Securing future water supplies is top of the agenda for Australian water provider, SunWater. Here the company gives IWP&DC an insight into its hydro and dam activities
With the spectre of permanent climate change and some 13 years of crippling drought impacting southern Australian states, Queensland to the north is gearing up its water security strategies. As Queensland’s leading commercial water provider, one of SunWater Limited’s most important ongoing activities is supporting the Queensland Government’s Statewide Water Policy.
In the northwest region of Australia, SunWater is reviewing local government proposals for a 300,000 ML dam and 195,000 ML off-stream storage to harvest seasonal floodwaters from the vast flows of two monsoonal river systems. These will provide for two new irrigated agriculture schemes to meet growing domestic and export food demands.
If proven to be economically and technically feasible, these two projects have the potential for federal government Water for the North funding under its A$12.8B (US$11.7B) programme to stimulate private sector investment opportunity.
The availability of secure and reliable water supplies is critical to the future economic prosperity of Queensland. An integral part of SunWater’s strategies to cater for growth and water security is maintaining the safety and efficiency of its A$7B (US$) infrastructure assets, which supply 40% of all water used commercially in Queensland.
This infrastructure comprises:
• 19 major dams.
• 63 weirs and barrages.
• 80 major pumping stations.
• 2500km of pipelines and open channels.
• 730km of drains.
SunWater manages a total water allocation of 2.82M ML, which includes 1.92M ML of customer-owned allocations. It also undertakes an important consulting role in contributing to cost-effective water solutions in Queensland. Some recent major projects supported with SunWater knowledge and expertise are:
• As a sub-alliance partner providing design services to the Western Corridor Recycled Water Project.
• Peer reviewer to the Hinze Dam Stage 3 raising.
• Consultant to Anglo Coal on a 20-year dam safety review for Bundoora Dam.
SunWater’s hydraulic laboratory in Brisbane forms an integral part of the company’s project management service, allowing internal and external clients to test scale models before construction, enabling considerable savings through design optimization. The models for the A$348M (US$318M) Wyaralong Dam, which is scheduled for completion by the end of 2010, are an example of the scale of the projects for which the laboratory can cater. The dam needed two models; the larger demonstrates the dam’s ability to safely pass flows up to the probable maximum flood at a scale of 1:80. The smaller model, at a scale of 1:30, provides crucial information related to the hydraulic conditions at the dam’s outlet. SunWater is the owner’s engineer for the project.
SunWater’s operational footprint across Queensland is broad. Its business activities and interests spread from as far north as Bamaga, west to Mount Isa, and south to St George. While the majority of its business operations are in Queensland, SunWater also operates and maintains water infrastructure in other states of Australia, including urban supply storage for Australia’s national capital, Canberra.
Historically, Queensland irrigators were the majority of SunWater’s clients; they still represent a significant portion of its 5000-strong customer base and will continue to be an important and significant market segment as agribusiness and water dependent food industry moves north to escape drought and climate change.
Hydro power is another means of diversifying that SunWater has been trialling over the last five years to add value to its storages without impacting on supply to customers. Tinaroo Falls Dam in the far north was SunWater’s first hydro power facility. It is a 1.6MW small hydro station, which began producing power in May 2004. Subsequently, the design of Paradise dam near Bundaberg included provision for a 2.8MW hydro station completed in December 2006.
SunWater is continuing its work with Stanwell Corporation in the preparation of Stanwell’s preliminary business case for a hydro generation scheme on either a raised Burdekin Falls Dam or at its current height. In the wet season the Burdekin River sends immense flood volumes to the Coral Sea.
The Burdekin Falls Dam’s current capacity is 1.86M ML and at its peak flow in February this year catchment inflows were sufficient enough to enable the dam to refill itself every one and a half days.
A proposed 2m raise of the dam would further enhance water supply certainty for the Burdekin region, holding back a fraction of the Burdekin’s massive flood flows both for posterity and green power production. It would increase the storage capacity by 590,000 ML to a total of 2.45M ML.
An additional 150,000 ML of yield would provide for demand from emerging and future economic development including mining and agribusiness in northern and central Queensland.
