Salt & Water: The hidden geological infrastructure of two basins

Natalya Egon (MArch I)

Project Overview

This research stemmed from an interest in the combined natural world of geology, science, and landscape infrastructures. The unique geological and transformative qualities of the Mississippi Delta have failed to reach a static end; there is continuous growth, decay, evolution, reduction, and augmentation. The challenging nature that this presents to humans as manipulators of our environment has required a continuous persistence of mankind in terms of engineering, survival, production, and transportation.

Southern Louisiana is home to one of the most diverse, forceful, and rich geological landscapes in the world. The coexistence of the constantly shifting Mississippi River Delta and the resource-rich Louann Salt Basin beneath has formed an intricate landscape of industry, distribution, navigation, and inhabitation. This site supports the underground storage of a vast petrochemical industry, explorative drilling and mining, and a complex aboveground network necessary to move people and products. The following is a documentation of these overlapping infrastructures, both natural and man-made, and searches for an answer to the ecological and spatial problem of geological infrastructures as uninhabitable or undesirable in the landscape. The morphing landscape and the industries that inhabit it, while problematic to many academics, are currently essential to the local and national population. Even major changes in national energy policies will not make these sites obsolete. This research explores the future of such a landscape by documenting the current state, a mere blip in the ever-changing form of the delta.

Project Information

The Louann Salt Basin and the Mississippi River Basin overlap and converge at the Gulf Coast, a landscape of flux, physically and culturally. The relatively slow and steady evolution of the salt basin over millions of years is drastically contrasted with the rushed and dramatic shifts that are characteristic of the river above. These elements (sedimentary salt and moving water) create a unique environment of highly static but incredibly malleable geological phenomenon. This malleability allows for the elastic creation of man-made sites such as petroleum reserve storage, radioactive waste storage, and other petrochemical processes, yet is stable enough to naturally maintain these sites with minimal catastrophic shifts or change.

The relationship that exists between the solid (salt) and liquid (water) is one of contrasts: underground versus aboveground, gradual vertical movement versus rapid horizontal movement, and limited versus limitless. This project aims to address these contrasts and the questions that accompany them: How is the natural and static underground infrastructure utilized to serve the shifting landscape above? What happens infrastructurally to a landscape that is consistently moving at the surface yet economically reliant on the stability and existence of what is below? In searching for the existing infrastructural relationships between the physical characteristics of the landscape and the manmade interventions, this project will explore the utilization of natural geological phenomenon and how they might be used in the future to create innovative, productive, and inhabitable landscapes.

The Mississippi River is a major geological force. The river basin is a massive drainage system for 32 states and 2 Canadian provinces. The river itself, split into the Upper and Lower Mississippi, begins in northern Minnesota at Lake Itasca and terminates in the Gulf of Mexico, southeast of New Orleans. The enormous volume and high velocity of the river itself has shaped and morphed the landscape tremendously, especially along the Lower Mississippi River. From the starting point at Cairo, IL the Lower Mississippi River originally flowed over 1100 miles into the Gulf, despite the fact that the actual distance from Cairo to the Gulf is about 600 miles. This was due to the many curves that the river continually made for itself in the relatively flat earth.

However, this distance constantly fluctuated as this forceful river was prone to create new curves or cut off old ones at any given time. The river also used to flood hundreds of miles of the floodplain at regular intervals; upon discovery by Hernando de Soto’s expedition in 1543 they saw such a flood which was described by the Indians as occurring every fourteen years. Even the delta itself, the site of this project, is a mobile delta. The delta has had at least five other locations before the current location south of New Orleans.

The Mississippi River is a landbuilder. It has actually built much of it’s own basin by depositing sediment into the original embayment that used to reach from the sea all the way up to Missouri. These sedimentary deposits, along with the rise in sea level over millions of years, eventually filled in the embayment and built up the land that exists today. Southern Louisiana would not exist if the river had not been free to flow and deposit sediment in any direction it wished.

This major geological force was problematic as land became valuable in the United States; boundaries became completely impermanent due to the always shifting river. For example, state lines used to be determined by the location of the river and if the river cut itself off overnight (which could and did occur) a farmer might find his farm to be in a different state in the morning. If this occurred in the early 1800s, a slave in Tennessee could wake up in Illinois the next morning and be a free man. Islands in the river could move or disappear altogether, plantations that were built along the river could lose their water supply, and others could gain waterfront property without moving. These economic swings were exacerbated by those who recognized the value of the changes in the river. Small ditches could be dug overnight between two bends and the river would begin to favor the new and illegal canal by morning.

