~ NORTH DAKOTA ~ DEPARTMENT of HEALTH 

September 16, 2015 

Mr. Carl Daly (8P-AR) 

Director, Air Programs 

U.S. EPA, Region 8 

1595 Wynkoop Street 

Denver, CO 80202-1129 

ENVIRONMENTAL HEALTH SECTION 

Gold Seal Center, 918 E. Divide Ave. 

Bismarck, ND 58501-1947 

701 .328.5200 (fax) 

www.ndhealth.gov 

Re: S02 Designation Recommendations 

Dear Mr. Daly: 

On March 2, 2015, the U.S. District Court for the Northern District of California entered a 

Consent Decree between the EPA, Sierra Club and Natural Resources Defense Council that 

requires the EPA to complete designations for the 2010 I-hour S02 NAAQS. This is to be 

accomplished in three rounds with the first round completed by July 2, 2016. EPA has 

established a deadline of September 18, 2015 by which states may submit updated 

recommendations and supporting information for this first round of designations. Attached to 

this letter is a letter from Governor Dalrymple with North Dakota's updated designation 

recommendations. In addition, attached are dispersion modeling analyses for the Coyote Station, 

Leland Olds Station/Coal Creek Station (combined analysis) and Tioga Gas Plant as well as 

other supporting information for those recommendations. 

In a conversation with EPA Region 8, EPA agreed to allow the Department further time to 

review the modeling analyses and provide any supplemental findings following that review. The 

Department will supply EPA any supplemental information based on our review of those 

analyses by December 1, 2015 . 

If you or your staff has any questions regarding this submittal, please contact Tom Bachman of 

my staff at (701) 328-5188. 

C)d Terry L. O'Clair, P.E. 

Director 

Division of Air Quality 

TLO/TB:saj 

Enc: 

Environmental Health 

Section Chiefs Office 

701 .328.5150 

Division of 

Air Quality 

701.328.5188 

Division of 

Municipal Facilities 

701 .328.5211 

Printed on recycled paper. 

Division of 

Waste Management 

701 .328.5166 

Division of 

Water Quality 

701 .328.5210 
- State of 

North Dakota 

O ffice o f th e G ove rn or 

Jack Dalrymple 

Governor 

Ms. Gina McCarthy 

c/o Mr. Shaun McGrath 

U.S. EPA, Region 8 

1595 Wynkoop Street 

Denver, CO 80202-1129 

September 16, 2015 

Re: Updated Sulfur Dioxide Designations Recommendation 

Dear Administrator McCarthy: 

On June 22, 2010, the United States Environmental Protection Agency (EPA) 

published its Final Rule regarding the Primary National Ambient Air Quality Standards 

(NAAQS) for sulfur dioxide (S02). See 75 F.R. 35520. On May 25, 2011, the State of 

North Dakota submitted its recommendation (with supporting data) that the entire state 

be designated as attainment for the new one-hour S02 NAAQS. This recommendation 

was based on the results of monitoring data from an extensive monitoring network 

located across the state. 

On March 2, 2015, the U.S. District Court for the Northern District of California 

entered a Consent Decree that requires EPA to make further designations for the onehour S02 NAAQS. No later than July 2, 2016, the EPA must designate two groups of 

areas: 1) areas that have newly monitored violations of the new one-hour NAAQS; and 

2) areas that contain any stationary source that emitted more than 16,000 tons of S02 in 

2012 or emitted more than 2,600 tons of S02 and had an annual average emission rate of 

at least 0.45 lb/ 106 BTU of S02 in 2012. The State of North Dakota has four plants that 

fit into the 2016 groups specified in the Consent Decree. These include the Lelands Olds 

Station, the Coal Creek Station, the Coyote Station and the Tioga Gas Plant. 

Based on the data collected by the Department of Health and information 

provided by the owners of the above listed facilities, it is recommended that the area 

around the Leland Olds Station, the Coal Creek Station and the Coyote Station be 

designated "attainment" for the 2010 one-hour S02 NAAQS (see attachments). 

