Global Water recently commissioned a sewer pump station for SA Water near the RAAF base at Edinburgh, north of Adelaide. Previous firefighting practises saw PFAS enter the underground aquafer and subsequently contaminate the ground water.

What is PFAS? How does it contaminate the ground water?

Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals used in products that resist heat, oil, stains and water. These chemicals are commonly used in household products and specialty applications including firefighting. They are an effective component in fighting liquid fuel fires.

Although this substance is being phased out of active use in firefighting applications, the presence of PFAS in groundwater has influenced recent infrastructure and development projects.

PFAS has since been banned from use in SA, with the South Australian Defense Force now phasing the use of these chemicals out as well, due to the harm caused on the environment.

The Challenge

Global Water sought a solution for the sewer pump station, appropriate for PFAS contamination and suitable for the site’s flow and head requirements.

In order to guarantee the integrity of the sewer pump station, and to ensure that there was no possibility of ground water entering the sewer network, Global Water investigated chamber water proofing options to meet demand.

The client outlined the following requirements:

• Pumps suitable for handling corrosive nature of raw sewage and solids
• Pumping Chamber suitable for installation in PFAS contaminated soil
• No possibility of PFAS entering sewer network system
• Accurate level measurement devices - capable of accurately controlling pumps in sewage applications

With these requirements Global Water investigated options and developed a sewer pump station fit-for-purpose.

The Solution

To meet the site requirements, Global Water suggested a heavy-duty mould formed and intensely vibrated reinforced concrete pumping chamber to 40mPa. The concrete mix on the base increment includes a specialized water-proofing additive Xypex Bio-San, which is added into the concrete mix. Due to its impervious properties this was the best solution to ensure that there was no possibility of PFAS entering the sewer network through the concrete. Additionally, Xypex is a unique chemical which protects concrete in harsh sewage conditions where high levels of hydrogen sulphide are present which causes microbial induced corrosion.

The complete pump station also included a fully welded internal HDPE liner. This liner forms a superior protective layer, which can substantially withstand both abrasion and harsh chemical environments

As part of the packaged pumping station, Global Water advised a twin Sulzer Model XFP, with Contrablock Plus impellers and 75mm free passage for solids. Constructed in ductile iron with heavy epoxy coatings, these Sulzer submersible pumps are for the toughest of sewerage applications. These pumps satisfied the requirements and achieved a duty of 8.0 L/second, at 8.5 meters total head.

To ensure that the pumps operate at the precise levels within the sewage pumping station, Global Water fitted a Vega Radar Level Measurement system. This device being IP66 rated, is hung in the pit and automatically operates the pumps based on the levels set.

The packaged pumping system was installed in early 2020.

Today

Following installation of Global Water’s packaging pumping solution, the RAAF site in Edinburgh has successfully managed the containment of PFAS from contaminating ground water. The addition of Xypex and the HDPE liner has ensured the integrity of the chamber and sewer network in existing PFAS contaminated soil.

Global Water are confident in the pump station’s ability to withstand the effects of PFAS. Our team will continue working closely with the local water authority to create solutions for the toughest of water pumping and treatment challenges.

For more information on Global Water’s capabilities, or to discuss your next project, give Global Water a call. We have a wide range of packaged pumping solutions, and can offer turn-key packages for tough, challenging applications.