Is it true that the whole of downtown Chattanooga was raised because it was a flood plain?

The story of downtown Chattanooga being raised is a complex one, with elements of truth and some lingering mystery. Here’s a breakdown based on the information available:

• The 1867 Flood:
  • Chattanooga experienced a devastating flood in 1867, causing widespread damage.¹ This event is a key part of the story.
  • The severity of the flooding prompted discussions about how to prevent future occurrences.
• Raising the Streets:
  • There’s evidence suggesting that efforts were made to raise the street level in parts of downtown Chattanooga.²
  • This was done to mitigate the impact of future floods.
  • However, the extent and exact methods of this raising are subjects of debate.
  • Lack of complete historical documentation contributes to the mystery.
• “Underground Chattanooga”:
  • The result of these efforts, and other city development, has led to what’s sometimes called “Underground Chattanooga,” where remnants of older street levels and building entrances can be found below the current surface.³
• TVA’s Role:
  • Later, the Tennessee Valley Authority (TVA) and the construction of dams, like the Chickamauga Dam, played a significant role in regulating the Tennessee River and reducing the risk of flooding.⁴

In essence, it’s accurate to say that:

• Flooding was a major problem in Chattanooga’s history.
• Efforts were made to raise street levels to address this.⁵
• This has created a historical layer beneath the modern city.

It’s important to note that the exact details of the street-raising project are still somewhat unclear, adding to the intrigue of Chattanooga’s history.

How Could that be? Who Approved it Without a Plan?

You’ve hit upon a key part of the mystery surrounding “Underground Chattanooga”: the lack of clear, formal documentation. This makes it difficult to definitively say who approved what, and how the work was precisely carried out. Here’s a deeper look at the factors contributing to this situation:

• The Nature of 19th-Century Urban Development:
  • In the mid-to-late 1800s, record-keeping wasn’t always as meticulous as it is today.
  • Urban development often occurred in a more piecemeal, reactive fashion, especially in response to emergencies like floods.
  • Therefore, a grand, comprehensively documented plan might not have existed.
• Community-Driven Efforts:
  • It’s likely that much of the work was driven by the community itself, with property owners and businesses taking initiative to protect their investments.
  • This could have involved a combination of:
    • Individual property owners raising their building foundations.
    • Local efforts to fill and raise street grades.
  • In such a scenario, formal city-wide approval might have been less structured.
• Evolution Over Time:
  • The raising of street levels likely occurred gradually over time, rather than in a single, massive project.
  • This incremental approach would have made it less likely to be recorded in a single, definitive document.
• The Difficulty of Tracing Historical Records:
  • Historical records can be lost, damaged, or simply become inaccessible over time.
  • This is particularly true for records from the 19th century.
• Alternative Explanations:
  • It is also worth noting that some historians point to the possibility that some of what is considered “raised streets” could also be attributed to normal city growth, and the changing of street grades that occurs over time in many cities, and the fact that basements were commonly built with access from street level.

In essence, the lack of a clear, formal plan reflects the realities of 19th-century urban development and the challenges of historical research. While the story of “Underground Chattanooga” may have some gaps in its documentation, the physical evidence in the city’s older buildings provides compelling support for the idea that significant changes did occur.

How Could the Structure Still Remain Without Planning?

The persistence of “Underground Chattanooga” despite the lack of formal planning can be attributed to a combination of factors, highlighting how urban development can occur through incremental, community-driven efforts:

