Prevention of Significant Deterioration (PSD) Construction Permit Application Narrative
Muscatine Expansion Facility
Submitted to:
Iowa Department of Natural Resources Air Quality Bureau 502 East 9th Street Des Moines, Iowa 50319
Attention: Jonathan Kreske, P.E. Environmental Engineer, Air Quality Bureau
Submitted on Behalf of:
Greenfield Agricultural Partners LLC 4200 Prairie Wind Drive, Suite 300 West Des Moines, Iowa 50266
Prepared by:
Calderwood & Harkness LLP 801 Grand Avenue, Suite 4400 Des Moines, Iowa 50309
Date: April 28, 2023
Regulatory Reference: Iowa Administrative Code 567—Chapter 33 40 C.F.R. §§ 51.166, 52.21 (Prevention of Significant Deterioration)
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Section 1: Introduction and Purpose
1.1 Purpose of Application
Greenfield Agricultural Partners LLC ("GAP" or the "Applicant") hereby submits this application to the Iowa Department of Natural Resources ("IDNR"), Air Quality Bureau, for a Prevention of Significant Deterioration ("PSD") Construction Permit authorizing the construction and operation of the Muscatine Expansion Facility (the "MEF" or the "Facility"), a new greenfield soybean processing and specialty fertilizer blending facility to be located at 14800 Highway 61 North, Muscatine, Iowa 52761, in Muscatine County, Iowa.
This application is submitted pursuant to the PSD permitting requirements set forth in Iowa Administrative Code ("IAC") 567—Chapter 33 and the corresponding federal PSD regulations codified at 40 C.F.R. § 52.21. As demonstrated in this narrative and the accompanying technical appendices, the MEF qualifies as a new major stationary source for purposes of PSD review. GAP is therefore seeking PSD preconstruction approval prior to commencing construction activities at the proposed site.
This narrative document accompanies and is intended to be read in conjunction with the completed IDNR Air Quality Bureau application forms, technical appendices (Appendices A through H), and all other supporting documentation submitted as part of this application package. The narrative is organized to address each substantive element of the PSD permitting process, including facility and site description, attainment status and PSD applicability analysis, emissions inventory, Best Available Control Technology ("BACT") analysis, air quality impact analysis (dispersion modeling), additional regulatory requirements, and proposed monitoring, recordkeeping, and reporting provisions. Together, these materials provide the IDNR with a complete and thorough basis upon which to evaluate GAP's application and issue the requested PSD Construction Permit.
GAP respectfully requests expeditious review and processing of this application. The Applicant and its technical and legal advisors are available to respond to any questions or requests for additional information that may arise during the IDNR's review.
1.2 Applicant Information
The following identifies the Applicant and its authorized representatives for purposes of this application:
Full Legal Name: Greenfield Agricultural Partners LLC
Entity Type: Iowa limited liability company, organized and existing under the laws of the State of Iowa
Iowa Secretary of State Filing Number: 548213
Employer Identification Number (EIN): 46-3827194
Headquarters Address: 4200 Prairie Wind Drive, Suite 300 West Des Moines, Iowa 50266
Authorized Contact Person: Patricia Caldwell General Counsel & Vice President of Regulatory Affairs Telephone: (515) 223-4800
Email: pcaldwell@greenfieldagpartners.com
Environmental, Health & Safety Contact: Derek Yun Director of Environmental, Health & Safety Telephone: (515) 223-4815
Email: dyun@greenfieldagpartners.com
Outside Counsel: Calderwood & Harkness LLP 801 Grand Avenue, Suite 4400 Des Moines, Iowa 50309 Rafael Dominguez, Lead Associate James Prentice, Responsible Partner Telephone: (515) 288-7200 Calderwood & Harkness Matter Number: 1020-00004
All correspondence, notices, and communications regarding this application should be directed to Ms. Caldwell at the above-referenced headquarters address, with a copy to Mr. Dominguez at Calderwood & Harkness LLP.
1.3 Company Background
GAP is an Iowa-based agricultural processing and specialty chemical company founded in 2011 by the Halverson family. Nils Halverson serves as Founder and Chief Executive Officer. Since its founding, GAP has grown into a significant regional participant in the soybean processing and crop-nutrient distribution industries. The company currently operates three existing soybean crush facilities—two in Iowa and one in Nebraska—and distributes specialty fertilizer products across the upper Midwest, serving agricultural producers and cooperatives in Iowa, Nebraska, Minnesota, South Dakota, and Illinois.
For fiscal year 2022, GAP reported consolidated revenues of approximately $485 million and earnings before interest, taxes, depreciation, and amortization ("EBITDA") of approximately $62 million. The company employs approximately 420 individuals across its existing operations. GAP's primary business activities fall within the agriculture and specialty chemicals sector, encompassing soybean processing, fertilizer blending, and crop-nutrient distribution.
The proposed MEF represents a strategic expansion of GAP's processing capacity and product portfolio. The Facility will enable GAP to increase its soybean crush throughput and add granular fertilizer blending capabilities, thereby strengthening the company's competitive position in the regional market and creating an estimated 85 to 100 new full-time positions in the Muscatine area.
1.4 Technical Consultants
GAP has retained the following qualified technical consultants to prepare the technical components of this application:
Air Quality Technical Appendices: The emissions inventories, BACT analysis, and air dispersion modeling report (Appendices C, D, and E, respectively) were prepared by Pinnacle Environmental Consultants Inc., located at 1120 Ingersoll Avenue, Suite 210, Des Moines, Iowa 50309, under the direction of Dr. Leonard Fisk, P.E., Principal of the Air Quality Practice. Dr. Fisk is a licensed professional engineer in the State of Iowa with over twenty-five years of experience in air quality permitting, emissions characterization, and regulatory compliance for industrial sources. Pinnacle Environmental has extensive experience preparing PSD permit applications for agricultural processing, grain handling, and chemical manufacturing facilities in Iowa and throughout the Midwest.
