Minnesota Pollution Control Agency 

520 Lafayette Road North I St. Paul, Minnesota 55155-4194 I 651-296-6300 

800-657-3864 I 651-282-5331 I WVfiloi..UelUIVI.US I !Oqwl ORJI!fWnity Employer 

May 1, 2015 

Dr. Susan Hedman 

Regional Administrator 

USEPA REGION 5 

77 West Jackson Boulevard 

Mail Code: R-19J 

Chicago, IL 60604-3507 

RE: Proposed Amendment to Minnesota's State Implementation Plan for Sulfur Dioxide 

Dear Dr. Hedman: 

The Minnesota Pollution Control Agency (MPCA) hereby submits to the U.S. Environmental Protection 

Agency (EPA) a request for revision of Minnesota's State Implementation Plan (SIP). 

The revision concerns Flint Hills Resources LLC's Pine Bend Refinery (FHR) and Northern States Power 

Company's Xcel Energy -Inver Hills Generating Plant (Inver Hills), both of which have facility-specific 

restrictions as part of Minnesota's SIP for sulfur dioxide (S02) in the Pine Bend area of Dakota County. 

Minnesota's SIP currently includes an Administrative Order (Order) issued to FHR and a joint Title 1/Title 

V permit for Inver Hills, which contain emission limits and other conditions that were found necessary to 

demonstrate compliance with the National Ambient Air Quality Standards (NAAQS) for S02. 

The primary purpose of this proposed SIP revision is to add a new process to enable the removal and 

recovery of more sulfur from fuel produced at FHR. This new process will allow FHR to produce gasoline 

that meets the EPA's Tier 3 gasoline sulfur standard. The SIP revision would also allow changes and 

updates to monitoring requirements and the facility's flaring policy. Additionally, this SIP revision would 

incorporate the new and revised Title I SIP conditions for FHR into Permit No. 03700011-012, which will 

serve as a joint Title 1/Title V document and replace the existing Order. 

This SIP revision also removes residual fuel oil as an allowable fuel type from the Inver Hills joint Title 

1/Title V permit. There are no SIP-relevant construction changes being made to the Inver Hills facility and 

therefore this proposed SIP revision does not authorize any new operations or emission units at that 

facility. 

This submittal includes Permit No. 03700011-012 and supporting technical documentation, including 

modeling, issued to FHR and Permit No. 03700015-004, issued to Inver Hills. It also includes the Revocation 

of the Ninth Amended Findings and Order issued to Flint Hills, effective on the date that EPA approves 

the SIP revision. The MPCA hereby requests that EPA incorporate in Minnesota's SIP all the conditions 

cited as "Title I Condition: 40 CFR Section 50.4, S02 SIP; Title I Condition: 40 CFR pt. 52, subp. Y" in 

Perming No. 03700011-012, replacing the current Title I SIP conditions from the Order (approved into 

Minnesota's SIP on May 15, 2013, 78 FR 28501). The MPCA also requests that EPA incorporate into 

Minnesota's SIP all conditions cited as "Title I Condition: SIP for S02 NAAQS, 40 CFR pt. 50" in 

Permit No. 03700015-003, replacing the current Title I SIP conditions in Permit No. 03700015-003 

(approved into Minnesota's SIP on December 5, 2007, 72 FR 68508). 
Dr. Susan Hedman 

Page 2 

May 1, 2015 

A full and accurate electronic copy of all the enclosed materials comprising this SIP submittal is also 

being submitted to EPA staff. Please contact Amanda Jarrett Smith of our staff at 651-757-2486 or 

amanda.smith@state.mn.us if you have any questions regarding Minnesota's SIP. 

