Part B The project
Environmental Assessment (NSW) Draft Environmental Impact Statement (ACT)
Chapter 5 Strategic context and need
5.1 Overview As Canberra has grown, so has the demand for water. Significant planning has been undertaken to identify options for securing the supply of water for existing and future ACT and Queanbeyan residents, leading to recommendations by the proponent to the ACT Government in 2007. Those recommendations recognised the need to diversify the source of water supply. The work was based on six key assumptions: • The ACT Government water conservation targets will be met; • Environmental flows will be delivered according to ACT Government guidelines; • Catchment re-growth will respond to bushfires; • The population will continue to grow according to the ACT Government's spatial plan; • ACTEW will meet its service obligations to customers; and • Projections of climate change and variability will occur in line with predictions. More recently, the proponent advised the ACT Government that assumptions relating to climate change and climate variability no longer appeared to hold. This was demonstrated by declines in inflows to the ACT's water storages compared to the long term average. There has been a significant decrease in runoff to the ACT’s water storages over the past six years. In 2006, inflows were the lowest on record. The proponent's advice was that the medium to long term outlook was for a further significant deterioration in inflows. Population projections also changed with projections by the Australian Bureau of Statistics of increases greater than foreshadowed and used in the Canberra Spatial Plan. The proponent indicated that the key challenge for the medium to long term was to build additional water supply assets that could cope not just with substantially reduced inflows but also with more frequent and longer droughts. The proponent recommended that the ACT Government: • Immediately increase storage capacity in the Cotter River catchment; • Diversify the source of water, in part by building infrastructure to extract water from the Murrumbidgee River, and transfer it to the underutilised Googong Reservoir; and • Purchase water from NSW for transfer to the underutilised Googong Reservoir via Tantangara Reservoir and the Murrumbidgee River (Tantangara Transfer project). The strategies that set the context for these recommendations and the project need are described in section 5.2. The project need is also driven by the future growth and development of the ACT region, guided by forward planning documents such as the Canberra Plan (section 5.3.6). Information on project benefits, objectives and timing is provided in section 5.4. 5.2 Strategic context for the project The Murrumbidgee River forms part of the Murray-Darling Basin. Planning and policies in relation to the Murray-Darling Basin form part of the strategic context for the project. 5.2.1 Murray-Darling Basin and national water planning Water availability in the Murray Darling Basin At the Murray-Darling Basin Water summit, convened by the Prime Minister on 7 November 2006, it was agreed to ‘Commission the CSIRO to report progressively by the end of 2007 on sustainable yields of
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surface and groundwater systems within the Murray-Darling Basin, including an examination of assumptions about sustainable yields in light of changes in climate and other issues.’ As a result, the CSIRO was contracted by the National Water Commission to report on current and future water availability in the Murray-Darling Basin. The findings of this assessment are documented in the report to the Australian Government from the CSIRO Murray-Darling Basin Sustainable Yields Project (CSIRO 2008a). The Sustainable Yields Project is a rigorous and detailed basin-scale assessment of the anticipated impacts of climate change, catchment development and increasing groundwater extraction on the availability and use of water resources. It represents the most comprehensive hydrologic modelling ever undertaken for the entire Murray-Darling Basin and includes modelling of rainfall-runoff and groundwater recharge. The information is linked to modelling of all major river systems and modelling of the major groundwater systems of the Murray-Darling Basin and their connections to the surface water system. The study summarises a number of key findings for the Murrumbidgee River region, which includes the ACT, including: • Average surface water availability for the Murrumbidgee River under the historical climate is 4,270 GL/year. The relative level of surface water use under current development is 53% (2,257 GL/year) which represents an extremely high level of development; • If the recent climate (1997 to 2006) were to persist, average surface water availability would reduce by 30%, diversions by 18% and end-of-system flow by 46%. The relative level of surface water use would be 6%; and • The best estimate of climate change by 2030 is less severe than the recent past. Average surface water availability would reduce by 9%, diversions by 2% and end-of-system flow by 17%. The study states that ‘New South Wales and Australian Capital Territory urban water demand would be met under … the dry or wet extreme 2030 climates’. The findings of this report are consistent with CSIRO climate change advice that was used to inform the ACT Government before it made its decisions in October 2007 on ACTEW’s major water security projects. The proponent has modelled water extraction from the Murrumbidgee River for the project and has determined that the most likely annual average extraction rate would be 8 to 10 GL initially. This amount represents approximately 15% of the ACT and region annual average water use. It also to less than 1% of the water available in the Murrumbidgee River and less than 5% of the average flow at Angle Crossing. The extraction from the Murrumbidgee River could also be increased should additional flows be released from Tantangara Reservoir via ACTEW’s so called Tantangara Transfer project, providing additional flexibility to the project and additional water security to the ACT region. The proponent acknowledges that flow in the river is very variable. When flow is low, water extraction would be limited or cease so that the flows necessary to maintain the environmental health of the Murrumbidgee River are protected. The National Water Plan On 23 May 2008 the Murray-Darling Basin Ministerial Council approved the ACT Water Cap, the total amount of water the Territory is allowed to use or divert from the Murray Darling Basin. The ACT Water Cap is: • 40 GL net (42 GL minus a 2 GL saving allocated to the Living Murray Initiative); • Climate-adjusted as recommended by the Independent Audit Group; and • Reviewed and increased by 0.75% of the current per capita consumption of water for population growth of Canberra and Queanbeyan.
