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Cuisine Solutions Ammonia Release

Overview

On July 31, 2024, at approximately 8:20 p.m., anhydrous ammonia was accidentally released at the Cuisine Solutions, Inc. food processing facility in Sterling, Virginia, when an emergency pressure relief valve discharged to the atmosphere. The released ammonia formed a toxic cloud, personnel evacuated, and many inhaled ammonia vapor and were injured. The CSB estimated the release at approximately 275 pounds of anhydrous ammonia.

Incident Details

  • location: Sterling, VA
  • accident_type: Ammonia release
  • investigation_status: The CSB's final report was released on September 25, 2025.

Key Findings

  • direct_causes: ['The cause of the incident was an overpressure in a vessel that released a toxic ammonia cloud through an emergency pressure relief valve that opened near the employee parking lot.', 'The ammonia cloud contained a significant liquid component, which caused much of it to rapidly drop to ground level, exposing workers while they evacuated.', 'The relief discharge that occurred at Cuisine Solutions was a two-phase release with a significant liquid component that resulted from liquid or two-phase flow to the relief valve inlet.', 'The relief discharge in the incident was angled downward by the bevel cut on the tee diffuser.']
  • contributing_factors: ['A failure to discharge this emergency pressure relief valve to a safe location.', 'A lack of engineering or administrative controls, such as an automated emergency refrigeration system shutdown, that could have minimized liquid or aerosol in the ammonia release.', 'The Cuisine Solutions Sterling plant’s insufficient emergency preparedness, including the site Emergency Action Plan which did not ensure workers could safely evacuate in the event of an outdoor ammonia release.', 'A lack of effective drills.', 'A lack of effective emergency shutdown.', 'inadequate liquid disengagement in the vessel headspace during relief', 'a high liquid level', 'overfill of the vessel', 'the bevel cut on the tee diffuser', 'the release elevation', 'the release orientation', 'the cloud density', 'building wake effect', 'wind dispersed ammonia vapor across the roof of the building']
  • organizational_systemic_factors: ['The Sterling plant did not record historical process data for the ammonia refrigeration system beyond food storage, chiller, or freezer temperatures required for food safety concerns.', 'The Sterling site’s Emergency Action Plan did not follow IIAR guidance and did not adequately address possible ammonia releases outside the building.', 'The Sterling plant did not have an emergency procedure for a system-wide ammonia shutdown and did not include the emergency shutdown buttons in its Emergency Action Plan.', 'The Sterling plant did not have an automated shutdown of the ammonia refrigeration system in the event of an ammonia release, and relied on human intervention, which did not occur during the incident or evacuation.']

Consequences

  • fatalities:
  • injuries: Thirty-three workers were transported to area hospitals for treatment. Four of them were admitted to the hospitals, including one who was placed in intensive care. Another seven people self-presented at local hospitals and urgent care facilities after the incident, and all patients were released within a week.
  • environmental_release: Approximately 275 pounds of anhydrous ammonia were released to the atmosphere.
  • facility_damage: Cuisine Solutions estimated the property damage, including loss of use, to be approximately $3 million.
  • operational_impact: One of the food production lines was shut down for approximately 16 days, and another production line was shut down for approximately 38 days.

Recommendations

  • recommendation_id: 2024-03-I-VA-R1
  • recipient: International Institute of All-Natural Refrigeration (IIAR)
  • status: Open – Awaiting Response or Evaluation/Approval of Response
  • summary: Update ANSI/IIAR 2 to include guidance for preventing or mitigating liquid or two-phase atmospheric discharges from emergency pressure relief systems, such as the guidance in API Standard 521, Pressure-relieving and Depressuring Systems. At a minimum, the guidance should: a. Identify at-risk scenarios such as horizontal surge vessels and other vessels containing saturated liquid with little vapor space; b. Address design considerations and controls to reduce the likelihood of identified scenarios leading to overpressure or equipment failure and ensure vapor-liquid disengagement (the separation of vapor from liquid) during pressure relief for identified scenarios; and c. Require mitigative safeguards in cases where vapor-liquid disengagement during pressure relief cannot be reliably ensured. This should also include alternative disposal systems where applicable.
  • recommendation_id: 2024-03-I-VA-R2
  • recipient: International Institute of All-Natural Refrigeration (IIAR)
  • status: Open – Awaiting Response or Evaluation/Approval of Response
  • summary: Update ANSI/IIAR 2 to include a requirement to assess whether emergency pressure relief devices discharge to a safe location, such as with a dispersion analysis.
  • recommendation_id: 2024-03-I-VA-R3
  • recipient: Cuisine Solutions, Inc., Sterling Site
  • status: Open – Awaiting Response or Evaluation/Approval of Response
  • summary: Reduce the likelihood or mitigate the consequences of liquid or two-phase atmospheric discharges from the ammonia refrigeration emergency pressure relief system at the Sterling plant. At a minimum: a. Identify liquid or two-phase release scenarios, particularly for horizontal surge drums and other vessels containing saturated liquid with little vapor space; b. Implement engineering controls to reduce the likelihood of high liquid level, overfill, or boiling overpressure scenarios; c. Implement engineering controls to mitigate the consequences of these scenarios where their likelihood cannot be acceptably reduced, such as through emergency pressure control systems, atmospheric knockout drums, or automatic shutdown systems; and d. Contract a competent third party to audit the pressure relief systems. The audit should ensure that (i) all relevant relief scenarios have been identified, (ii) preventive and mitigative engineering controls adequately address the hazards, and (iii) engineering controls are maintained in such a way that they function properly when required.
  • recommendation_id: 2024-03-I-VA-R4
  • recipient: Cuisine Solutions, Inc., Sterling Site
  • status: Open – Awaiting Response or Evaluation/Approval of Response
  • summary: Implement an electronic process data historian and management system to ensure that critical process parameters are collected, tracked, and stored. The system should be available to refrigeration technicians so that they can monitor the refrigeration system and respond to and investigate process upsets.
  • recommendation_id: 2024-03-I-VA-R5
  • recipient: Cuisine Solutions, Inc., Sterling Site
  • status: Open – Awaiting Response or Evaluation/Approval of Response
  • summary: Update the Cuisine Solutions Sterling site’s Emergency Action Plan using guidance such as the IIAR’s Critical Task Guidance for Ammonia Refrigeration System Emergency Planning. At a minimum, the updated plan should address indoor and outdoor ammonia releases separately, including the distinct alarms and responses to them; clearly specify appropriate evacuation routes and muster points, including alternates; provide guidance for using windsocks to remain upwind of a release during evacuation; implement shelter-in-place strategies, emergency protective equipment, and emergency shutdowns, as appropriate; and include requirements to conduct annual ammonia release drills that include all onsite personnel (including corporate employees). The annual drills should include separate indoor and outdoor ammonia release scenarios and address the use of windsocks to assist with determining evacuation routes, alternate evacuation routes, muster points, and consideration for the decision to shelter-in-place. Additionally, the drills should exercise each evacuation alarm, emergency protective equipment, and emergency shutdowns, where appropriate.
  • recommendation_id: 2024-03-I-VA-R6
  • recipient: Cuisine Solutions, Inc., Sterling Site
  • status: Open – Awaiting Response or Evaluation/Approval of Response
  • summary: Add an alarm or alarms specific to ammonia releases, so that workers can properly respond to a release. The alarm response should be documented in the updated Emergency Action Plan, and may include multiple distinct alarms and responses, such as one for shelter-in-place and one for evacuation.

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