Sincer�l,y1 

(JL._.� � 

Jo 

Commissioner 

JLS:AM/jlr 

Enclosures 

cc: Kathleen D' Agostino, EPA 

Mary Portanova, EPA 

Mary Jean Fenske, MPCA 

Amanda Jarrett Smith, MPCA 
Background Information for State Implementation Plan Revision 

Flint Hills Resources, Rosemount, MN 

This document describes the State Implementation Plan (SIP) revision for Flint Hills Resources Pine Bend Refinery, 

located in the Rosemount/Pine Bend area of the Twin Cities Sulfur Dioxide (SO2) maintenance area for the three-hour, 

24-hour, and annual SO2 National Ambient Air Quality Standards (NAAQS). Flint Hills Resources (FHR) is currently subject 

to an Administrative Order (Order) containing SO2 emission limits in order to ensure that the Pine Bend area continues 

to maintain the SO2 NAAQS. 

This SIP revision is being proposed to incorporate specific changes to the facility’s operating conditions and to transfer 

all of the SIP requirements into the federally enforceable Part 70 permit, which serves as a joint Title I/Title V document, 

subsequently terminating the current Order, approved into the SIP on May 15, 2013 (78 FR 28501). The Order, and all 

the conditions therein, will continue to apply until this SIP revision is approved by the U.S. Environmental Protection 

Agency (EPA). 

This SIP revision is being submitted in conjunction with a major modification of the facility’s operating permit (Air 

Emission Permit No. 03700011-012). The permit and its technical support document (TSD) provide information on the 

proposed changes to FHR’s operations. This document concentrates on the relevant changes to the facility’s Title I SIP 

conditions for SO2. 

The proposed SIP revision is referred to as “SIP10” because this is the tenth time that the site-specific SIP requirements 

for FHR have been amended. The currently effective Administrative Order, approved into the SIP in 2013, is referred to 

as “SIP9.”

1. Reasons for Changes to the Site-Specific SIP Requirements and Placing them in Joint Title I/Title V Document 

FHR requested changes to its SIP-included Order and its associated facility permit in order to make certain changes at 

the FHR facility. The changes to the Order are as follows: 

· Installation of a new process to convert gas containing sulfur and nitrogen into a stable, non-hazardous, aqueous 

liquid fertilizer, ammonium thiosulfate (ATS), which will result in a new SO2 emission point. 

· Changes to the fuel gas sulfur monitoring requirements for the 45 unit mix drum to add direct monitoring of fuel 

gas total sulfur as an additional monitoring option to the current requirement to monitor at a representative 

stack for sulfur dioxide emissions. Remove historic requirements for monitoring H2S. 

· Incorporate new, more restrictive language reflecting FHR’s current flaring policy, which clarifies that flaring is 

only allowed in the event of unplanned and infrequent events (i.e., malfunction). 

· Assorted updates that serve to clarify the requirements of the Order by removing completed requirements and 

placeholders. 

· Move all SIP requirements from the Order and into the joint Title I/Title V document. 

New ATS Process Unit (EU361) 

The primary reason for this SIP revision involves modifications proposed by FHR to meet EPA’s Tier 3 gasoline sulfur 

standard which becomes effective in 2017. The Tier 3 Program will set new vehicle emissions standards and lower the 

sulfur content of gasoline. To accomplish the removal of additional sulfur from gasoline produced at the refinery, FHR 

plans to increase the amount of hydrotreating in the 33 and 38 Unit gas-oil hydrotreaters (GOHTs) to remove sulfur from 

intermediate fuel products. No physical changes are required at the GOHTs to accommodate the additional 

hydrotreating. However, additional sulfur removal via hydrotreating increases the removal of nitrogen, which taxes 

existing sulfur-management units, including amine systems, the sour water system, and the sulfur-recovery plant. 

FHR proposes to install a process to convert gas containing sulfur and nitrogen into a salable, non-hazardous, aqueous 

liquid fertilizer: ammonium thiosulfate. FHR also proposes to use a more efficient amine solution in the existing amine 

treatment units. FHR plans a sour-water skimmers and tanks improvements project to reduce potential process safety 

risks. This will improve FHR’s skimming and storage systems for sour water. This project will be funded separately and 

completed independent of the ATS process unit or other project-related work. 
Fuel Gas Sulfur Content Continuous Emissions Monitoring System 

As part of the SIP10 action and permit reissuance, an additional monitoring option will be added. FHR will be permitted 

to add and maintain a total sulfur continuous emissions monitoring system (CEMS) to monitor total sulfur content in the 

45 unit mix drum fuel gas stream. As part of SIP9, FHR added a CEMS to measure reduced sulfur in the 41 unit mix drum 

fuel gas stream and a CEMS to measure SO2 at the 45 unit mix drum. These monitoring systems together form a 

comprehensive monitoring strategy that provides a more robust SO2 emissions calculation than the current SIPapproved system, which monitors for H2S. 

