Pensacola Culvert Stabilization

The Challenge

Soil loss threatened the integrity of this culvert.

A 3 cell drainage culvert, each cell being 7 foot by 7 foot in cross section, runs underneath Northpointe Boulevard in Pensacola. Flow of water through the culvert had caused soil washout at the downstream end.
Borings were taken inside the culvert and it was determined that a void up to 6 feet deep had been created, which extended approximately 25 feet inwards from the downstream end. This erosion passed behind 2 angled wing walls on the ends of the culvert, causing a failure of these walls. This led to concern that the culvert would begin to settle and cause the overhead road to collapse.

Key Facts

The Solution

Voids were filled with polyurethane.

Groundworks was chosen to fill the void and stabilize the culvert by installing polyurethane foam with a density of 4 pounds per cubic foot and a compressive strength greater than 8500 pounds per square foot.
Through boring measurements, it was determined that approximately 38 cubic yards of void would need to be filled to prevent the structure from failing. Polyurethane was first free sprayed at the end of the culvert, where the void was uncovered, to dam off the exposed area. Polyurethane was then injected using 5/8 inch diameter holes drilled through the structure’s bottom slabs.

The Impact

Structural integrity was restored.

Throughout the injection process, elevation was carefully monitored to ensure the slope of the culvert remained unchanged, preventing any impact to the flow rate of stormwater runoff. This level of control allowed Groundworks to stabilize the structure without altering its functionality.
The installation process successfully filled the void, restoring support to the culvert and preventing further soil loss. By addressing the erosion beneath and behind the structure, Groundworks effectively halted the progression of damage that had already compromised the wing walls.
With the void eliminated and the soils stabilized, the risk of culvert settlement and potential roadway collapse was mitigated. This solution preserved the drainage system and protected the roadway from potential failure, ensuring continued safety for surrounding infrastructure and the traveling public.