The Tioga Gas Plant has recently undergone an expansion to enable the facility to 

process sweet gas and reduce flaring incidents. Because of the characteristics of the gas 

processed, the plant experienced periodic upsets and malfunctions. These upsets resulted 

in elevated concentrations of sulfur dioxide. An enforcement action was taken and several 

600 E Boulevard Ave. • Bism a rck, ND 58505-0001 • Ph one: 701.328.2200 • Fax: 701.328.2205 • www.governor.n d.gov 
Ms. Gina McCarthy 

September 16, 2015 

Page 2 

operational changes have been implemented at the plant. The Department of Health believes 

the issues that resulted in elevated concentrations in the immediate area of the plant have been 

rectified. Although the latest ambient data indicate the plant is complying with the NAAQS, it is 

recommended the immediate area around the Tioga Gas Plant be designated as "unclassifiable" 

while the Department of Health continues to gather additional data to demonstrate the plant is 

in compliance. In early 2018, after more data has been collected, a recommendation for 

reclassification will be submitted based on the monitoring data from 2015-2017 and other 

available information. Attached to this letter are ambient monitoring data and other supporting 

information for this recommendation. 

The Department of Health has not fully reviewed the modeling data that is submitted 

with this recommendation. However, as agreed in a telephone conversation with staff at EPA 

Region 8, the data will be reviewed by the Department of Health and any supplemental 

information submitted by December 1, 2015. 

If you have any questions, please contact the Division of Air Quality at the Department 

of Health at (701)328-5188. 

C: Terry Dwelle, State Health Officer 

Sincerely, 

Jack Dalrymple 

Governor 

Dave Glatt, Environmental Health Section Chief 

Terry O'Clair, Division of Air Quality Director 

Enc. 

37:68:56 
.. 

Tioga Gas Plant 

The Tioga Gas Plant was constructed in 1954 in Williams County North Dakota near the town of 

Tioga to process gas generated by the first oil wells drilled in North Dakota. The plant, which 

has had many owners, is currently owned and operated by Hess Corp (Hess Tioga Gas Plant, 

LLC). The plant was originally designed to process 100 - 120 million standard cubic feet per 

day (MMSCF) of sour gas (3.5 - 4% H2S). In 1967, a 105 long ton per day (LTD) sulfur 

recovery unit (SRU) was added to the plant which was replaced in 1991witha220 LTD SRU. 

Since 1987, the Department has required Hess to operate two ambient air quality monitoring 

sites near the plant. One site is approximately 0.75 miles northeast of the plant and the other is 

approximately 0.5 miles southeast of the plant. The data from these sites has not been certified 

by either the Department or Hess as being accurate. In addition, the quality assurance 

procedures did not strictly adhere to 40 CFR 58 requirements. 

In 2008, development of the Bakken shale formation accelerated, primarily for oil. However, 

there is a significant amount of gas produced with the oil from the Bakken. This gas is primarily 

sweet gas(< 0.0004% H2S). The Tioga Gas Plant began processing the Bakken gas which 

helped reduce flaring in the field and offset the decline in gas production from older non-Bakken 

wells with sour gas. Because the Tioga plant was designed to handle sour gas, the plant 

experience numerous operational problems as it switched over from sour gas processing to a 

sour/sweet mix including the Bakken gas. Starting in 2012, these operational problems lead to 

plant upsets where Hess had to "learn" how to operate the plant with the sour/sweet gas mix. 

These upset resulted in equipment malfunctions, periodic flaring and reduced gas production. 

During several of the upsets, elevated levels of S02 above of the 1-hour S02 design value were 

recorded at the southeast monitor (no elevated levels have been monitored at the site northeast of 

the plant). Initially, Hess believed that the problems would be readily solved; however, due the 

characteristics of the Bakken gas, consistent operations with the sweet/sour gas mixture proved 

to be more difficult than expected. 