The proposed total sulfur CEMS for the 45 unit mix drum will use a technology where the sulfur in the fuel gas is oxidized 

and measured as SO2. The measured SO2 concentration will provide a basis to calculate SO2 emissions from the fuel gas 

fired emission units that are supplied by the 45 unit mix drum. 

In the original SIP Order, hydrogen sulfide (H2S) was monitored and used to calculate SO2 emissions; however, the 

combination of monitoring approaches approved in SIP9 and proposed in SIP10 will take account of other sulfur 

compounds beyond H2S to provide a more accurate emissions calculation. We are also requesting the removal from the 

SIP historic references to monitoring H2S, which will be redundant and thus no longer needed once the new monitoring 

strategy is SIP-approved. H2S monitoring will remain in the joint Title I/Title V document, but not as a SIP requirement, 

since H2S monitoring continues to be required in the Title V permit for compliance demonstration under New Source 

Performance Standards for petroleum refineries (J and Ja). 

Note that the proposed changes to the monitoring system are unrelated to the addition of the ATS unit. 

Hydrocarbon Flare System 

We are requesting to update the existing flare language in the SO2 maintenance SIP to include more restrictive language 

that is consistent with FHR’s actual operation and management of its hydrocarbon flare systems. The proposed 

language confirms that the flares are intended only to be used during unplanned and infrequent events (i.e., 

malfunctions) and that gases resulting from refinery operation, including gases from scheduled startups and shutdowns 

of refinery process units, are not flared except during unplanned and infrequent events. 

Other Updates 

Finally, the update generally serves to clarify the requirements of the SIP by removing references to or placeholders for 

requirements that have previously been removed from the Order and by also clarifying or removing completed 

requirements. 

This SIP action proposes to remove Boiler B-10 (EU337) from the SIP. Boiler B-10 was added to the SIP as part of SIP8. 

FHR subsequently decided not to continue with this project and the boiler was never installed. 

Incorporation of Title I SIP Conditions into Operating Permit 

In 1997 MPCA and EPA came to an agreement about placing permanent “Title I Conditions” on sources through the 

issuance of state and federal permits. Prior to that agreement, facilities deemed culpable sources for non-attainment of 

the NAAQS operated with requirements imposed on them both by State or Part 70 permits and by permanent Orders 

approved into the SIP and delineating those requirements necessary to obtain the relevant NAAQS in a specific area. 

MPCA and EPA agreed to streamline these requirements by placing all SIP conditions in the permit. In the context of the 

SIP, the relevant permit acts as a joint Title I/Title V document and contains all applicable requirements for each source, 

including SIP requirements. 

In order for permit requirements to be eligible for inclusion in the SIP, they had to be permanent. For this reason, 

Minnesota’s permit rule created the term “Title I Condition” as defined in Minn. R. 7007.0100 subp. 25. Item B of this

subpart specifically addresses SIPs: 

Title I SIP condition definition: 

(Minn. R. 7007.0100, subp. 25, item B) 
Any condition based on a source specific determination of ambient impacts imposed for the purpose of 

achieving or maintaining attainment with the national ambient air quality standard and which was part 

of a state implementation plan approved by the EPA or submitted to the EPA and pending approval 

under section 10 of the act. 

Any permit term designated in the permit as a Title I Condition does not expire, even though other parts of the Part 70 

permit may expire in five years (Minn. R. 7007.1050, subp. 4). Also, as required by Minn. R. 7007.0450, subp. 2, not only 

do Title I conditions remain in effect regardless of permit expiration, but these conditions must be reinstated in the 

reissued permit. 

