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Lake Cathie/Bonny Hills Sewerage Scheme

The Lake Cathie/Bonny Hills Sewerage Treatment Scheme consists of a wastewater treatment plant (WwTP) which was upgraded in 2011.  The augmentation involved converting the process from an intermittent decant extended aeration plant (IDEA) to a continuous activated sludge process.  The WwTP is in Magellan Place, Bonny Hills.

The plant has a capacity of 12,000 EP - in other words, it has the capacity to treat raw sewage equivalent to that generated by a population of 12,000 people.    

Please refer to brochures:   "Wastewater - A User's Guide"1MB pdf(PDF, 1MB) and  "Wastewater Systems - How the system works 'after the flush'".2MB pdf(PDF, 2MB)

Pre Treatment

The incoming sewage is screened via two automated step screens to remove any solids larger than 10mm.  Grit removal is also utilised to remove any sand that enters through the wastewater system.  The screening and grit are disposed of to landfill while the remaining sewage continues on to the main process.

Main Treatment

The Lake Cathie/Bonny Hills WwTP treatment process includes the activated sludge secondary treatment via three continuous activated sludge tanks.  The activated sludge process concentrates the naturally occurring bacteria in sewage to remove the organic waste and reduces the nutrient load prior to discharge of the treated effluent.  The process also includes a large anoxic tank that increases the effectiveness of the nutrient removal from the sewage.

Following the activated sludge process the effluent is treated to a high standard with membrane filtration. The membrane filters provide a physical barrier filtering solids out down to 0.2 microns (0.0002mm) which not only removes all solid particles but also removes pathogens such as bacteria and protozoa. 

The effluent is further disinfected using UV lamps and chlorination which eliminate any microorganisms remaining.  The highly treated effluent is then gravitated through an 800 meter long sand exfiltration trench in the dunes behind Rainbow Beach at Bonny Hills.

Sludge Treatment

Sludge generated from the Lake Cathie/Bonny Hills WwTP is collected in four sludge lagoons on site, which hold the sludge whilst any water released is returned to the treatment process for additional treatment.

As with all other organic solids produced by wastewater treatment plants in the Port Macquarie-Hastings area, the biosolids are transported to the Cairncross composting facility to be incorporates into compost.

Please refer to the attached brochure: ' Wastewater - How it works - Lake Cathie/Bonny Hills Wastewater Treatment Plant1MB pdf(PDF, 1MB)' .

HEMS Scheme

In response to ongoing effluent disposal issues within the Local Government Area (LGA), and requirements of the Environmental Protection Authority (EPA) in the approval given for the augmentation of the Port Macquarie Wastewater Treatment Plant (WwTP) in 1995, Council following much public consultation adopted the Hastings Effluent Management Strategy (HEMS) in November 1998.

Options were developed for all existing plants based around the catchments into which they discharge effluent.  At the time HEMS adopted the broad principles of maximising the beneficial reuse of effluent within the LGA, whilst maintaining in the short-term the existing disposal system already in place.

The effluent reuse markets appearing most likely to provide for large scale irrigation include the dairy and agricultural industries, vineyards, privately owned playing fields in the LGA, and Council.  This would be achieved either locally around WwTP's or within catchments, or by ultimately constructing a network of effluent mains capable of transferring effluent from plant to plant within the LGA, or to reuse markets yet to be established.

Southern Effluent Pipeline Network

In response to the ongoing issues at the Lake Cathie/Bonny Hills WwTP, and under the banner of HEMS, Council adopted in March 2004 to continue to develop a southern effluent pipeline system based on a concept developed by Hunter Water Australia (HWA), transferring effluent from the Lake Cathie/Bonny Hills WwTP to effluent reuse markets in the southern area of the LGA.  The concept was developed to reduce the amount of effluent discharge to the sand dunes, maximise the amount of reuse in the area and cater for future development in the southern LGA coastal area.

The effluent pipeline from Lake Cathie/Bonny Hills WwTP to the Port Macquarie Golf Club is now complete and Council is currently pursuing Section 60 approval for this scheme. 

An application for the reuse of effluent from the recently augmented Camden Haven WwTP for irrigation of local residential estate areas is also underway in consultation with land owners to make use of the high quality effluent from the WwTP.

Effluent Reuse Strategy Revision

The Effluent Reuse Strategy is now being completely revised to take into account legislative changes, cost to produce, longer term beneficial reuse from carrying grades of treated effluent and the limitations in doing so.

The revised strategy provides future direction for effluent/reclaimed water usage in the Port Macquarie-Hastings LGA.

This page was last updated on: 18 June 2020