On February 13, 2013 the Department issued Hess a Notice of Violation for these elevated S02 

levels. In December of 2013, a Consent Agreement was signed by the Department and Hess 

(attached). This Consent Agreement required Hess to complete facility upgrades to improve the 

SRU operations and, most importantly, other upgrades that improved the reliability of the plant 

to minimize upsets that were occurring too frequently. Since these upgrades were installed and 

fine tuned in July 2014, plant operations have stabilized and become consistent. Only one hour 

of monitored S02 concentrations has exceeded the 75 ppb design value in last year (see attached 

data). This occurred on February 25, 2015 and was attributed to an abnormal startup of the plant. 

As shown on the attached graph, the S02 emissions from the plant have been decreasing since 

2005. 
Attached is a dispersion modeling analysis prepared for Hess by Bison Engineering that uses 

current emissions rates (starting with September 2014) and three years of meteorological data. 

The results indicate the plant will comply with the NAAQS (maximum design concentration of 

50 ppb or 131 μg/m3

) . Although the Department has not reviewed the modeling in depth, it will 

do so and provide any updates or additional information by December 1, 2015. 

The Department believes the incidences of elevated S02 concentrations at the plant have been 

resolved. Both the frequency and duration of plant upsets have been substantially reduced. 

Normal operations of the plant over many years have shown compliance with the ambient 

standards and actual emissions are decreasing. Because of the high 99th percentile values of 

the daily maximum I-hour concentration in 2013 and 2014 ( 264 ppb and 180 ppb respectively) 

and the averaging of three years of monitoring data for determining compliance with the onehour S02 NAAQS, the 2015 and 2016 design values will likely be elevated. The Department 

proposes that the area be classified as "unclassifiable" until monitoring data are available for 

2017. At that time, the Department will propose a reclassification (attainment or non-attainment) 

based on the design value for that year and other pertinent information. 
\ 

Leland Olds Station 

Coal Creek Station 

Combined Analysis 

The Leland Olds Station is a lignite/subbituminous coal-fired steam electric generating plant 

located in southeast Mercer County approximately four miles southeast of Stanton, North 

Dakota. The plant consists of two units with a nameplate capacity of 222 MW e and 44 7 MW e. 

Sulfur dioxide emissions are controlled by two new wet scrubbers. The Unit 2 scrubber was 

placed into service in October 2012 and the Unit 1 scrubber in June 2013 . The plant has a BART 

S02 limit of 0.15 lb/106 Btu (effectively 393 lb/hr and 770 lb/hr for Units land 2 respectively) or 

95% reduction which was effective in the Leland Olds Title V Permit to Operate on January 1, 

2014. The units vent emissions through separate flues in a common stack that is 600 feet high. 

The plant is operated by Basin Electric Power Coop. 

The Coal Creek Station is a lignite-fired steam electric generating plant located approximately 

six miles southwest of Underwood, ND in McLean County. The plant consists of two units each 

with nameplate rating of 605 MWe. Sulfur dioxide emissions are controlled by a wet scrubber 

on each unit. Each unit vents through a separate stack that is approximately 683 feet high. The 

plant is operated by Great River Energy. 

Attached is dispersion modeling analysis report prepared for Basin Electric and Great River 

Energy by AECOM Environmental. The analysis was conducted using the AERMOD modeling 

system, version 15181 . Emissions data for the Leland Olds Station used the BART allowable 

emission rate for the 2012-2014 period. 2012- 2014 S02 CEM data was used for the Coal Creek 

Station. The report includes the results from two separate dispersion modeling analyses. The 

first analysis utilized the EPA regulatory default options. The results indicate a maximum 

predicted design concentration of 163.8 μg/m3

. The second analysis utilized the AERMET 

ADJ_ U* and the AERMOD LOWWIND3 options. The results of that analysis indicate a 

maximum design concentration of 117.2 μg/m3

. The Department has not reviewed the analyses. 

The Department will review the analyses and submit any additional or updated information by 

December 1, 2015. 

