Keller was responsible for the excavation, survey, fabrication, and placement of reinforcing steel, handling/stockpiling of drill spoils, backfilling shafts poured below grade, CSL Testing of selected shafts, and concrete placement.
Vogtle Electric Generating Plant was planning to add two additional reactors, Units 3 and 4. They also needed to install two cooling towers, that were planned to be 550 feet tall and required drilled shaft foundations.
Excavation included drilling through a porous Utley zone (marine-type limestone).
Keller installed 28 drilled shafts with 48-inch diameters and 208 drilled shafts with 72-inch diameters for both towers. The lengths varied but were 100 feet long on average (some were installed up to 128 feet deep). The work included performing a load test program for the drilled shafts prior to production, this included four lateral load tests and four axial load tests.
The general installation procedure consisted of vibrating 78-inch diameter temporary casing, up to 70 feet in length, and excavating the remainder of the shaft under polymer slurry.