Water Technology, through strong client relationships, has developed solutions to the most challenging flooding and stormwater management issues on all scales of development across Australia.
From one to two lots to tens of thousands of lot subdivisions, Water Technology’s solutions provide cost effective and workable solutions that achieve practical outcomes. Our staff are well known to local government authorities and our teams provide results that not only meet the required guidelines, but also maximise outcomes for the property owners through aesthetically appealing designs that enhance property value.
Our solutions are effective in achieving short and long-term goals, which result in long-term low maintenance costs. Through listening to our client’s requirements, we apply the development’s drivers to our design to ensure fit-for-purpose whole of water cycle management. We can also assist in 5-star rating compliance and UDIA’s EnviroDeveloper accreditation.
- Due Diligence Assessments
- Flood modelling, impact assessments and mitigation strategies.
- Stormwater Management Plans.
- Whole of Water Cycle Management and Integrated Water Management Strategies
- Water Sensitive Urban Design Assessments for Development Applications
- Flood Warning Advice and Flood Emergency Management Plans
- Conceptual and Functional Design of all forms of drainage assets
- EnviroDeveloper applications
- Urban Lake/ Canal/ Marina Water Quality and Turnover Analysis and Design
- Water quality monitoring and reporting
- Expert Witness Work
- Water Balance Modelling and Stormwater Harvesting
Nudgee landfill was formed adjacent to the Boondall Wetlands in 1976. The site was closed in 2002 with remediation completed in 2006. Water Technology staff were members of a team invited to undertake an ecological and water quality study to assess the influence of the Nudgee Landfill on the Boondall wetlands (now a RAMSAR listed site). The study included review of all existing monitoring and modelling data, as well as the design and implementation of targeted soil, water and biological monitoring program over a 2 year period. Automatic water quality and depth sensors (with data loggers) were used extensively. Manual sampling and laboratory analysis was also undertaken.
The Boondall Wetlands water quality monitoring sites were influenced by a number of interacting processes such as rainfall, tidal flushing, time of year and distance from Moreton Bay. Further, the impact of these processes on site water quality varies depending on the site and water quality parameter. Therefore, while the “raw” monitoring data may give a precise measure of water quality at the particular moment of sampling, the incomplete sampling coverage across all sites and times, along with the confounding effects of these various processes, meant that the raw data alone did not provide a complete description of water quality variation over time either at a site or between sites. Advanced statistical analysis was used to model and isolate the various physical, chemical and biological processes occurring within the study area.
The Boondall Wetlands have been subject to numerous historical changes apart from the construction of the landfill. These include, land clearing, drain construction, and waterway dredging. The study was able to isolate and identify the effect of natural and anthropogenic impacts on the wetlands.
Water Technology has been involved in the development of Wyndham Harbour since the early conceptual planning stages in 2003. The Harbour has evolved from the initial conceptual design through to final design and construction with the help of the Water Technology coastal and environment team. The key work items over the life of the project have included:
- Coastal processes and sediment transport studies
- Sampling and analysis of coastal sediments – Numerical modelling of harbour water quality, tidal and pump driven circulation and optimisation of harbour design and configuration
- Design and implementation of water quality testing and analysis programme
- Fate and transport of marine pollutants within the Harbour and the impact on Port Phillip Bay ecology – Breakwater design and optimisation through analysis of height, rock size, slope etc
- Management of verification of breakwater design through physical testing
- Assessment of dredging schedule and methodology
- Numerical modelling of impacts of dredging turbidity and optimisation of dredging and turbidity mitigation methods
- Application for Coastal Management Act Consent for Dredging
- Reporting to support the Environmental Effects Statement and presentations to the EES Panel hearing.
The work at Wyndham Harbour, combined with similar harbour and marine development projects at Martha Cove, Mornington Safe Harbour and Portarlington have provided Water Technology unparalleled experience and knowledge of the environment and coastal and oceanographic processes within Port Phillip Bay along with the procedure required to take a concept design to built product.
Water Technology was engaged to prepare specialist investigations relating to flooding and water quality associated with a proposed Childcare Facility in Surfers Paradise and to support a development application to Gold Coast City Council. The proposed development includes a childcare centre for around 44 children up to the age of 6 years.
The child care centre is located within the Nerang River Floodplain and is partially inundated under the 1% AEP flood event. A variety of technical assessments and investigations were undertaken in respect to regional flooding at the site and having regard to Council’s codes and policies relating to development within flood prone areas. Aspects investigated included flood storage and volume considerations for the site (and maintaining storage provisions following development), site egress and access provisions, flood impacts and non-worsening as well as building and flood immunity provisions. The technical assessments were successful in identifying a suitable site arrangement that satisfactorily addressed each of the Council performance criteria for flooding.
