycle heat inputwill also remain unchanged. This is the basis forthe assertion that the turbine retrofit will not impact the operation ofthe boiler. To maintain the current turbine cycle heat input, Minnkota will require thatthe retrofit be specifically designed such thatthe heat inputto the turbine cycle afterthe retrofit will be the same (within the limils ofthe manufactures design margins) as before the retrofit. The currenl heal input 

### 10the Unil1 turbine cycle will be determined 

### bytests utilizing indUStry recognized test codes and procedures such as the ASME (American Society ofMechanical Engineers) Perfonnance Tesl Code 6. The successful retrofit supplierwill be contractually bound to perfonn the appropriate tesling as part oftheir scope ofwork. The tests normally would be conducted at the following operating conditions, as a minimum:1. The first test condition would utilize the steam cycle configuration typically used to determine the maximum eiectrical output as defined bythe Uniform Rating of Generating Equipment (URGE) test. 2. The second test condition/steam cycle configuration would be at "Valves Wide Open", all feedwater heaters in service, at design throttle pressure. As illustrated previously, the modifications to the turbine will not impactthe heat inputto the bolier. Therefore, this retrofitwill not result in any increases in hourly emissions of any aircontaminate. Both unlis at Milton 

### R. Young Station are "base load" units; they do not respond 

### to hourlychanges in load, but are operated atthe maximum generation levels possible based upon boileroperating conditions (coal quality, ash fouling, boiler water and steam purity, etc). As this turbine retrofit projectwill not impactthe hours of operation orthe levels of operation ofthe Unit 1 bolier, annual emissions will not be impacted 

### by this project (Annual eITlissions may increase ordecrease in future years. This may occurdue to changes in c6al qualliy, changes in boileroutage rates, changes in the accuracyoflhe CEMS, etc.)

.'.

__ Putting aside any consideration ofthis project being excluded from the definition of a "Major Modification" bythe "routine maintenance. repair, and replacement" exclusion, Minnkota has determined that this project will not be a "major modification" because ," .there will be no significant net emissions increase. Therefore, this project will not be subjectto regulation underSection 33-15-15-01, Minnkota requests your concurrence in this determination. Should you have any questions concerning the above, please contact me at 701-795- 

### 4221.

John T. Graves, P.E. Environmental Manager

C: Luther Kvemen David Sogard Tom Anseth Stu Libby Kevin Thomas Reger Gazur