Process and Civil Engineering Data: Process flow diagrams, mass-balance data, equipment specifications, and site layout plans (Appendix G) were provided by Ridgeline Engineering Group LLC, located at 7700 Pioneers Boulevard, Suite 105, Lincoln, Nebraska 68506. Thomas Novak, P.E., Project Manager at Ridgeline, directed the preparation of the engineering design data. Mr. Novak is a licensed professional engineer in both Nebraska and Iowa with specialized expertise in soybean processing facility design and fertilizer blending operations.
Section 2: Facility and Site Description
2.1 Project Overview
The following provides a summary overview of the proposed project:
Project Name: Muscatine Expansion Facility ("MEF")
Facility Type: Soybean processing and specialty fertilizer blending
Design Capacity: The MEF is designed with a soybean crush capacity of 3,200 tons per day and a granular fertilizer blending line capable of processing 450 tons per day.
Nature of the Source: The MEF is a new (greenfield) stationary source to be constructed on a previously undeveloped parcel of agricultural land. The Facility is not a modification, reconstruction, or expansion of any existing source. No prior industrial operations have been conducted on the proposed site, and there are no existing emission units or air quality permits associated with the parcel. As a new source, the MEF is evaluated for PSD applicability based on its potential to emit, without reference to any baseline actual emissions.
Total Estimated Project Capital Cost: The total estimated capital investment for the MEF, including land acquisition, site preparation, process equipment, buildings, utilities, and all associated infrastructure, is approximately $178 million. This investment reflects GAP's commitment to constructing a state-of-the-art facility employing modern, efficient process technologies and the best available pollution control equipment.
The MEF will receive raw soybeans by truck and rail, process them through a solvent extraction and meal-drying operation to produce soybean meal and crude soybean oil, and produce granular blended fertilizer products for distribution to agricultural producers. The facility will include all necessary material handling infrastructure, storage capacity, process heating equipment, cooling systems, and emissions control systems, as described in greater detail in Section 4 of this narrative.
2.2 Site Location and Description
The MEF will be located at the following site:
Site Address: 14800 Highway 61 North, Muscatine, Iowa 52761
Muscatine County Parcel Identification Number: 0735-19-200-004
Total Acreage: 147 acres
The site was acquired by GAP from the Reinholt Family Trust on January 20, 2023, for a purchase price of $3,820,000, which equates to approximately $25,986 per acre. The acquisition was an arm's-length transaction between unaffiliated parties. Prior to GAP's acquisition, the parcel was used exclusively for agricultural crop production (primarily corn and soybean rotation) and had no history of industrial use or development.
The site is located in a predominantly agricultural area along U.S. Highway 61 in unincorporated Muscatine County, Iowa. The parcel is situated north of the City of Muscatine and is bordered to the north, south, and west by active agricultural fields. U.S. Highway 61 provides primary vehicular access to the site and connects to Interstate 80 approximately 15 miles to the north, providing excellent transportation connectivity for raw material receiving and product distribution. The Vireo Enterprises ("BNSF") rail line runs parallel to U.S. Highway 61 approximately 0.3 miles west of the site, and GAP plans to construct a rail spur connecting the facility to the main line to facilitate rail receiving and shipping of grain and finished products.
The general topography of the site and surrounding area is characterized by gently rolling terrain typical of the eastern Iowa landscape. The Mississippi River valley lies approximately 3 miles to the east of the site. Elevation at the site ranges from approximately 590 to 610 feet above mean sea level. There are no significant topographic features (ridgelines, bluffs, or deep valleys) in the immediate vicinity that would materially affect atmospheric dispersion of emissions from the proposed facility. The site drains generally to the east toward tributaries of the Mississippi River.
2.3 Zoning and Local Land-Use Approvals
The proposed facility site is located within an area zoned Agricultural-Industrial ("AI") by Muscatine County. The AI zoning designation permits agricultural processing and related industrial uses, subject to the issuance of a Conditional Use Permit ("CUP") by the Muscatine County Board of Supervisors.
GAP applied for and was granted Conditional Use Permit No. MC-2022-041 by the Muscatine County Board of Supervisors on November 15, 2022. The CUP authorizes the construction and operation of a soybean processing and fertilizer blending facility on the subject parcel, subject to the conditions set forth therein. The CUP approval followed a public hearing process in which the Board of Supervisors considered the proposed use, its compatibility with surrounding land uses, traffic impacts, and other factors relevant to the county's zoning ordinance.
A complete copy of the CUP approval, including all conditions of approval and the Board of Supervisors' written findings, is attached to this application package as Appendix A.
2.4 Site Control Documentation
GAP holds fee simple title to the 147-acre parcel on which the MEF will be constructed. Title to the property was conveyed by warranty deed from the Reinholt Family Trust at the closing on January 20, 2023. A title search was conducted prior to closing, and title insurance was issued by Hawkeye Title & Escrow LLC, 220 West 2nd Street, Muscatine, Iowa 52761. The title search revealed no encumbrances, liens, easements, or restrictions that would prevent or materially impair construction and operation of the proposed facility on the site.
Copies of the recorded warranty deed, title commitment, and other site-control documentation are provided in Appendix B to this application package.