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The ACT Water Cap allows the ACT, mostly through ACTEW’s network (as presented in Figure 3.2), to take a net 40 GL of water per year from rivers in the Basin within the ACT, that is, total water extracted less water returned to the river system from sewerage treatment facilities in the ACT and Queanbeyan. The 40 GL/year ACT Water Cap is enough water for the ACT to use sustainably. For example, in 2007-08, the ACT and Queanbeyan net use was approximately 21 GL, made up of 44 GL through ACTEW’s network, plus about 4 GL used by others, less 27 GL returned to the river. The National Water Initiative The National Water Initiative is Australia's enduring blueprint for water reform. Through it, governments across Australia have agreed on actions to achieve a more cohesive national approach to the way Australia manages, measures, plans for, prices, and trades water. The Intergovernmental Agreement on a National Water Initiative was signed at the 25 June 2004 Council of Australian Governments meeting. Under the National Water Initiative, governments made commitments to: • Prepare water plans with provision for the environment; • Deal with over-allocated or stressed water systems; • Introduce registers of water rights and standards for water accounting; • Expand the trade in water; • Improve pricing for water storage and delivery; and • Meet and manage urban water demands. Each state and territory government was required to prepare a National Water Initiative implementation plan, accredited by the National Water Commission. Under its plan, the ACT Government committed to provide a long term, reliable source of water for the Territory and region, by improving water use efficiency and by augmenting the source of supply. This project is one of the principal means of augmenting the source of supply proposed in the National Water Initiative. 5.3 Project need The ACT Government’s water resources strategy, ‘Think Water, Act Water’, is consistent with the National Water Initiative. The project is one element of an integrated strategy that is seeking to improve the efficiency of water utilisation, implement demand management measures and diversify and supplement water supply sources. 5.3.1 ACT’s current water situation The ACT region has experienced severe drought conditions over the period 2001-2006. The total inflow into Cotter Dam and Googong Reservoir over the period 2003 – 2009 has averaged at approximately 71 GL/year, well below the average inflow of 200 GL/year over the past 130 years (ACTEW 2008b). In 2006 alone, water storage decreased from 51% to 39%. Inflow of water into the ACT catchments for 2008 were also down by almost 90% from the long term average, exceeding the decrease from the long term average storage inflow by 2030 as predicted by CSIRO. The medium and long term outlook (i.e. beyond 2030) of water supply suggests a further decline to long term average inflows. These dramatic reductions in storage inflows can be seen in Figure 5.1 and Figure 5.2. Figure 5.1 shows the combined inflow for Corin, Bendora and Googong reservoirs between 1871-2008 and Figure 5.2 shows the gradual decline of the total water storage of Corin, Bendora and Googong reservoirs from 2000 to 2009.
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Figure 5.1 Combined Corin, Bendora and Googong inflows (1871-2008)
There is increasing evidence that the recent climatic patterns that have resulted in a significant decline in inflows will now occur more frequently and with greater variability (ACTEW 2008g).
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0% Jul-00 Jul-01 Jul-02 Jul-03 Jul-04 Jul-05 Jul-06 Jul-07 Jul-08 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09 Total Water Storage - Corin, Bendora & Googong
Figure 5.2 Total water storage of Corin, Bendora and Googong reservoirs from 2000-2009
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5.3.2 Demand management The ACT Government’s water resources strategy, ‘Think Water, Act Water’, encompasses and supports the elements of the National Water Initiative that are applicable to the ACT. The strategy provides key targets on water saving and water re-use: • A 12% per person reduction in mains water by 2013 and 25% by 2023 through water efficiency measures, sustainable water recycling and the use of stormwater and rainwater; and • An increase in the use of reclaimed water from 5% to 20% by 2013. It is intended that a variety of means be used to achieve these targets, including: • Education and advertising; • Permanent water conservation measures; • Effluent reuse; • Stormwater harvesting; • Rainwater tanks; • Greywater reuse; • Water efficient appliances and fittings; • Leakage reduction; • Government subsidised indoor and outdoor water tune-ups; • A requirement for new developments to achieve a 40% reduction in water use through water-sensitive urban design; and • Ongoing pricing reforms. It is predicted that demand management alone could achieve the 12% by 2013 target. Indeed, permanent water conservation measures and a general increased awareness of the need for water conservation may well have already delivered this saving. Even with this saving, it is expected that source substitution (for example, rainwater tanks, greywater reuse, effluent reuse, stormwater harvesting) will be required to reach the 25% by 2023 reduction target. As source substitution methods are relatively expensive, it is expected that the 12% target by 2013 will be more easily achieved than the 25% target by 2023. Permanent water conservation measures were introduced in Canberra and Queanbeyan in November 2005. However, they only applied for a year before temporary water restrictions were reintroduced. The component of the permanent measures that has the most significant impact on consumption is limiting sprinkler and other irrigation systems to the hours of 6 pm to 9 am, except during winter. This measure encourages garden watering in the morning or evening when absorption rates are higher than in the middle of the day. The intent behind the permanent measures is to discourage inefficient water use through means that should cause very little inconvenience to the community. The target reduction for the permanent measures was 8%. A 23% reduction in consumption was observed during the year that they were introduced, relative to the pre water restriction consumption pattern. However, this reduction is unlikely to be sustained in the long term because: • The permanent measures were applied after a severe drought. Awareness of water conservation was at a very high level and many gardens that required high water use were adversely affected by the drought and had not been re-established; and • Many users may be maintaining habits established during the water restrictions scheme, such as only watering every second day. These patterns may not be maintained indefinitely.
