Sludge from Barwon Water’s wastewater treatment process is taken to the Thermal Drying Facility (operated independently to Barwon Water under contract) located adjacent to the Black Rock plant. Here the sludge is dried and turned into small pellets (bioprill product). These pellets are then safely reused as a soil conditioner.

Unplanned repairs were required at the biosolids Thermal Drying Facility (TDF) at Black Rock Water Reclamation Plant (WRP) during September, requiring temporary storage of sludge in a lagoon across the road from the plant.

After the stockpile was established in late September, we began using chemical sprays designed to reduce odours, alongside our ongoing monitoring. These sprays worked well initially, but in late October and throughout November, severe winds and heavy rain meant we needed to apply the sprays more often, and they became less effective.

We then applied a lime slurry, which is a more robust odour control method, especially after rain. While this initially made a noticeable difference, ongoing wet weather has unfortunately reduced its effectiveness.

Ongoing monitoring is being conducted through a combination of daily odour sweeps and tracking specific parameters within the sludge stockpile—such as temperature, moisture content, and indicators of biological activity.

Following reports from community members and onsite staff of increased odour in late October 2025, we’ve been undertaking regular treatments of the biosolids stockpile to help minimise any localised odour. Our priority is to manage odour risk from the stockpile area.

Positive outcomes from odour treatment trial

We’re working with specialist consultants in sludge and odour management to identify the best approach to resolve this odour issue. The advice from consultants has indicated that we’re unable to disturb the stockpile until its biological properties are stabilised. If the stockpile was to be removed from the site, the odour impact would be far greater than current levels. This means the stockpile will need remain in place for a longer period of time than first anticipated.

We’ve established rapid trials with mulch as a biofilter barrier on a small stockpile sample. We’ll now be progressing with the installation of a mulch biofilter at the stockpile area based on:

• consultants’ advice to not disturb the stockpile for approximately a period of 12 - 18 months (to disrupt the stockpile prior to this time would risk a large-scale odour event)
• rapid trials onsite demonstrating a positive impact in reducing odour emissions
• biofilters as a well-established odour treatment technology.

As we establish our biofilter, we’ll implement further monitoring to ensure that it’s functioning as it is required, and to inform ongoing maintenance. This is likely to include frequently checking moisture levels and biofilter depth.

When sludge sits undisturbed, it forms a hard crust. This crust traps odours and stops them from spreading. We’re confident that the warm and dry weather will help the crust re-form following heavy rainfall in the past few months.

The mulch biofilter acts as a cap to the stockpile. Left undisturbed, odour is expected to be reduced and remain localised.

Once the material is stabilised, we’ll aim to reuse the biosolids – most likely via land application as a beneficial soil conditioner.

We’ll keep neighbours and the surrounding community updated with the latest information as we undertake further action.

Prolonged maintenance works and severe weather led to higher odour emissions

Technical issues at the TDF in September / October meant the temporary storage of wastewater sludge in the lagoon on Black Rock Road had to be extended beyond our original plan. Initially, we had scheduled to transfer the stockpile back into the facility within a few weeks once maintenance was completed.

Other factors, such as extreme winds and heavy rainfall, has exacerbated odours being released from the stockpile.

Additionally, due to a power outage for the Barwon Heads and Connewarre area on Saturday 22 November, the Biosolids Thermal Drying Facility at the Black Rock Water Reclamation Plant experienced a temporary shutdown, which resulted in a release of odour. We followed up with the facility operator immediately to confirm that the equipment has been reset and to ensure the facility is operating as it should. This temporary increased odour on Saturday morning is unrelated to the recent odour caused by the nearby biosolids stockpile area.

How to report odour issues to Barwon Water?

We continue to encourage residents to provide feedback, as your input is invaluable in helping us monitor and address local concerns promptly.

If you’re noticing increased odour near your property, please call 1300 656 007, press 2 for ‘service fault’ (24/7). Calling us directly will enable our operational team to quickly investigate any further causes to the issue and devise a response in coordination with our regulators.

While this odour poses no physical risk to human or animal health, we recognise it causes impact to our neighbours and people working on the site. We apologise for this and thank you for your patience and understanding as we work through these odour issues.