Based on the results of the attached dispersion modeling analyses, it recommended that the area 

around the Leland Olds Station and Coal Creek Station be designated "attainment". 
Coyote Station 

The Coyote Station is a lignite-fired steam electric generating unit located approximately 3 miles 

southwest of the City of Beulah in Mercer County. The plant consists of a single unit and has a 

nameplate rating 450 MWe. Sulfur dioxide emissions are controlled by a spray dryer/baghouse 

system and emissions vent from a stack that is 498 feet tall. The plant is operated by Otter Tail 

Power Co. 

Attached is dispersion modeling analysis report prepared for Otter Tail by AECOM 

Environment. The analysis was conducted using the AERMOD modeling system, version 

15181, and continuous emissions monitor data for 2012-2014. The report includes results for 

two different methods of conducting the analysis. The first method uses the EPA regulatory 

defaults for all options. The results of this analysis predict a maximum design concentration of 

115.9 μg/m3

. The second analysis utilized the AERMET ADJ_U* and the AERMOD 

LOWWIND3 options. The results of the second analysis are similar to the results of the 

regulatory default analysis with a design concentration of 106.1 μg/m3

. Because of the short 

time available to make an updated classification recommendation, the Department has not 

reviewed the analyses. The Department will review the analyses and submit any additional or 

updated information by December 1, 2015. 

There are five sulfur dioxide ambient air quality monitoring sites located within approximately 

20 kilometers of the Coyote Station. The attached monitoring results from these sites for 2012-

2014 indicate design values for 1-hour S02 concentrations well below the NAAQS. The 

maximum design value of any of these monitors is 47 ppb or 63% of the NAAQS in 2012. 

However, data for 2013 and 2014 show declining concentrations with a maximum design value 

in 2014 of34 ppb or 45% of the NAAQS. 

Based on the results of Otter Tail's dispersion modeling analyses for the Coyote Station and the 

nearby ambient monitoring data, it is recommended that the area around the station be designated 

"attainment" for the 1-hour S02 NAAQS. 
Ambient Monitoring Data 

1-Hr. 502 

Vicinity of Coyote Station 

YEAR Beulah DGC12 DGC14 DGC16 

Annual 3-yr. Avg. Annual 3-yr. Avg. Annual 3-yr. Avg. Annual 3-yr. Avg. 

99th pctl. 99th pctl. 99th pctl. 99th pctl. 99th pctl. 99th pctl. 99th pctl. 99th pctl. 

(ppb) (ppb) (ppb) (ppb) (ppb) (ppb) (ppb) (ppb) 

2006 26 28 26 39 

2007 40 37 36 30 2008 31 32 29 31 26 29 29 33 2009 26 32 38 35 27 30 23 27 

2010 52 36 46 38 54 36 44 32 2011 23 34 31 38 32 38 38 35 2012 28 34 37 38 27 38 58 47 2013 18 23 17 28 22 27 22 39 2014 23 23 33 29 26 25 21 34 
>graphic Area: Mercer County, ND 

lutant: 502 

1r: 2014 

:eptional Events: Included (if any) 

8632 47 

8609 58 

8700 46 8700 39 8702 36 

39 

43 

30 

25 

33 

23 362 

33 360 

26 365 

21 365 

19 365 

6 

7 7 

5 

4 

4 

5 

6 

5 

4 

Monitor Values Report 

0 1.07 None 380570004 6024 Highway 200 Not in a City Me

0 1.15 None 

0 0.94 None 

0 1.11 None 

O 0.87 None 

3805701 02 Oge #12 

380570118 Oge #14 

1 380570123 Oge #16 1 380570124 Oge #17 

Not in a city Me

Not in a city Me

Not in a city Me

Not in a city Me

jetailed information about this report, including column descriptions, at http://www.epa.gov/airquality/airdata/ad_about_reports.html#mon 

ata reports are produced from a direct query of the AQS Data Mart. The data represent the best and most recent information available to 

may be absent due to incomplete reporting, and some values may change due to quality assurance activities. The AQS databas

I organizations who own and submit the data. Please contact the appropriate air quality monitoring agency to report any data problems. 