On May 2, 1995, EPA approved MPCA’s revised operating permit program as a SIP revision (60 FR 21447). MPCA 

submitted the operating permit program for inclusion in the SIP in part so that permits issued under the program could 

be considered federally enforceable vehicles for imposing emissions limitations on culpable sources located in 

nonattainment areas. 

All conditions necessary for maintaining the NAAQS and included in the SIP are designated in Minnesota’s permits as 

“Title I Condition: 40 CFR Section 50.4, SO2 SIP; Title I Condition: 40 CFR pt. 52, subp. Y ,” making it clear that the term is 

part of the SIP. In SIP submittals, Minnesota requests that only those requirements with the term “Title I Condition: 40 

CFR Section 50.4, SO2 SIP; Title I Condition: 40 CFR pt. 52, subp. Y ” be included into the SIP. Consistent with past 

procedures of revising the SIP when changes were made to the Order, any changes to these “Title I Condition: 40 CFR 

Section 50.4, SO2 SIP; Title I Condition: 40 CFR pt. 52, subp. Y ” conditions will require a major permit amendment and a 

SIP revision, with all the associated EPA review and public participation requirements. 

In a letter dated July 3, 1997, EPA found MPCA’s approach to issuing permits that contain SIP conditions to be 

acceptable under both Title I and V of the Clean Air Act. MPCA then began moving SIP conditions into permits as they 

are opened. 

2. Changes to the Permit 

As noted previously, this SIP revision removes the Order for FHR and places all applicable requirements in the joint Title 

I/Title V document. Therefore, all continuing requirements from the Order are listed in the joint document and 

designated “Title I Condition: 40 CFR Section 50.4, SO2 SIP; Title I Condition: 40 CFR pt. 52, subp. Y.” Attachment 6 is a 

table which serves to outline where each of the Order’s requirements can be found in the Title I/Title V joint document. 

Any changes to the language have also been noted in this table. If no change is noted, then the language in the joint 

document is identical to that in the Order. A state revocation of the Order can be found in Attachment 7. 

3. Emission Changes 

Table 1 shows the SO2 emission changes from SIP9 to SIP10 for each NAAQS averaging time. SIP10 adds a new SO2

source – the ATS Process Unit – however, the overall modeled emissions from the facility are reduced from SIP9. This is 

primarily due to the removal of the Merox unit and the reduction of several generators to insignificant activity

(addressed in SIP9). See Attachment 3 for more detail. 

Table 1: Emission Changes for Each Averaging Time 

 

1 Hour SIP Emission 

Rate 

3 Hour SIP Emission 

Rate 

24 Hour SIP Emission 

Rate 

Annual SIP Emission 

Rate 

 (g/s) (lb/hr) (g/s) (lb/hr) (g/s) (lb/hr) (g/s) (lb/hr) 

SIP9 152.4568 1209.975 152.3608 1209.213 134.7588 1069.514 108.1188 840.7426 

SIP10 143.5938 1139.633 143.4978 1138.871 125.8958 999.173 99.7678 780.524 

change -8.863 -70.3413 -8.863 -70.3413 -8.863 -70.3413 -8.351 -60.2185 

% change -6% -6% -6% -6% -7% -7% -8% -7% 
4. Modeling Data 

The tables below show the ambient SO2 concentrations predicted by AERMOD (v14134) modeling. These results include 

both FHR and nearby sources. The SIP10 modeled NAAQS results summarized in Table 2 demonstrate that the proposed 

updates to the facility do not cause an exceedance of the modeled SO2 standards. 

