MMA Civil was awarded the contract by Sydney Water to construct the new SPS, gravity mains, rising main and to decommission the old SPS. Pezzimenti Tunnelbore was awarded the microtunnelling works by MMA.
The launch shaft was located in the excavation of the proposed wet well of the new SPS. The depth of the shaft was 11m. The site set up required a steep lead-in ramp to a lower level.
Significant Cost Savings
The 150m microtunnel through sandstone was completed in 6 days. The self-supporting nature of the ground conditions allowed the Pezzimenti LaserboreTM Microtunneling System to employ the Freebore mode, meaning that no encasing pipe (steel or concrete) was required.
This resulted in significant cost savings for the project. Pipes were sliplined into the microtunnel and the annulus grouted.