River Bridge Casisson
- DFS was contacted by a contractor regarding a ongoing project in Rutland Vermont. The contractor needed to drill a foundation shaft for a bridge across the Otter Creek, but was encountering cobble and gravel mixed with clay that was unforseen in geotechnical reports.
- The contractor had originally attempted to drill with just water, but could not maintain hole integrity below the 20 feet of casing. The caisson was 8 feet in diameter and 135 feet deep.
- Built a slurry program based on the feedback from the driller.
- Mixed and added a high viscosity slurry to maintain head pressure and maintain hole integrity with groundwater and cobble.
- Drilled shaft was able to be accomplished and maintained to bedrock and rock coring was accomplished the last 30 feet of the caisson.