As part of the Sydney Water Priority Sewerage Program for first time sewering of properties, sewage was required to be transferred at depths up to 12m through a ridge for a distance of 580m to accommodate a 300mm Hobas sewer pipe. The design came down to 2 microtunnels the first 318m long and the second 262m long.

Appine Pezzimenti Microtunneling Method Freebore is Self Supporting Ground

Appin Pezzimenti Microtunneling Length Diameter Ground Pipes

Allowances at the design phase for intercept bore

During the design phase allowance had been made to microtunnel from either end of each bore in case the intercept method was required. PSP excavated the shafts and the 318m bore was staged with the first half of the bore drilled to 200m from the downstream end. The rig was then relocated to the upstream end and 118m drilled to intercept the first bore. The Hobas pipe was then pushed in and the annulus grouted.

Single Longest Microtunnel at 262m

The 262m long bore was commenced from the downstream end and completed as a single drive to the exit shaft. This was the longest single drive accomplished so far by Pezzimenti Tunnelbore eclipsing the old record by 2m.

Appin Microtunneling Pezzimenti deep shaft

Deep Shaft and access.

Appin Pezzimenti Microtunneling Freebore

First stage of the interept bore complete.

Appin Microtunneling Pezzimenti looking down microtunnel rods and laser

Second StageĀ of the intercept bore in progress

Appin Microtunelling Pezzimenti Download Project Case Study