Three more years before sewage overflows fixed in Wollongong, Shellharbour

Sydney Water had been ordered by the Environment Protection Authority (EPA) to fix its network after a series of major sewage overflows in wet weather.

This work, in both Wollongong and Shellharbour, was meant to bring the number of wet weather overflows down to an average of four a year - as per Sydney Water's licence conditions.

It was due to be completed by June last year, but Sydney Water said after starting work it found the problems were worse than it first realised.

It asked for another three years, to June 2026, and the EPA agreed.

In both Wollongong and Shellharbour an average of 10 overflows per year for each will be tolerated until then.

It's largely urban residential areas that suffer from sewage overflow in heavy rains, like the southern end of Wollongong CBD, where Kembla and Swan streets meet, and nearby.

Residents in these affected areas know only too well how regularly the overflows have happened over many years.

Action after horrendous sewage spills

After some very large and very public sewage overflows the EPA took action in February 2021 and issued a "pollution reduction program" to Sydney Water.

The water company was ordered to pay $1 million in 2022 over three overflows that caused raw sewage to flow across the fairways at Wollongong Golf Course on February 17, 2020, July 27, 2020, and March 24, 2021.

The July 2020 incident was perhaps Wollongong's worst, with about 967,000 litres of sewage flowing across the fairway, forcing a month-long closure of the northern end of the course.

Also in July 2020, a Sydney Water pipe failed and released 430,000 litres of untreated sewage in Shellharbour.

"This flooded Darley St, Shellharbour, flowing into residents' properties and causing damage," the EPA said while ordering Sydney Water to pay $600,000 to Shellharbour City Council for environmental works.

Work identifies problem even worse

Keeping overflows below 40 every ten years is a condition of Sydney Water's EPA licence. Returning the system to compliance with this was also made a condition of its licence. It has now been given until June 2023, with Sydney Water saying the next stages of construction would start in 2025.

The earlier work, which identified the need for more work, had been going on since 2018 and it was only after 2021 that better modelling was able to diagnose the true extent of the problems, with more sites and assets needing work.

"In 2018, based on existing wastewater modelling, Sydney Water identified several works to improve wet weather overflow performance in the Wollongong and Shellharbour systems," a spokeswoman said.

"A significant amount of work was completed by 2021.

"Sydney Water then rebuilt and recalibrated the hydraulic sewer system models associated with these systems in 2022.

"This more sophisticated modelling system provided a more comprehensive assessment of the wet weather overflows, including more detailed mapping of network assets, pump stations, emergency relief structures and the pipe network.

"This upgraded modelling system and the increased data available identified a significant increase in the scope of work required to bring these systems back to compliance, thus increasing the timeline for these works to be completed to June 2026."

It was unable to specify at this stage what the works were that would take so long, as the "detailed planning" needed to be completed first.

EPA gives the tick

In approving the three-year extension the EPA endorsed the work done so far which identified further problems.

"The EPA commends Sydney Water on the works undertaken to date and acknowledges the unforeseen issues encountered which resulted in delays bringing the system into compliance," it said in a document varying Sydney Water's licence to include the extension.

The EPA document also explained Sydney Water's reasoning.

"Condition U1 [of its licence] required Sydney Water to undertake all works and actions necessary to return the sewage treatment system to compliance with the wet weather overflow limit of 40 overflows per 10 years by 30 June 2023," the extension document states.

"However, the identification of the Wollongong system model being non-compliant, and the time required to rectify, delayed Sydney Water being able to assess the system performance.

"The resultant assessment identified that the system performance was significantly worse than previously understood and requires a new planning study and further rectification works would be required."