2.5 Nearest Receptor
The nearest sensitive receptor to the proposed facility is a residential property located approximately 0.42 miles (2,218 feet) east-northeast of the proposed principal stack location (EU-01 process heater stack). This receptor was identified through a review of Muscatine County parcel records, aerial imagery, and a field survey conducted by Pinnacle Environmental Consultants Inc. in February 2023. A discrete receptor was placed at this location in the AERMOD air dispersion modeling analysis to evaluate the facility's air quality impacts at this nearest point of potential exposure, as discussed in Section 6 of this narrative.
Beyond the nearest residential property, the surrounding area is sparsely populated and characterized by dispersed farmsteads separated by large tracts of cultivated agricultural land. There are no schools, hospitals, nursing homes, day-care facilities, or other institutional receptors within 1 mile of the proposed facility site. The nearest school is Muscatine High School, located approximately 4.2 miles to the south-southeast in the City of Muscatine. The nearest hospital is Ostrander Partners LLC, located approximately 5.1 miles to the south in the City of Muscatine.
Section 3: Attainment Status and PSD Applicability
3.1 Area Attainment Designation
Muscatine County, Iowa is currently designated as being in attainment (or unclassifiable/attainment) for all National Ambient Air Quality Standards ("NAAQS") established for criteria pollutants under the Clean Air Act ("CAA"), including ozone (O₃), particulate matter (PM₁₀ and PM₂.₅), carbon monoxide (CO), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and lead (Pb). This designation is current as of the date of this application, as confirmed by EPA's Green Book database and IDNR's attainment/nonattainment designations.
Because Muscatine County is in attainment for all criteria pollutants, new major sources and major modifications to existing major sources located in the county are subject to PSD preconstruction review under 40 C.F.R. § 52.21 and the corresponding state regulations at Iowa Administrative Code 567—Chapter 33. The nonattainment New Source Review ("NNSR") provisions are not applicable to this project.
3.2 Source Category and Major Source Threshold
The PSD regulations establish two tiers of major-source thresholds. For sources that fall within one of the 28 specifically listed PSD source categories enumerated in 40 C.F.R. § 52.21(b)(1)(i)(a), the major-source threshold is 100 tons per year ("tpy") of any regulated NSR pollutant. For all other source categories—referred to as "unnamed" source categories—the major-source threshold is 250 tpy.
The 28 listed source categories include, among others, fossil fuel-fired steam-electric plants, petroleum refineries, Portland cement plants, primary metals facilities, and chemical process plants. GAP has evaluated the MEF against each of the 28 listed categories and has determined that the soybean processing and fertilizer blending facility does not fall within any of the specifically listed categories. While the MEF involves agricultural processing and chemical blending activities, these operations are distinct from the chemical process plant category, which contemplates facilities engaged in the manufacture of organic or inorganic chemicals through chemical reaction. The fertilizer blending line at the MEF is a dry blending and granulation operation, not a chemical synthesis process.
Accordingly, the MEF is classified as an unnamed PSD source category, and the applicable major-source threshold is 250 tons per year of any regulated NSR pollutant.
3.3 PSD Triggering Analysis
GAP has calculated the MEF's potential to emit ("PTE") for each regulated NSR pollutant, as summarized in Section 4 and detailed in Appendix C. PTE represents the maximum capacity of a source to emit a pollutant under its physical and operational design, considering any physical or operational limitations that are federally enforceable. For new sources, PTE is calculated prior to the application of any proposed enforceable permit limitations.
Based on this analysis, PSD review is triggered for the MEF because the facility's PTE for nitrogen oxides ("NOx") is 312 tpy, which exceeds the 250 tpy major-source threshold for unnamed source categories. Accordingly, the MEF is a new major source subject to PSD preconstruction review.
Once PSD is triggered for at least one pollutant (here, NOx), the PSD regulations require review for each additional regulated NSR pollutant for which the facility's emissions exceed the applicable significance levels established in 40 C.F.R. § 52.21(b)(23). The following table presents GAP's PTE for each criteria pollutant alongside the applicable significance level, and indicates whether PSD review is required:
With respect to SO₂, the facility's PTE of 28 tpy is below the 40 tpy significance level. Therefore, PSD review is not required for SO₂, and no BACT analysis for SO₂ is included in this application.
With respect to greenhouse gases ("GHGs"), the MEF's PTE expressed on a carbon dioxide-equivalent ("CO₂e") basis is 148,600 tpy. Under the PSD program as currently implemented, GHG emissions are subject to PSD review only at sources that independently trigger PSD for another regulated NSR pollutant—so-called "anyway" sources. Because the MEF triggers PSD for NOx (and for PM₁₀, PM₂.₅, CO, and VOC at the significance level), it is an "anyway" source. The CO₂e emissions of 148,600 tpy exceed the 75,000 tpy CO₂e threshold applicable to "anyway" sources under 40 C.F.R. § 52.21(b)(49)(iv). Accordingly, PSD review, including BACT analysis, is required for GHG emissions expressed as CO₂e.
In summary, BACT analysis is required for the following pollutants: NOx, PM₁₀, PM₂.₅, CO, VOC, and CO₂e. The BACT analysis presented in Section 5 of this narrative focuses on the primary pollutants of concern—NOx, PM₁₀, PM₂.₅, and CO₂e—with additional discussion of BACT for CO and VOC provided for completeness. The air quality impact analysis presented in Section 6 addresses all modeled pollutants for which PSD review is required.
Section 4: Emission Units and Emissions Inventory
4.1 Overview of Emission Units
The MEF will include six emission units, designated EU-01 through EU-06. These emission units encompass all stationary sources of air pollutant emissions at the facility, including combustion sources, material handling and storage operations, an emergency generator, and cooling tower systems.