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5.3.3 Meeting the demand for water in the ACT The report ‘Options for the Next ACT Water Source’ (2004) identified traditionally, predicting when a new water source was needed for the ACT involved estimates of population growth, measuring existing water consumption patterns, current environmental flows and used historical climate data. This information was then modelled to predict the timing of a new supply based on the size of the population that could be served. The output from this model identified the need for a new water supply when the population of the ACT and Queanbeyan reached 405,000. The Australian Bureau of Statistics mid-range forecast estimates that this population would be reached in 2017. As a result, the ‘Options for the New ACT Water Source’ report identified that there was a need to re-examine these assumptions, as well as the modelling methodology, and include effects due to bushfires, climate change, climate variability, water consumption and possible water supply to NSW. The report ‘Options for the Next ACT Water Source’ (2004) suggested that bushfire, climate change impacts and other factors mean that it would not be feasible for more efficient water use alone to meet the needs of the future population. The report suggested that based on the outcomes of a preliminary assessment, the likely timing for a new water source would need to be bought forward. ‘Options for the Next ACT Water Source’ (2004) noted that the need to consider water supply options for the ACT arises from possible shortages in water availability from the existing storages (dams in the Googong and Cotter catchments) that are predicted to emerge within the next ten to twelve years. While in most years the water supply system is adequate for the ACT’s needs, a repeat of the worst sequence of drought years experienced in the last 100 years combined with increased population growth means that the water supply is at risk of not being able to meet the territory’s requirements. While drought contingency projects enable ACTEW to avoid stage 4 restrictions (no use of potable water for gardens, and permits system for other external uses of potable water), it became clear that additional supply was required to secure long term supply. To combat the effects of climate change and variability, additional supply capacity and greater diversification of water sources was required. The proponent completed a comprehensive and detailed review of the ACT and region’s water supply options and submitted four key water security recommendations to the ACT Government in July 2007, when it released the report ‘Water Security for the ACT and Region: Recommendations to the ACT Government’ in light of the significant reductions of inflows to storages. The purpose of this report was to recommend options to further secure the water supply for Canberra and the region. The impact of climate change and climate variability meant that it was necessary to review water security and the need for diverse supply options. These circumstances meant that options less dependent on rainfall and local catchments, such as water purification and the Tantangara transfer, were examined. Ten supply options were examined in detail. Modelling of the options revealed that if only one option was to be implemented, recovery from the drought is likely to be protracted, unless there is a return to average rainfall conditions. The recommendations of the report are as follows: ‘1. Immediately commence the detailed planning and construction of an enlarged Cotter Dam to 78 GL capacity; 2. Add to its capacity and operational flexibility to extract water from the Murrumbidgee River by undertaking the work necessary to proceed to construction of a pumping capability near Angle Crossing, which could also be used to transfer additional flows released from Tantangara Dam if such flows become available; 3. Obtain additional water from a source not largely dependent on rainfall within the ACT catchments through either: a. The Tantangara Transfer option; or b. The Water Purification Scheme; and
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4. Assess how any additional energy used may be offset through measures such as carbon offsets (such as planting of trees) or renewable energy capacity.’ These recommendations were generally accepted by the ACT Government, and work commenced on initial design and seeking approvals for enlargement of the Cotter Dam and the project. In December 2008 ACTEW released the report ‘Water Security for the ACT and Region: Progress Report and Recommendations to ACT Government’. The report made recommendations to continue work on the enlarged Cotter Dam; to begin work on the Murrumbidgee to Googong transfer; to pursue the Tantangara Transfer; and to defer the construction of the Demonstration Water Purification Scheme subject to the successful implementation of the other three water supply projects and no further deterioration in dam inflows. In March 2009 the Government announced it had accepted ACTEW’s recommendations. 5.3.4 Meeting the demand for water in NSW Importance of ACTEW’s Water Security- Major Projects to NSW ACTEW’s Water Security-Major Projects has key benefits for the NSW Government’s Sydney-Canberra corridor, particularly in securing the future availability of water to sustain Queanbeyan’s expected substantial growth over the next thirty years, including new growth areas. Additionally, all modeling undertaken by ACTEW in the development of the Major Projects included an allocation for future cross border supply to areas such as Yass, Bungendore or Goulburn should the need arise. Supplying water to the growth area The NSW and ACT governments have a Regional Management Framework to manage cross border matters, which includes a memorandum of understanding on Cross Border Water Supply, which has also been ratified by the Commonwealth Government. The NSW Department of Planning’s Departmental Review of the Queanbeyan City Council Residential and Economic Strategy 2031 states: ‘The power of the ACT Government to be involved with the decision making process over the proposed residential development proposals in the area derives from its control of the water supply. Both the Settlement and Water Supply MOUs require the NSW Government to consult and work with the ACT Government in the preparation of a cross border water strategy before water is allocated.’ The NSW government’s objectives for the corridor; to provide for the ongoing flow of trade, tourism and ideas within the region and between capital cities and the eastern seaboard, relies on appropriate natural and built resources. Water is a key resource that has the capacity to constrain development if its availability cannot be secured. The infrastructure, which is proposed under ACTEW's Water Security – Major Projects, is aimed at securing supply for the ACT and region, which includes Queanbeyan. The Murrumbidgee to Googong Water Transfer is a vital part of the ACT’s water security, transferring water from the Murrumbidgee River to the Googong Reservoir in NSW. The pipeline will travel through NSW and therefore NSW planning approvals are required. ACTEW’s modelling and planning for the future water supply has taken into consideration the developments that are taking place in Queanbeyan. The NSW Government has a 25 year land use strategy which will provide up to 25,200 new homes for the 46,350 additional people expected to be living in the region by 2031. This includes 14,200 in the southern sub region, most of which will be in the Queanbeyan area. These include the developments of Googong and Tralee. Council also recognises that the cross border management framework has influence on the residential and employment land development in Queanbeyan.
