DM Civil worked in conjunction with DJ MacCormick Contractors to undertake two microtunnelled drill shots as part of their DN600 Collection Sewer in Bertram. Sections of limestone cap rock with an estimated hardness of 60MPa were required to be drilled. This entailed 2 shots of DN800 steel casing installed in lengths of 60m and 174m for DN600 GRP pipe to be sleeved inside with the annular void grouted. Depths of the sewer ranged from 5m to 6m deep with variable ground conditions of cavernous limestone and sand.
View more information about the Christmas Avenue DN600 Collection Sewer project.
The Rockman TRW800 slurry microtunnelling machine was thoroughly prepared by the workshop and, along with Chad Auth and crew, tasked with embarking on our most challenging microtunnelling drive to date. The shorter of the 2 drives was successfully completed, first to aid with the overall project construction sequencing and to prove the machine was up to the task prior to undertaking the longer, riskier bore.
The crew then reset the machine and sent it on its way for the longest drive that DM Civil has undertaken. They followed their methodical approach to tunnelling operations by utilising our internally developed procedures that have helped us grow into the reliable tunnelling contractor we are today.
Despite all procedures developed, tunnelling by nature has inherent risks associated with limited access to the equipment and being somewhat blind to the ground conditions encountered. This drive was no different and the crew had their challenges in overcoming mechanical aspects, inconsistent ground conditions and head blockages.
It was a mammoth effort and the result was DM Civil’s longest drive of 174m completed successfully, within a tolerance of 20mm of the required level. What an outstanding result! This was a major success for us and demonstrates our positioning in the market as one of Western Australia’s leading trenchless contractors.
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