The $A4.1 million project involved relining the Hay Street stormwater channel and was awarded the Streets Opening Conference Engineering Heritage Award at the Institute’s NSW Division Excellence Awards in Sydney.

The channel runs under the busy intersection of Hay and Harbour Streets near the Sydney Entertainment Centre forecourt in Haymarket.

The channel was constructed by the Sydney City Council in 1863 and is a semi-elliptical structure built from sandstone blocks. It was one of the first combined sewers constructed in Sydney and was designed to improve public health by diverting stormwater and sewage off the streets and discharging it into the harbour.

It provides an excellent snapshot of infrastructure in early Sydney and is an excellent example of late nineteenth century engineering and construction techniques.

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Kallard Ross, Water Infrastructure Group Manager for the project, said that his team developed specific methods for the unique conditions in the Hay Street Channel.

“The new liner is made from marine grade N60 sulphate resisting concrete reinforced with SS304L stainless steel bars to provide a minimum design life of 100 years and maintenance free period of 50 years.

“Soft grout filling has been used in the cavity between the new liner and the original channel to protect the stonework. No heritage fabric was removed and a membrane was placed against the original stone to allow for removal of the grout and liner if required using a dismantling procedure we developed for NSW Heritage Office records,” Mr Kallard said.