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5.3.5 The link between the Murrumbidgee to Googong Transfer and the Tantangara Transfer Project The Tantangara Transfer, although a discrete project amongst ACTEW’s water security projects, is closely linked to the project. The transfer would provide extra water security and further diversity to the region’s water supply, as it does not depend upon rainfall falling in local catchments. In prolonged and severe droughts of the kind that now need to be accommodated, the Enlarged Cotter Dam and the Murrumbidgee to Googong project together may not suffice. The Tantangara Transfer would give access to water purchased from downstream NSW irrigators who are willing to sell. The Tantangara Transfer involves the following main actions: • Purchasing water licenses from irrigators downstream of the ACT; • Storing purchased water in Tantangara Reservoir, a reservoir located well upstream of Angle Crossing; • Transferring that water from Tantangara to the ACT via the Murrumbidgee River; and • Transferring the water from the Murrumbidgee for storage in Googong Reservoir. Alternatively, the water from Tantangara releases can be pumped from the Murrumbidgee River to the Mount Stromlo Treatment Plant via the Cotter pump station, although this is unlikely to be a frequent occurrence. Economic and hydrologic studies show that the Murrumbidgee to Googong Transfer is viable without the Tantangara Transfer project. The Tantangara release project, while endorsed by the ACT Government, requires the following steps to take place before it can be implemented: • The purchase of about 20 GL of general security water entitlements and conversion to about 11 GL of high security water entitlement; • Intergovernmental arrangements to allow water trade to occur between NSW and ACT; and • A commercial agreement between ACTEW and Snowy Hydro Limited for use of infrastructure to store and release water purchased by ACTEW to the ACT when required from Tantangara reservoir. Water entitlements are being purchased by ACTEW on the water market. These entitlements will remain within the Murrumbidgee Regulated River Water Source. In order to transfer water allocations to the Googong Reservoir, ACTEW will enter into a commercial agreement with Snowy Hydro Limited and negotiate intergovernmental arrangements between NSW and ACT Governments. The project involves a high level of legal and political assurance to provide the confidence to rely on this option. The proponent is confident that water can be transferred from NSW to the ACT due to the significant amount of cooperation and support from the NSW Government. The Tantangara Transfer project is relatively low cost, would enhance the diversity of the ACT and Queanbeyan water resources and improve water security. 5.3.6 Future development of the ACT ‘The Canberra Plan’, released in March 2004, sets out the long term vision for the ACT. As a strategic planning framework for the ACT Government and the community, it provides the direction for Canberra’s future growth and development. ‘The Canberra Plan’ has three key planning components ‘The Social Plan’, ‘The Economic White Paper’, and ‘The Spatial Plan’. The draft Canberra Spatial Plan (2003) stated (page 60) that ‘[recent] events and the strong urban growth within the region have highlighted the need to plan for water supply on a regional basis. In particular, the viability of potential development areas outside the ACT is dependent on the availability of a potable water supply. The Territory will, through a range of strategies, defer as long as possible, the need for a new dam. However, with the continued development of the ACT and surrounding region, additional potable water supplies are expected to be required in the long term.’ One of the actions recommended by the final Canberra Spatial Plan (2004) is ‘planning for an adequate new water supply undertaken with ACTEW in the context of an agreed regional water supply strategy.’ Thus,
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Canberra’s key planning document endorses the continued planning for the next supply, and assumes that planning would occur, taking regional growth into consideration. The project also supports the strategic aims of the NSW Government for intergovernmental collaboration to support growth in the NSW southern region as outlined in the draft ‘Sydney-Canberra Corridor Regional Strategy 2007-31’ (Department of Planning 2008). 5.4 Project benefits and objectives 5.4.1 Benefits The project is beneficial because it: • Increases the diversity of water sources in the ACT region; • Provides additional supply into Googong Reservoir. Inflows into Googong Reservoir have decreased by about 85% during the period from 2001 to 2008; • Provides greater operational flexibility in extracting water from the Murrumbidgee River than is possible solely with the Murrumbidgee River pumping station located near the Cotter Pump Station; • Importantly, in the case of severe bushfires in the Cotter catchment (such as occurred in 2003), it provides a reliable alternate water source to Googong Reservoir and therefore will lower the risk of adverse impacts on the ACT region’s water supply, should any fires occur in the future; and • The most recent modelling (March 2009) indicates a net economic benefit in excess of $500 million over the period 2010 to 2030 (CIE, 2009). 5.4.2 Project objectives The overall objective of the project is to secure a water supply for the ACT that can account for the more frequent, longer, drier droughts that are predicted to occur without having to go into high-level water restrictions for extended periods. The project would assist in securing the ACT’s water supply by transferring water from the Murrumbidgee River to Googong Reservoir in a sustainable manner, which: • Protects the health and ecology of the Murrumbidgee River, Burra Creek and Googong Reservoir; • Does not cause significant impact in the pipeline corridor; and • Does not significantly impact local communities.
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Chapter 6 Project description
6.1 Overview The project involves construction and operation of infrastructure with the capacity to transfer up to 100 ML/day of water a distance of approximately 13 km from the Murrumbidgee River at Angle Crossing, to the Googong Reservoir via run-of-river flow in Burra Creek (refer to Figure 1.1). Water would be pumped from the Murrumbidgee River via an intake/low lift pump station and a high lift pump station, and transferred to Burra Creek via underground pipeline. The water would discharge into Burra Creek via an outlet structure. Following discharge, water would flow along Burra Creek to the Googong Reservoir, which forms part of the ACT’s water supply (refer to Figure 3.2). Associated with the pipe and pumping infrastructure would be a mini-hydro power facility to capture and reuse part of the energy required to transfer the water. This electricity would be used by the high lift pump station to reduce the projects overall energy requirements. To supplement the electricity captured from the mini-hydro power facility, the project also involves construction of an 11 kV power supply for the operation of the intake and pump station, and various associated works. The main components of the project are described below in section 6.2 - 6.5. The ancillary infrastructure (such as power infrastructure) required to support the construction and operation of the project is described in section 6.6. The construction methodology is described in section 6.7. Operation and maintenance procedures are described in section 6.9 - 6.10. This description provides the information on the project for which approval is sought. It also provides the basis for the impact assessment described in Part C. 6.2 Intake/low lift pump station 6.2.1 General The intake/low lift pump station would be located on the eastern bank of the Murrumbidgee River, approximately 15 m upstream (to the south) of the Angle Crossing causeway. The intake/low lift pump station would comprise an open sided concrete box structure built into the riverbank. It would include four functional modules: • The intake module; • The filtration module; • The pump module; and • The valve module. Flow through the modules occurs in four separate trains, each train of nominal capacity of 25 ML/day to give total nominal capacity of 100 ML/day. The four modules that make up the intake/low lift pump station are described below. The site for the intake/low lift pump station, comprising structure and adjacent maintenance hardstand areas, would occupy an area of approximately 750 m2. The structure is shown in Figure 6.1 and Figure 6.2. Location figures are provided in chapter 3.