Emissions from each emission unit have been calculated based on multiple data sources to ensure accuracy and conservatism, including: (a) process design data provided by Ridgeline Engineering Group LLC; (b) EPA-published emission factors from the Compilation of Air Pollution Emission Factors ("AP-42"), including applicable chapter and section references; (c) vendor-guaranteed performance data for proposed control equipment; and (d) site-specific mass-balance analyses, particularly for material handling operations where mass throughput and material characteristics are used to estimate fugitive dust emissions. In all cases, emission estimates are conservative and represent upper-bound estimates of expected actual emissions.
Detailed emission calculations for each emission unit and each pollutant are provided in Appendix C, which was prepared by Pinnacle Environmental Consultants Inc. under the direction of Dr. Leonard Fisk, P.E. Appendix C includes the individual emission unit calculation worksheets, references to applicable emission factors and data sources, and supporting assumptions.
4.2 Emission Unit Descriptions
The following subsections describe each of the six emission units at the MEF, including the equipment description, operational parameters, principal pollutants emitted, and proposed emission controls.
4.2.1 EU-01: Natural Gas-Fired Process Heater
Description: EU-01 is a natural gas-fired process heater that provides thermal energy to the soybean extraction process. The process heater supplies heated oil to the hexane extraction and desolventizing-toasting stages of soybean meal production. The heater is a critical process unit that must operate continuously to maintain the required process temperatures for efficient solvent extraction and product quality.
Fuel: Natural gas (pipeline quality), supplied via a dedicated lateral from the Harborview Corporation distribution system.
Rated Capacity: 120 million British Thermal Units per hour ("MMBtu/hr") heat input.
Hours of Operation: 8,760 hours per year (continuous operation, 24 hours per day, 365 days per year). The process heater is designed for continuous operation with scheduled maintenance shutdowns of approximately two to three weeks per year; however, PTE is calculated based on 8,760 hours per year to represent maximum capacity.
Principal Emissions: NOx, CO, PM₁₀/PM₂.₅, VOC, SO₂, and GHG (CO₂, CH₄, N₂O).
Controls: EU-01 will be equipped with low-NOx burners ("LNB") with integrated flue gas recirculation ("FGR"). This combination technology reduces NOx formation by lowering peak flame temperatures and reducing the availability of excess oxygen in the primary combustion zone. The LNB+FGR system is described further in Section 5 (BACT Analysis). In addition, the process heater will be equipped with automated combustion controls to maintain optimal air-fuel ratios and minimize incomplete combustion, thereby controlling CO and VOC emissions. A waste heat recovery economizer will be installed on the process heater exhaust to recover thermal energy and improve overall process efficiency, which also contributes to reduced GHG emissions per unit of product output.
4.2.2 EU-02: Soybean Dryer
Description: EU-02 is a natural gas-fired rotary dryer used to dry processed soybean meal to the required moisture content for storage and shipment. Following solvent extraction and desolventizing, the soybean meal is conveyed to the rotary dryer, where it is exposed to a stream of heated air in a co-current flow configuration. The dryer reduces the moisture content of the soybean meal from approximately 18 percent to 12 percent (wet basis), which is the target specification for finished meal products.
Fuel: Natural gas (pipeline quality).
Rated Capacity: 80 MMBtu/hr heat input.
Hours of Operation: 8,760 hours per year (continuous operation).
Principal Emissions: NOx, CO, PM₁₀/PM₂.₅ (including condensable particulate matter from soybean oils that may be released during the drying process), VOC, SO₂, and GHG (CO₂, CH₄, N₂O). The PM emissions from this unit include both filterable particulate (soybean meal dust) and condensable particulate (organic condensable matter from soybean oil vapors). Both components are accounted for in the emissions inventory.
Controls: EU-02 will be equipped with low-NOx burners with flue gas recirculation (LNB+FGR), consistent with the controls proposed for EU-01. In addition, a cyclone separator will be installed downstream of the dryer and upstream of the exhaust stack to collect filterable particulate matter (soybean meal dust) from the dryer exhaust stream. The cyclone separator is designed to achieve a minimum particulate removal efficiency of 85 percent for particles greater than 10 microns in aerodynamic diameter. The combination of LNB+FGR for NOx control and cyclone separation for particulate control represents BACT for this emission unit, as discussed in Section 5.
4.2.3 EU-03: Fertilizer Granulation Dryer
Description: EU-03 is a natural gas-fired rotary dryer serving the granular fertilizer blending line. In the fertilizer blending process, dry raw materials (including ammonium sulfate, urea, muriate of potash, and micronutrient blends) are combined in precise proportions, granulated, and then dried in the rotary dryer to produce a uniform, free-flowing granular fertilizer product. The dryer reduces moisture added during the granulation step and produces a finished granule suitable for storage and field application.
Fuel: Natural gas (pipeline quality).
Rated Capacity: 60 MMBtu/hr heat input.
Hours of Operation: 5,200 hours per year. The fertilizer blending line is operated on a seasonal and intermittent basis, with production concentrated during the spring and fall fertilizer application seasons. The 5,200-hour annual operating limit represents approximately 60 percent of a full calendar year and reflects the seasonal nature of fertilizer demand. GAP proposes to accept this operational limitation as a federally enforceable permit condition for purposes of PTE calculation.
Principal Emissions: NOx, CO, PM₁₀/PM₂.₅ (including fertilizer dust from the granulation and drying processes), VOC, trace quantities of ammonia (NH₃) released from ammonium-containing fertilizer materials during the drying step, and GHG (CO₂, CH₄, N₂O).