 

Table 2: SO2 SIP10 Modeling Results Summary 

Pollutant Avg. Period NAAQS 

(ug/m3

) 

Total Modeled Conc. (ug/m3) 

(Includes background & 

nearby sources)

Percent of Standard (%) 

SO2 3-hr 1300 539 41.5% 

24-hr 365 177 48.5% 

Annual 80 22 27.5% 

Though this maintenance plan SIP revision addresses the 3-hour, 24-hour, and annual SO2 standards, section 110(l) of 

the CAA requires that a SIP revision not interfere with any applicable requirement concerning attainment or any other 

applicable requirement of the Act. For this reason, the SIP must also demonstrate that the proposed actions do not 

interfere with the 1-hour SO2 NAAQS, even though the area has not yet been designated under this standard. As agreed 

upon with the EPA, the 2010 1-hour primary NAAQS is addressed by a demonstration that the 1-hour Significant Impact 

Level (SIL) is met with Permit 03700011-012. Table 3 shows the 1 hour high 1st high SO2 project-only modeled results 

compared to the 1 hour SO2 SIL. The emissions increases resulting from the Tier 3 project are less than the SIL, 

demonstrating that its impacts are insignificant. 

Table 3: Tier 3 Clean Fuels Project SO2 SIL Modeling Results Summary 

Pollutant Avg. Period SIL (ug/m3) Total Modeled Conc. (ug/m3) Percent of Standard (%) 

SO2 1-hr 7.83 (SIL) 4.63 59.1% 

In addition, Table 4shows the most recent quality-assured ambient air monitoring data from the four monitors located 

around the FHR site. This data shows attainment of all the current SO2 NAAQS, including the 1-hour standard. 

Table 4: SO2 Monitoring Data around the FHR Facility 

Monitor FHR 420 FHR 423 FHR 442 FHR 443 

Standard Years 

Design 

Value 

Percent 

of 

Standard 

Design 

Value 

Percent 

of 

Standard 

Design 

Value 

Percent of 

Standard 

Design 

Value 

Percent of 

Standard 

1-hour 

(75ppb) 

2011-

2013 14 19% 8 11% 3 4% 2 3% 

24-hour 

(140 

ppb) 2013 4 3% 3 2% 1 1% 1 1% 

3-hour 

(500ppb) 2013 10.0 2% 5.6 1% 21.3 4% 2.0 0% 

Annual 

(30ppb) 2013 0.7 2% 0.6 2% 0.6 2% 0.4 1% 

The combination of monitoring and the SIL analysis indicates that the emissions increases from the Tier 3 project will not 

jeopardize continued attainment of the NAAQS. 
Attachments 

Attachment 1: Air Emission Permit No. 03700011-012, Issued to FHR, Including Modeling Exhibit 

Attachment 2: Technical Support Document for Related Permit Action 

Attachment 3: Air Quality Dispersion Modeling Reports (AQDM-06 and AQDM-07) 

Attachment 4: Markup Version of Air Emission Permit No. 03700011-012 

Attachment 5: Markup Version of Current SIP-Approved Administrative Order 

Attachment 6: Table of Administrative Order Requirements’ New Locations in Air Emission Permit No. 03700011-012 

Attachment 7: Administrative Order Revocation 

Attachment 8: Public Notice 

Attachment 9: Completeness Review 

This summary was prepared by Amanda Jarrett Smith, Environmental Analysis and Outcomes Division of the MPCA.
Background Information for SIP Revision 

Xcel Energy, Inver Hills Facility, Saint Paul, Minnesota 

This document describes the State Implementation Plan (SIP) revision for Northern States Power Company’s Xcel Energy 

– Inver Hills Generating Plant (Inver Hills), located in the Rosemount/Pine Bend area of the Twin Cities Sulfur Dioxide 

(SO2) maintenance area for the three-hour, 24-hour, and annual SO2 National Ambient Air Quality Standards (NAAQS). 

Inver Hills is subject to a joint Title I/Title V document containing SO2 emission limits in order to ensure that the Pine 

Bend area continues to maintain the SO2 NAAQS. 

This SIP revision is being proposed in conjunction with the reissuance of a Title V/Part 70 total facility operating permit 

(Air Emission Permit No. 03700015-004). The permit and its technical support document (TSD) provide information on 

the proposed minor changes to Inver Hills’ operations, none of which are SIP-applicable. This document concentrates on 

the changes to the permit that are relevant to the facility’s Title I SIP conditions for SO2. 

The proposed SIP revision is referred to as “SIP3” because this is the third time that the site-specific SIP requirements for 

Inver Hills have been amended, including Inver Hills’ initial inclusion in the SIP. The currently effective joint Title I/Title V 

document, approved into the SIP on December 5, 2007, is referred to as “SIP2.”

