Wastewater Infrastructure Expansion

Mount Barker Wastewater Treatment Plant 

Expansion to Service Growth

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 the next 20 years from a current population at 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. 

 

With the MDPA Council have developed a ‘Wastewater Strategy to Service Growth’ (the Strategy) which has been regularly reviewed and updated to reflect Council’s future strategies by considering public health outcomes and wastewater management principles. The Strategy, with an estimated delivery cost in the range of  $55 - $66M in capital expenditure (to be developer funded), identifies a long term plan utilising existing wastewater infrastructure wherever possible to accommodate future growth in the above mentioned MDPA zones.  This infrastructure expansion includes the necessary capital investment relating to trunk main collection network, treatment and disposal.

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. 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.

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. 

 

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

A final layout is yet to be settled.

 

Project Stages

The current aerated lagoon is neither capable of meeting the future capacity nor able to meet the required treated effluent quality without significant upgrade. The upgraded treatment plant at Springs Road will receive 11.1 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 that 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 in 2027/28 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:

  • 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 two (2) main sources for funding the delivery of the project will be through Annual Service Charges and Infrastructure Connection Fees.

 

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.

 

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.

 

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 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 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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