Stage one of the investigation completed a pre-feasibility study and preliminary business case. Stage two, including preliminary design and environmental investigation, is on hold pending confirmation of commercial viability of the associated Water for Bowen project, or for other significant demand emerging.
Raising of Burdekin Falls Dam is just one of the major projects and proposals SunWater currently has on its books, which in total are worth in excess of A$3B (US$2.7B).
In July 2007, the Department of Infrastructure and Planning (DIP) formally chose SunWater as proponent for the development of business cases for seven major regional water supply projects to underpin the Statewide Water Policy. SunWater’s investigations have included prudent funding options which could include additional debt and equity raising to maintain an appropriate capital structure, in the event these projects proceed to construction. Two of the most strategic of the proposed projects are highlighted below:
Connors River Dam and pipelines
The proposed dam is located on the Connors River some 235km northwest of Rockhampton and 100km south of Mackay. The storage is expected to have a maximum capacity of approximately 373,700 ML, which will conceptually provide a high priority yield of 49,500 ML/yr and 5,000 ML/yr lower priority product.
The majority of demand will be derived from the coal mining industry in the northern and central Bowen basin and from the Galilee basin (a massive undeveloped thermal coal deposit west of the Bowen basin).
The project has been declared a significant project under the State Development and Public Works Organisation (SDPWO) Act 1971. An environmental impact statement is scheduled for the Queensland coordinator-general’s review in late 2009. Public release of the EIS will follow. The project remains ‘on track’ for a financial decision in late 2010. Construction completion remains scheduled for late 2013.
Nathan Dam and pipelines, Dawson River
The Nathan Dam site is located on the Dawson river. The storage is expected to have a capacity of 1M ML, to provide high priority yield of around 90,000 ML. The majority of demand is likely to be sourced from the mining sectors in the southeast Bowen and Surat Basins.
A pipeline is currently under investigation to supply water to Surat basin coal mining and power generation customers which could extend as far as Dalby with a total length of 270km, forming the spine for SunWater’s proposed Surat basin water grid. The grid would initially transport treated coal seam gas water to customers until that wanes and is replaced by Nathan dam construction and supply. The dam and pipelines project has also been declared as being of State significance under the SDPWO Act.
Business cases and investigations for other significant water infrastructure projects and upgrades to existing assets include:
Glebe weir raising and pipeline, Dawson river
SunWater is working with Xstrata to deliver the supplementary EIS for the Wandoan coal project, for which Glebe weir raising is one water supply option under consideration. Feasibility and engineering investigations are expected to progress at the end of 2009 or early 2010.
Nullinga dam, Walsh river Mareeba
The preliminary business case report submitted to the government recommended no further work until clarification of the required environmental flows for the system.
Kinchant dam raising – Pioneer Valley MacKay
Following geotechnical investigation, SunWater’s preliminary business case recommended no further work be undertaken because of high costs.
Lower Fitzroy river infrastructure
The project focuses on the feasibility of constructing a weir near Rookwood Crossing, and raising Eden Bann weir, an existing SunWater asset, to augment short-medium term industrial, residential and agribusiness supply for the Rockhampton and Gladstone Regions. Completion of the business case is scheduled for June 2010.
Underpinning the long-term sustainability and cost-effectiveness of water supplies in SunWater’s 23 water schemes relies on comprehensive asset planning, incorporating new and emerging requirements for safety, environment, and water efficiency.
SunWater’s most recent investment under its dam safety upgrade programme has been a A$21M (US$19M) project to improve the safety of Tinaroo Falls dam, commissioned in 1959 to supply water the Mareeba-Dimbulah water supply scheme.
When the spillway capacity upgrade is completed in October 2010, the dam will be able to pass an extreme flood equivalent to 100% of the acceptable flood capacity (AFC) by strengthening the main dam structure and allowing floods to pass over the non-spillway abutments.
Works will include the installation of stressed tendons through the body of the dam which are anchored into the foundation rock, and protection of the downstream foundation by construction of an erosion protection slab along the downstream toe of the non-spillway abutments.
Overall, the next decade promises some demanding challenges and exciting business opportunities for SunWater.
For more information visit www.sunwater.com.au