Mount Barker Wastewater and Recycle Water Infrastructure Upgrade Project
The Mount Barker District Council currently operates the largest South Australian Council CWMS scheme utilising proven management processes and procedures. It is a licensed Water Industry Entity and considers itself well positioned to provide wastewater solutions to the future growth areas.
The existing Mt Barker Wastewater Treatment Plant services wastewater catchments within the Mt Barker, Littlehampton, Nairne and Brunkunga Townships.
In December 2010 the State Government rezoned a large amount of land within the Council area (particularly in Mount Barker and Nairne townships) to accommodate state population growth. This Ministerial Development Plan Amendment (MDPA) resulted in the rezoning of approximately 1,300 Ha as residential development. Many developers in the MDPA area have signed agreements with Council (approximately 3000 lots).
The major township of Mount Barker has been growing at a consistent rate of 3% p.a. for the past decade and is forecast to grow by 64% over a 20 year period based on population data obtained from the 2016 census of 33,810 to 55,416 by 2036. This rezoning will almost certainly ensure that this trend continues in the foreseeable future. With this growth Mount Barker will become the second largest city in the State after Adelaide.
Council is developing a Strategy to upgrade and expand existing wastewater and recycled water infrastructure to service growth within the MDPA area and also to provide acceptable Levels of Service to existing customers during the growth period. The upgrade and expansion of infrastructure will reflect Council’s future strategies by considering public health outcomes and wastewater management principles.
The strategy will encompass the staged upgrade of wastewater and recycled water infrastructure within the following service sectors:
- Upgrade and expansion of collection networks within the MDPA zone – i.e. Littlehampton, Nairne and Mt Barker (Eastern, Central & Western)
- Gradual upgrade of aging septic effluent infrastructure in Mt Barker CBD to sewer collection network
- Staged upgrade of the existing Mt Barker lagoon based wastewater treatment plant to a biological treatment plant that will produce high quality effluent to assist in management of the expected increasing influent volumes and changing influent water quality within the catchments.
- Upgrade and expansion of wastewater disposal scheme to sustainable commercial markets within the Mount Barker region to ensure beneficial reuse of recycled water
Stage 1 of the strategic upgrade of the existing wastewater and recycled water infrastructure will be completed over the next few years with an estimated delivery cost in the range of $60 - $70M in capital expenditure.
The staged upgrade of the Mt Barker WWTP expansion will deliver on the following strategies associated with the Mount Barker 2035 District Strategic Plan:
Community Wellbeing (CW)
- CW 2.7 – Provide a wastewater treatment service to deliver public health outcomes
Urban Environment (UE):
- UE 5.1 - Continue to build on Council’s reputation as a leader in wastewater management
The Mount Barker Wastewater Treatment Plant currently treats an average dry weather flow (ADWF) of approximately 4.2 ML/day using aerated lagoon followed by pre-treatment storage lagoon and tertiary treatment processes. The treated effluent is either discharged to the Mt Barker Creek via Laratinga wetlands or diverts for further treatment to produce South Australian standard Class A reclaimed water for reuse.
Currently the Mount Barker District Council catchment zone produces approximately 1.2GL of recycled water per year from the Mount Barker Wastewater Treatment Plant (WWTP). The volume of recycled water is projected to increase significantly over the next 20 years as residential development progresses in the area. The commercial market for recycled water in the Mount Barker region is currently limited to some local agricultural enterprises and the mining industry.
The major disposal path for the treated wastewater from the Mt Barker WWTP has been through the sale of recycled water to the Hillgrove Mine. Given the limited life of the mine Council is actively engaging with local markets to secure alternative disposal paths to limit the discharge of treated effluent into the Mt Barker Creek.
Downer Utilities Pty Ltd was engaged on the 28 August 2017 to undertake an ‘Investigation & Project Development Study’ for the staged upgrade of the existing Mt Barker WWTP to accommodate increase plant flows. This is a multi-disciplinary engagement considering the design envelope for the future plant expansion to provide engineering assessments of possible treatment options, commercial considerations, staging, capital/operational costs and procurement options that reflect key risks and mitigation strategies.
The Downer Consultancy study concluded with the submission of the Final Downer Concept Design report on the 12 June 2018 that included all updates in line with commentary returned by Council Officers and external subject matter experts that included commentary from regulatory authorities. This report will form the basis of further development of the concept design and tendering process.
Typical Membrane Bioreactor (MBR) Treatment Plant Layout
The consultancy study has produced further concept design development of the proposed treatment plant and a 3D model of preliminary plant layout is included below.
Due to limited footprint on the existing MT Barker WWTP site the construction of the new MBR treatment will occur within the existing storage lagoon (eastern lagoon). Mount Barker District Council is in the process of decommissioning of the eastern storage lagoon to ensure timely delivery of the necessary construction work in 2019.
Future Mt Barker WWTP 3D Model Fly-Through Image
The photo below the shows the state of the existing storage lagoon where the majority of the effluent within the lagoon had be drained down and treated for disposal through the exiting recycled water scheme. The drain down and disposal of the effluent will have no adverse impact on the receiving environments.
Once this lagoon is fully decommissioned, Council will commence with the desludging and rehabilitation process to ensure the space made available within the lagoon footprint will be fit for purpose to allow the construction of the new wastewater treatment plant or improve the treatment capabilities of the existing plant.
With the conclusion of the Downer Study Council has now an opportunity to review present short- and long-term strategies for the upgrade of existing wastewater infrastructure to service growth. This internal review process, with the support of selected external subject matter experts, will consider key drivers for the establishment of Council’s strategies and delivery models for the execution of the work associated with stage 1 of the upgrade.
