Like everyone else, I am affected by the crippling rise in prices of fossil fuels. It’s not just the cost of a tankful of gasoline that hurts; natural gas that many of us use for heating, hot water and cooking now costs double what it did just a few years ago. For that reason, I am glad to see any industry efforts to stabilize or reduce prices.  

AGL Resources currently stores natural gas in deep salt caverns beneath Lake Peigneur and provides it when demand is highest. There has been vocal opposition to AGL Resources and their plans to extend their operations.

I have extensive experience as a consultant on salt dome geology and the company asked me last year to evaluate the geological aspects of arguments being presented against the project. I reviewed a recording of a hearing before the state Legislature and have also watched a propaganda video compiled by the opposition group. A consistent theme is an emotional, rather than scientifically sound, appeal to the audience. The dimensions of the existing caverns are compared, for example, to the World Trade Center, rather than the Empire State Building or the Sears Tower. Not very subtle!

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Most of the serious concerns of local residents are related to periodic bubbling and foaming seen at the lake in recent years. The fear is that this is caused by gas escaping from the storage caverns. When it is pointed out that the bubbling occurs over the flooded mine rather than over the storage caverns, complicated scenarios are presented to explain how gas could be escaping from the caverns through weak zones in the salt into the old mine before rising to the surface.

This is where my own experiences make me most critical of the arguments. I co-authored a technical paper some years ago in which I and Dr. Don Kupfer — the authority quoted most often by the opposition group — corrected the misused terminology concerning anomalous areas in salt encountered during underground mining. These anomalous areas or zones were being referred to as “shear zones,” which suggests cracks and fractures. In fact, these zones are composed of salt which commonly is harder to mine than normal salt. Rock salt has the property of quickly healing any fractures and indeed of closing in mine openings and drill holes at a surprising rate. This is why salt is essentially impermeable and is so highly regarded as a repository. No other common rock type is so well suited for this purpose, particularly in the form of domes, like the Gulf Coast occurrences.

So what is the cause of the bubbling at Lake Peigneur? The strongest clue is the association with the collapsed salt mine. At the time of the accident in 1980, I predicted that additional ground movements and salt dissolution could be expected for decades. Undoubtedly, pockets of air were trapped at the time and some of these may now be being released.

Additionally, some quantities of natural gas occur within salt and further dissolution by lake waters in the mine may be releasing small gas pockets. If the bubbles were of gas from the deep storage caverns, a steady stream would be expected, not the intermittent bubbling actually observed, and a loss of pressure in the storage units would be measured.

I could write at much greater length about the numerous natural disasters listed by the opposition group in their propaganda, but it is sufficient to say that none of their examples is appropriate to the deep storage caverns at Lake Peigneur. I am only surprised that they did not include the Great Chicago Fire of 1871. Their arguments are based on emotion and lack geological credibility.

Brian Lock holds a Ph.D. in geology from the University of Cambridge (United Kingdom). He is the author of numerous technical articles, including a book on the history and geology of South Louisiana salt mining available through the Louisiana Geological Survey. He has consulted extensively on salt dome geology.

EDITOR’S NOTE:

The following is a guest editorial written by Brian Lock, who over the last two years has provided technical expertise to the AGL on several occasions by reviewing reports and other documents related to salt domes.