Lismore City Council is investing $1 million in important remediation work on two water reservoirs after a scheduled in-depth health check on the system's condition.

The two identified for repairs are the Esmonde Street and Wyreema Avenue reservoirs. Both require the complete emptying of all water to ensure all necessary repairs and remediation can be successfully achieved.

Work has already begun on the 1938-built Esmonde Street Reservoir. It is a 7.38-meter-high, 30.5-meter-diameter water storage tank with 5.68 megalitres, equivalent to almost three full-size Olympic Swimming Pools.

The Wyreema Reservoir, constructed in 1959, will begin its remediation work in early 2025. At a total capacity of 2.84 megalitres, it is half the size of the Esmonde Street reservoir. Both reservoirs are critical to Lismore’s water supply network.

Lismore City Council’s Head of Water and Wastewater, Matt Potter, said work has already started, and remedial works like this are important to ensure Lismore continues to maintain its perfect 100% water quality compliance.

“Typically, concrete assets like these, which are 50 to 80 years old, require in-depth service and maintenance which will extend their lifespan for many more years,” he said.

“The Esmonde Street Reservoir is empty, and we’re sealing the inside concrete construction joints, which involves applying an adhesive and a bandage system to the internal wall and floor joints to strengthen its design further.

“Concrete spalling, which is when the concrete begins to degrade or break away, was also detected in several locations, necessitating remediation to the concrete.

"It's fascinating to be inside the reservoir now that it's empty; seeing the sheer size and engineering up close is incredible.”

Mr Potter also said that between large remediation works such as this, Council conducts spot health checks using unexpected methods.

“Much to everyone’s surprise, our Water Operations Team uses scuba divers to inspect and clean the reservoirs, preventing sediment buildup and ensuring water quality all year round,” he said.

“Divers are part of our regular maintenance schedule and help keep the water safe for usage. They also provide the Council with a Condition Assessment Report on the internals of the tank.

“Lismore City Council’s water is tested weekly at all the reservoir sites and the results are vetted against the trigger limits listed in the Australian Drinking Water Guidelines.”

After the major remediation works are done, the reservoir is cleaned and disinfected making it safe and ready for refilling.

Mr Potter also said that while the scaffolding is up, it’s also an opportunity to install new water nozzles, which fill the reservoir with water.

“We’re installing directional nozzles, which will improve water quality even more by ensuring even circulation throughout the system,” he said.

The Esmonde Street Reservoir is filled by gravity with water from Council’s High Street Reservoir, which means there is no pumping requirement due to the pressure differential between the two reservoirs.

The primary function of these reservoirs is to store and deliver potable water to customers in the Lismore LGA, as required by the Australian Drinking Water Guidelines.

During the remediation of both reservoirs, customers will not experience any water interruptions.

The Esmonde Street works are expected to be completed by October this year, with the Wyreema Avenue works expected to start early next year and finish by June 2025.