The Sewerage infrastructure network in the Bega Valley Shire consists of:
The diameter of sewer mains depends on the number of properties served. The minimum diameter is 150mm. Sewer mains are made of a variety of materials including polyethylene (PE), unplasticized polyvinyl chloride (uPVC), vitrified clay (VC), asbestos cement (AC), cast iron (CI), ductile iron (DI) and concrete.
The diameter of the low pressure sewer mains ranges from 40 mm up to 225 mm. Pipe material is high density polyethylene (HDPE). Other features of low pressure sewerage systems include isolation valves, flushing points, air release valves and check and stop valves at the junction of each property connection with the pressure sewer main.
Sewerage assets are operated and maintained to:
Levels of service for sewerage assets include:
Frequency of system failures:
Response time to system failures:
Assets are continually assessed for condition and serviceability. Condition assessment involves consideration of the material, asset age and identification of defects and deterioration. Serviceability assessment involves consideration of hydraulic performance, energy efficiency, frequency of maintenance and repair, break history, complaints and performance in comparison with levels of service.
Asset renewal and new asset programs are based on condition and serviceability assessments.
The replacement value of sewerage assets is estimated at $230 million. The average annual operation and maintenance expenditure required for sewerage assets is estimated at 2.3% p.a. or $5.29 million. This relatively high annual capital expenditure is to maintain a high standard of asset condition and ensure a reliable service and positive environmental outcomes.
More information on renewal expenditure can be found in the following documents:
Routine maintenance is regular on-going work that is necessary to keep sewerage assets operating. Maintenance includes:
Council’s Water and Sewerage Services Area Field Teams and Technical Services Team implement reactive, proactive and cyclic sewerage asset maintenance under the supervision of the Water and Sewerage Network Operations Superintendent and the Water and Sewerage Operations Coordinator.
Maintenance Work Reports are completed by the field teams after maintenance works are undertaken. The Maintenance Work Reports are provided to the Water and Sewerage Services Management Team to update Council’s AssetPlan asset management system for scheduling investigations and capital upgrades.
Asset renewals are capital works to restore, rehabilitate, replace or renew water supply assets to their original service potential. Renewals do not increase the design capacity of the assets. Sewerage system renewals include:
New assets are required to improve existing assets beyond their capacity and/or to provide a higher level of service. This occurs as a result of growth, social or environmental needs and/or changes to statutory requirements or regulations. Over the next 5 years we will be building a deep water ocean outfall at Merimbula to replace the existing beach face outfall and also upgrades to Merimbula STP to improve effluent quality.
An ocean outfall was selected by a community and stakeholder focus group as the best effluent disposal option based on a range of environmental, economic and social criteria.