A facility used for storing anhydrous ammonia in pressure vessels and transferring the liquid fertilizer by swing booms into mobile nurse tanks for field application

Anhydrous ammonia is widely distributed in Missouri as a nitrogen fertilizer product. It is a colorless gas, stored as liquid under pressure. It has a noxious odor and pH of 11. Exposure to high levels of anhydrous ammonia can cause severe chemical burns, loss of vision and respiratory distress.

In 1996, EPA published U.S. Code of Federal Regulations 40 C.F.R. Part 68, establishing the chemical accident prevention requirements for facilities handling hazardous substances. Included in the rulemaking was a list of substances that posed a risk to the public and environment if released, anhydrous ammonia was included in that list of substances. 

The Agricultural Anhydrous Ammonia Rule was delegated to the Missouri Department of Natural Resources through House Bill 3, which became effective Jan. 2, 2023. Code of State Regulations 10 CSR 10-6.255, also known as the “Chemical Accident Prevention of Agricultural Anhydrous Ammonia”,  went into effect on Feb. 28, 2025. This rulemaking allowed the department to be the delegated enforcement authority of the federal rule. 

The department's Agricultural Anhydrous Ammonia Workgroup has been instrumental in the rulemaking process. 

Key Rule Requirements

Missouri's Chemical Accident Prevention of Agricultural Anhydrous Ammonia rule applies throughout Missouri to agricultural anhydrous ammonia facilities, which includes retail agricultural anhydrous ammonia facilities, and distributor or terminal agricultural anhydrous ammonia facilities.

Exemptions

Agricultural anhydrous ammonia held by farmers for individual use is exempt from the state and federal rule. Anhydrous ammonia not used for an agricultural fertilizer is exempt from the state rule, but may still be subject to the federal rule.

Fees and Reporting

See the department's Agricultural Anhydrous Ammonia Tonnage and Fee Reporting webpage for more information.

Inspections

Due to the potential danger anhydrous ammonia presents to users and the public, facilities are required to submit a Risk Management Plan. The plan outlines the hazards associated with the facility and how the facility plans to operate to minimize risk. Facilities are also required to maintain process equipment to recognized and generally accepted good engineering practices, namely the American National Standards Institute's (ANSI) CGA G-2.1-2023 standard. For more information, visit ANSI's Storage and Handling of Anhydrous Ammonia in CGA G-2.1-2023 webpage.

The department's Agricultural Anhydrous Ammonia Unit conducts inspections, as stated under 10 CSR 10-6.255, verifying that facilities are meeting the requirements of both the state and federal rule.

Compliance Assistance

The Missouri Department of Natural Resources makes it a priority to work with the regulated community to ensure compliance with environmental laws. The department's Agricultural Anhydrous Ammonia Unit wants to help agricultural anhydrous ammonia facilities better understand their regulatory requirements. Facilities can request a compliance assistance visit either through direct communication with the department's Agricultural Anhydrous Ammonia Unit or by completing the department's online Compliance Assistance Visit Request form. Compliance assistance visits do not require additional payment and are designed to benefit the facility in achieving and maintaining compliance.

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