Awards for Excellence - 2018 Stormwater Victoria WinnersEXCELLENCE IN STRATEGIC OR MASTER PLANNING
Shaping our water future: Ballarat City Integrated Water Management Plan
EXCELLENCE IN INFRASTRUCTURE
EXCELLENCE IN ASSET MANAGEMENT
Lincoln Square Flood Mitigation and Stormwater Harvesting – Purge Analysis
Kingston Stormwater Quality In-lieu Contributions Scheme
EXCELLENCE IN INTEGRATED STORMWATER DESIGN
Gippsland Heavy Industrial Wetlands
At the height of the millennium drought, Ballarat was a city in water crisis with dry lakes, brown recreational areas, dusty sporting grounds, floundering gardens and community event cancellations. Over the past decade, the planning paradigm has shifted from responsive crisis mode to a systematic planning approach. This evolution of planning maturity initially created a series of collaborative projects and initiatives that alleviated drought impacts and generated support and leverage to create long term plans and build a secure water future. This commitment to collaboration and sustainable planning has culminated in the community articulating a clear vision for the future and the development of an integrated water management plan for the Ballarat City.
Ultimately, the plan delivers a roadmap of outcomes for implementation which includes:
A consultative planning process was central feature of the plan. It was highly constructive and provided significant insights into community aspirations and long-term improvements. The Ballarat community demonstrated a passionate interest in protecting their natural environment, waterways, lakes and green spaces while ensuring a secure water supply future. These insights were unlikely to have been gained through quantitative analysis only, and the plan demonstrates how meaningful engagement can underpin a successful delivery plan that has real buy-in.
Booran Reserve is a unique project, which saw the redevelopment of the former Caulfield Water Service Reservoir, which was decommissioned in the late 1970s, into a sustainable, recreational and educational space for use by the local community. In 2010, Council was appointed to manage the site, which had been disused for more than 30 years, on the basis that it would be redeveloped for public open space. To honour the site’s original use, the project aimed to use a water theme to provide opportunity for environmental education, whilst ensuring sustainable operations through ESD features to minimise energy and water usage.
From an environmental sustainability perspective, numerous specialised design elements, building techniques and automated systems have been used to deliver long-term, measurable sustainable outcomes. More than 95 per cent of the existing site materials were recycled and re-used, with on-site concrete crushing and screening, soil sifting and reconditioning, and retention of some key structures and elements as heritage features. The site is equipped with energy management, irrigation and lighting systems, solar power to offset day time running of an underground water play plantroom, irrigation plant room, two toilet blocks and CCTV, a 500KL stormwater harvesting and treatment system used for irrigation and toilet flushing, and WSUD to improve water quality.
From a project management perspective, it was a highly complex project requiring diverse engineering input to deliver sustainable outcomes.
The City of Casey is growing rapidly and has a growing number of WSUD assets that have been constructed through capital projects and inherited through development.
When Council developed the Integrated Water Management Strategy in 2015 it was noted that the water sustainability outcomes expected from the significant investment in infrastructure were not being realised with many assets underperforming due to lack of active maintenance. Council developed the Integrated Water Management Plan to provide the strategy for achieving the desired water quality and water saving outcomes. This was used as the driver for committing funding to improve existing stormwater assets. Various partners were engaged to assist with auditing, development of technical specifications, design and construction renewal. Specialist advice was provided on why schemes weren’t working as expected, and what would be required to improve their function.
Council devised a program of auditing to understand how assets could be improved. Audits were completed with the assistance of consultants which then developed the scope for the renewal projects.
A list of upgrade and renewal works was provided for both the WSUD and GPT assets and Council invested in taking an underperforming system to one that met expectations for water quality improvements. The cost of the renewals has been on average 10% of the asset value. This was considered to be a very good investment for Council to get WSUD and GPT assets working properly.
E2 Design Lab provided the audit and recommendation for 8 WSUD sites in 2015 followed by an audit and Technical Specifications for 14 sites in 2016. Optimal Stormwater provided the audit and recommendation for 26 existing GPTs in 2015/16 and Stormy Water Solutions provided the audit and recommendation for 22 WSUD sites in 2017. The outcomes included recommendations and technical specifications for the renewals works. Council subsequently went out for tender with two different WSUD renewal tenders covering 25 WSUD assets and 5 GPT assets which related to the highest priority WSUD and GPT assets. Felix Botanica has been engaged as the lead contractor for the renewal work for the last two contracts.
This project explores the increasing demand for stormwater harvesting systems to comprise the dual objectives of water supply and flood detention in a highly urbanised area facing climate change and increasing density of urbanisation. The City of Melbourne identified the Carlton Squares green spine, comprising Lincoln, Argyle and University Squares, as a forefront opportunity to provide the desired water supply and flood mitigation benefits. This area lies within the upper portion of the flood prone Elizabeth St drain catchment, classed as ‘extreme’ under Melbourne Water’s flood risk classification. As such flood mitigation was a key driver of the project. In competition with this, Council proposes stormwater harvesting as a means to provide a resilient water supply option for irrigation of the three parks.
Diversion, capture and storage options were investigated and performance was assessed based on the reliability of water supply via water balance modelling optimised against the results of a peak flow detention model expressing the impact of the system on a flood event. Climate change scenarios were also investigated to assess sensitivity.
