Location: Michigan City, IN
Owner: Sanitary District of Michigan City
Completed: May 2011
This project entailed microtunneling 2,303 lineal feet of 78” Hobas Jacking Pipe, and installation of five shafts with interlocked steel sheeting and concrete ring whalers supports. Due to groundwater at or near the ground surface we used dewatering deep wells around shafts to draw down water during shaft construction, launching, and receiving of MTBM. The tunnel portals at the shafts were chemically grouted to prevent soil movement upon receiving of MTBM. The tunnel drives were rather long so we implemented Intermediate Jacking Stations on each drive to overcome any high ground pressures throughout the drives. The fine beach sand like soils were pretty consistent throughout this project and required constant use of bentonite to prevent freezing of the line during tunneling. We also worked 24 hours a day, 7 days per week to keep the line pressures in a safe range. This project was completed several months early with no claims/disputes.