The Nambucca Shire water supply is a single source supply drawn from bores sunk into alluvial deposits adjacent to the Nambucca River upstream of the town of Bowraville. Studies have confirmed that the acquifer has limited storage capacity and cannot be expected to meet current and future water supply demands during periods of drought. During the drought of 2002 two of the eight bores began to run dry and it was estimated that there was between 30 to 60 days supply of water available when the drought broke.
The Bowraville Off River Water Storage Project was set up with the aim of providing a means for the Shire water supply to be secured against drought. The project that has been constructed was chosen from a range of alternative schemes in 2006, following community consultation. The project involved the construction of a series of new bores, collection tank, water transfer pipeline, water pumping station and a new water storage dam all within the Bowraville area. The water storage will be filled by pumping water from the enlarged borefield during times when river flow is not low. Environmental flows will be maintained in the river by feeding the stored water directly into the town water supply system during periods of low river flows.
The project was being delivered by Nambucca Shire Council with the assistance of the NSW Department of Public Works as Project Managers and the NSW Office of Water as funding partners with a final cost in the order of $54 million. The project is part of a wider integrated water cycle management strategy for the region which may also include further water conservation and effluent reuse measures.
The project was undertaken in three phases designated as the preconstruction phase, construction procurement and the construction itself.
The preconstruction phase involved the following works:
Council engaged NSW Public Works to manage the preconstruction phase of the project and GHD Pty Ltd were engaged to prepare the Environmental Impact Statement as well as the concept and detailed designs of the project infrastructure.
The Environmental Impact Statement (EIS) was completed in October 2009 and was placed on public exhibition for community comment until February 2010. The EIS was assessed by Council following consideration of all submissions and Council granted development approval for the project in October in 2010. Please click here to view the Environmental Impact Statement.
Detailed design of the project was completed in February 2012.
Council invited Expressions of Interest (EOI) for construction works on the project in July 2011 and 14 submissions were received. Following evaluation of the EOI submissions Council selected four contractors to participate in an Early Contractor Involvement (ECI) process with a view to being invited to tender on the construction work for the project.
The ECI process involved attendance at a number of workshops where the contract designs and documentation were reviewed in detail and the allocation of risks were clarified. This process aimed to ensure that any ambiguity in the documents was eliminated and all potential tenderers were fully informed on the project and expected outcomes prior to submitting a tender.
The ECI process also advised the contractors that the construction works would be let as two separate work packages. Package A was for storage construction including embankment earthworks, outlet tower, spillway, valve house and the access road. Package B was for the bores, collection tank, pump station, valve cluster and transfer pipework.
All contractors selected for the ECI process were subsequently invited to submit a tender for the construction works. These contractors were:
McMahon Contractors Pty Ltd (Package A & B)
John Holland Pty Ltd (Package A & B)
Haslin Constructions Pty Ltd (Package A & B)
Ledonne Constructions Pty Ltd (Package B only)
Tenders closed on 24 April 2012 and following a detailed evaluation of the tenders a report was prepared for Council recommending that the tender be awarded to two separate contractors – Haslin Constructions Pty Ltd for Package A and Ledonne Constructions Pty Ltd for Package B
At the ordinary meeting of Council on 11 July 2012 Council resolved to proceed with the construction project and award the construction contracts in accordance with the recommendation above.
NSW Public Works (Coffs Harbour) were appointed as project managers for the construction works and their team brought with them a wealth of experience from the recent construction of the Shannon Creek Dam for the Coffs Harbour and Clarence Councils.
Construction contracts were awarded in August 2012 with a contract completion period of 60 weeks. This contract time frame porved to be very optimistic as wet weather and changes to the scope of the work caused sigificant delays in the Package A contract in particular. Package A works were granted extensions of time that saw the completion date run out to November 2014. The package B works were completed in October 2013.
Photos of progress on the works can be viewed on the Dam Construction Photo Gallery link on Council's website.
Council secured funding assistance for the project from both the State and Federal Governments. The State Government provided a subsidy for 39.8% of the original contract price through the country town water supply and sewerage scheme. This amounted to $14.8 million. The Federal Government has committed $10 million to the project of which $1 million was contributed to the design work.
An extensive program of community consultation was an essential part of this project. Consultaton included regular newsletters, information in local media including the Nambucca Shire Newsletter and Hibiscus Happynings, and stakeholder briefings.
Council engaged consultants KJA, to undertake community consultation during the investigation and design phase of the project.
Council also arranged a number of open days during the construction period where members of the general public were invited to undertake a tour of the dam site to view construction progress.
The first water was pumped to the dam in September 2014 as part of commissioning works on the transfer pump station. Filling in earnest commenced in late November 2014. During filling Council is required to release a percentage of the runoff water from rainfall events to Bowra Creek. Once the dam is filled for the first time the continued operation will require all runoff water must be released. The dam is not expected to be completely filled until mid 2016.
The Off River Storage was offically opend by the Hon. Warren Truss, Deputy Prime Minister and Minister for Infrastructure and Regional Development, at a ceremony held on 28 February 2015.
The storage was named Bowra Dam.
You can find out more by contacting Council's Manager Water and Sewerage, Richard Spain on 6568 0234.
Council engaged the NSW Public Works (NSW Water Solutions) to prepare a concept design for an upgrade of the works along with a REF (Review of Environmental Factors) to investigate the likely social and environmental impacts of the proposal.
An Environmental Impact Statement (EIS) was prepared on behalf of Nambucca Shire Council for the proposed Bowraville Off River Water Storage in the Nambucca Valley.
Bowra Dam Construction Gallery Feruary 2013