As the development of industry, mobility, and urbanity grew along the river with first the steamboat and later the railroads (and thus bridges), the government was pressured to control the shifting of the river. While the engineering of the river began in the 1800s with the proposal and use of levees, jetties, and spillways, the flood of 1927 particularly pushed the Army Corps of Engineers to fully control the volume, velocity, and location of the river. The river actually makes natural levees for itself over time, but they were not high enough to control the inevitable floods. Therefore, the Army Corps of Engineers has spent the past century building and monitoring different methods of infrastructural control of the Mississippi River Basin.

The river no longer overflows every fourteen years or cuts itself off, yet is still part of a massive national system of water. The Army Corps of Engineers has prevented major contemporary shifts but has not been able to predict or prevent all of the natural tendencies of the river. The floods of 1937, 1945, 1973, 1983, and 1993 are proof of that, as are the effects of Hurricane Katrina.

The earth that the river flows over contrasts greatly to the earth that lies below. The land itself is soft; there is “no terra firma” thus the river cuts easily through the sedimentary soil. The river deposited this soil during the Pleistocene period (2 to 0.1 million years ago) while the basin structure below was deposited during the Jurassic period (208 to 144 million years ago). This salt basin resulted from the breaking up of Pangaea; a depression formed between North and South America where seawater gathered and then dried up over time. Sediment was deposited on top of the salt basin by the Mississippi River and other ancient rivers.

The Louann Salt Basin lies 20,000 to 50,000 feet below ground and is the origin of numerous salt domes. Since the density of salt is lower than that of sedimentary soil and rock, it actually rises over time under the pressure of the surrounding rock. Underground, salt is not actually hard and brittle but quite malleable due to the heat that it naturally conducts and the intense pressure surrounding it. The dynamics of salt allow it to form pillars underground that reach towards the surface as capped salt domes.

It is possible to see the evidence of salt domes at certain locations of the Gulf Coast; collapse basins form particularly around a salt dome or cluster of salt domes. Mounds or depressions in the landscape can form, which stand out in the relatively flat landscape of southern Louisiana.

Infrastructurally, salt domes are important in that they are made up of impervious material, conduct heat naturally, and can be carved out relatively easily using water. While some salt domes are naturally hollowed out, industrial companies have created methods to pump water down into the dome, dissolve the interior salt into a brine, and pump out the brine, leaving a massive cavern. This brine can be used in chemical processes and the cavern can be used to store hazardous or sensitive materials. Sulfur can also be extracted from the salt dome caps using steam.

The United States uses Gulf Coast salt domes to store over 729 million barrels of oil as part of the Strategic Petroleum Reserve program. Distributed over 4 sites and 22 salt domes in Texas and Louisiana, the caverns have no risk of leaking (they are simply surrounded by more salt), they naturally churn the oil as it conducts heat, and are hidden neatly underground. For the same reasons that oil is safely stored underground, salt domes are also the sites of radioactive, hazardous, and waste material storage.

The underground structure of the Louann Salt Basin and the aboveground dynamics of the Mississippi River Basin, converging at the Gulf, are related to each other infrastructurally. Salt domes in the delta are hollowed out with water from the river (or from lakes and other rivers that the river feeds); the DOE proposed using water from the Pascagoula River for salt dome construction to bring the national SPR up to one billion barrels. The process would have diverted fifty million gallons of water a day for five years from the river and piped the resulting brine out into the Gulf.

Aside from the use of water for salt dome infrastructure, the Mississippi River provides much of the industrial transport in the delta. Salt domes in the area, particularly the Venice Salt Dome, are sites of oil extraction and only accessible from New Orleans and refining centers via arteries of the delta. Extracted petrochemical products from salt dome sites are reliant on the network of the river.

This accumulation of geological and industrial processes, visible and invisible networks, and shifting landscapes above and below ground in the Louann Salt Basin and Mississippi River Basin creates a dynamic narrative in the cultural, economic, and environmental landscape. By documenting and analyzing existing conditions this project allows for the synthesis of new narratives of a changing landscape. In describing the soft landscape that makes up the delta, Joan Busquets posits that “the relations between river, sea, wind, and vegetation explain the natural processes to which the intervention of humankind must be added.” But to those natural processes must be added the natural structural development of the land itself and how humankind intervenes at that level as well. It is important to view these overlapping networks of extraction sites, transport, and infrastructural developments that exist along both as a negotiation between the natural landscape and the man-made environment. By documenting them together it will be possible to evaluate the future of infrastructure in the geological landscape.

