River Bridge Casisson

Rutland, Vermont

 

Challenges:

    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. 
     

Solutions:

  • 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.