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.

 

Background

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 three 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 it is important that alternative disposal paths be identified to limit the discharge of treated effluent into the Mt Barker Creek. 

Concept Plans

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 Mount Barker Wastewater Treatment Plant (WWTP) upgrade Consultancy Study consisted of the following three stages:

  • Stage 1 –  Development of an overall wastewater treatment approach
  • Stage 2 – High level process assessment of four treatment options to evaluate them and select a preferred treatment option
  • Stage 3 – Further concept design development of the preferred treatment option and procurement/delivery strategy.

Stage 2 of the Downer Consultancy Study concluded that the Membrane Bioreactor (MBR) treatment technology is to be considered as the preferred treatment option for the future expansion of the existing treatment plant. Mt Barker District Council endorsed this preferred treatment option for further concept development as part of stage 3 of the Consultancy Study.

 

Typical Membrane Bioreactor (MBR) Treatment Plant Layout

Stage 3 of 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.

Concept Design WWTP

Typical MBR Plant Layout

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.

Lagoon Storage

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.

 

Project Stages

The current collection network and aerated lagoon treatment plant are neither capable of meeting the future capacity nor able to meet the required treated effluent quality without significant upgrade. With the expansion of the wastewater collection network within the MDPA zones, the upgraded treatment plant at Springs Road will receive ober 11 ML/day ADWF in 2049/50. The staged upgrade of the treatment plant to service ultimate growth of 60,000EP, will occur over two stages. 

The first stage of the upgrade works, which is scheduled to be constructed and commissioned by 2020, will ensure a treatment capacity of ADWF of 6.0 ML/day. Stage 2 of the upgrade is planned to occur within the 2028/29 financial year with the ultimate plant fully operational by the end of 2028 for an ultimate treatment capacity of 11.1 ML/ day ADWF (60,000EP).

The plant design flow rates for two stage upgrade are presented in the table below.

Plant design flow for two stages upgrade

 

 

Stage 1

Stage 2

Ultimate

Average Dry Weather Flow (ADWF), ML/day

6.0

5.1

11.1

Peak Dry Weather Flow (PDWF), ML/day

(2.5 x ADWF)

15

12.75

27.75

Peak Wet Weather Flow (PWWF), ML/day

(6 x ADWF)

36

30.6

66.6

 

Council’s target timings for stage 1 are as follows:

  • May 2018 – Completion of Downer Consultancy Study
  • May 2018 - Decommission and Desludging of existing Storage Lagoon
  • December 2018 – Detailed design complete
  • February 2019 – Commence enabling construction works
  • September 2020 – full operations hand-over

 

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. 

 

Project Stakeholders

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.

 WWTP Buffer Zone

 

Community Engagement

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  council@mountbarker.sa.gov.au  or on 08 8391 7200.   

 

 

 

 

6 Dutton Road, Mount Barker SA 5251
T 8391 7200
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