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Figure 6.1 Intake/low lift pump station structure
Figure 6.2 Main components of the intake/low lift pump station structure
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6.2.2 Intake module The intake module (refer Figure 6.2) would consist of four intake chambers, one for each 25 ML/day intake train. The intake chamber screen (or trash rack) bars would be orientated parallel to the river flow with bars positioned across the intakes both horizontal and parallel to the river flow to prevent flotsam and limit grit from entering the intake chambers and to maximise the self cleaning capability of the screen by utilising the natural river velocity. The trash rack bars would consist of structural steel rectangular hollow sections installed in removable panels. The bars would be robust enough to withstand flood flotsam loading and vandal damage, and would be spaced 25 mm apart to minimise risks of subsequent blockages in the pumps of the system. The bars would also be designed to keep intake velocities below that which would hold flotsam (including plastic bags, leaves and grass). The intake screen would be inclined to match the natural river bank slope and to increase the available surface area for the intake of water. This would also minimise river flow stream disruption and turbulence and ensure cross-screen velocities of the natural river flow (typically 1.0 to 3.0 m/s) are greater than intake velocities (average 0.14 m/s). Once within the intake chambers, grit in the water would settle into hoppers built into the intake chamber floor. Each intake chamber would have two hoppers: a ‘lead’ hopper located directly beneath the trash rack bars; and a secondary hopper located in the floor of the filter module. The trash rack bars would span across from the side wall and would also include drop board slots which could accommodate drop boards to separate the intake and filtration modules. Jet inductors in each hopper sump would automatically transfer water volumes with suspended grit and sediment through a 200 mm diameter pipe to be returned to the river north of the Angle Crossing causeway. A separate transfer pipe is necessary for each of the eight hoppers, therefore a group of eight pipes would cross underneath Angle Crossing causeway and terminate at the mid stream bed of the river downstream of the causeway. This discharge location would allow transferred flows to be fully integrated within turbulent flows over the causeway. An anti-siphon break pressure pit would be provided in the bank near the causeway to prevent siphoning of flows when the jet eductors are not operating. The jet inductors would cyclically operate by automatic valves on a timer basis, with each jet eductor operation timer controlled at intervals that would vary depending on river flow conditions, as measured by river level and turbidity sensors at the pump station. The automatic timer would ensure that grit and sediment is not normally stored within hoppers but would be transferred to the river continuously (subject to environmental approvals). This would ensure river suspended material levels at all times downstream are, as near as practical, those material levels upstream of the pump station. This would, in particular, ensure both visible ‘plumes’ and unnatural concentrations of handled materials downstream are avoided in the river. Ultrasonic sediment level detectors in each intake chamber provide back up to provide automatic response to unusual conditions such as: • Sediment load occurring in major river storm flows (particularly first flush loads); • Sediment build up in a prolonged stand down of station operation; and • Control system failure. 6.2.3 Filter module Four fish egg filtration units, with screen size of 0.5 mm, would be installed over sediment removal hoppers within each intake train. These units would be used throughout the year to filter fish eggs from the water and would discharge filtered water through a dividing wall into the distribution through of the pump module. Valves would close off each filtration unit to enable water backwashing from the units to return filtered fish eggs to the river via the hoppers and jet inductors and eductor flows. The filtration assembly units would be mounted on guide rails and the filter module would have a removable heavy duty cover at ground level to allow removal of the filtration systems by a crane for inspection and maintenance in the same way as submersible pumps.
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6.2.4 Pump module Four 3.3 kV pumps would be provide for each intake train, installed in two pump wet wells separated by a dividing wall with a connecting penstock which would normally be open. 6.2.5 Valve module The valve module would comprise one large valve pit that would house all the pipes from the pump wells. The non return valves and valves for pump isolation would be housed in the valve pit along with the grit eductor jet and filter backwash system. 6.2.6 Other works/features All major electrical control gear and sampling, testing and hydraulic drive power packs would be located in the high lift pump station. Major power cable and high pressure hydraulic drive lines from the high lift pump station trench would be installed in a separate trench installation and a separate route to the water pipelines for security and safety reasons. Sampling water pressure and gravity return lines would be installed with the main transfer pipeline. Hardstand areas would be provided behind and each side of the intake/low lift pump station for maintenance purposes, particularly heavy-duty mobile crane location. 6.2.7 Flow transfer The system would be designed to allow the flow rate to be increased and decreased, with the maximum nominal flow rate of 100 ML/day flow being achieved after a 48 hour period. Each step in the ramp would be activated by the automatic control system every 12 hours, with the steps in the flow rate being achieved with a combination of low lift and high lift pumps (the pumps would be designed to run at fixed speeds). Table 6.1 provides a summary of the combination of the pumps that operate to achieve the given flow rate.