In executing my research, I visited, photographed, and filmed my observations from a few different vantage points. Most discoveries and examinations were made by driving throughout the landscape – I rented an SUV that allowed me to take gravel and muddy roads to places rarely traveled by the public. This vehicle also permitted unquestioned access to some sites that are not explicitly private, but are not necessarily intended to be seen by the public: places where only trucks and sports utility vehicles frequented. What I also discovered was that having a slightly higher viewpoint than a typical automobile was extremely beneficial; I could see just a bit further into the bayous, waterways, and marshes.

I drove to the Mississippi River Model near Jackson, MS on a rainy day; I encountered no one and was given free reign over the site. I was able to walk the thousands of miles of the river in a scaled down version on the 200 acre site and visit the multiple trailers that once tested the levees, gathered data, and influenced the decisions of the Army Corps of Engineers.

The Bonne Carre Spillway was a detour made last minute in order to observe the how engineering efforts alter a given landscape. This flood control operation allows floodwaters from the Mississippi River to empty into Lake Pontchartrain before arriving at New Orleans. When the gates are closed, however, the spillway is open to the public for hunting, fishing, boating, and hiking from 5:00 in the morning to 10:00 at night. This unexpected setting provided an intimate and telling look at the convergence of the river, industry, and recreation. It was here where I first learned that recreational sport in the Louisiana landscape often and usually takes place within view of petroleum infrastructure if you desire to drive. The road infrastructure primarily laid down for tankers and workers serves the public second.

Shifting my observations from the Mississippi River to the Gulf of Mexico, I met with a member of the Gulf Restoration Network, who recommended certain places at the “end” of the river or bayou to explore over a series of days. The clarity and relative ease of following a river road or crossing bridges suddenly became blurred with the realization that there is no one edge or boundary to pinpoint as a destination for my SUV to drive to, though the local knowledge I gained from my contact helped immensely. The truth is that the edge of Louisiana is not an edge at all; the land breaks up slowly and there is no way to navigate or explore it in an automobile unless you take one of the few well-constructed roads that have been built and maintained.

Visiting Grand Isle, LA and Venice, LA certainly reinforced the notion of edgelessness in the vastly networked landscape. I filmed both of the drives, each which took around 2 hours from New Orleans, in different directions. The horizon rarely changes in these short films, becoming the dominant characteristic of the landscape. It is truly a flat place; it is vulnerable to change because of this flatness and the embedded forces. Both drives eventually became elevated or surrounded by bayous. However, at Grand Isle the road ends at the start of the Gulf of Mexico, while in Venice there is only more bayou, marsh, and oil infrastructure to see.

The drive to Venice in particular was a startling experience, mostly because I had been studying the site quite closely through maps and Google Earth prior to my visit. The aerial of the site, next to the salt dome, is an incredible image. But once physically there, at the edge of the salt dome, there is nothing to see but the line of the horizon and marsh grasses; nothing to hear but the drone of nearby refineries and helicopters in the distance.

These drives were then supplemented with a flight over the Mississippi Delta. I was able to ride along in an investigative flight run by a nonprofit (SouthWings) that specializes in conservation; the purpose of the flight was to locate an existing oil spill and to see if there were any new ones in the delta (incidentally, we did find two unreported spills stemming from underwater pipelines). This proved to be an important part of the trip, allowing an oblique view of the delta that maps and Google Earth cannot replicate. I gained a better understanding of the delta, it’s natural and manmade networks, and the role of mankind in those two hours than I ever could have on the ground or on a computer.

The immense scale of the blurred “coast” of Louisiana became more apparent once in the air. Canals crisscross and reach out far into the bayous and lead out into the Gulf; unseen platforms miles away are their destinations. While the river has made its own winding and organic outlets that bring silt and water into the Gulf, these canals are abnormally straight and reveal the existence of a crude oil pipeline below. They represent something other than the political and environmental controversy often associated with offshore drilling. Rather, these canals are essentially channels of water that offer direct views to a horizon that was previously not visible to those on the ground or in the water. Of course, these canals can continue for miles so perhaps the Gulf is too far off to see, but their existence as manmade waterways for the efficiency of pipelines is a marker of a guaranteed exit or entrance to the delta.

By traveling the multiple coasts of Louisiana (the river, bayous, marshes, and finally the Gulf ) at different speeds, scales, and perspectives I was able to fully observe how the delta is truly a multilayered condition. The delicate and vulnerable existence of the Mississippi Delta is countered by the insistence of man to inhabit and utilize such a unique landscape in static ways. Regardless of the success or failure of these attempts the tendency to remain edgeless will always dominate the landscape. The fact that this edgelessness implies that there is no visible “end” to the delta is an important one; it establishes a place that can be interpreted as either the end or the beginning of something else.

Natalya Egon


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