The specialist assessments also included the assessment of on-site stormwater quality and quantity measures to comply with Council’s development guidelines. A variety measures were investigated and these include a range of water quantity and water quality measures (including Water Sensitive Urban Design measures). The adopted stormwater strategy at the site comprised Rainwater Harvesting Tanks (RWT), Stormwater Detention Tanks, Bioretention Basin as well as Coarse Sediment Forebay system incorporated within the car parking areas.
In addition to the above, Water Technology also developed and prepared a Flood Emergency Management Plan (FEMP) for the site. The purpose of the FEMP is to provide management and staff of the business with detailed knowledge of flooding in the area and a concise framework for training staff on procedures should flooding be likely to occur due to heavy rainfall being experienced. The principal aim of the FEMP is to ensure that any risk from flooding to people that use the facility is low. The FEMP strategy devised for the site was designed to achieve full evacuation of the site prior to flooding reaching a threshold level upon which evacuation was not possible. The FEMP was successful in demonstrating that the site could operate in the manner intended as a child care facility within the context of the FEMP strategy to provide for the safe evacuation of the site.
Water Technology was commissioned to provide specialist services in the areas of flooding and water quality for the proposed 107 lot residential estate located at Jacobs Well in the Gold Coast. The 10 hectare site was subject to significant flood constraints which included regional flooding from the Pimpama and Logan Rivers as well as being located within an overland flowpath associated with an external rural/residential catchment some 60 hectares in area. Flood levels at the site were found to be dominated by storm tide conditions from the Broadwater.
The various sources of flooding that heavily constrained development of the site proved to be challenging in order to achieve a non-worsening outcome having regard to the development layout. A number of iterations were required to the master plan and development footprint for the site in order to reach a suitable development outcome which could be supported and approved by Council. Water Technology were able to define a suitable central drainage channel profile and arrangement to both address Council’s specific requirements as well as providing an acceptable flood outcome for the estate. Earthworks filling scenarios were also assessed in combination with the central drainage arrangements and internal road crossings to achieve suitable flood immunity outcomes for the development having regard to off-site impacts. A combination of 1D and 2D modelling was used for the flood and drainage assessments.
The services provided for the project also included stormwater quality management whereby various Water Sensitive Urban Design features were sized to fit within the proposed master plan. Inclusion of WSUD features as part of the developed also provided challenges given the limited area available within the estate.
Water Technology (WT) has provided specialist flood analysis and design services for the Heritage Estate Residential Development located on Foxwell Road in Coomera, Gold Coast. The estate will provide 122 low density residential lots ranging in size from 375 to 530 square metres. Water Technology have provided all specialist services relating to flooding and on-site stormwater quantity management (detention) for the development and assisted in securing development approval from the Gold Coast City Council.
One of the key aspects to the services was associated with the significant flood and drainage assessments required to provide a heavily engineered and modified central waterway corridor to service the estate. Through consultation with Council and civil designers, WT were able to incorporate an on-line detention basin within the central waterway corridor for management of stormwater and flooding for the site, as well as assisting in mitigating flooding to the downstream catchment.
The project is currently the subject for detailed civil design for future operational works approvals through Council. WT is continuing to provide specialist flood and stormwater services through the detailed civil design process and will continue to provide further assistance throughout construction as well as post-construction design certification requirements required for Council works approvals
Water Technology is often engaged by land developers of all scales to assist with proposals that are located within floodprone land. Through the use of the latest technologies and data sets, Water Technology can accurately define the potential impacts of any proposed development on floodplain depths, velocities, hazard and afflux to assist in approvals with local Councils, and Floodplain Authorities such as Melbourne Water and CMAs.
Water Technology was engaged by a local developer to assist in a small scale subdivision within the Land Subject to Inundation Overlay. After receiving a letter of objection from the Floodplain Authority, Water Technology worked with all parties to update the flood mapping in the area and suggest minor modifications to the site layout to facilitate better 1 in 100 year flood flows through the subject property. The study found that the development did not cause any adverse impact on the surrounding properties and flood levels and velocities within the development would not pose a risk to resident or visitor safety. The report resulted in the objection being removed and the development going ahead.
Rapid land developed is occurring in Lyndhurst in response to significant demand for new housing and industrial land. Water Technology investigated opportunities to optimise the footprint of retarding basins and wetlands. Due to the high cost of industrial land acquisition, footprint area was critical. Water Technology used a linked 1-d and 2-d model to optimise the design of a significant retarding basin for Melbourne Water. When compared to the initial hydrological (RORB) modelling, the results showed a significant reduction in the required basin footprint. The reduction in retarding basin footprint size resulted in significant cost savings to Melbourne Water due to the reduction in expensive industrial land required.
Since the completion of this study, Water Technology has assisted many developers in the area to work through detailed designs of channel crossings and basin construction, as well as the setting of appropriate floor levels to prevent flood damage and reduce flood risk. Extreme events such as the 500 and 1,000 year ARI events were also tested in the hydraulic model to test the performance of the basin in these conditions.