Table 6.1 Summary of pump operation for the intake/low lift pump station
Nominal transfer flow rate ML/D Low lift pumps in operation High lift pumps in operation
18 1 1 small
49 2 1 large
62 2 1 large + 1 small
90 3 2 large
97 3 2 large + 1 small
When there is a transition during an increase/decrease in the flow rate (where high lift pumps are started/stopped to achieve the different flow rates) then the pump to come on-line is started prior to the shut- down of the one which is no longer required. An example of this is the transition from 18 ML/day to 49 ML/day, where the large high lift pump would be started before the small high lift pump is shutdown. 6.3 High lift pump station 6.3.1 General The high lift pump station would be located adjacent to Angle Crossing Road, approximately 290 m east of the intake/low lift pump station (refer to chapter 3). This pump station would ‘lift’ the water to the geographical high point at Gibraltar Range, from where it would run under gravity in the pipeline to the outlet in Burra Creek. The high lift pump station would consist of three sections, the pump hall and an electrical services/amenities building (described below), separated by a truck bay. The building would be approximately 8 m high, and would be designed to integrate as much as possible with the surrounding environment. The building would be located within a fenced compound with an access gate. The fenced site for the high lift pump station would occupy an area of approximately 4,200 m2.
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A conceptual layout of the high lift pump station is shown in Figure 6.3. Location figures are provided in chapter 3.
Figure 6.3 Concept layout of the high lift pump station
6.3.2 Pump hall The design of the pump hall would incorporate sufficient space around all machinery to allow for maintenance. A stairway would provide access to the rear walkway over the discharge pipelines and front emergency exit doors. Direct access would be provided from the truck bay to the pump hall and adjacent electrical services rooms. The approximate dimensions of the building would be 8 m high, 24 m long and 9 m wide, including the truck bay. The building would be mechanically ventilated. The pump hall would accommodate two large and one small pumps and, in combination with the pumps in the low lift pump station, would have the capability of pumping in approximately 20 ML/day increments. 6.3.3 Electrical services/amenities building The electrical services/amenities building would consist of the switch rooms and an office/control room and amenities. Parking for three cars would be provided adjacent to the building. The approximate dimensions of the building would be 8 m high, 16.5 m long and 9 m wide. 6.3.4 Tanks/drainage Under the floor of the truck bay there would be a series of tanks/pits such as: • Cooling water return tank; • Oil/grease sediment trap; and • A pit that would capture the releases from the centre drain along the truck bay, and would also house the pressure relief valves and rupture disk.
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The water separated by the oil/grease sediment trap would overflow into the cooling water return tank. The overflow of the cooling water return tank would be to the centre drain, which would discharge to the stormwater drain. 6.4 Pipeline 6.4.1 Description of the pipeline The pipeline would be constructed of mild steel, and would be located beneath ground level. Air valves and scour valves would be located at regular intervals along the pipeline to provide air release and entry and to allow cleaning. The pipeline would have an outside diameter of 1,016 mm and a wall thickness of 8 mm to 10 mm. It would be lined with cement mortar or epoxy. The pipeline would be laid in a shallow continuous trench to depths of approximately 1.8 m to 4 m below ground level. Figure 6.4 shows a typical cross section of the pipeline. A 40 m wide (maximum) corridor has been considered for construction. A 15 m wide easement along the length of the pipeline would be acquired for operation and maintenance purposes. The proponent is currently undertaking landholder negotiations regarding access during construction, rehabilitation activities, and operation of the project. This is discussed further in 6.7.5. The pipeline would also include auxiliary items at various positions along the pipeline route, such as isolation valves, concrete pits, air valves and scour valves. Water from the scour valves would periodically be collected by a tanker, which would traverse the alignment from the nearest access point. Pipeline marker posts would also be installed at regular intervals (approximately every 200 m) to warn of the location of the underground water pipeline and cable from the mini-hydro power facility to the high lift pump station (see 6.6.2).
Figure 6.4 Typical cross-section of the water transfer pipeline
6.4.2 Description of the route The route extends from the intake/low lift pump station at the Murrumbidgee River in the ACT, via the high lift pump station located adjacent to Angle Crossing Road in the ACT, to the outlet structure at Burra Creek in NSW. The route is shown in Figure 1.1 and is described below.
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The route takes a direct path from the river at Angle Crossing to the high lift pump station located near the descent of Angle Crossing Road towards the river. The route generally rises towards the east/northeast until it reaches the proposed crossing point of the Monaro Highway, which is about 3.5 km from the starting point. In this section, and in the section between the highway and the Goulburn to Cooma Railway, the route avoids as much as possible the vegetation and rocky outcrops that provide fauna habitat. The route then heads in an easterly direction across pasture-improved paddocks used for sheep grazing, for approximately 3 km before reaching Williamsdale Road. It then turns in a northeasterly direction and follows closely the alignment of Williamsdale Road up and over a high point which is about 1 km southwest of Gibraltar Hill. It is located in the road reserve for about a third of the 6 km distance along Williamsdale Road, largely following Palerang Council’s proposed road realignment. For the remainder of this section it is located in and/or adjacent to rural residential properties, which are predominantly used as hobby farms and grazing properties. The route then veers off Williamsdale Road and continues through rural residential properties. Remnant vegetation exists in some small areas along this section of the route, which would be avoided as far as possible. The route crosses Burra Road, before it reaches the discharge point at Burra Creek, approximately 100 m downstream from the Burra Road Bridge within the area known as Googong Foreshores. 6.5 Outlet structure The outlet structure would take the form of a weir box arrangement located in the western bank of Burra Creek just east of Burra Road. It would be located approximately 100 m downstream of the Burra Road Bridge, downstream of the gauging weir on Burra Creek. The structure would comprise a rectangular concrete box built into the creek bank with a weir located on the sidewall closest to the creek (refer Figure 6.5). Water would flow into the weir box from the pipeline and would discharge over the weir and run down the creek bank to the creek, which flows to Googong Reservoir. This method of discharge is designed to prevent scouring of the creek bed. The installation of the outlet facility would require excavation into the creek bank up to approximately 3.5 m depth (upslope) and approximately 10 m in length, in a direction parallel to the creek alignment. The incoming pipe would be centred on a 2 m end wall. Water would flow into the weir box from the pipe and would well up to flow over a 10 m long weir located on the sidewall closest to the creek. Once discharged over the weir, the water would run down the creek bank to meet the creek water level prevailing at the time. It is proposed to provide rock protection to the bank and install a rock rip rap across the creek bed to prevent scour and erosion in the vicinity of the outfall weir. The site for the outlet structure would occupy an area of approximately 1,200 m2.
