Updated 30 May 2013
CONTRACT COMPLETION FEBRUARY 2013
The existing Nambucca Heads Sewerage Treatment Plant was running close to its design capacity of 10,000 EP (Equivalent Persons) and was in need of upgrading. It consists of a trickling filter system constructed in the early 1970's and an extended aeration tank system constructed in the mid 1980's.
The augmentation works had a priority listing on the NSW State Government Country Towns Water Supply and Sewerage Scheme. Following Council's application for Stage 2 Section 60 approval to proceed to tender the NSW Office of Water have confirmed funding for 25% of the cost of the project. This subsidy applies to the cost of works involved in the investigation, design, documentation, project management as well as the accepted tender price for construction.
Council also secured a 10 year interest free loan from the Federal Government for $12M which will greatly assist in the funding of the project.
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.
The works involve the construction of a new 10,000 EP extended aeration tank to supplement the existing aeration tank together with a balance tank, sludge lagoons, sludge drying beds and a UV disinfection system. The existing trickling filter system will be demolished, however the overall capacity of the plant will increase by 5,000 EP to 15,000 EP and the effluent discharged will meet the requirements identified in the National Water Quality Management Strategy and ANZECC 2000. The augmentation works also involve the reconstruction of a number of sewage pumping stations and the upgrade of pumping equipment and switchboards in others.
Tenders for the construction works closed on 16 July 2009 and following a detailed review of all submissions Council resolved to award the contract to Monadelphous Engineering Pty Ltd. Monadelphous commenced work on site in November 2009. Council also engaged NSW Public Works (Coffs Harbour) to project manage the works.
Construction works on the project were severely delayed due to the consistent rainfall being experienced during the contract period. All works on the new treatment tank and pump stations have now been completed. Sewage was diverted into the new tank in early March 2012 and the treatment process has now stabilised.
Demolition of the old trickling fitter plant was completed in July 2012. There were a number of defects and variation claims to resolve prior to the payment of final claims and agreed completion of works in February 2013.
All sewage is currently being treated in the new aeration tank and the old tank has remained off line until such time as flows increase. This has provided Council with the opportunity to arrange for corrosion repair works to be undertaken on the aeration and decant structures in the tank as well as construct new inlet manifold pipeworks.
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 aquifer 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.
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