Water storage dams and flood detention basins are complex structures that need careful management to ensure they are fit for purpose and the dams’ performance and public safety is maintained. Providing services for dam safety is a natural extension of our extensive work in floodplain management and internationally recognised expertise in flood emergency response planning, evacuation analysis, flood damage estimation, flood warning systems and community education. Our services include dam safety documentation including operation & maintenance manuals and emergency management plans (EMP's), dam safety inspections, dam surveillance reviews and reporting, risk assessment and hazard/consequence classification.
Stage 1 Paradise Dam Safety Risk Profile Mitigation Study
Paradise Dam is located on the Burnett River upstream of Bundaberg. The dam was constructed in 2005 with the primary purpose of providing irrigation water. During the 2011 Queensland floods, a large flood flow occurred at the dam that activated the spillway and partially damaged the dam. This was followed by a much larger flood that occurred in 2013. Investigations and risk assessments were undertaken into improving the safety of the dam as well as looking at the potential for increasing the dam capacity through raising the dam wall. A key action was that SunWater reduce the risk profile at Paradise Dam through actions to improve the emergency management and response.
Molino Stewart was engaged undertake an external literature review to investigate the premise that improving emergency management response capability would indeed reduce the dam safety risk profile.
Dam Surveillance & Reporting for Flood Detention Basins in The Hills Shire Council Area
Molino Stewart conducted regular dam surveillance inspections of 22 flood detention structures, including four which are prescribed dams. We also prepared Dam Surveillance Reports and Dam Safety Emergency Plans and undertook dam failure analyses for the prescribed dams to meet Dams Safety Committee requirements.
Three Tributaries Floodplain Risk Management Study and Plan
Molino Stewart was engaged by Fairfield City Council to undertake the development of a Draft Floodplain Risk Management Study and Plan for the three major tributaries of Prospect Creek within the Fairfield local government area. The project addressed the flooding, environmental and planning issues associated with the management of flood prone land within the catchment areas of the tributaries, as well as assessing the status of the detention basins within the catchment. This also included dam safety analysis of 10 detention basin, which involved geotechnical investigations, dam break modelling, consequence analysis and dam safety emergency planning. Dam Safety Emergency Plans were developed for the nine basins which required them.
Following this initial work, Molino Stewart was appointed in 2021 to prepare additional dam safety reporting. Specifically, we prepared Operations and Maintenance Plans for 11 declared detention basins in the LGA, to meet the requirements of the 2019 NSW Dams Safety Regulation and the guidelines provided by DSNSW. Each plan contained site-specific maintenance inspection checklists, with diagrams or pictures of critical operations or maintenance issues. Council also commissioned Molino Stewart to create Emergency Plans for six declared detention basins and the determination of consequence category, societal and individual risk for four of them. Each plan needed to comply with the recently released DSNSW guidelines for Emergency Plans.
Liverpool Detention Basin Safety Management
Molino Stewart has been engaged under various contracts to prepare surveillance reports for two detention basins, undertake dam break modeling and consequence analysis for eight basins, and prepare or update the Dam Safety Emergency Plans for ten basins. The work was based on meeting the requirements of the NSW Dams Safety Committee and ANCOLD Guidelines on Dam Safety Management.
Blacktown Detention Basin Dam Safety Emergency Plans
Molino Stewart prepared Dam Safety Emergency Plans for two prescribed flood detention basins within the Blacktown LGA to meet Dams Safety Committee requirements.
Paramatta Detention Basin Safety Surveillance
Molino Stewart has been undertaking dam safety surveillance inspections and reporting for Muirfield and Northmead detention basins since July 2016 when these two basins transferred to Parramatta City from the Hills Shire due to local government area boundary changes. Inspection reports are documented by Molino Stewart using a report template based on Dams Safety NSW guidelines.
Molino Stewart was later appointed to prepare the Emergency Plan, Operation and Maintenance Plan and Type 2 Surveillance Report for the two basins. All reports adopted a new layout to explicitly address the requirements of the 2019 NSW Dams Safety Regulations, and to adapt these to typical earthfill, passive detention basins. The reports were later audited by DSNSW and assessed as fully compliant.