WATER SECURITY – MAJOR PROJECTS 74 AUGUST 2009
Figure 6.5 Outlet structure
6.6 Ancillary infrastructure The following additional infrastructure would be required to support the construction and operation of the project. 6.6.1 Construction power Due to the remote location of the project, diesel generators would generally provide power during construction. 6.6.2 Mini-hydro power facility A mini-hydro power facility is proposed to be incorporated into the project to reduce the overall energy requirements of the project during its operation. The electricity associated with pumping is estimated as 1,138 kWh/ML based on the pipeline design. The mini-hydro power facility would have the capacity to generate approximately 1.2 mega watts of electricity by recovering approximately 26 to 27% of the energy generated by the water moving along the pipeline. The electricity generated would be used to power the pump stations. The electricity would be transmitted via an underground transmission cable located within the pipeline trench, which would terminate at the proposed electrical substation near Angle Crossing, or at the high lift pump station. The facility would be located near the outlet structure within the pipeline construction corridor away from the immediate environs of the Burra Creek bank to minimise local impacts and to protect the infrastructure from flooding. The facility would comprise of a turbine, generator and substation, and would, with the exception of the substation, be located primarily below ground, with some minor above ground auxiliary components.
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The above ground dimensions (foot print area) are anticipated to be 10.7 m x 7 m (approximately 75 m2). The facility would include a buried valve pit with an exposed top and enclosing structure designed to reduce the potential for any noise emissions. Key features of the facility would include: • A generating plant comprising a hydro generating unit; • A 11 kV substation; • A main water control inlet valve to the turbines; • Fire detection and fire fighting facilities; • Drainage structures for stormwater collection; and • Oil spill collection and separation units. 6.6.3 Power supply An 11 kV power cable would be required for the pump stations. The electrical infrastructure also comprises a substation and connection to the future 132 kV Williamsdale to Theodore line. The underground power line would generally follow the route of Angle Crossing Road and would terminate at a switchyard and transformer located adjacent to the high lift pump station. This switchyard and transformer would be housed within a 10 m square enclosure, which would be fenced. Underground power conduits would be installed from this enclosure into a cable room within the high lift pump station. All electrical equipment for the low lift pump station would be housed within the high lift pump station. This would negate the need for another structure to be built adjacent to the low lift pump station to house the electrical equipment. The low lift pump station would be connected to the power via underground cables. As these cables would be approximately 300 m in length, the low lift pumps would operate at 3.3 kV. A 10 m wide corridor along this route would be sought by ActewAGL to provide for construction and maintenance access, vegetation management and land use controls. Electricity provided by the grid would be supplemented by electricity generated by the mini-hydro power facility (described in section 6.6.2). 6.6.4 Water supply and storage Construction Construction water requirements are expected to be approximately 20,000 litres/day for dust suppression, which would be sourced from the settlement dams where possible. The settlement dams would be installed for construction of the project, to capture runoff from construction areas and would also provide the project with a water recycling opportunity. However, due to the uncertainty of rainfall, it is likely that there would be a shortfall in the availability of water from settlement dams, and additional construction water would need to be sourced from the Murrumbidgee River at Angle Crossing. Water carts would fill from these settlement dams or from the river. Settlement dams would be used in conjunction with a suite of soils erosion and sediment control measures to minimise impacts on the environment. A sediment pond would be required in the vicinity of Angle Crossing, and is primarily linked to the construction works at the low lift pump station and associated infrastructure. The required sediment pond would be designed and sited in consultation with the ACT Environmental Protection Authority taking into account any requirements they may have. Potable water would be approx 33,000 litres per week for drinking and sanitary needs. Typically, this could be transported using a 14,000 litre stainless steel container on a truck filled with potable water from the Canberra main. Operation Rainwater harvested from the high level pump station roof would supply non-potable water use.
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Drinking water at the high lift pump station would be supplied by a water cooler using delivered bottled water. 6.6.5 Sewerage Construction Temporary portable toilet facilities would be provided at construction compounds. Operation Sewage and waste water would be collected in a pump out tank at the high level pump station for periodic removal and dispersal to an approved receival station. 6.7 Construction of the project 6.7.1 Construction methodology An indicative construction methodology is provided below for the main components of the project. The construction methodology would be confirmed by the construction contractor following the detailed design phase of the project. Intake/low lift pump station • Site establishment including storage hardstand and parking facilities in the existing carpark, access roads to the site, compound and erosion and sedimentation control facilities; • Construction of earth or rock pad within the river to facilitate access for suitable piling rig; • Construction of coffer dam and erosion control facilities; • Excavation works (approximately 5-6 m vertically), which may include rock hammering and blasting; • Formwork, reinforcement and concrete placement activities; • Installation of discharge pipe and manifold; • Mechanical fitout; • Electrical installation; and • Restoration and completion works. High lift pump station • Site compound establishment including erosion and sedimentation control facilities; • Excavation and filling works to level building pad; • Construction of access road; • Installation of discharge pipework; • Formwork, reinforcement and concrete placement activities; • Structural steel installation; • Erection of precast panels; • Roof works; • Building finishing trades (internal and external); • Yard piping and services installation; • Mechanical fitout; • Electrical installation; • Completion works; and • Revegetation and landscaping.
