Bombo Water Resource Recovery Facility

Tackling odour

We're working on a series of construction projects to improve operations at the Bombo Water Resource Recovery Facility. This one includes reducing odour through a new chemical dosing unit and carbon filter.

About this project

The Bombo facility is located on a 20.4 hectare site in a former quarry on Bombo Headland off Darien Avenue. It serves the townships of Kiama Heights, Kiama, Bombo, Kiama Downs and Minnamurra. It was built in 1984 as a secondary wastewater treatment plant using intermittently decanted aeration lagoons (IDAL) as the secondary treatment facility. A cliff face underwater ocean outfall was constructed in 1984 to dispose of the treated wastewater to the South Pacific Ocean.

In 1993, 2 catch ponds were constructed to facilitate attenuation of decanted wastewater flows, and to capture solids if sludge was carried over during the wastewater decant phase.

In 2005, flows from Jamberoo were transferred to the Bombo facility. In March 2005, a new fourth IDAL, an extra step screen, a grit tank and 2 additional sludge tanks were added.

The Bombo facility produces biosolids. This involves dewatering one of the facility's sludge lagoons, bringing in heavy machinery to deliver a mobile centrifuge used to create the biosolids, and loading the end product into semi-trailers to remove it from the site. Currently, 100% of the biosolids produced here are beneficially reused in agriculture, forestry and land rehabilitation. This activity occurs every 5 to 6 months. There may be intermittent odours during this time. We apologise for the inconvenience this may cause local residents, and we appreciate your patience and understanding as we complete this work as quickly as possible.

We've identified a number of odour-reducing initiatives as part of an extensive odour monitoring and improvement program, including a new chemical dosing unit and carbon filter.

Benefits

We will be installing a chemical dosing unit at the sludge lagoon. This unit will enable us to introduce magnesium hydroxide liquid (MHL) to our treatment process to address odours during sludge lagoon dewatering.

This specialised unit administers precise doses of MHL to effectively neutralise odours during the treatment process. The project will include storage tank, mixer, dosing pumps, valves, safety showers, and a bund for chemical deliveries. It will be automated and integrated into the facility's existing control system. The magnesium hydroxide storage and dosing system will be sheltered under a carport-type roof and contained in an existing concrete embankment. We'll be doing some civil work to facilitate the installation of this unit. This will include the building of a truck turning bay for the chemical truck.

Impacts

During dewatering, there may be a slight increase in odour for up to 2 days. To minimise the impact on our community, we'll have an odour-neutralising spray system set up around the dewatering operations.

During construction, there will be an increase in noise and traffic, particularly along Darien Avenue, as contractors, delivery trucks and special equipment are required on-site.

Reporting odour

If you're experiencing odour issues, please let us know using our short online form. This is the quickest way to submit your experience and for us to respond.

Terminology

• Sludge: The residue that accumulates in WRRFs. It's the solid, semisolid or slurry residual material that is produced as a by-product of treatment processes. With further biological treatment to reduce pathogens, odours and particles that attract insects and vermin, we produce biosolids.
• Slurry: A thin, sloppy, wet mixture of liquid and solid components that is a by-product of the treatment process.
• IDAL: Intermittently decanted aeration lagoon. Wastewater is collected in the IDAL tanks and pumped with air through diffusers. The air works with microorganisms in the tank to break down nitrates (nitrification) and organic matter.
• Diffuser: Aeration device used to transfer the air into the tank.