CSB Releases Final Investigation Report on Fatal Hydrogen Sulfide Release at Aghorn Waterflood Station

U.S. Chemical Safety and Hazard Investigation Board (CSB), May 25, 2021

The US Chemical Safety Board (CSB) has released its final investigation report into the October 26, 2019 hydrogen sulfide (H2S) release that fatally injured two people at the Aghorn Operating, Inc. (Aghorn) waterflood station in Odessa, Texas. The waterflood station receives produced water, a by-product of oil extraction in the area, from approximately 68 crude oil wells in the Foster Field of the Permian Basin. The station is used to inject produced water back into the oil-bearing formation to improve the extraction of oil from underground oil reservoirs. On the night of the incident, one of the two pumpers responsible for operating, inspecting, and maintaining the site's equipment was alerted of a pump malfunction. At some point after entering the pump house to investigate, he was overcome by toxic H2S and fatally injured. Later that evening, the pumper's spouse, worried that she had not heard from her husband for several hours, drove to the waterflood station to locate him where she too was overcome by toxic H2S and fatally injured.

The CSB's final investigation report identifies six serious safety issues that led to the deadly incident:

  1. Nonuse of Personal H2S Detector. The pumper fatally injured in the release was not wearing his personal H2S detection device the night of the incident, and there is no evidence that Aghorn management required the use of these devices.
  2. Nonperformance of Lockout / Tagout. At the time of the incident, Aghorn did not have any well-documented
    Lockout / Tagout policies or procedures. The pumper fatally injured did not perform Lockout / Tagout to deenergize Pump #1 before performing work on it, and the automatic activation of the pump allowed water containing H2S to release from the pump.
  3. Confinement of H2S Inside Pump House. The pump house ventilation methods did not adequately ventilate the toxic H2S gas from the building during the incident, contributing to the high H2S levels to which the two individuals fatally injured were exposed.
  4. Lack of Safety Management Program. Aghorn did not have adequate company safety or operational policies or procedures in place at the time of the incident.
  5. Nonfunctioning H2S Detection and Alarm System. The pump house was equipped with an H2S detection and alarm system. However, the H2S control panel did not receive signals from the internal and external detection sensors at the facility, and, therefore, did not trigger either of the two H2S alarms on the night of the incident.
  6. Deficient Site Security. As per Aghorn’s informal policy, when an Aghorn employee is working at the facility, the access gates are normally left unlocked. The unlocked gates allowed the pumper's spouse to drive directly to the waterflood station and enter the pump house, where she was exposed to toxic H2S gas and fatally injured.

To prevent future chemical incidents, and in the interest of driving chemical safety change to protect people and the environment, the CSB's final report provides safety recommendations to Aghorn Operating (and similar companies), the Occupational Safety and Health Administration (OSHA), and the Texas Railroad Commission. 

CSB Chairperson, Katherine Lemos, stated that "the recommendations that we issued (in this report) go a long way to set the example for how companies of all sizes should prioritize the safety of their workers, and what they need to do to demonstrate that. Meeting the minimum mark is essential. Going beyond this is a commitment to your employees."

"Safety management programs are a comprehensive approach to risks at any chemical facility, and we encourage all operators to embrace these principles and practices, whether this is mandated by any regulatory oversight authority," she added.

The CSB urges companies operating facilities that handle toxic chemicals to review the key lessons learned from this incident and implement the appropriate changes to better protect workers and the public.


About the CSB

The CSB is an independent, non-regulatory federal agency whose mission is to drive chemical safety change through independent investigations to protect people and the environment. The agency’s board members are appointed by the President and confirmed by the Senate. CSB investigations look into all aspects of chemical incidents, including physical causes such as equipment failure as well as inadequacies in regulations, industry standards, and safety management systems. For more information, contact Communications Manager Hillary Cohen at or by phone at (202) 446-8094.

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