Water Technology was commissioned by Browns Consulting on behalf of Armstrong Creek Developments to document the flood behaviour of the Armstrong Creek Western Precinct for the development of Stages 1-6. Stages 1-6 were under construction as part of the multi stage development. The study detailed the hydrologic and hydraulic analysis of the study area in existing conditions with Stages 1 – 6 included. Water Technology undertook modelling using RORB and MIKE Flood packages to ensure that no adverse flood impacts are caused as a result of construction of stages 1-6.
A comparison between pre-development, current (stages 1-6) and full development was undertaken showing that the inclusion of Stages 1-6 have very little impact on flood conditions when compared to previous modelling of both existing and developed conditions.
Widespread flooding occurred over large areas of Queensland in December 2010 and January 2011. On the 17th January 2011 a Commission of Inquiry into the Queensland Floods of 2010/2011 was established (termed the Queensland Flood Commission of Inquiry (QFCI)). The QFCI released its final report on 16 March 2012. The report made 177 recommendations across a broad range of issues including floodplain management, land use planning, building regulations, insurance, mines, emergency management and dam management. The QFCI was the catalysts for the Queensland Flood Mapping Project (FMP). Phase 3 of the FMP was transitioned to the Department of Natural Resources and Mines (DNRM), Queensland.
Flood Risk Assessment and Hazard Mapping
Water Technology was commissioned by the DNRM to carry out flood risk assessment and hazard mapping for a total of 12 rural towns located throughout Queensland in two distinct stages. The towns assessed as part of the study included Condamine, Flinton, Dulacca, Goomburra, Isisford, Jandowae, Karara, Kolijo, Nebo, Woorabinda, Gogango and Goomburra Upper, and included seven Local Government Areas throughout Queensland including the Western Downs Regional Council, Southern Downs Regional Council, Mackay Regional Council, Rockhampton Regional Council, Woorabinda Aboriginal Shire Council, Longreach Regional Council and Isaac Regional Council.
The project included the preparation of two dimensional flood models for each of the 12 regional towns located throughout greater Queensland. The hydraulic models were validated to historical flood information provided by the DNRM which included flood levels, flood extent as well as anecdotal flood records available for each of the towns. Once validated, the hydraulic models were used to assess flood risks for a range of design flood events ranging in magnitude from the 2% AEP to 0.2% AEP events. Additionally, the models were also used to prepare a range of gauge increment maps to aid in emergency and disaster management functions. Extensive GIS mapping including flood animations were prepared to fully inform the outcomes from the flood risk assessments for each of the towns.
Water Technology was able to successfully deliver all 13 township flood risk assessments (comprising 48 separate TUFLOW models), including reporting, 170 GIS maps, and flood animations within a period of four weeks from commissioning. Water Technology was the only consultant to complete their studies on time and received great feedback from DNRM on the quality of the work and the manner in which it was undertaken.
The flood information generated from this project is provided to each of the Local Government Agencies throughout Queensland and will also ultimately be uploaded to the Queensland Governments Flood Portal FloodCheck, which is an interactive web portal to provide a centralised database and repository of flood related information for use by Local Government and other associated agencies.
If you’d like to know more about Queensland flood risk assessments and hazard mapping, please call +61 7 3105 1460.
Hepburn Shire Council
Creswick experienced significant flooding in late 2010 and early 2011 experiencing several large events in a short period. This had a devastating impact on the community.
Water Technology was commissioned to undertake a detailed flood study for Creswick to assist in providing the community with a greater level of protection from future flooding. The study involved detailed hydrological and hydraulic modelling of Creswick Creek, flood mapping, quantification and assessment of flood damages, and development and assessment of potential flood mitigation options.
A rainfall-runoff model was developed in RORB, which incorporated Creswick Creek, several tributaries and two upstream storages (Cosgrave Reservoir and St Georges Lake). A coupled 1D/2D hydraulic model was developed using MIKE FLOOD, to assess the extent of inundation, depths and water levels. Both models were developed using industry best practices and were rigorously calibrated and verified against historical flood events.
The hydraulic model was also used to test the effectiveness of a number of potential mitigation options, including deepening/widening of the creek, additional culverts and various levee alignments. A key element attributed to the success of this study was the active engagement of the community. This was developed over the course of the study and included community information sessions, questionnaires, media releases and meetings with the Technical Working Group and community based Steering Committee. The community concerns regarding levee heights were listened to and a level of protection was adopted to protect against the January 2011 flood level but which maintained the aesthetics of the township.
The final plan recommended a number of structural and non-structural options (warning systems, increased awareness and amended planning scheme overlays). As a result of extensive consultation, it was clear that the recommendations for Creswick had strong community support. Economic analysis indicated that the proposed mitigation option would reduce the cost of flood damages by up to 75%, with a benefit cost ratio of 0.8 (not including associated non-monetary costs).
The Creswick study has been held up as the example for all flood investigations to follow in Victoria. It led to an acceptable flood mitigation plan being developed and implemented in record time, and has dramatically reduced the flood risk for the Creswick community.