Milwaukee, Wisconsin
1998
A new 84 inch diameter sewer tunnel was to be installed beneath an existing railway track embankment. Settlement of the active railway lines had to be minimized during the excavation of the tunnel in order not to interrupt CP Rail’s operation.
An extensive grouted soil-conglomerate arch was created above the tunnel trajectory to prevent settlement of the CP Rail tracks during the excavation of the sewer tunnel through the underlying embankment. The grouting program included the following:
- Installing an access shaft,
- Installing horizontal sleeve-pipe,
- Perform in-situ hydraulic conductivity tests,
- Depending on the in-situ permeability, injecting (multiple phase) regular or microfine cement based suspension grouts, or sodium silicate solution grout,
- Re-injecting the soil conglomerate with sodium silicate based solution grout,
- Real time monitoring with CAGES (Computer Assisted Grouting Evaluation System) to monitor the reduction in hydraulic conductivity.
Settlement of the underlying embankment was perfectly controlled and CP Rail’s regular operations were not interrupted, when the tunnel was constructed.
ECO was involved in the design, inspection and supervision of this project.