CO2 pipeline incident due to landslide

"On February 22, 2020, a carbon dioxide (CO2) pipeline ruptured in proximity to the community of Satartia, Mississippi. The rupture followed heavy rains that resulted in a landslide, creating excessive axial strain on a pipeline weld.
• Carbon dioxide is considered minimally toxic by inhalation and is classified as an asphyxiant,
displacing the oxygen in air. Symptoms of CO2 exposure may include headache and drowsiness.
Individuals exposed to higher concentrations may experience rapid breathing, confusion,
increased cardiac output, elevated blood pressure, and increased arrhythmias. Extreme CO2
concentrations can lead to death by asphyxiation.
• When CO2 in a super-critical phase (which is common for CO2 pipelines) releases into open air, it
naturally vaporizes into a heavier than air gas and dissipates. During the February 22 event,
atmospheric conditions and unique topographical features of the accident site significantly
delayed dissipation of the heavier-than-air vapor cloud. Pipeline operators are required to
establish atmospheric models to prepare for emergencies

• Local emergency responders were not informed of the rupture and the nature of the
unique safety risks of the CO2 pipeline. As a result, responders had to guess the nature of the risk,
in part making assumptions based on reports of a “green gas” and “rotten egg smell” and had to
contemplate appropriate mitigative actions. Fortunately, responders decided to quickly isolate
the affected area by shutting down local highways and evacuating people in proximity to the
release. No fatalities were reported.
• This event demonstrated the need for:
o Pipeline company awareness and mitigation efforts directed at addressing integrity
threats due to changing climate, geohazards, and soil stability issues.
o Improved public engagement efforts to ensure public and emergency responder
awareness of nearby CO2 pipeline and pipeline facilities and what to do if a CO2 release
occurs. This is especially important for communities in low-lying areas, with certain
topographical features such as rivers and valleys". 

Source: https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2022-05/Failure%20Investigation%20Report%20-%20Denbury%20Gulf%20Coast%20Pipeline.pdf