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McRobert inspects and relines deteriorated pump station

In 2017, trenchless contractor McRobert completed the structural relining of a Type 180 pump station in WA.

McRobert Contracting Services initially conducted a level two 3D laser scan of a sewer pump station in Mandurah, in the Peel Region of Western Australia in 2016.

The inspection revealed all internal concrete surfaces had been severely affected by biogenic sulphide corrosion. Significantly, it showed over 100 per cent of the concrete cover had deteriorated from the lower sections of the wet well walls.

In 2017, McRobert was subsequently contracted to complete the structural relining of the pump station inlet chamber and wet wells, using it’s patented relining methodologies.

The wet well walls ready for pH tests and reinforcement repairs.

Due to the extent of the deterioration, the contractor performed concrete and reinforcement repairs to the walls of the pump station, prior to installing rigid PVC as per the company’s patented whaler system. Initially, the walls were cleaned and loose corroded material from the walls was removed until only sound concrete remained.

pH testing was completed to ensure this was achieved. At this stage, McRobert completed a secondary laser scan to determine the true extent of the deterioration, which was illustrated to be significantly more than expected.

From the results of the laser scan, the company was able to accurately fabricate all required components for the structural relining.

Pump station prior to McRobert completing structural relining.


Steel reinforcement repairs were completed on the walls where reinforcement bars were exposed and corroded. McRobert’s lining system was then employed to cover the existing walls, essentially rebuilding the initial structure with a new 12 mm thick PVC lining and minimum 40 mm of grout between the existing concrete and new PVC wall.

A 3D point cloud illustration outlining data collected during the initial inspection of pump station.

The contractor then removed the original benching from the inlet chamber and wet wells, before fabricating and installing new benches made from a combination of both rigid and flexible PVC. All internal surfaces were now fully plastic lined and welded. Two penstocks were installed to the inlet chamber and all new gatic lids were retrofitted to the existing plastic-lined top slab.

Final touches

Finally, all internal plastic lined surfaces were spark tested, to ensure a 100 per cent complete gas tight seal within the pump station, ensuring complete protection from any further corrosion. McRobert provides a 50-year guarantee on all materials and workmanship completed as part of the company’s patented lining methodologies.

The inlet chamber with penstocks post-rehabilitation.

This article was featured in the March edition of Trenchless Australasia. To view the magazine on your PC, Mac, tablet, or mobile device, click here.

For more information visit the McRobert website.

If you have a project you would like featured in Trenchless Australasia contact Assistant Editor Chloe Jenkins at

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