Rehabilitation of Mosman Submain

Solving complex problems and exceeding community expectations in Mosman

Interflow successfully overcame some major challenges on the Mosman Submain Rehabilitation project through careful planning and focussed community engagement.

The project was to rehabilitate 160 meters of 990mm x 660mm oviform sewer using CIPP relining over a 4 month contract duration. Works included line preparation including existing liner removal, grinding, cleaning, community consultation, provision and maintenance of public access and flow bypass.

Interflow’s on-site management and personnel took ownership of all stages of planning and implementing the works with a focus on mitigating possible impacts on the community as each task was undertaken.


Interline CIPP and flow bypass

160m of pipeline


Measures taken for the purposes of minimising disturbance and maintaining safe access included implementing a bypass route through residential properties, that while not the simplest or most direct, took advantage of individual property layouts. It achieved the project’s objective of causing the least possible disruption.

The welded polyethylene bypass line was constructed in situ and positioned to run to one side of driveways and an easement. Where the line needed to cross a backyard it was placed as far away from the house as possible, so that access and residents’ use of their properties was not unduly affected.

Temporary pipework along roadways was laid in trenches so there were no forced road crossings and no disruption to local traffic. Other measures included installing a non-slip walkway to maintain access to a local walking track.

The challenge

An 1890’s brick oviform sewer, previously lined and running beneath heritage listed properties in the upmarket Sydney harbourside suburb of Mosman.

Project complexities included the need for 400 metres of above-ground bypass coupled with the need for mitigation of unacceptable inconvenience to residents affected by the works.

The solution

Interflow, in partnership with Sydney Water, engaged in planning and consulting extensively with all affected residents to develop a unique bypass solution to enable CIPP relining of an
oviform sewer.

Planning of work activities in and around the bypass meant minimising disruption to affected residents and the wider Mosman community.


This was a difficult and complex project due to both the type of work involved and its location.

Its success was recognised by Sydney Water with the presentation of a ‘Lifestream Team Award’ which commended the Interflow team for delivery project outcomes which exceeding all expectations.

A great technical outcome that was delivered on time and on budget. Completed with zero complaints and seven significant resident compliments.

Interflow is committed to offering its customers optimum solutions of the highest value for pipeline rehabilitation.

Sydney Water


Mosman, NSW


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