Thinking Outside the Box (Culvert): the Innovative Repair of a Culvert at Penrith Wrp

Abstract

The Penrith Water Recycling Plant treats 24 million litres of wastewater each day. Culvert 1, which transfers treated wastewater from clarifiers to nearby filter pumps and evaporation ponds, was showing signs of ageing and surcharging when pressurised. The surcharges and condition of the culvert presented a risk to the local environment and was causing damage to aboveground infrastructure. Sydney Water engaged Interflow to rehabilitate two downstream sections of the culvert using twin spiral-wound liners. After work had commenced, a further 38m of culvert was added to the scope. Upon inspection it was discovered that the culvert did not have a consistent shape all the way through. A portion tapered down to around 50% of the original height before increasing again to full capacity. Installing twin liners through this section would have resulted in an unacceptable hydraulic capacity. Stainless steel sleeving was considered but ruled out earlier because of the associated cost and the weight of each section. Digging up, demolishing and replacing the section of culvert could have produced an acceptable end result, but at significant cost and impact. Instead, Interflow proposed rehabilitation of ~30m of the culvert using an innovative solution called Channeline, a prefabricated GRP structural lining technology that is manufactured and installed in easy-to-handle segments. This was one of, if not the smallest Channeline installations in the Southern Hemisphere. This project demonstrates that when asset owners and their delivery partners think outside the box, non-standard solutions can be found for non-standard pipes and culverts. 1 No-Dig Down Under 2023 Thinking outside the box (culvert): the innovative repair of a culvert at Penrith WRP Paul Everett, Jared Roberts and David Gowan