>://www.epa.gov/airquality/airdata/ad_contacts.html> 

:lers are cautioned not to rank order geographic areas based on AirData reports. Air pollution levels measured at a particular monitoring s

e air quality for an entire county or urban area. 

report is based on monitor-level summary statistics. Air quality standards for some pollutants (PM2.5 and Pb) allow for combining data f

11ary statistic that can be compared to the standard. In those cases, the site-level statistics may differ from the monitor-level statistics up

Paqe 1 of 1 

Source: U.S. EPA 
>graphic Area: Mercer County, ND 

lutant: 502 

1r: 2013 

:eptional Events: Included (if any) 

8664 29 8702 21 8675 26 8647 33 

6483 28 

26 

19 

23 

32 

22 

18 365 3 

17 365 4 

22 362 5 22 362 11 

19 271 4 

3 

4 

4 

7 

3 

Monitor Values Report 

0 0.56 None 380570004 6024 Highway 200 Not in a City Me

0 0.83 None 

0 0.83 None 

O 0.79 None O 0.42 None 

380570102 Oge #12 

380570118 Dgc#14 

1 380570123 Oge #16 

1 380570124 Oge #17 

Not in a city MeNot in a city Me

Not in a city MeNot in a city Me

:letailed information about this report. including column descriptions, at http://www.epa.gov/airquality/airdata/ad_about_reports.html#mon 

ata reports are produced from a direct query of the AQS Data Mart. The data represent the best and most recent information available to 

may be absent due to incomplete reporting, and some values may change due to quality assurance activities. The AQS databas

I organizations who own and submit the data. Please contact the appropriate air quality monitoring agency to report any data problems. 

i://www.epa.gov/airquality/airdata/ad_contacts.html> 

:lers are cautioned not to rank order geographic areas based on AirData reports. Air pollution levels measured at a particular monitoring s

e air quality for an entire county or urban area. 

report is based on monitor-level summary statistics. Air quality standards for some pollutants (PM2.5 and Pb) allow for combining data f

11ary statistic that can be compared to the standard. In those cases, the site-level statistics may differ from the monitor-level statistics up

Paqe 1 of 1 

Source: U.S. EPA 
>graphic Area: Mercer County, ND 

lutant: 502 

1r: 2012 

:eptional Events: Included (if any) 

8279 62 8690 43 8729 39 8737 72 8710 72 

35 

42 

35 

67 

61 

28 347 7 

37 363 9 

27 366 10 

58 366 10 

41 364 19 

5 

7 

6 

9 

11 

Monitor Values Report 

0 None 

0 0.92 None 0 0.67 None 

O 1.27 None O 1.24 None 

1 380570004 6024 Highway 200 Not in a City Me

3805701 02 Oge #12 

380570118 Oge #14 380570123 Oge #16 

1 380570124 Oge #17 

Not in a city Me

Not in a city Me

Not in a city MeNot in a city Me

fotailed information about this report, including column descriptions, at http://www.epa.gov/airquality/airdata/ad_about_reports.html#mon 

ata reports are produced from a direct query of the AQS Data Mart. The data represent the best and most recent information available to 

e values may be absent due to incomplete reporting, and some values may change due to quality assurance activities. The AQS databas

I organizations who own and submit the data. Please contact the appropriate air quality monitoring agency to report any data problems. 

i://www.epa.gov/airquality/airdata/ad_contacts.html> 

::lers are cautioned not to rank order geographic areas based on AirData reports. Air pollution levels measured at a particular monitoring s

e air quality for an entire county or urban area. 

report is based on monitor-level summary statistics. Air quality standards for some pollutants (PM2.5 and Pb) allow for combining data f

11ary statistic that can be compared to the standard. In those cases, the site-level statistics may differ from the monitor-level statistics up

Paqe 1 of 1 

Source: U.S. EPA