This 440 yard hydraulic pipeline sits below the construction site of a new freeway tunnel. There was evidence that the foundations alongside the tunnel were unstable and could be further damaged from soil compaction during freeway construction. A monitoring program was developed to measure ground and water pressure stress before, during and after the construction phase.
Using 30 optical strands, a temperature sensor and one monitoring station it was determined that the deformations were remaining with a small amplitude interval. The results remained the same during, for example, chemical grouting construction for soil improvement and the construction was able to proceed without stopping the water flow of the tunnel.