To support Council has commissioned various interim Consultancy Studies to inform the overall strategy for delivering the Wastewater and Recycled Water Upgrade works to service growth and economic development that focus on the following key elements:
- The development of a Business Case for the staged upgrade and expansion of wastewater and recycled water infrastructure ensuring Council maintain a viable financial position;
- Delivery of a market sounding consultancy to enable Council to expand its Recycled Water precinct with the Southern Mt Lofty Region;
- Assessment of the wastewater collection network infrastructure expansion strategy with Mt Barker CBD and Nairne Township;
The consultancy studies will consider the following key criteria to support Council’s development of a strategy to upgrade existing infrastructure to support future population growth in the region and to satisfy stringent regulatory requirements:
- Staged upgrade of the existing Mt Barker WWTP to limit Council’s initial capital expenditure;
- Consideration of sustainable and innovative wastewater treatment solutions that will achieve all project objectives with capital expenditure and operational costs that clearly demonstrate value-for-money;
- The loss of a significant water recycling customer when the nearby Hillgrove open cut mine reduces its operations. It is assumed that the recycled water consumption at the mine will be nil by the end of the 2020 onwards;
- Establishing and managing replacement and additional reuse options / irrigation customers and necessary infrastructure in a timely fashion;
- Ensuring acceptable recycled water quality is maintained as future wastewater flows and loads increase;
- Ensuring acceptable discharge water quality is produced to maintain the ecological values linked to the Laratinga Wetlands and Mount Barker Creek to meet regulatory and community expectations;
- Ensuring acceptable plant operations are maintained during the construction phase;
- Minimise environmental impacts – i.e. offsite odour and noise impacts.
Outcomes of the Interim Consultation Engagements and feasibility studies will support the following key deliverables to support the decision making process:
- The development of a Business Case for the preferred Mt Barker WWTP upgrade option.
- Refinement of the financial model for the preferred upgrade option.
- Minimise Council’s investments by staging of the plant. This includes giving due consideration for staging sub components for the ultimate treatment plant.
- Treatment option and will deliver on the requirement to limit the impact on receiving and local environments (effluent quality, noise & odour)
- Technical requirements/specifications as guidance for future design and construction engagements.
- Procurement strategy for delivering the staged upgrade of the WWTP and associated services (i.e. collection, treatment & disposal)
Funding the Project
The Mount Barker District Council wishes to provide a financially sustainable wastewater service on a full cost recovery and ‘beneficiary paid’ basis. The stage 1 capital expenditure will initially be financed by Council with the long term return on investment occurring through three (3) main sources – i.e. Annual Service Charges, Infrastructure Connection Fees and the sale of recycled water.
Annual Service Charge - Annual Service Charges are based on Council’s objective to achieve a long term price path that sustains the business. As per ESCOSA Guideline No 3, Council seeks to recover the full cost of providing the service from the users of the service. The full cost of the service equates to a “whole of life” approach to determine costs and includes Plant operation and maintenance costs; capital renewal and plant upgrade costs to achieve the required Levels of Service (LOS).
Infrastructure Fees (Developer Contribution fees) - Infrastructure Fees are also set in accordance with the ESCOSA Guideline No 3 where Council seeks to recover the cost associated with capital expenditure in full via Infrastructure Fees. The Infrastructure Fees will be gradually received over time from developers as triggered by development. Council has currently secured legally binding commitments from developers via ‘Wastewater Commitment Deeds’ to service the Mount Barker growth area with negotiations continuing to seek to increase this number.
Sale of Recycled Water - Many water authorities, and water utility providers, around Australia have generally viewed the market for recycled water as one of “disposal” with commercial sale typically a requirement to ensure a cost-neutral commercial outcome. The upgraded of the Mt Barker WWTP to produce high-quality effluent, and the expansion of the recycled water scheme, present a real opportunity for Council to reframe its approach and position of creating a viable and sustainable commercial market in the Mount Barker region for beneficial reuse of recycled water.
Managing the Facility
Council is still investigating the preferable procurement model for managing and operating the new expansion of the Mount Barker Wastewater Treatment Plant to ensure satisfactory services to the broader community. Details of the facility management model(s) will be communicated in due time once Council Members had agreed on the desirable model.
The Mount Barker Wastewater Treatment Plant Staged Upgrade has a large, complex and diverse range of stakeholders including:
- The Environment Protection Agency (EPA)
- Essential Services Commission SA (ESCOSA)
- SA Health (DHA)
- Office of the Technical Regulator (OTR)
- Department of Environment, Water and Natural Resources (DEWNR)
- Developers within the MDPA zones
- Adjacent Land Owners (Land Owners within, or adjacent to the Mount Barker Wastewater Treatment Plant Buffer Zone)
- Land Owners downstream of the WWTP discharge point to the Mt Barker Creek.
The community engagement process will mostly entail the announcement of key project decisions and milestones to keep local Land Owners, and where deemed necessary, the broader community well informed. In saying this Council will work closely with the Regulatory Authorities to confirm the extend of community engagement to be undertaken to gain approvals where licensing conditions are being impacted by the work.
In general a community engagement plan will be developed to make information available to Local Land Owners, and the broader community, of the wastewater treatment plant expansion concept plans, pending development approvals and timing of the works.
Project Point of Contact
If you have any queries regarding this project, please email Thomas Coetzer, Senior Project Manager Wastewater Infrastructure Expansion at firstname.lastname@example.org or on 08 8391 7200.