Controls: EU-03 will be equipped with a cyclone separator followed by a wet scrubber system. The cyclone separator serves as a pre-collector to remove coarse particulate (fertilizer dust) from the dryer exhaust. The wet scrubber downstream of the cyclone provides additional particulate removal for fine particulate and also absorbs trace ammonia emissions. The combined cyclone-scrubber system is designed to achieve an overall particulate removal efficiency of approximately 95 percent for PM₁₀. NOx emissions from the dryer combustion are controlled with low-NOx burners with flue gas recirculation (LNB+FGR), consistent with the controls proposed for EU-01 and EU-02.
4.2.4 EU-04: Material Handling and Storage
Description: EU-04 encompasses all grain receiving, handling, storage, and loadout operations at the facility, as well as fertilizer material handling and loadout operations. Specific equipment and operations included within this emission unit designation are as follows:
• Grain receiving elevators (truck dump and rail dump pits with associated leg elevators)
• Bucket elevators serving grain and meal transfer within the processing complex
• Enclosed belt conveyors connecting receiving, processing, and storage areas
• Grain storage silos and bins (total grain storage capacity of approximately 2.4 million bushels)
• Finished soybean meal storage and loadout facilities
• Fertilizer raw material receiving and storage bins
• Finished fertilizer product storage and loadout facilities
• Truck and rail loading operations for outbound soybean meal, crude soybean oil, and finished fertilizer products
Emission Sources: The primary emissions from EU-04 are fugitive particulate matter (PM₁₀ and PM₂.₅) generated during the transfer, conveying, elevation, and loading/unloading of granular materials. Each material transfer point (drop point) is a potential source of fugitive dust emissions. Emissions are a function of material throughput, material moisture content, particle size distribution, wind speed, and the degree of enclosure and control at each transfer point.
Principal Emissions: PM₁₀ and PM₂.₅. VOC and other gaseous pollutant emissions from grain handling operations are negligible and are not material contributors to the facility's emissions inventory.
Controls: All enclosed material transfer points, elevator heads and boots, storage bin vents, and loadout operations will be equipped with pulse-jet baghouse filters. The baghouse filters will be designed and operated to achieve an outlet particulate concentration of no greater than 0.005 grains per dry standard cubic foot ("gr/dscf"), corresponding to a control efficiency of approximately 99.5 percent. All belt conveyors will be fully enclosed to minimize fugitive emissions during material transport. At open transfer points (such as truck dump receiving areas), water spray dust suppression systems will be installed to supplement the enclosed handling and baghouse filtration controls. The combination of baghouse filtration on enclosed transfer points, enclosed conveyors, and water spray suppression at open transfer points represents BACT for material handling particulate emissions, as discussed in Section 5.
4.2.5 EU-05: Emergency Diesel Generator
Description: EU-05 is a standby/emergency diesel engine-driven generator that will provide backup electrical power to critical facility systems (fire protection, safety systems, and essential process controls) in the event of a utility power outage. The generator is not intended for, and will not be used for, peak-shaving, demand response, or any non-emergency power generation purpose.
Rated Capacity: 2,000 kilowatts ("kW") (approximately 2,682 brake horsepower).
Fuel: Ultra-low sulfur diesel ("ULSD") with a maximum sulfur content of 15 parts per million ("ppm").
Operational Limit: GAP proposes a federally enforceable permit condition limiting operation of the emergency generator to a maximum of 500 hours per year. This operational limit encompasses all hours of operation, including emergency use, maintenance, and readiness testing. The 500-hour annual limit is consistent with EPA guidance for emergency stationary internal combustion engines under 40 C.F.R. Part 63, Subpart ZZZZ.
Principal Emissions: NOx, CO, PM₁₀/PM₂.₅, SO₂, VOC, and GHG (CO₂).
Controls: The emergency generator will be powered by an engine that meets EPA Tier 4 Final emission standards for stationary compression ignition internal combustion engines, as set forth in 40 C.F.R. Part 60, Subpart IIII. Tier 4 Final engines incorporate advanced emission control technologies, including diesel particulate filters and selective catalytic reduction or equivalent NOx aftertreatment, to achieve the lowest emission rates commercially available for this engine class. In addition, the use of ULSD fuel minimizes SO₂ and particulate emissions from fuel sulfur content.
Note: EU-05 is subject to the New Source Performance Standards ("NSPS") at 40 C.F.R. Part 60, Subpart IIII, and the National Emission Standards for Hazardous Air Pollutants ("NESHAP") at 40 C.F.R. Part 63, Subpart ZZZZ, applicable to reciprocating internal combustion engines. Compliance with these standards is addressed in Section 7 of this narrative.
4.2.6 EU-06: Cooling Towers
Description: EU-06 consists of a two-cell, induced-draft cooling tower system providing process cooling water to the soybean processing operations. The cooling towers reject waste heat from the solvent extraction, desolventizing, and oil processing operations to the atmosphere via evaporative cooling.
Circulating Water Flow: 18,000 gallons per minute ("gpm") combined, with each of the two cells handling 9,000 gpm.
Principal Emissions: PM₁₀ and PM₂.₅. Cooling tower emissions of particulate matter result from "drift"—small droplets of circulating cooling water that are entrained in the exhaust air stream and carried out of the tower. These droplets contain dissolved and suspended solids present in the circulating water. When the water droplets evaporate, the dissolved and suspended solids are released as fine particulate matter. The quantity of particulate emissions is a function of the drift rate (expressed as a percentage of circulating water flow), the total dissolved solids ("TDS") concentration of the circulating water, and the circulating water flow rate.
