West End 375mm Trunk Main Robotic Concrete Removal - TDG Environmental

case study

West End 375mm Trunk Main Robotic Concrete Removal

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TDG was contacted about using our high-pressure robotic cutter to remove concrete slurry that had entered a 375mm trunk sewer main during construction. Another contractor had started the process of removing the concrete deposit but their robotic milling unit was proving to be ineffective and as a result an alternative methodology was needed.


Initially two methodologies were proposed both utilising the same robotic milling unit but with different pressures, one Ultra High Pressure 18lpm @ 28,000psi the other High Pressure 16lpm @7,250psi.


Due to the poor condition of the host pipe it was decided to use 7,250psi to reduce the chance of further damage.


  • Dense Residential area
  • Work times reduced due to impact on residents
  • Residents directly affected by works due to location of access points
  • Pipe located in underground carpark of unit block
  • Pipe had large belly causing flow to pond, hindering cutting efficiency
  • 50% of pipe full of concrete for 30 meters
  • Poor condition of existing concrete pipe that required trenchless repair midway through works

The outcome

Over a period of 40 days TDG successfully removed over 30 meters of solid concrete most of which was at levels of 40% of the host pipe diameter.


Throughout the project TDG staff and supervisors had to continually develop methodology’s to remove dislodged pieces of concrete as well as removing water that would build up in the pipe during high pressure blasting.


The water build-up was due to a large belly in the trunk sewer line that prevented flow escaping downstream hindering the high pressure blasting robots performance.


Lessons Learned

Since the completion of works TDG has taken on an Ultra High Pressure Specialist Operator to assist with robotic cutting techniques, comprehensive UHP training has also been performed with the manufacturer to give a greater understanding of the robots potential.


Standard practice for all concrete removal jobs even in seriously deteriorated pipes is to use Ultra High Pressure water cutting, operators are able to remove concrete significantly faster then traditional robotic cutting techniques greatly reducing the impact on sewer networks and stakeholders.


Government and Council



Project Highlights

  • Achieving up to 1m of concrete removal daily
  • Success development of methodology to effectively remove the concrete from the sewer main.
  • Liaising directly with client to provide daily progress updates

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