Riverton WY Electrical Substation, Drilled Shafts - 58, Length - up to 25 ft., Diameter - 30 in. to 78 in.
Soilmec R-312/200, Great Dane Slurry Trailer
General Contractor and Owner:
Intermountain Electric Service, Inc., Pacificorp, Rocky Mountain Power
This project presented difficult conditions including caving sands and rock. As you can see in one picture, the large bolt pattern precluded the use of temporary casing that would interfere with the stability of the bolts as the casing was extracted.
Slurry displacement was the method of choice. The polymer slurry displaces the excavated cutting and balances the ground water pressure so that the drilled shaft maintains its arc circumference and does not create voids from caving or infiltration of the concrete mix design. One picture shows the tremmie pour method while the slurry is pumped out to the slurry trailer where it is filtered and reused.
Ludwig Drilling worked closely with the power company to coordinate power outages and moving of overhead lines.