The Jeffersonville North WWTP Expansion led to the discovery of an underground cave. SME led the project team in evaluation and risk assessment associated with construction over the cave. Using a gyroscope laser scanner, SME was able to justify the originally proposed foundation design without modification or increased costs.

The Jeffersonville North WWTP Expansion was launched to support the River Ridge Commerce Center area, which generates over $1 billion of economic value and supports over 18,200 jobs in southern Indiana. Construction on the Jeffersonville North WWTP was going steadily when a challenge emerged on the site intended for an oxidation ditch. The Lochmueller Group noticed warm vapor rising from a vertical shaft in limestone at the exposed cut subgrade, indicating a possible void of substantial size. SME was asked to conduct a geotechnical evaluation due to concerns regarding foundation support for the new oxidation ditch.

A GoPro camera was used to confirm that the vertical shaft led into a cave of unknown size and shape. SME used a gyroscope laser scanner, an innovative and unique solution, to map the cave’s structure and location. This particular gyroscope is typically utilized in the mining industry for evaluation of abandoned underground mines and not commonly used in geotechnical applications. Scanning from multiple entry points was necessary to image around obstructions.

SME then combined four scans obtained from different entry points/elevations into one cohesive model. Using the 3D map produced by the laser scanner, the project team determined that oxidation ditch could be constructed without relocating it or modifying the design.

Rather than jumping to problem solving, we were able to determine that designing or implementing another solution wasn’t necessary. Our study and input from the design team justified the original structure design, thereby preventing necessitating building the structure in a different location that would be more expensive to build at due to rock removal costs. This project not only met urgent water treatment needs for the Jeffersonville North WWTP Expansion but also facilitated continued economic expansion in the region. SME’s Insight for this project fills in more details on the story from the perspective of the engineers who mapped the cave.