State of Wisconsin DEPARTMENT OF NATURAL RESOURCES

September 16, 2015 Regional Administrator Susan Hedman U.S. Environmental Agency- Region V 77 West Jackson Boulevard Mail Code: R-19J Chicago, IL 60604-3507 Scott Walker, Governor Cathy Stepp, Secretary

Telephone 608-266-2621 Toll Free 1-888-936-7463 TTY Access via relay

- 711

SUBJECT: Updated Wisconsin Designation Recommendations for the 2010 1-Hour Sulfur Dioxide (S02) National Ambient Air Quality Standard (NAAQS) Dear Regional Administrator Hedman: This letter addresses two groups ofareas identified in Janet McCabe's March 20, 2015 letter to Secretary Stepp regarding future rounds ofarea designations for the 2010 1-hour S02 NAAQS. Inthe letter, and based on preliminary data, EPA identified one source (Columbia Energy Center) and one monitor (Green BayEast High in Brown County) in Wisconsin as meeting the criteria established in a March 2, 2015 court order. The following recommendations and supporting information for EPA to consider when making final determinations associated withthis first round ofdesignations include: • The ColumbiaEnergy Center no longer meets the criteria established bythe court order and is not subject to the designations timeline established inthat order. • Modeling conducted bythe department and application ofthe five factors described in EPA's S02 area designations guidance indicate that EPA should designate the county in which ColumbiaEnergy Center is located (Columbia County) as attainment for the 2010 1-hour S02 NAAQS. Additionally, future intentions regarding the Brown County S02 monitor at Green BayEast High School are addressed in this letter. Columbia Energy Center and Columbia County Inthe March 20, 2015 McCabe letter, EPA proposed that ColumbiaEnergy Centermetthe criteria established in the March 2, 2015 court order. Specifically, EPA's data showed that ColumbiaEnergy Center exceeded a threshold of 16,000 tons ofS02in 2012 or emitted more than 2,600 tons ofS02 and had an emission rate ofat least 0.45 lbs. S02/MmBtu. Since 2012, several changes affecting S02 emissions from the ColumbiaEnergy Center have occurred. On June 18, 2013, the facility entered into consent decree 13-cv-266 with EPA and the Sierra Club, which required the installation and operation ofpollution control equipment and practices that would achieve significantreductions ofS02,NOx and PM emissions. The consent decree specified that byJanuary 1, 2015, the ColumbiaEnergy Center hadto continuously operate dry flue gas desulfurization (DFGD) so that units 1 and 2 could achieve and maintain a 30-day rolling average emission rate for S02 ofno greater than 0.075lbs/MmBtu. The consent decree further specified an annual S02 limit of3,286 tons starting in 2015. On September 10, 2015, WDNRrevised the facility's construction permit (14-POY -174-R1, enclosed) to include limitations, conditions and other requirements contained in the consent decree, which make the S02 limitations and conditions permanent and federally enforceable. Since the facility is currently complying with a permanent and enforceable S02 limit below 16,000 tons, and otherwise does not meets the criteria as specified in the March2, 2015 court order, the ColumbiaEnergy Center is no longer subject to the July 2, 2016 round ofarea designations established bythat order. Page2

Based on a technical analysis, including dispersion modeling, completed bythe department and provided as an enclosure to this letter, and considering subsequent guidance on 

### S02 

### NAAQS implementationreleased by EPA, WDNRrecommends that EPA designate the county in which ColumbiaEnergy Center is located (Columbia County) as attainment for the 2010 1-hour 

### S02 

### NAAQS. EPA's March 20, 2015 

### S02 area designations guidance describes five factors to consider when determining the appropriate attainment boundary when designating areas for the 

### S02 

### NAAQS. WDNRhas fully addressed these criteria in support ofits recommendation, as follows: 1. Dispersion modeling results. WDNRmodeled Columbia Energy Center's new limits using a dispersion modeling protocol based on EPA's December 2013 

### S02 

### NAAQS Designations Modeling Technical Assistance Document (TAD) and developed collaboratively withthe facility and EPA Region 5. The results ofthe modeling (enclosed) show that the Columbia Energy Center will notviolate the 

### S02 

### NAAQS when complying with its new permanent and enforceable 

### S02 limit. 2. Emissions-related data. As described in the enclosed analysis, the dispersion modeling conducted for Columbia Energy Center included and considered all stationary sources of

### S02 located within Columbia County. 3. Meteorology. As described in the enclosed analysis, WDNR's modeling included meteorology appropriate to the area as described in EPA's Designations Modeling TAD. 4. Geography and topography. WDNRconsidered geography and topography when considering both the sources to include in the modeling and where to place modeling receptors, taking into account specifically the Baraboo Hills area ofthe county. This is described further in the enclosed analysis. 5. Jurisdictional boundaries. EPA's 

### S02 area designations guidance describes how county boundaries may be appropriate for defining attainment areas in the absence ofany otherrelevant information that would help define a more specific boundary around the 

### S02 source in question. WDNRhas appropriately considered all 

### S02 emissions sources in the county in the enclosed analysis, and the results support designating all ofColumbia County as attainment. Based onthe five factor analysis, a designation ofattainment for Columbia County, Wisconsin for the 2010 1- hour 

### S02 

### NAAQS is supported. WDNRrecommends thatthe EPA designate Columbia County as attainment at the earliest possible date, but no later than July 2, 2016. Brown County The March 20 letter also identifiedthe Green BayEast High air quality monitor (55-009-0005) in Brown County as violating the 2010 1-hour 

### S02 

### NAAQS based on preliminary 2012-2014 data and therefore potentially subject to the designations schedule established inthe court order. EPA's 

### S02 area designations guidance describes the consideration ofcertified 2015 

### S02 monitoring data for fmal determinations on designation recommendations. WDNRwill evaluate the monitor's certified data once the 2015 monitoring season has concluded. Ifthe resulting 2013-2015 monitored design value does not show a violation ofthe 

### NAAQS, WDNR intends to recommend that EPA designate Brown County, Wisconsin as attainment at the earliest possible date, but no later than July 2, 2016. Further, on April8, 2013, the department recommended that EPA designate forty Wisconsin counties as attainment for 2010 1-hour 

### S02 

### NAAQS, including Brown County. As WDNR conveyed at the time, Brown County's monitored design value was belowthe 

### NAAQS, as had beenthe case for several years. WDNRbelievesPage3

EPA should have already designated Brown County as attainment based on that information, andrequests EPA act expediently on any further attainment recommendation WDNRmay make for this county in 2016. Thankyou for considering this information and Wisconsin's recommendations. Ifyou have any questions or require additional information, please contact Gail Good, acting Air Director, at Gail.Good@wisconsin.gov or 608-266-1058. Sincerely,

Bart Sponseller DeputyDivision Administrator Environmental Management Division Enclosures

cc: Cathy Stepp, Secretary Mike Bruhn, Assistant Deputy Secretary Pat Stevens, Administrator, Environmental Management Division Gail Good, Acting Air Director