The Hay Street stormwater channel, which was built as a sewer in 1863 and converted to a stormwater channel in the early 1900s, was awarded the SOC Engineering Heritage Award at the Institute’s NSW Division Excellence Awards.

Sydney Water Managing Director Kerry Schott said the award recognised the significant challenges involved in maintaining key operational infrastructure with heritage value.

"The Hay Street stormwater channel was one of the five original combined sewers built in Sydney and played a major role in improving public health by diverting sewage and stormwater off the streets," Dr Schott said.

"The solution involved inserting a liner that acts like a sleeve inside the stormwater channel, ensuring the channel is structurally sound while protecting the original stonework from further erosion and damage. Importantly the liner can be removed in future if required without damaging the original channel."

Article continues below…

Dr Schott said the methods used in the $A4.1 million project were specifically developed to suit the unique conditions in the Hay Street stormwater channel.

The original channel is a semi-elliptical structure built from sandstone blocks. Each cross-section has 21 sandstone blocks, ten either side of a centre keystone. Mortar has only been used occasionally between some joints, as the majority of the stones bear directly against each other.

The liner is also elliptical in shape and is held in place by a soft grout filling the cavity between the new liner and the original channel. No heritage fabric has been removed and a membrane has been placed against the original stone to allow for removal of the grout and liner if required.

“Sydney Water has over 200 heritage listed assets in Sydney, the Illawarra and the Blue Mountains, many of which are vital to the operation of water, wastewater or stormwater systems,” Dr Schott said.

“Projects like this are part of Sydney Water’s commitment to conserving and protecting heritage assets for future generations.”

The Streets Opening Conference is an association of all major utilities concerned with underground services, designed to foster coordination of service providers’ works and minimising the impacts caused by opening roads. Sydney Water has been a member of the Streets Opening Conference since its inception 100 years ago.