Hydrogen Sulfide (H₂S)

Hydrogen sulfide (H₂S) is a colorless, flammable, and highly toxic gas commonly encountered in hydrocarbon production across the Permian Basin. It is naturally present in crude oil and natural gas and can be released during drilling, production, and processing activities. Even at low concentrations, H₂S poses serious health and safety risks to workers and the public.

According to the Occupational Safety and Health Administration (OSHA), exposure to H₂S can cause a range of health effects depending on concentration and duration. Symptoms may include eye irritation, nausea, headaches, and respiratory discomfort. At higher concentrations, exposure can lead to unconsciousness, respiratory failure, and even sudden death. Because of its toxicity and potential for rapid dispersion, H₂S is considered a critical safety concern in oil and gas operations.

When Must Operators Have an H₂S Contingency Plan in Place?

Within the Permian Basin, both New Mexico and Texas have specific regulatory thresholds that trigger the requirement for an H₂S contingency plan. These thresholds are designed to protect not only oilfield personnel but also the general public and emergency responders who may be affected by an accidental release.

In general, any operator—whether upstream, midstream, or downstream—who anticipates handling H₂S at a concentration of 100 parts per million (ppm) or greater must calculate the radius of exposure (ROE). This calculation is based on the Pasquill-Gifford dispersion model and considers both the concentration and the escape rate of H₂S from the facility.

In both Texas and New Mexico, an H₂S contingency plan is required if:

• The 100 ppm ROE intersects a public area.
• The 100 ppm ROE is equal to or greater than 3,000 feet.
• The 500 ppm ROE intersects a public road.

Key Definitions

• Public Area: A building or structure not associated with the well, facility, or operations for which the radius is being calculated, and used as a dwelling, office, business, church, school, hospital, government building, or any location generally accessible by the public.
• Public Road: Any state, federal, municipal, or county road or highway.

Regulatory Drivers

In New Mexico, H₂S contingency plans are governed by the New Mexico Oil Conservation Division (NMOCD) and codified under 19.15.11 NMAC. In Texas, the Railroad Commission (RRC) enforces similar requirements under Statewide Rule 36 (SWR 36). Both rules aim to mitigate the risks associated with H₂S exposure and ensure that operators are prepared to respond effectively to emergency situations.

These regulations are not merely administrative—they are rooted in public safety. The presence of H₂S near populated areas, public roads, or sensitive infrastructure demands a proactive approach to risk management. Contingency plans serve as a blueprint for emergency response, helping operators coordinate with local authorities, inform the public, and deploy protective measures quickly.

General Plan Requirements

While New Mexico and Texas each have unique regulatory frameworks, their H₂S contingency plan requirements share many common elements. Both states align their expectations with the American Petroleum Institute’s Recommended Practice 55 (API RP 55), which provides industry-standard guidance for managing H₂S in oil and gas operations.

Key components of a compliant H₂S contingency plan include:

• Emergency procedures: Detailed steps for responding to an H₂S release, including activation of alarms, shutdown protocols, and deployment of safety equipment.
• Detection and monitoring systems: Specifications for gas detection equipment, alarm thresholds, and maintenance schedules.
• Chemical characteristics and health hazards: Information on the properties of H₂S and sulfur dioxide (SO₂), which is released during some H₂S control measures, including exposure limits and physiological effects.
• Facility maps: Visual representations of the site, including evacuation routes, exposure zones, public impact areas, and nearby infrastructure.
• Training and drills: Documentation of employee training programs, emergency drills, and public outreach efforts, including shelter-in-place and evacuation procedures.
• Coordination with emergency responders: Plans should include communication protocols with local fire departments, law enforcement, and Local Emergency Planning Committees (LEPCs).

Operators are also encouraged to maintain records of ROE calculations, safety audits, and plan updates to demonstrate ongoing compliance and preparedness.

Conclusion

If your operations involve—or are likely to involve—H₂S concentrations at or above regulatory thresholds, Trinity Consultants can help you assess your obligations and develop a compliant, site-specific contingency plan. Our team has deep experience navigating both NMOCD and RRC requirements and can support your efforts to maintain regulatory compliance and a strong safety culture.

Securing an H₂S contingency plan not only helps you meet legal requirements—it also demonstrates your commitment to protecting your workforce, your community, and your assets. Whether you’re planning a new facility or updating an existing plan, Trinity Consultants is ready to assist.

For any questions surrounding H₂S contingency plans, please contact Trinity Consultants’ Albuquerque office at 505.266.6611 or email Oliver Seekins.