Controls: Each cooling tower cell will be equipped with high-efficiency drift eliminators designed to minimize the rate of drift loss. The proposed drift eliminators are rated to achieve a maximum drift rate of 0.0005 percent of the circulating water flow, which represents the highest-performing drift elimination technology commercially available for induced-draft cooling towers. PM₁₀ emissions from the cooling towers have been calculated based on this drift rate and a design-basis TDS concentration, as documented in the emissions calculations in Appendix C.
4.3 Potential-to-Emit Summary Table
The following table summarizes the facility-wide potential to emit for each regulated NSR pollutant:
The PTE values presented above are calculated on the basis of maximum rated capacity for each emission unit, maximum hours of operation (or, in the case of EU-03 and EU-05, the proposed permitted operational limits), and worst-case emission factors. PTE is calculated prior to the application of any proposed enforceable control requirements or permit conditions, except for the operational limitations on EU-03 (5,200 hr/yr) and EU-05 (500 hr/yr), which GAP proposes to accept as federally enforceable permit conditions.
A detailed emission unit-by-emission unit breakdown of PTE for all pollutants is provided in Table 4-2, which is included in Appendix C to this application package.
GHG emissions are expressed on a CO₂-equivalent basis using the 100-year global warming potentials ("GWPs") from 40 C.F.R. Part 98, Table A-1 (GWP of 1 for CO₂, 25 for CH₄, and 298 for N₂O). The GHG emissions inventory accounts for CO₂ from natural gas and diesel combustion, as well as minor quantities of CH₄ and N₂O from combustion processes.
4.4 Hazardous Air Pollutants (HAPs)
GAP has evaluated the MEF's emissions of hazardous air pollutants ("HAPs") listed under Section 112(b) of the Clean Air Act. The facility's potential HAP emissions are attributable primarily to trace organic compounds in natural gas combustion exhaust and hexane (a listed HAP) used in the soybean solvent extraction process, with controls and solvent recovery systems minimizing hexane releases to the atmosphere.
Based on this evaluation, the facility's PTE for any individual HAP is below the 10 tpy major-source threshold, and the facility's PTE for total HAPs (the aggregate of all individual HAP emissions) is below the 25 tpy major-source threshold. Accordingly, the MEF is classified as an area source for HAP purposes under Section 112 of the Clean Air Act, and the major-source NESHAP requirements are not applicable.
A complete HAP emissions inventory, identifying each HAP and its estimated annual emissions, is provided in Table 4-3 in Appendix C.
Section 5: Best Available Control Technology (BACT) Analysis
5.1 BACT Methodology
Section 165(a)(4) of the Clean Air Act and 40 C.F.R. § 52.21(j) require that each new major source subject to PSD review apply Best Available Control Technology ("BACT") for each pollutant subject to regulation under the Act that the source would have the potential to emit in significant amounts. BACT is defined as an emission limitation based on the maximum degree of reduction for each regulated pollutant, taking into account energy, environmental, and economic impacts, and other costs, as determined on a case-by-case basis.
The BACT analysis presented herein was conducted using the EPA's well-established "top-down" methodology, as described in the EPA's Draft New Source Review Workshop Manual (October 1990). Under the top-down approach, the analysis proceeds through the following five steps for each pollutant and emission unit:
Step 1: Identify all available control technologies for the pollutant and emission unit under consideration, including technologies applied at similar sources, innovative technologies, and technologies transferred from other industrial applications.
Step 2: Eliminate technically infeasible options. A control technology is technically infeasible if it has not been demonstrated in practice on the same or a similar type of emission unit, or if the applicant can demonstrate that there are technical difficulties that would preclude successful application of the technology to the specific emission unit.
Step 3: Rank the remaining technically feasible control technologies by control effectiveness, from the most effective (top) to the least effective (bottom).
Step 4: Evaluate the most effective control technology for energy, environmental, and economic impacts. If the top-ranked technology is not eliminated based on these factors, it is selected as BACT. If it is eliminated, the analysis proceeds to the next most effective technology.
Step 5: Select BACT. The most effective control technology that is not eliminated in Steps 2 through 4 is proposed as BACT.
As part of the BACT analysis, Pinnacle Environmental Consultants Inc. conducted a comprehensive search of the EPA's RACT/BACT/LAER Clearinghouse ("RBLC") database to identify recent BACT determinations at comparable facilities, including soybean processing plants, grain handling facilities, and fertilizer manufacturing operations. The RBLC search targeted determinations issued within the preceding ten years (2013–2023) and focused on facilities with similar emission unit types (natural gas-fired process heaters and dryers, grain handling operations, and emergency generators). The results of the RBLC search were used to inform the identification of available control technologies and to benchmark the proposed BACT emission limits against limits accepted at comparable sources.
The complete, detailed BACT analysis for each pollutant and emission unit is provided in Appendix D, which was prepared by Pinnacle Environmental Consultants Inc. The following subsections present a summary of the proposed BACT for each pollutant.
5.2 BACT for NOx
5.2.1 EU-01 (Process Heater) and EU-02 (Soybean Dryer)
The top-down BACT analysis for NOx from the natural gas-fired process heater (EU-01, 120 MMBtu/hr) and soybean dryer (EU-02, 80 MMBtu/hr) considered the following control technologies, listed in order of decreasing effectiveness:
1. Selective Catalytic Reduction ("SCR"): SCR is a post-combustion NOx control technology in which a reducing agent (typically aqueous ammonia or urea) is injected into the exhaust gas stream upstream of a catalyst bed. The reducing agent reacts with NOx in the presence of the catalyst to form nitrogen (N₂) and water (H₂O). SCR systems are capable of achieving NOx reduction efficiencies of 80–90 percent or greater when applied to natural gas-fired sources.
