PERMIT REVIEW SUMMARY

Permit Writer:	Ryan Wigginton 
Date:			July 16, 2026
Company Name:	Olin Winchester LLC
Facility Location:	411 County Road 101
Source Number:	1420-00029
County: 		Lafayette

FACILITY DESCRIPTION
Olin Winchester, LLC, is a manufacturer of small arms ammunition.  The operations include two (2) adjoining business units: the Rimfire facility and the Centerfire facility.  The Rimfire facility is used for the production, assembly, and shipping of small arms ammunition, power tool loads, and military ammunition.  The Centerfire facility is used for production, assembly, and shipping of small arms ammunition.  The facility’s operations fall within SIC Codes 3482 (Small Arms Ammunition) and 2892 (Explosives) as well as NAICS Codes 332992 (Small Arms Ammunition Manufacturing) and 325920 (Explosive Manufacturing).  With the limitations in the current permit, this site is considered a synthetic minor source as it relates to the Title V program, as well as a synthetic minor source of hazardous air pollutants (HAPs).

PROJECT/PERMIT ACTION DESCRIPTION
On April 17, 2026, MDEQ was contacted by representatives for Olin regarding replacing an existing, emergency engine (Emission Point AB-005).  Due to the facility classification as a “synthetic minor,” Olin was required to submit a modification application for this replacement action.  MDEQ received the Synthetic Minor Operating Permit (SMOP) Modification on May 1, 2026.  Emission Point AB-005 in the current SMOP is described as a “0.887 MMBTU / Hour (260 kW) Diesel-Fired Emergency Fire Pump Engine [manufactured in 1970].”  The replacement unit as described in the application and draft permit is a “0.48336 MMBTU / Hour (190 hp / 142 kW) Diesel-Fired Emergency Fire Pump Engine [manufactured in 2025].”

On June 15, 2026, MDEQ received a SMOP renewal application.  This included additional changes: 
•	Emission Point AA-001 corrected from three tundishes and three hydron continuous billet casters to four each.
•	Emission Point AA-012 modified to state the size of the tanks (4,500-gallons each).  Additionally, these tanks were existing units; however, they were replaced and the original tanks are currently still at the site.  The valves are blanked off with plans to remove in the near future.
•	Emission Point AC-002 to include two sealant dispensing machines and one external cartridge sealer (an increase to 26 total lines).
•	Replacement of methylene chloride used in Emission Point AC-003 and AC-004 to a cyclohexane-based material in accordance with EPA’s 2024 ban on methylene chloride use in most industrial processes.  A monitoring condition to track methylene chloride has been modified to require the permittee maintain documentation that verifying that no compounds containing methylene chloride are used.  This condition was not modified to track cyclohexane material used due a facility-wide monitoring condition to track all VOC/HAP containing material.

EMISSION SUMMARY

Pollutant	Potential-to-Emit (tons/year)	
Particulate Matter (PM)	40.65	
Sulfur Dioxide (SO2)	0.24	
Nitrogen Oxides (NOX)	39.89	
Carbon Monoxide	91.95	
Volatile Organic Compounds (VOC)	99.01	
Lead (Pb)	6.13	
Total HAP	24.01	
Individual HAP	9.01	
1Facility-wide permit limits established in Permit to Construct to maintain SMOP status.

APPLICABLE/PROPOSED PERMIT LIMITATIONS
Emission Point(s)	Applicable Requirement	Pollutant / Parameter	Limitation / Standard	Monitoring	
AA-000
(Facility-Wide)	11 Miss. Admin. Code, Pt. 2, R. 2.2.B(10)., as established in Permit to Construct issued February 28, 2011

