Bombo WRRF is located on a 20.4 ha site in a former quarry on Bombo headland off Darien Avenue. The facility serves the townships of Kiama Heights, Kiama, Bombo, Kiama Downs, and Minnamurra. In 2005, flows from Jamberoo were transferred to the facility.

The facility was constructed 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, two catch ponds were constructed to facilitate attenuation of decanted wastewater flows and to capture solids if sludge is carried over during the wastewater decant phase.

In March 2005, a new fourth IDAL, an extra step screen, grit tank and two additional sludge tanks were added.

The Bombo WRRF produces biosolids. This involves dewatering one of the facilities sludge lagoons, bringing in heavy machinery to deliver a mobile centrifuge used to create the biosolids, and load the end product into semi-trailers to remove from site. Currently 100% of the biosolids produced at our facility are beneficially re-used in agriculture, forestry, and land rehabilitation.

This activity happens every five to six months, with the next dewatering process to start in March 2024, taking about three weeks to finish. Unfortunately there may be intermittent odours during this time and we apologise for the inconvenience this may cause local residents, but we do appreciate your patience and understanding as we complete this work as quickly as possible.

Bombo Water Resource Recovery Facility (WRRF) on Bombo Headland

Bombo WRRF Update May 2024

We’ll soon be starting a series of construction projects to improve the operation of the Bombo Water Resource Recovery Facility (WRRF).

Chemical Dosing Unit

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 neutralize 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 plants 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 which will include the building of a truck turning bay for the chemical truck.

Work is scheduled to begin in early May and will take up to seven months to complete, weather permitting.

Dewatering delayed and will now begin in May

At Bombo, we produce organic solids (sludge) during the wastewater treatment process. This sludge is collected and processed to convert it into a safe fertilizer product called biosolids. We use sludge lagoons to break down and stabilise the sludge. This makes nutrients available to plants and reduces pathogens and odour. Finally, we use a high-speed centrifuge to remove water from the biosolids (dewatering), making it easier to transport in trucks.

We previously let you know that dewatering will begin in April, however, due to wet weather, this work was delayed and will now commence in early May.

What you need to know

• During dewatering, there may be a slight increase in odour for up to two days. To minimise the impact on our community, we’ll have odour neutralising spray system setup 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 is required on site.

Bombo WRRF Update July 2023

Last year, Sydney Water completed an extensive odour monitoring program from which, a report was developed that outlined a number of odour reducing project options.

These options are currently being planned and will be delivered by Sydney Water in stages over the next three years.

Current short term works include:

• Finalising the design of an active carbon filter on the inlet works exhaust system, due to be installed in 2024.
• Finalising plans to install a chemical dosing system to neutralise odours from the lagoons, with installation planned for 2024.

Both these projects are designed to reduce odour emissions from the Bombo facility.

Completed short term works:

Sydney Water has been proactively working to ensure odour from the Bombo WRRF is controlled as much as possible. The following activities have been completed:

• all drains around inlet works of the plant has been covered.

• leachate from the grit/screenings bin has been plumbed and sealed

• all vents have been sealed

• grit withdrawal has been programmed to only occur at night.

We are currently finalising our long term plans for Bombo WRRF, once these have been confirmed, we will provide the community with an update.

Dewatering in August:

At Bombo, we produce organic solids (sludge) during the wastewater treatment process. This sludge is collected and processed to convert it into a safe fertilizer product called biosolids.

We use sludge lagoons to break down and stabilise the sludge. This makes nutrients available to plants and reduces pathogens and odour.

Finally, we use a high-speed centrifuge to remove water from the biosolids (dewatering), making it easier to transport in trucks.

The next dewatering is scheduled for this August and during this time there may be a slight increase in odour because of this process. To minimise the impact on our community, we will have odour neutralising spray system setup around the dewatering operations.

Reporting Odour

If you’re experiencing odour issues you can let us know using a short online form or by clicking report odour . This is the quickest way to submit your experience and for us to respond.

Where do I get more information and help?

If you would like to be kept informed about the project and receive updates via email and/or SMS, please provide us your details by clicking here

If you would like to know more, please contact our community engagement team on 1800 006 113 (option 6) or email us at Delivering4Customers@sydneywater.com.au.

Thank you for your cooperation during this essential work.

Bombo WRRF Update February 2023

Recent Odour Issues

There was an increase in odour at the Bombo Water Resource Recovery Facility (WRRF) in January. This odour was coming from one of the sludge lagoons that was brought online on 11 December 2022.

Bombo WRRF operates sludge lagoons as part of the treatment process to capture solids in line with its NSW Environment Protection Authority (EPA) licence. The plant operates up to two lagoons based on demand. At the time of the odour, one of the lagoons was full and the second was required to come online to maintain performance. When a lagoon comes online, it can take several weeks for a crust to form on the surface and cap odours.

The crust that had been developing, was softened by rainfall on 30 and 31 December 2022. Strong winds in the subsequent days also impeded the re-formation of the crust, potentially allowing odour to emanate from the lagoon. The operations team monitor the formation of the crust and it is checked daily during operating hours.

With the recent dry weather, the crust has thickened and is developing well with local odour subsiding. As the crust continues to develop on the lagoon over the coming weeks, it will greatly assist in reducing potential odour impacts.

Future Plans

Sydney Water is working to reduce odour around the Bombo Water Resource Recovery Facility by covering all drains around the plant and sealing all vents.

An upgrade to the facility, which will further reduce odour issues, has been approved and will be completed in stages over the next three years. We will provide the community with an update on these plans in the coming weeks.

Kiama Downs Rising Main Project

A temporary pipe was installed on the ground along Cliff Drive, Kiama Downs, eight years ago. Although this was a temporary solution following a landslide which caused permanent damage to the original rising main aqueduct, the pipe is sound and inspected regularly.

The replacement project has proven to be complex, involving multiple stakeholders and landowners. It is also a site with unstable ground conditions, difficult access and is adjacent to a rail corridor.

In collaboration with Transport for NSW, investigation work including geotechnical surveys has been completed. An options assessment and an options report identifying a solution is also complete. Draft design drawings for the identified solution have been prepared.

The project team is progressing with stakeholder engagement to get agreement on the preferred solution, access arrangements, site setup/construction area, and work towards delivering this project as a priority.

Need to contact us?