2. Low-NOx Burners with Flue Gas Recirculation ("LNB+FGR"): Low-NOx burners are designed to reduce the formation of thermal NOx by staging the combustion process, controlling the mixing of fuel and air, and reducing peak flame temperatures. Flue gas recirculation supplements the LNB technology by redirecting a portion of the cooled flue gas back into the combustion zone, which further reduces peak flame temperatures and the oxygen concentration in the primary flame zone. The combined LNB+FGR system typically achieves NOx emission rates in the range of 0.03 to 0.05 lb/MMBtu for natural gas-fired units.
3. Low-NOx Burners Alone ("LNB"): LNB technology without FGR typically achieves NOx emission rates in the range of 0.05 to 0.10 lb/MMBtu for natural gas-fired units.
4. Good Combustion Practices ("GCP"): Proper air-fuel ratio management, burner tuning, and maintenance constitute the baseline level of NOx control and do not achieve NOx reductions beyond the inherent performance of conventional burner designs.
All four technologies were determined to be technically feasible for application to the process heater and soybean dryer.
Evaluation of SCR: Although SCR is technically feasible for natural gas-fired process heaters and dryers, the cost-effectiveness analysis demonstrated that the incremental cost of SCR (relative to LNB+FGR) exceeds $10,000 per ton of NOx removed. Specifically, the annualized cost of an SCR system for EU-01, including capital amortization, catalyst replacement, ammonia reagent consumption, and additional energy costs, was estimated at approximately $485,000 per year. The incremental NOx reduction achieved by SCR over LNB+FGR for EU-01 is estimated at approximately 38 tons per year. The resulting incremental cost-effectiveness is approximately $12,800 per ton of NOx removed. A similar analysis for EU-02 yielded an incremental cost-effectiveness of approximately $14,500 per ton of NOx removed. These values exceed the range of cost-effectiveness typically accepted as BACT in recent RBLC determinations for comparable natural gas-fired process heaters at soybean processing and similar facilities. Furthermore, the use of ammonia in SCR systems introduces the potential for ammonia slip emissions, an adverse collateral environmental impact that must be weighed in the BACT evaluation. Based on the above factors, SCR was eliminated as BACT for EU-01 and EU-02.
Selection of LNB+FGR: Low-NOx burners with flue gas recirculation are technically proven, widely implemented, and commercially available for natural gas-fired process heaters and dryers in the soybean processing industry and other comparable industrial applications. The RBLC search identified multiple BACT determinations at similar facilities that specified LNB+FGR with emission limits in the range of 0.03 to 0.05 lb/MMBtu. The technology imposes no adverse energy or environmental impacts and is economically reasonable.
Proposed BACT: LNB+FGR is proposed as BACT for NOx from EU-01 and EU-02.
Proposed NOx Emission Limit: 0.036 lb/MMBtu (on a 1-hour averaging basis), as demonstrated by continuous emissions monitoring. This emission limit is consistent with the performance of modern LNB+FGR systems on natural gas-fired units and is at or below the limits established in recent BACT determinations for comparable sources identified in the RBLC search.
The proposed 0.036 lb/MMBtu limit applies to both EU-01 (120 MMBtu/hr) and EU-02 (80 MMBtu/hr).
5.2.2 EU-03 (Fertilizer Granulation Dryer)
The top-down BACT analysis for NOx from the fertilizer granulation dryer (EU-03, 60 MMBtu/hr) considered the same suite of control technologies as evaluated for EU-01 and EU-02.
LNB+FGR is proposed as BACT for EU-03, with the same emission limit of 0.036 lb/MMBtu (1-hour average). The intermittent operating schedule of EU-03 (5,200 hours per year, compared to 8,760 hours for EU-01 and EU-02) further undermines the cost-effectiveness of SCR, as the annualized cost of the SCR system would be amortized over fewer operating hours and fewer tons of NOx reduced. The incremental cost-effectiveness of SCR over LNB+FGR for EU-03 was estimated at approximately $18,900 per ton of NOx removed, which further confirms the elimination of SCR as BACT for this emission unit.
5.2.3 EU-05 (Emergency Diesel Generator)
For the emergency diesel generator (EU-05), the BACT analysis considered the applicable engine emission standards and operational limitations. The generator will be powered by an engine certified to meet EPA Tier 4 Final emission standards under 40 C.F.R. Part 60, Subpart IIII. Tier 4 Final standards represent the most stringent emission limits promulgated by EPA for this class of stationary compression ignition engines and incorporate advanced aftertreatment technologies (diesel particulate filters and NOx aftertreatment).
Given the emergency and standby nature of this engine, its limited operation (500 hours per year maximum), and the application of the most stringent available engine emission standards, the combination of EPA Tier 4 Final engine standards and good combustion practices constitutes BACT for NOx from EU-05. The use of ultra-low sulfur diesel fuel further ensures minimal emissions. No additional post-combustion NOx controls (such as standalone SCR) beyond those integral to the Tier 4 Final engine package are warranted or cost-effective for an emergency engine operating 500 hours per year or less.
5.3 BACT for PM₁₀ and PM₂.₅
5.3.1 EU-01, EU-02, EU-03 (Combustion Sources)
Natural gas combustion is inherently a low-emitter of particulate matter. The clean-burning properties of pipeline-quality natural gas—which is essentially free of ash-forming constituite and contains negligible sulfur—result in very low PM₁₀ and PM₂.₅ emissions from natural gas-fired combustion equipment. PM emissions from natural gas combustion consist primarily of condensable sulfate particulate and minor quantities of filterable particulate, both at very low mass emission rates.
