Emergency Declared for Calcasieu Parish Salt Cavern Operation Near Sulphur Mines Due to Concerns about Stability

By Zephyr Sullivan
Published September 20, 2023

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Louisiana Governor John Bel Edwards and Louisiana Commissioner of Conservation Monique M. Edwards have recently taken urgent action by declaring a state of emergency. This decision was made due to concerns about the future stability of a salt cavern located on the western side of the Sulphur Mines Salt Dome in Calcasieu Parish.

Despite the absence of any immediate signs of collapse or major surface impact, the Governor and Commissioner Edwards (no relation) have invoked their emergency powers to quickly bring in experts and resources. The aim is to gain a deeper understanding of the current situation underground and to assess the potential risks that could affect the stability of other caverns in the surrounding area.

This proactive approach highlights the importance of preparedness and the need for swift action to minimize any adverse impacts that may arise. The safety and well-being of the public remains a top priority, and the authorities are working diligently to ensure that all necessary measures are taken to safeguard the community.

“Our Office of Conservation scientists and inspectors are telling us they are seeing significant early warning signs of a potential subsurface problem on the Sulphur Mines Salt Dome. I want them to have access to every tool available to best understand what is going on in and around these caverns and map out the best response to ensure protection of our people and the environment,” Governor Edwards said.

Louisiana Governor Edwards has enacted Executive Order 160. This grants permission to the head of the Governor’s Office of Homeland Security and Emergency Preparedness (GOHSEP) to carry out any legally authorized actions concerning the declared emergency. The order also instructs all state departments to provide necessary assistance.

The main concern of the Office of Conservation (OOC) relates to the PPG-7 brine cavern, operated by Westlake US 2 LLC, found on the salt dome’s western side. The central issue is the PPG-7 cavern’s inability to sustain steady pressure without continuously pumping salt water into it. Several locations on the salt dome’s central and western areas have been documented by OOC staff, where natural gas is surging to the surface in water bodies and nearby wellheads. Moreover, at least one oil leak has been identified, and initial evidence of potential rapid downward motion from area monitoring. The neighboring PPG-6 cavern, which Westlake also operates, is being closely tracked due to its closeness to PPG-7.

“Nothing we are seeing out there indicates we are past the point of no return on the structural integrity of these caverns yet. I am hopeful our established requirements for monitoring and reporting by cavern operators are giving us time to apply the best science available to understand what is developing underground and mitigate future impacts,” Commissioner Edwards said.

Commissioner Edwards has reported that her team has investigated numerous issues with salt caverns of similar age to the PPG-7 caverns. While these issues could be considered routine, the recent combination of gas seepage and pressure concerns along with an acceleration in subsidence has prompted the declaration of an emergency. The commissioner has emphasized that the primary concern is the threat of subsidence and its potential impact on groundwater in the area. As a result, the commissioner’s office will exercise emergency authority, including hiring contractors and experts, to respond to the threat.

“We know this situation will bring back memories of Bayou Corne in 2012, but we have some advantages the state did not have then,” Commissioner Edwards said. “We have learned lessons from that and our regulations have evolved, giving us better tools for detecting potential issues earlier and understanding the expertise we need to draw upon. In this case, we have seen some markers that are similar to what was seen then, but nowhere near as severe. We also still have direct access to the caverns we are concerned with.”

The Injection and Mining Division (IMD) of OOC is presently supervising the response, liaising as necessary with the GOHSEP, Louisiana Oil Spill Coordinators Office, the state Department of Environmental Quality, the state Department of Health, and the U.S. EPA Region 6 office.

The two caves of worry, PPG-6, and PPG-7, were initially bored as brine extraction wells to provide salt water for petroleum chemical procedures in the middle of the 1950s. This was long before the initiation of the state’s Underground Injection Control (UIC) program run by the OOC.

In 1979, the caverns were seized by the U.S. Department of Energy for the use of Strategic Petroleum Reserve (SPR) oil storage. This continued until the mid-1990s when ownership of the caverns was handed back to the private sector, to the company PPG Industries. This company was the predecessor for what we know today as Westlake Chemical. Both PPG-6 and PPG-7 stopped their brine mining operations by 2014, and ever since, both caverns have been unused and inactive.

The ongoing monitoring required by OOC regulations flagged an irregular pressure reading in December 2021 in the caverns located on the Sulphur Mines Salt Dome. Further insights revealed that particular attention needed to be directed towards PPG-6 and PPG-7, especially PPG-7. As investigations prolonged into 2022, problems were discovered concerning PPG-7’s pressure retention capabilities. This eventually led to the cave failing the Mechanical Integrity Test (MIT) in 2022, despite its clearance on a similar test in 2021.

Ongoing observations revealed PPG-7’s failure to maintain pressure independently, prompting Westlake to inject brine into the cavern to sustain the necessary pressure. In the latter part of 2022 and throughout 2023, operators and OOC staff noticed spots where natural gas was bubbling and oil was seeping over and surrounding the dome. These observations, along with those from subsidence monitoring, resulted in OOC Governor Edwards issuing emergency declarations.

“At this point, we are monitoring internal pressure of these caverns and other caverns across the salt dome, seismic activity in the area, subsidence above the salt dome and the extent of natural gas bubbling and potential impacts to nearby groundwater,” Commissioner Edwards said. “Next steps include bringing in additional expertise to better understand the potential for structural failure, the impacts of that and what we can do to mitigate or minimize threats to people and the environment.”