Detailed design for construction of a second outlet for Melbourne central business district’s sewer catchment

Spencer Street Sewer Augmentation Stage 1

The existing hand-built sewer in Melbourne’s central business district (CBD) is 100 years old and nearing capacity. An increase in demand for sewerage capacity due to population growth within the CBD initiated a four-stage sewer augmentation strategy developed by City West Water.

Stantec was engaged to provide the detailed design for construction of a new sewer and was responsible for developing innovative solutions to minimise risk. Tunnelling seven to eleven metres deep along the southbound lane of Spencer Street, Stage 1 sewer construction would run from Lonsdale Street to a temporary delivery point at Flinders Lane, along with the renewal of an existing sewer from Little Lonsdale Street to Lonsdale Street. Our key challenge was locating and navigating around many existing underground services. Employing sub-surface utility engineering skills, we ​successfully identified and managed all utilities in line with Australian Standards.

By tunneling as opposed to an open cut approach, our work significantly reduced impact on the project area. This augmentation of the sewer system is helping Melbourne provide safer waste removal for its communities now and into the future.