Water Infrastructure Group (WIG) was awarded the relining contract by ActewAGL, for the 458 m section of the Main Outfall Sewer (MOS) using the company’s Panel Lok PVC lining system.

The section runs between Cotter Road and Lady Denman Drive in the Equestrian Park.

The MOS is a 1.68 m high, 1.12 m wide oviform sewer built of brick and concrete. Construction commenced in 1915 but was delayed during World War I. It was finally completed in 1926, in time for the 1927 opening of Old Parliament House.

Running 7 km underground from the former Canberra Hotel site in Commonwealth Avenue to the former Weston Creek treatment works site, the outfall is now connected by a more recent sewer to the Lower Molonglo Water Quality Control Centre.

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WIG Project Manager Pieter Schoofs said Panel Lok provided an ideal rehabilitation solution.

“The concrete lining of the MOS had deteriorated due to aggressive gas attack on the concrete surface,” he said. “The narrow oviform shape of the concrete makes relining more complicated so we have carried out research and testing using a timber prototype with the exact measurements of the MOS.

“The results of our trials were very positive and we are now confident that we have selected the best material and developed an efficient technique for relining the MOS.”

Mr Schoofs said the company would normally complete these relining projects in live flows, when the level drops low enough to safely enter, which is usually at night.

“For the MOS relining project, we will divert the live flow through a bypass so we can work during daytime hours and in a dry environment to ensure that we achieve the highest quality installation. This will also minimise disruption to the local community.”

In addition to the main relining work, the company is also carrying out repair works on the Yarralumla Creek aqueduct and renovating four manholes with a protective coating. WIG will be constructing a new manhole that will act as a bypass chamber and facilitate access for future maintenance.

Work on the MOS rehabilitation project commenced in June and is expected to be completed by the end of October 2011.