Keller completed all drilled shaft construction in less than 30 calendar days.
A section of the Leo Frigo Bridge that spans the Fox River sank two feet unexpectedly. Keller was chosen to reinforce the bridge foundations with drilled shafts.
In order to keep to a tight deadline, three drill rigs worked 24 hours per day, 7 days per week. Excavations had to be made through 120 feet of clay, sand, and gravel under polymer slurry support.
Keller constructed 20 drilled shafts with 5 foot diameters drilled to depths of 125 feet with 7 foot deep rock sockets into 40,000psi limestone. Down hole hammers assisted in removing the rock. Final drilled shaft construction included full length reinforcing cages, which were spliced over the hole due to limited headroom. 5,000psi concrete was placed using tremie methods.