The biggest upgrade to Melbourne CBD’s sewer network in more than 120 years has reached a milestone with City West Water’s completion of tunnel boring works to install a 900 metre-long new sewer under Lonsdale Street.

As part of the $21 million Lonsdale Street Sewer Upgrade, a 6.3-metre-long, 16.3 tonne tunnel boring machine (TBM) was used to make way for the new 1.5m diameter sewer pipe on Lonsdale Street, built between Elizabeth Street and Spencer Street.

The TBM was lowered into a 23 metre-deep shaft in March this year and excavated from William Street to Elizabeth Street, before returning to William Street to complete its final 350 metre journey towards Spencer Street last week.

The new sewer will provide additional capacity to the existing sewer catchment, which was constructed in the 1890s and had been nearing capacity.

Expected future growth in the number of city residents, visitors and workers means an increase in the capacity of the CBD’s current sewer network is vital.

The upgrade has created 35 jobs and will deliver efficient, safe and environmentally responsible sewerage services for the community.

It’s part of City West Water’s $80 million four stage capital improvement program to maintain service reliability for the fast-growing population of Melbourne’s CBD.

The Lonsdale Street Sewer Upgrade project is expected to be completed by the end of the year and will link with the Spencer Street Sewer Upgrade (Stage 1) which was completed in December 2018.

Construction on Stage 3, which includes construction of a new sewer along Elizabeth Street, will begin in 2021.