Beresfield Pipe Fill Outlet End with Terefil

Overcoming the challenges associated with decommissioning ageing pipe infrastructure

In Australia, decommissioning and rehabilitating ageing infrastructure including gas, water and sewer pipes, is becoming an increasingly pressing issue for government and infrastructure stakeholders.

As infrastructure ages, failure rates increase along with risks to the environment and public safety.

When decommissioning or rehabilitating pipelines including culverts, a thorough ground and site assessment is critical to determine whether other significant underlying ground issues are present. Such issues can include underground voids which can lead to subsidence, soil destabilisation and water ingress that might lead to more serious ground collapses.

Finding a cost-effective solution to address ageing pipe infrastructure, particularly when sensitive environmental considerations are at play, can be a major challenge for engineers. However, new and innovative technologies are now available to help address a number of common technical challenges such as the structural integrity of the pipe, pipe lining erosion, water or tree root ingress.

Mainmark has introduced a number of technically advanced solutions that were successfully used to both remediate and decommission pipelines for a major water infrastructure project in NSW. Contractors were required to abandon an in-ground water pipe and construct a new main, however because the old pipeline ran underneath a highway, school and private land, digging the pipes out using traditional means was not feasible. The pipe’s construction and placement less than a metre underground meant there was a risk that it could rust and collapse, potentially damaging the structures above it.  The safest and most effective approach was to fill the pipe.

Decommissioning abandoned pipeline running underneath a busy road at Wolli Creek, NSW, Sydney.

Mainmark was able to provide a fast, cost effective solution using Terefil®, our proprietary lightweight cementitious grout solution that enabled the project to be completed in just four days. Terefil is a unique solution, able to be pumped across long distances, making it ideal for large infrastructure projects where long pipes are involved.

One of the key features of Terefil is its pumpability. We placed more than 400m3 of Terefil along 620 metres of the 900mm diameter pipe in a single shift. At its peak, the team pumped 68m3 of Terefil per hour. As a result, the pipe was safely filled without damage or inconvenience to the school or any local property owners. A conventional approach would have involved digging up to seven holes to access the pipe, which would have taken at least a week to complete.

Mainmark has also been instrumental in remediating pipe infrastructure assets using ENCAP6®, our technologically advanced anti-corrosion spray-on solution that revitalises and prolongs the life of ageing steel or concrete infrastructure.

ENCAP6 is a low-cost polymer coating solution that can be used to rehabilitate and maintain assets because it has exceptional chemical resistance, hydrolytic stability and abrasion resistance. It also provides excellent, long term structural performance.

It is easy to apply and it bonds tenaciously with prepared concrete, brick, earthenware, vitreous and metal surfaces to effectively seal and protect the substrate. It can be applied in varying thicknesses to deliver the required structural performance and is more stable than most other alternatives. Most importantly, it is environmentally inert and cost effective.

Gladstone Council utilised ENCAP6 to remediate a galvanised steel drainage pipe that ran underneath three factories. The pipe was at risk of collapsing due to the surface weight of structures above. By coating the drain with ENCAP6, and supporting the pipe by applying expanding engineered resin beneath it, the council was able to avoid excavation, which delivered a significant cost saving.

By William Lindsay

William Lindsay is the Group Technical and R&D Manager at Mainmark. He has over 25 years experience in working within the construction and civil engineering industries, having a wide breadth of experience, in the capacity of quantity surveyor, project manager/representative, business manager, general manager and group technical and research & development manager.