Stainless steel solutions for long-term water performance
Critical wastewater infrastructure at the Alfred Street Pumping Station in Slacks Creek, Queensland, has been future-proofed through the design and manufacture of two custom stainless steel penstocks – the heavy duty gates that control water flow through a pumping station – by ASSDA Member and Accredited Fabricator Australian Water Engineers (AWE).
Engaged by Logan Water Alliance as part of Logan Water’s Wastewater Pipeline and Maintenance Hole Renewal Program, AWE was tasked with replacing outdated, non-functional penstocks essential to the isolation and control of inflow to the pumping station. The project forms part of a broader strategy to extend the lifespan and operational efficiency of existing water assets.
Stainless steel built for harsh environments
Operating in aggressive sewage conditions demands materials that will not corrode, pressure, and constant cycling. Grade 316L stainless steel was selected for its superior and proven corrosion resistance, strength and long-term cost effectiveness. Stainless steel materials for the project were supplied by ASSDA Members Midway Metals, Stirlings Performance Steels, and Vulcan.
The two custom penstocks – one DN1500 and one DN1050 size – were fabricated using 12mm, 10mm, and 6mm plate, along with stainless steel angles, round bar and pipe. The larger gate weighed more than 2 tonnes, with the smaller weighing approximately 1.3 tonnes. Both were designed to operate against 8m of head pressure while achieving very tight water leakage performance.
All major components, including hydraulic cylinders, spindles, and support brackets, were manufactured from 316 stainless steel, ensuring durability and material consistency throughout. Designed to exceed a specified 20-year service life, the penstocks are expected to perform reliably for decades in one of the most demanding water sewage environments.
Precision design under complex constraints
Installation at depths of up to 13m, integration within existing concrete block-outs and mountings and accommodation of a sloping chamber wall required tailored engineering solutions.
AWE’s in-house design and fabrication teams worked closely to ensure precise fitment and performance. Flatness tolerances of less than 1mm across seating faces were achieved, critical to ensuring a reliable sealing under pressure. This level of precision highlights the technical capability behind locally manufactured stainless steel solutions.
Quality assured through local fabrication 
As an ASSDA Accredited Fabricator, AWE maintained rigorous quality standards throughout the project.
Fabrication was completed in accordance with AS/NZS 1554.6 Structural steel welding: Welding stainless steel for structural purposes, with all welding undertaken using prequalified procedures to mitigate risks such as crevice corrosion. The finished penstocks were pickled and passivated to ASTM A380 Standard practice for cleaning, descaling, and passivation of stainless steel parts, equipment, and systems to further enhance corrosion resistance.
The penstocks were thoroughly tested at the workshop under different pressures and repeated operational cycles to ensure reliable performance before delivery.
Local fabrication enabled close collaboration between designers and trades, strict quality control, and full compliance with Australian standards, delivering confidence in long-term performance for critical water assets.
Sustainability through longevity
Stainless steel’s durability plays a significant role in reducing lifecycle impacts. Its extended service life minimises the need for premature replacement, lowering material consumption and whole-of-life costs. Stainless steel is also 100% recyclable, with a recycling rate of approximately 95%, further strengthening its sustainability credentials.
The upgraded penstocks also enable safer and more efficient maintenance of surrounding components, improving the overall serviceability and resilience of the pumping station.
Addressing ageing water infrastructure
With water utilities across Australia facing the growing challenge of ageing infrastructure, target renewals such as the Alfred Street Pumping Station upgrade demonstrate the value of intelligent material selection and quality fabrication.
By choosing stainless steel and partnering with an ASSDA Accredited Fabricator, Logan Water has invested a long-term solution designed to enhance reliability, reduce maintenance costs, and strengthen the resilience of critical water assets.
Through precision engineering, advanced stainless steel fabrication, and a commitment to quality, Australian Water Engineers has delivered a durable, future-ready solution that will support the local community and protect essential water infrastructure for decades to come.
This article was featured in Australian Stainless Magazine Issue 84.
Photo credit: Australian Water Engineers (AWE).