(Title V Avoidance Limits)	VOCs	< 99.0 tpy	Monitoring and recording of all VOC/HAP containing materials used on a monthly basis.	
		HAPs	< 9.9 tpy (Individual)
< 24.9 tpy (Total)		
	11 Miss. Admin. Code Pt. 2, R. 1.3.A.	Opacity
(smoke)	< 40%	Margin of compliance is expected to be significant; therefore, no additional requirement needed.	
	11 Miss Admin. Code Pt. 2, R. 1.3.B.	Opacity			
	11 Miss. Admin. Code Pt. 2, R. 1.3.F(1).	PM
(filterable)	E = 4.1 × p0.67	Ensuring the adequate operation of baghouses, the margin of compliance for these standards should be significant.
The facility is required to operate any baghouse in accordance with manufacture’s specifications.	
AA-013	11 Miss. Admin. Code Pt. 2, R. 2.2.B(10).  	PM
(filterable)	Requirement to use fabric filters and cease operation if filters malfunction.	Monthly inspections on fabric filters.	
AB-000	11 Miss Admin. Code Pt. 2, R. 1.3.D(1)(a).	PM	< 0.6 lb/MMBTU	By solely using natural gas, the margin of compliance for these standards is expected to be significant given that the units combust natural gas.  Therefore, no additional requirements are needed.	
AB-001
AB-002
AB-003	11 Miss. Admin. Code Pt. 2, R. 1.4.A(1).	SO2	< 4.8 lb/MMBTU		
	11 Miss. Admin. Code Pt. 2, R. 1.3.D(1)(b).	PM	E = 0.8808 ×  I-0.1667		

NSPS APPLICABILITY
40 CFR Part 60, Subpart Dc – Standards of Performance for Small Industrial-Commercial-Institutional Steam Generating Units: this subpart applies to steam generating units constructed after June 9, 1989, and have a maximum design heat input capacity between 10 and 100 MMBTU/hr.  Emission Points AB-001, AB-002, and AB-003, are natural gas-fired boilers manufacturing in 2011 with a capacity of 10.2, 10.2, and 16.3 MMBTU/hour, respectively; therefore, this subpart does apply.  The applicable requirements regarding Subpart Dc remain in the proposed permit.   

40 CFR Part 60, Subpart IIII – Standards of Performance for Stationary Compression Ignition Internal Combustion Engines:  this subpart applies to compression ignition (CI) engines constructed after June 12, 2006.  In previous permitting, this subpart was applicable to Emission Point AB-008 (an emergency generator manufactured in 2008).  This permitting action included the removal and replacement of Emission Point AB-005.  This engine will be considered a new emergency CI engine; therefore, this subpart now applies to both AB-005 and AB-008.  Both engines will meet the requirements of the subpart by purchasing certified engines and operating and maintaining them in accordance with the manufacturer’s emission related instructions.  Olin will confirm the engines maintain emergency status by recording all use of the engines through non-resettable hour meters.

40 CFR Part 60, Subpart JJJJ – Standards of Performance for Stationary Spark Ignition Internal Combustion Engines: this subpart applies to spark ignition (SI) engines constructed after January 1, 2009.  Emission Point AB-004 is an emergency SI engine constructed after 2009; therefore, this subpart does apply.  The applicable requirements regarding Subpart JJJJ remain in the proposed permit.

MACT APPLICABILITY
40 CFR Part 63, Subpart ZZZZ – National Emission Standard for Hazardous Air Pollutants for Stationary Reciprocating Internal Combustion Engines: This subpart applies to engines.  Olin currently operates three engines at the site (Emission Points AB-004, AB-005, and AB-008); therefore, this subpart does apply.  However, in accordance with 63.6590(c), engines subject to the requirements of 40 CFR 60, Subpart JJJJ or IIII, will comply with those requirements and remain in compliance with the conditions of Subpart ZZZZ.  In previous permits, Emission Point AB-005 was subject to additional requirements of Subpart ZZZZ due to it being a 1970 model engine.  When this engine is replaced, it will be considered new and subject to Subpart IIII.  Therefore, nothing besides applicability of the NESHAP is included in the permit. 

40 CFR Part 63, Subpart XXXXXX – National Emission Standards for Hazardous Air Pollutants for Nine Metal Fabrication and Finishing Source Categories (Area Sources): While an area source for HAP emissions, the facility does not primarily engage in any of the operations specifically outlined in Table 1 of the subpart.  Moreover, based on EPA guidance documents, the facility’s primary operation does not fall under any of the corresponding Standard Industrial Classification (SIC) and North American Industry Classification System (NAICS) codes that apply to this subpart.  Therefore, this subpart is not applicable.

40 CFR Part 63, Subpart JJJJJJ – National Emission Standards for Hazardous Air Pollutants for Industrial, Commercial, and Institutional Boilers and Process Heaters for Area Sources: The boilers are all gas-fired boilers and are therefore exempt.  

PUBLIC PARTICIPATION

The 30-day public notice period began on August 5, 2026, when the notice was posted on MDEQ’s website and ends September 7, 2026.