Good combustion practices—including proper burner tuning, maintenance, and automated combustion controls—constitute BACT for PM₁₀ and PM₂.₅ from natural gas-fired combustion units. This determination is consistent with numerous BACT determinations identified in the RBLC for natural gas-fired process heaters and dryers. Add-on particulate controls (such as fabric filters, electrostatic precipitators, or scrubbers) are not warranted or cost-effective for natural gas-fired combustion sources with inherently low PM emission rates.
The PM₁₀ emission factor applied to EU-01, EU-02, and EU-03 for natural gas combustion is 0.0075 lb/MMBtu, consistent with AP-42, Chapter 1.4 ("Natural Gas Combustion"). PM₂.₅ is assumed to equal PM₁₀ from natural gas combustion, given the fine particle size distribution characteristic of combustion-generated particulate.
For EU-02 (soybean dryer) and EU-03 (fertilizer granulation dryer), PM emissions also include process-related particulate (soybean meal dust and fertilizer dust, respectively) entrained in the dryer exhaust. The cyclone separator on EU-02 and the cyclone-scrubber system on EU-03, as described in Section 4.2, provide additional particulate control for these process-related PM emissions. These controls are addressed under the particulate BACT determinations for the respective emission units in the detailed BACT analysis (Appendix D).
5.3.2 EU-04 (Material Handling and Storage)
EU-04 is the primary source of particulate matter emissions at the MEF and warrants the most detailed BACT analysis for PM₁₀ and PM₂.₅. The top-down BACT analysis for PM₁₀/PM₂.₅ from material handling and storage operations considered the following control technologies, listed in order of decreasing effectiveness:
1. Baghouse Filters (Pulse-Jet Type): Fabric filter baghouses using pulse-jet cleaning technology are capable of achieving outlet particulate concentrations of 0.005 gr/dscf or lower, corresponding to control efficiencies of 99 percent or greater. Pulse-jet baghouses are widely used in the grain handling and fertilizer blending industries and are commercially available from multiple equipment vendors for the types of emission points found at the MEF.
2. Cartridge Filters: Cartridge filter dust collectors use pleated filter media rather than conventional felt bags. Cartridge filters are capable of achieving outlet particulate concentrations comparable to pulse-jet baghouses but may be less suitable for high-dust-loading applications and grain handling environments where the risk of moisture-induced filter blinding or grain dust accumulation is elevated.
3. Cyclone Separators: Mechanical cyclone separators are effective for removing coarse particulate (typically greater than 10 microns) but have limited efficiency for fine particulate in the PM₁₀ and PM₂.₅ size fractions. Typical cyclone efficiencies for PM₁₀ range from 70 to 90 percent.
4. Wet Suppression Only: Water spray dust suppression systems reduce fugitive emissions by increasing the moisture content of the material and wetting exposed surfaces. Wet suppression alone is typically credited with 50–70 percent fugitive dust control effectiveness, depending on the application.
5. Enclosure Only: Enclosing material transfer points and conveyors reduces windborne fugitive emissions but does not capture and collect particulate from the enclosed airspace. Enclosure alone, without ventilation and filtration, is the least effective control option.
All five technologies were determined to be technically feasible. However, based on the step-by-step evaluation:
Selection of Baghouse Filters (Pulse-Jet Type) as BACT: Pulse-jet baghouse filters represent the most effective control technology for particulate emissions from grain handling and fertilizer material handling operations. The technology is widely applied at comparable facilities throughout the Midwest and is well suited to the types of dust generated at the MEF (grain dust, soybean meal dust, and fertilizer dust). The RBLC search confirmed that baghouse filtration is consistently identified as BACT for grain handling and fertilizer blending facilities, with outlet concentration limits typically in the range of 0.005 to 0.01 gr/dscf.
Cartridge filters were considered but were not selected as the top-ranked technology due to operational concerns regarding suitability for the higher dust loadings and humidity conditions characteristic of soybean and fertilizer material handling, as well as higher media replacement costs. Cyclone separators, wet suppression, and enclosure alone were eliminated as lower-ranked alternatives.
Proposed BACT: Pulse-jet baghouse filters on all enclosed material transfer points, elevator heads and boots, storage bin vents, and loadout operations. Enclosed conveyors for all belt conveying operations. Water spray dust suppression at open transfer points (e.g., truck dump receiving areas) as a supplemental control measure.
Proposed PM Outlet Concentration: 0.005 gr/dscf at the outlet of each baghouse filter.
Control Efficiency: 99.5 percent.
5.3.3 EU-06 (Cooling Towers)
The top-down BACT analysis for PM₁₀/PM₂.₅ from the cooling towers (EU-06) considered the following control technologies:
1. High-Efficiency Drift Eliminators: High-efficiency drift eliminators use multiple passes of blade or cellular media to capture entrained water droplets from the cooling tower exhaust air stream before the air exits the tower. Modern high-efficiency drift eliminators are capable of achieving drift rates of 0.0005 percent of circulating water flow, which represents the lowest drift rate achievable with commercially available technology.
2. Standard Drift Eliminators: Conventional or standard drift eliminators typically achieve drift rates in the range of 0.001 to 0.005 percent of circulating water flow.
Both technologies are technically feasible and are standard features of modern cooling tower systems. High-efficiency drift eliminators are commercially available from all major cooling tower manufacturers and add minimal incremental cost relative to standard drift eliminators when specified as part of a new tower construction.
Proposed BACT: High-efficiency drift eliminators on each cooling tower cell.
Proposed Drift Rate: 0.0005 percent of circulating water flow.