A reliable waste management service is critical to public health, and the facilities providing this service need to be dependable and durable. Headlined by the largest upgrade in recent memory for the state’s largest wastewater treatment facility, SA Water is taking steps to maintain reliable sewer services for years to come.

With 28 wastewater treatment plants located across South Australia, SA Water is responsible for treating hundreds of millions of litres of sewage each day. Maintaining a reliable sewer system is central in efforts to protect public health, and is why SA Water continues to invest in essential infrastructure that ensures the community can continue to thrive.

Investing in Adelaide’s primary wastewater plant

Located in Adelaide’s northern suburbs, SA Water’s Bolivar Wastewater Treatment Plant receives an estimated 150 million litres of sewage each day – the equivalent of roughly 60 Olympic-sized swimming pools.

As part of a sizeable $64 million investment, work is well underway to replace the plant’s current inlet structure – which is the first stage of the sewage treatment process – to support higher projected flow rates as Adelaide’s population grows into the future.

Upgrading the capacity of Bolivar will also lead to significant environmental outcomes at the site through more efficient treatment processes, helping to drive down energy use and improve the quality of recycled water.

SA Water Senior Manager of Production and Treatment, Lisa Hannant, said that this upgrade has been ten years in the making, and will augment the plant with the additional capacity required to support the community’s long-term growth for generations to come.

Overhead shot including the crane that will be utilised during construction – the grey area is the plant’s existing inlet structure.

Importantly, our treatment plants have evolved into sustainable sources of energy and climate-independent water. By upgrading the plant, we’ll be helping it operate more efficiently – optimising treatment processes to use less energy, while improving the quality of recycled water that’s made available for further use,” Ms Hannant said. “Currently, the inlet structure is able to process and treat 300 million litres of sewage per day from homes and businesses across Adelaide – representing around 70 per cent of the city’s total.

“We’ve been working to understand the condition and performance of the original inlet structure – built in the 1960s – and what we anticipate future daily flow volumes to be as the population grows, which is expected to be up to 550 million litres per day. “The inlet structure is where raw sewage arrives by ten large pipes connected to our wider sewer network across Adelaide.

“Large pumps push sewage up into the inlet and equally distribute the flow, with a series of screens removing solid inorganic material such as wet wipes, paper and plastic – which should never have been flushed in the first place – to prevent blockages or damage to the plant’s pipes and pumps downstream,” “As part of planning for the inlet works upgrade, we’ve identified a new design to enable a capacity increase, which will see a larger inlet built next to the existing structure with new screens and solids handling equipment.

“We’ll also construct three new pipes to accommodate the increased flow into the plant over time, linking the existing pipes to the upgraded inlet as the old inlet is decommissioned. “We’re kicking off the project with our crews relocating services and completing temporary works to ensure optimal flows into the plant until the new inlet is operational, which we expect to be completed in late 2025.”

More than 30 per cent of South Australia’s sewage is recycled every year for a range of uses including irrigating horticulture, regional vineyards and city parklands, with SA Water’s Bolivar Wastewater Treatment Plant recycling around 20 billion litres in 2022. Ms Hannant said that improved safety for plant operators was another key outcome of the upgrade.

“At times, we can experience higher flows through the plant which can lead to the accumulation of solid items and grit within the screens.

“Our upgrades will help limit any safety risks to our people associated with cleaning, repairing and maintaining the inlet screens, by reducing the amount of manual handling.”

Close-up of the plant’s proposed new inlet structure, showing the construction footprint and major equipment.

Flushing bad sewer habits

While continued investment is an important part in maintaining South Australia’s sewer infrastructure, sustaining a healthy and functioning wastewater network is a shared responsibility with the community.

After continued education efforts by SA Water, new data has shed a light on the sustained shift in South Australians’ flushing and rinsing habits, with the utility recently recording a 30 per cent drop in sewer blockages caused by the ‘unflushables’.

A group of objects, led by wet wipes, cooking fats and oils, and even weird and problematic items such as superhero costumes, these unflushables were responsible for 1,746 blockages over a six-month period from October 2021, compared to only 1,268 over the same period from October 2022.

The sharp decline has resulted in a more than $230,000 reduction in SA Water’s expenses related to clearing and disposing of blockages, along with less impact to the environment from sewage overflows.

“South Australians should be commended for the role they’re playing to help keep our sewers healthy, and I’d like to thank people for their ongoing support in flushing out the unflushables,” Ms Hannant said.

“It’s clear people are making a concerted effort to break their old habits and consider what they’re putting down the sink, or flushing down the loo, and it’s led to a significant drop in blockages caused by the typical suspects, including cooking fats and oils, tissues and wet wipes.

“This positive shift is incredibly encouraging and coupled with infrastructure upgrades and other operational initiatives such as a proactive sewer cleaning program, we’re hopeful we will continue to see a constant decline over the long term.”


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