• Gradual Accumulation:
  • The raising of street levels likely wasn’t a single, monolithic project. Instead, it probably happened over time, with various property owners and the city undertaking smaller-scale fill and grading projects.
  • This gradual accumulation of fill, rather than a planned, engineered elevation, explains why remnants exist without a master plan.
• Individual and Collective Action:
  • In the 19th century, especially during emergencies like floods, communities often took matters into their own hands.
  • Property owners, seeking to protect their investments, would have raised their building foundations or added fill around their properties.
  • This type of decentralized action can result in significant changes to the urban landscape, even without formal city-wide planning.
• The Nature of Fill Material:
  • The fill material used to raise street levels wasn’t necessarily engineered or uniform.
  • It likely consisted of whatever materials were readily available, such as dirt, foundry waste, and sawmill scraps.
  • This heterogeneous fill, while not ideal from an engineering standpoint, was sufficient to raise street levels and create the “underground” spaces we see today.
• Adaptation and Reuse:
  • As street levels rose, the original ground floors of buildings became basements.¹
  • In some cases, these spaces were adapted and reused, while in others, they were simply abandoned.
  • The fact that some of these spaces remain intact is a testament to the durability of the original building construction.
• The factor of normal city developement:
  • It is important to remember that cities are constantly being changed. Roads are repaved, and utilities are placed under ground. These constant changes will alter the levels of the ground over time. This is also a factor in the changes that can be seen in Chattanooga.

In essence, the “structure” of Underground Chattanooga is a product of cumulative actions and adaptations, rather than a single, planned project.

How Did New Structures Not Sink If They Did Not Understand the Foundations?

That’s an excellent question that gets to the heart of how construction practices have evolved. While it’s true that 19th-century foundation knowledge differed from modern engineering, builders of that era weren’t without their own understanding of structural stability. Here’s a breakdown of how they managed:

• Traditional Building Practices:
  • Even without precise engineering calculations, 19th-century builders possessed a wealth of practical knowledge passed down through generations.
  • They understood the importance of:
    • Using strong, durable materials like brick and stone.
    • Building on stable ground.
    • Creating foundations that distributed the weight of the structure.
• Foundation Types:
  • Common foundation types of the era included:
    • Stone foundations: These provided a solid base, especially when built on bedrock or stable soil.
    • Brick foundations: Brick was also used to create foundations, offering durability and strength.¹
    • These foundations although not as advanced as modern foundations, were sufficient for the buildings that were being constructed at that time.
• Soil Compaction:
  • While they might not have had modern soil compaction equipment, builders understood the importance of creating a firm base.
  • They would often compact the soil by hand or with simple tools.
• Experience and Observation:
  • Builders relied heavily on experience and observation.
  • They learned from past successes and failures, adapting their techniques as needed.
• Building Size:
  • It is important to remember that the buildings that were being built at that time, were generally much smaller than many modern buildings. Therefore, the requirements for foundations were less intense than what is required today.
• Adaptation:
  • As the city streets were raised, many of the original first floors of buildings became basements. In many cases, these buildings had already proven to be structurally sound. So the raising of the street level did not cause a need for new foundations to be placed under those structures.

In essence, while 19th-century foundation practices may seem rudimentary by today’s standards, they were effective enough to support the buildings of that era.

But Building Were Much Heavier Then

You’ve raised a very valid point. It’s true that many 19th-century buildings, particularly those built with masonry, were indeed very heavy. This is due to the extensive use of materials like:

• Brick:
  • Masonry buildings relied heavily on brick, which, while durable, is quite dense and heavy.
• Stone:
  • Stone was another common building material, and its weight contributed significantly to the overall mass of structures.
• Lack of Lightweight Alternatives:
  • Modern building materials like steel framing and lightweight concrete were not yet widely available. This meant that heavier materials were the primary choice.

Here’s how those heavy buildings were supported:

• Massive Foundations:
  • Builders compensated for the weight by constructing very robust foundations. These foundations were often made of stone or brick and were designed to distribute the load over a large area.
  • The sheer mass of these foundations helped to stabilize the buildings.
• Load-Bearing Walls:
  • 19th-century masonry buildings often relied on thick, load-bearing walls to support the weight of the structure. These walls transferred the load down to the foundations.
• Material Strength:
  • While the materials were heavy, they were also strong. Bricks and stones, when properly laid, can withstand significant compressive forces.
• Construction Techniques:
  • Craftsmanship played a crucial role. Skilled masons understood how to lay bricks and stones to create strong and stable walls.

Therefore, while 19th-century buildings were often heavier, they were also built with techniques and materials that could handle the load.

It’s important to recognize that:

• The evolution of building materials and techniques has allowed for the construction of much taller and more complex structures today.
• However, the enduring presence of 19th-century buildings is a testament to the skill and ingenuity of builders from that era.