1. Reasons for changes to the applicable conditions in the Title I/Title V document 

Inver Hills has requested the following changes to its SIP-included joint Title I/Title V document: 

· Residual fuel oil has been removed as an allowable fuel type in accordance with the revised SIP 

· Removed SIP limits that were terminated on the date the EPA approved the revision to SIP2 

There are no SIP-relevant construction changes being made to the facility and therefore this proposed SIP revision does 

not authorize any new operations or emission units. 

Sulfur content of fuel and compliance demonstration 

The maximum sulfur content of the fuel that is now provided to Inver Hills from its supplier is .0015 percent by weight. 

The facility has requested that this be reflected in its joint Title I/Title V document. Method A and B of demonstrating 

compliance with this new, lower standard will also be updated to reflect the change. 

Language removal 

Permit No. 03700015-003 included SIP-applicable changes to allowable fuel sulfur content. These changes were

approved by EPA on December 5, 2007 as part of SIP2. References to terminated limits and transitional language are to 

be removed from the SIP. 

2. Changes to the Permit 

Sulfur content of fuel and compliance demonstration 

Permit 03700015-004 will require a lower sulfur content in liquid fuel used at Inver Hills. GP 001 Electric Generating 

Combustion Turbines is being modified to require a sulfur content of less than or equal to .005 percent by weight for all 

fuels. Language is included to indicate that the old limit of .48 percent by weight will be terminated and the new limit of 

.005 percent by weight will become effective upon EPA approval of SIP3. 

GP 001 is also being modified to update the compliance demonstration necessary for the lower sulfur standard. Method 

A will be changed from .48 percent by weight to .005 percent by weight and Method B will be changed from .10 percent 

by weight to .0015 percent by weight. Inver Hills has a guarantee from its fuel supplier, Flint Hills Resources, to provide 

fuel oil containing no more than .0015 percent sulfur by weight. Language is included to indicate that the old methods 

will be terminated and the new methods will become effective upon EPA approval of SIP3. 
Language removal 

Permit No. 03700015-003 included SIP-applicable changes to allowable fuel sulfur content. This SIP action (SIP3) 

removes the limits that were terminated upon the approval of that SIP revision (SIP2) on December 5, 2007. It also

removes language stating that the new conditions would become effective on the date of approval of SIP2. Relevant 

conditions can be found in Subject Item GP 001 Electric Generating Combustion Turbines of Permit 03700015-003. 

3. Modeling and NAAQS Attainment 

Because the revision to the SIP conditions simply reduces the allowable sulfur content of liquid fuels used at Inver Hills, 

air dispersion modeling was not conducted. 

Modeled attainment of the area with the SO2 NAAQS continues to be demonstrated. Included in the same EPA 

submittal is a SIP modification (SIP10) for Flint Hills Resources (FHR), which is also included in the Pine Bend 

Maintenance Area. The SO2 levels modeled in the FHR SIP10 submittal are included in Table 1. This modeling includes 

nearby sources, of which Inver Hills is one. 

Table 1: SO2 Modeling Results Summary for FHR SIP10 

Pollutant Avg. Period NAAQS 

(ug/m3

) 

Total Modeled Conc. (ug/m3) 

(Includes background & nearby 

sources)

Percent of Standard (%) 

SO2 3-hr 1300 539 41.5% 

24-hr 365 177 48.5% 

Annual 80 22 27.5% 

For more detail, see the FHR SIP modification and related attachments. Because this SIP revision reduces the allowable 

sulfur content of liquid fuels used at Inver Hills, this SIP modification will not jeopardize continued attainment of the 

NAAQS. 

Attachments 

Attachment 1: Permit No. 03700015-004 issued to Inver Hills (SIP3 relevant) and related technical support document 

Attachment 2: Permit No. 03700015-003 issued to Inver Hills (SIP2 relevant) 

Attachment 3: Permit No. 03700015-003 red-line version 

Attachment 4: Public Notice 

Attachment 5: Completeness Review