To maximise stormwater harvesting yield the tank needs to be full. However, to maximise flood mitigation potential the tank needs to be empty. These conflicting objectives lead to the concept of purging the tank before a large rainfall event and then leaving the tank full after that event had passed.
To optimise sizing of infrastructure to achieve the project objectives an iterative modelling approach was adopted. System performance was assessed by a coupled water balance and peak flow assessment. The reliability of water supply via water balance modelling was optimised against the results of a DRAINS detention model expressing the system’s impact on a 1 in 20 Year event.
The water balance accounted for detention requirements by anticipating storm events (hours ahead), and emptying the storage accordingly. This simulates a warning system that links to flood warning data activating an actuated gate valve to release water.
Storm previously designed all the infrastructure and controls to facilitate the purging of the tank prior to a pre-determined rainfall however the question is how this should be operated to maximise detention without compromising stormwater harvesting yield. Storm’s Principal Engineer had visions of operating the storage like the large dams are operated in a flood. Therefore, specific algorithms had to be developed to operate the actuated valve that releases the stored water and creates airspace for detention. This was named purge analysis.
The optimised system became a 2 ML storage tank pumping to header tanks at each of the squares for irrigation. The detailed design of the system includes a flood warning component within the controls that links to live weather data. The weather data sends a warning in advance of a flood event which triggers an actuated gate to release stored water and allow detention space at the onset of the event.
Driven by the stormwater quality best practice targets in Kingston Integrated Water Cycle Strategy and concerns over the performance and longevity of privately built stormwater quality assets in Kingston, Council has explored over the past five years how it could best improve stormwater quality in the municipality.
Kingston’s evaluations have shown that the municipality cannot meet the stormwater quality targets in the Strategy or SEPP(WoV) targets within a reasonable timeframe by relying on privately built stormwater assets and smaller streetscape treatments alone.
Kingston’s evaluations showed the most cost-effective means of achieving stormwater targets is for Kingston to build and manage an alternative type and scale of Water Sensitive Urban Design (WSUD) project compared to lot-scale.
Modelling work undertaken by DesignFlow in 2013-14 identified 31 locations where Council could implement medium scale WSUD projects. These medium scale council projects will primarily be located on passive open space within Council reserves. Importantly, the modelling work concluded that medium scale projects were more cost effective than small scale projects. On average, constructing:
Implementation and maintenance of the 31 medium scale Council projects requires an investment in the order of $27.5 million between now and 2030. With rate capping Kingston does not have the money available to fund the building and maintenance of a significant stormwater management portfolio.
To achieve better stormwater outcomes and provide flexibility for developers, Kingston City Council determined to introduce an option for off-site stormwater mechanism into their planning process. This mechanism embeds a sustainable approach to Integrated Water Cycle Management into planning by allowing developers and property owners to pay a fee to Council in-lieu of meeting all or a portion of their best practice environmental management guidelines (BPEMG) stormwater compliance obligations on-site. Council then uses these funds to the 31 medium scale WSUD projects off-site that deliver equivalent or better stormwater quality outcomes.
The in-lieu mechanism developed for the Kingston scheme represents a significant policy innovation in terms of stormwater funding policy in Melbourne and Australia. These innovations mean that the in-lieu mechanism developed by Kingston City Council reduces many of the risks and downside outcomes associated with other offsite stormwater mechanisms that have been implemented in Melbourne and other Australian capital cities, such as stormwater offsets and developer charges.
Since inception in 2017 and formal launching in January 2017, Kingston has received 46 applications for contributions, and received just over $500,000 in in-lieu payments. The largest payment has been $61,000 for an industrial warehouse development of 6,400 m2 impervious area.
The striking architectural design focussed on being a fully functioning system to treat industrial stormwater of its pollutants and contaminants to levels greater than required, while taking into account cost/ benefits, life cycles, maintenance duties, community opportunities and environmental outcomes.
The wetland is located on the edge of an industrial estate so was previously never used by community. It is now a well-used and visited space by many members of the public and user groups for recreational and educational purposes. It has been as incredible transformation to see people travel to what is essentially still an industrial site to enjoy what is now a fully functioning ecosystem and community walking spot.
Some of the wetlands features include:
The site has also been used to trial the outcomes of floating wetlands installed within a local government area. A partnership with the local university has been a collaborative innovation, primarily to undertake independent testing and monitoring of the site and floating wetlands, as well as provide hands-on experience for students. The site has been the focus of much interest in the trials, testing and findings from parties across Victoria and Interstate.
The intense monitoring programs on this site have concluded new methods of managing this type of asset and this facet will continue to be developed further. The project has set a high standard for continued learning and development in this increasingly growing field.
With community being our biggest stakeholder, it was key to ensure locals had a significant involvement with the project. Community members assisted with a much of the soft landscaping. Community engagement projects were delivered most days throughout the project, even during the civil construction works. Community member have great pride and ownership of this project which has seen it succeed in a way not seen in other WSUD assets. It has helped to increase community’s knowledge about these types of assets and their function.
The surrounding environment has greatly benefited from the improved water quality and enhanced environmental outcomes.
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|2018 Stormwater Victoria Conference
WEDNESDAY 6TH – FRIDAY 8TH June, 2018 | sheraton melbourne hotel, VICTORIA