Stormwater Rehabilitation – Mooloolaba

Project Summary Sheet

Customer: Sunshine Coast Council

Location: Mooloolaba, Qld

Delivered: December 2017

The Challenge

The Mooloolaba stormwater outfall, a heavily oyster encrusted 1,800mm diameter reinforced concrete pipeline, was letting in groundwater and soil through leaking joints. The reduced flow capacity was causing flooding in the town centre.

The upstream end of the pipeline was under a busy intersection, while the downstream end at the marina was at least partially submerged most of the time.

The Solution

Interflow overcame all challenges by installing a grouted SPRTM RO – Rotaloc (Rotaloc) spiral wound liner.

A coffer dam was constructed at the downstream end, which required additional measures to be undertaken due to the deteriorated state of the revetment wall.

Much of the work was carried out at night with complex traffic management in place to minimise community disruption.

The Project

Interflow was able to carry out the work without the need to decommission the existing line or excavate the road, park or pedestrian pavement surfaces above.

After cleaning the encrustation with ultra-high-pressure jetting and chain flails, Interflow installed a structural Rotaloc liner.

The downstream end was mostly submerged so a piled coffer dam was installed to gain access to the pipeline to install the Rotaloc liner. However, the deteriorated wall around the outlet meant seawater was penetrating and entering through the leaking pipeline joints.

The solution involved installing a removable plate that blocked the pipeline end during working periods and excavating a small pit just upstream of the submerged end. The pipeline could be dewatered from this pit.

Measures were put in place to protect the delicate marine environment during the works.

All lining work was carried out over a 3 week period – a short duration compared to the alternative of excavation and pipeline replacement.


Since completion of the renewed outfall, flooding during high rainfall periods has been effectively eliminated.

Interflow is committed to offering its customers optimum solutions of the highest value for pipeline rehabilitation. We do this by living our core values of honesty, reliability and competence.