SOLVED

The tunnel construction work consisted of 2,435 linear feet of 78-inch diameter pipeline, installed by Two-Pass Tunneling Techniques. The tunnel ranged in depth from twenty to eighty feet below the ground surface. The excavation of the tunnel was performed using a Lovato TBM that was 10’-2” in Diameter and required Rib & Lagging ground support directly behind the TBM. Excavation removal was conducted using muck boxes and a crane for hoisting. The final lining was 78-inch diameter Reinforced Concrete Pipe that crossed under local City of St Joseph roads, the BNSF railway, and Interstate I-229. These crossing were the main purpose for constructing the pipeline by tunnel methodology. The ground was typical St. Joseph Area Till that consisted of silt, clay, and a very fine sand matrix, containing granule-to boulder-size fragments of limestone, chert, shale, and erratic boulders. Due to these ground conditions soil Pre-Conditioning was required for installation of the tunneling shafts. Jet-Grouting was the contract specified soil conditioning system. Prior to bidding the work all contractors to construct the tunnel had to be pre-qualified. NTP was issued on 2/25/13 with SAK actually starting field construction on 4/25/13.