Resilient stormwater pump stations

Natural disasters are occurring more often and with greater severity. How communities and governments work together to rebuild is critical to building resilience.

With populations growing and climate change becoming an ever-present issue, governments are looking to take a proactive approach to reducing the impact of future disasters. These departments seek to help communities recover faster and minimise the future shock on these vulnerable populations.

The New South Wales Reconstruction Authority (RA) is one example of such a department. It works with communities, businesses and all levels of government to complete essential planning and preparation work, reducing the impact of extreme weather events on cities and towns across New South Wales.

Staff work closely with emergency services and community leaders to understand what is needed to help affected communities recover. RA will also lead recovery efforts once the immediate threat has passed, in conjunction with community leaders and other partners.

It’s people like Geoff Waterhouse, the Program Director for the Northern Rivers Recovery & Resilience Program at RA, who are helping communities recover from extreme weather events. He’s an electrical engineer by trade who found himself in hydrology works. The creation of a new stormwater pump station in Murwillumbah was the first major pump works program he worked on, and it provided him with significant learnings.

The need for investment

The new stormwater pump station was located on the corner of Dorothy and Williams Street in Murwillumbah. Murwillumbah is a town in the Northern Rivers of New South Wales and associated with the Tweed Valley region. Tweed Shire Council undertook this project in partnership with the National Emergency Management Agency (NEMA), RA, and the New South Wales Department of Climate Change, Energy, the Environment and Water (DCCEEW).

“One of the biggest reasons for building this flood pump station was to assist in removing stormwater and excessive water,” Mr Waterhouse said. “We get that within low-lying areas from storm fronts that come through the region. They usually provide a lot of rain, so the pump station will help remove that excess stormwater.”

Murwillumbah has dealt with significant floods over the years, with the town being inundated at least seven times in the last 70 years. In the last 20 years alone, the people of Murwillumbah have had to deal with significant disruptions from floodwaters that cut off the town from the north and south.

“The Dorothy Williams area desperately needs this upgrade. The biggest impact of flooding has been on residents and the football club. The Murwillumbah Brothers Leagues Club exists for the community and has been a centre for rugby league for many years now.”

Another benefit of installing the new stormwater pump station is to improve evacuation times for people wanting to leave the area. It provides a path for people to leave safely – particularly the case when it comes to flood events that could breach the levees throughout the central business district.

“2022 was the most recent time Murwillumbah was flooded,” Mr Waterhouse said. “It didn’t breach the levees completely, but we had breaches in specific locations. It got very close in 2017, and we have had breaches of the system in the past. With climate change, our wet season seems to be especially wet.”

The stormwater pump station

The stormwater pump station was part of a broader strategy to mitigate and build resilience to natural disasters and the impact of climate change. It is located behind the Dorothy Street levee, which runs in an east-west direction.

During the 2017 flood, the Dorothy Street levee was overtopped by about 300mm at the peak of the event. This overtopping and significant local catchment flooding around Brothers Leagues Club filled this basin. This water impacted the Leagues Club and several homes around William Street. Peak water levels from this section of the Rous River appear to have exceeded one per cent of the annual exceedance probability (AEP) levels in this event.

“Williams is a brand new greenfield site,” Mr Williams said. “The pumps will sit in a manufactured concrete well that sits at about the five-metre mark. The whole pump station has been designed to allow water to flow naturally without being pressurised by the pump sets. This will allow us to control more water flow when required, particularly in an extreme weather event. An additional benefit is the option to control the velocity of each pump. It allows for better control and water flow throughout the system.”

The team has installed two vertical in-shaft submersible pumps from Flygt, part of the Xylem group. One of the issues facing the RA during the installation was ensuring product continuity across the approximately 100 pump stations within the Tweed region. The Flygt pump set manufacturer supports every pump.

“The idea is to keep everything in that commonality, which makes maintenance nice and easy,” said Mr Williams. “It also means that if we need spare parts, we can source them locally and very quickly.”

Project challenges

Any project of this magnitude is subject to risks and challenges, and this project was no different. Like any government project, a risk review was undertaken to understand what could happen.

“We identify existing services in the ground while looking at everything that needs to be done from a mitigation point of view,” Mr Williams said. “The goal is to try to lower that risk, so we worked with the principal contractor to ensure they had the capabilities and resources to undertake this work. We also needed to ensure that any work done would create higher risks through the design development process.”

As part of the product selection phase, the RA team undertook a rigorous design and development process before selecting the type and category of pumps. There was also considerable work put into the hydrology report.

“We needed to know how much water was going to stay in the area that we would need to remove under pressure,” said Mr Williams. “We measured that and compared it against the natural water flow. Once we looked at it relative to rainfall records and collection data, we could predict and forecast what a one per cent AEP event would look like in the area. We can measure that in litres per second or cubic metres.”

In a water-soaked environment that can be subject to extreme conditions, it is vital to ensure that the pumps are durable for long-term use. The Flygt range of pumps is designed for these situations, which is one advantage. Mr Williams also looked to reduce risk in this situation.

“Durability, performance and capability were the three biggest requirements that we looked for,” he said. “That’s particularly the case when we are looking at an area subject to extreme stress and pressure during flooding events. As a general rule, we try to match product types where possible. That makes life significantly easier when it comes to maintenance, while also accounting for those rare situations where something might need an urgent replacement. With renowned manufacturers and distributors in the local area, we could ensure that they could support us in times of need.”

Benefits for community

It’s often the case that people do not appreciate the benefits of proper stormwater management until they are impacted by poor stormwater management.

“The major benefit or outcome for the community is seen when excess water is removed from an area that is usually prone to flooding,” Mr Williams said. “While an individual flood pump station will never stop all the flooding forever, it helps remove large amounts of water quickly, particularly as part of a larger stormwater management system.”

Keeping homes and businesses as dry as possible during extreme weather events is key to keeping the community happy. Looking at what he has experienced, Mr Williams pointed to the Murwillumbah Brothers Leagues Club operating as an important business for the community.

“We’re always trying to help businesses and organisations like that open their doors every day that they can,” he said. “If we are doing that, it’s a huge outcome for the community and for us.”

Tri-partisan support

During an emergency and the subsequent recovery, all levels of government need to work together to help the community. The creation of the Northern Rivers Recovery and Resilience Program (NRRRP) came from the National Emergency Management Authority (NEMA), which is a department of the Federal Government. The NRRRP is administrated and managed through RA at a state level. The events of the 2022 flood event saw over $10 million invested in the Murwillumbah region alone.

“This funding came from the Federal Government, and it was used to improve and upgrade existing flood assets within the town,” Mr Williams said. “We’ve been able to build the new pump station on the corner of Dorothy and William Streets. There are several new pump stations being installed on George Street in East Murwillumbah as well as on Wharf Street by the council chambers. We also have one of the largest pump stations under installation at Lavender Creek. There are also two civil projects that will help with the entry and exit points to the bridge across the Tweed Valley River.”

All the pump stations and civil works started in 2024, with the pump stations due for completion in the middle of 2025. The last two projects should be finished by the end of 2025.

“It’s important to note that most of the hydrology works for improving flood assets and pump stations is happening across the Northern Rivers, including Murwillumbah, Lismore and surrounds,” Mr Williams said. “That investment by the Federal Government is enormous and with the support of RA, there are incredible engineering projects being undertaken. All this work represents incredible benefits for the community, not just here in Murwillumbah, but across the entire region.”

Image: New South Wales Reconstruction Authority

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