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Pipeline • Advance works; • Identify and tag any environmentally sensitive areas; • Establishment of erosion and sedimentation control facilities; • Right of way clear and grade; • Potential pre-ditching in hard rock zones; • Trenching (including excavation works and blasting); • Pipe stringing; • Trench preparation and bedding; • Pipe laying and jointing; • Pipe coating repairs and joint reinstatement; • Padding and backfill; • Anchorage of pipeline; • Valve installation; • Hydrostatic testing; • Reinstatement and rehabilitation; and • Marker posts and signs. Outlet structure • Site establishment including erosion and sedimentation control facilities; • Excavation works associated with outlet structure in bank; • Formwork, reinforcement and concrete works; and • Rehabilitation of the area. 6.7.2 Construction timing and hours Construction is estimated to take approximately 18 months, commencing in the first quarter of 2010, or as soon as planning approvals are obtained. The approximate construction period for the project components, which would occur concurrently, is as follows: • Intake/low lift pump station – 12 months; • High lift pump station – 14 months; • Pipeline – 12 months; and • Outlet structure – 5 months. Construction works would generally be carried out during standard construction hours (i.e. 7 am to 6 pm Monday to Friday and 8 am to 1 pm Saturday). There may be infrequent occasions where work outside these hours would occur. For example, concrete pours and some road crossings may need to start or finish out of hours to reduce the potential for traffic impacts. Some after hours delivery of equipment may be required. Areas away from residences would be specified to minimise disturbance.
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6.7.3 Construction sequencing To meet the construction timeframe, three pipeline crews would be required to construct the pipeline. All pipeline crews would commence concurrently. Construction of the pipeline between the pump stations (first pipeline crew) would commence early in the construction program. This pipeline crew would continue through to the Monaro Highway. Another crew would construct the pipeline from the Monaro Highway to the high point of Gibraltar Pass, with the remaining crew constructing the pipeline between the Gibraltar Pass and the outlet structure at Burra Creek. The outlet structure is scheduled to commence approximately mid way through the construction period in order to enable the pipeline at the outlet structure to be in position. 6.7.4 Construction workforce For the main project elements, it is estimated that a construction workforce of approximately 100 people would be required on site at one time. In addition to this, a construction workforce of approximately 15 would be required for the mini-hydro power facility and approximately 15 for the 11 kV power cable and substation power supply. 6.7.5 Construction footprints/easements, site compounds and stockpile areas Site accommodation, storage and lay down areas would be required at various locations along the pipeline. The proposed locations of the facilities have generally been selected to occupy existing cleared areas. In general, site accommodation would be in the form of portable buildings. Amenities provided would cater for lunch facilities, ablution, storage of site materials, minor works zones, office space for on-site personnel and associated parking. Each site would be securely fenced with temporary fencing. All necessary signage advising the general public of access restrictions relevant to each site would be provided. These areas would be reinstated at completion of use. Construction easement and lay down areas are shown in Figure 6.6 and described below. Construction corridor In general, a 40 m wide construction corridor would be required along the pipeline route to allow for trench excavation; equipment storage and movement of construction vehicles along the pipeline corridor; storage of topsoil, backfill and spoil; and bi-directional right of way access. Clearing and grading would be minimised where practicable to the extent necessary for construction of the pipeline and would not exceed the 40 m construction corridor. The area that would be directly impacted upon by construction activities would range in width from 15 m to 40 m, depending on a range of factors considered that include occurrences of critical habitats for endangered species and communities, vegetation sensitivity and quality, constructability, construction management and safety considerations, land form, slopes and anticipated sub-soil structures. Direct impacts would be reduced as far as practicable with narrower construction corridors proposed where feasible and in areas this may only require a 15 m wide corridor (possible only for short stretches). In areas of steep terrain (that impact on construction methodology’s available and construction safety) and problematic sub-soil conditions, the impact area would be wider than 15 m, but would always be less than 40 m. The proponent has based the environmental assessment on an indicative corridor width that would be refined by the construction contractor. As mentioned in section 3.3, access to land for the purposes of construction, rehabilitation and operation of the pipeline is the subject of discussions and negotiations between the proponent and the landowners. Construction compound for intake/low lift pump station A storage compound as well as space for amenities is proposed in the existing car parking area at Angle Crossing. It is proposed to extend the existing car park to the east by up to 50 m, to allow for a lay down area approximately 2,300 m² in size. There may also be a temporary water treatment facility in the existing car park / laydown area to treat water pumped from the coffer dam, so it can be recycled to river.
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Construction component for high lift pump station A site office as well amenities, site storage and car parking would be provided within the proposed site for the high level pump station. The proposed area required is 5,500 m², inclusive of the construction footprint. Pump station and pipeline lay down, storage facility and possible site accommodation A lay down and storage facility is proposed on land owned by the proponent. This land is located just after the cattle grid where the pipeline crosses Angle Crossing Road. This area is predominantly cleared and is well grassed. A hardstand area up to 4,200 m² would be required to provide storage for the high lift pump station as well as a pipe lay down for the western most pipes run. Main office, storage facility and pipe lay down The main office is proposed to be located on private land. This site was chosen due to its proximity to the Monaro Highway as well as being in an existing reasonably well cleared area. Access is also possible from the pipeline easement. This site would be approximately 9,500 m2 in size, and would also provide storage for pipeline construction west of the Monaro Highway. Pipe lay down It is proposed to create a pipe lay down on a strip of land approximately 1,300 m² in size, located along the access road into a private property, abutting the pipeline corridor. Spoil and pipe storage An existing borrow pit or storage area located within a road reserve at (refer to Figure 6.6) would be used as a stockpile area for pipe, spoil or bedding and padding material. This area would be levelled out to enable suitable storage, for an area approximately 1,300 m² in size. Pipe lay down and material storage There is an area of widening in the road reserve located at (refer to Figure 6.6) which appears to have recently been used for aggregate storage. This site would be used as a pipe lay down and material stockpile. A site approximately 5,800 m² in area would be required. Outlet structure compound, pipe lay down and material storage Amenity facilities, pipe lay down and a storage area is proposed near the outlet structure at Burra Creek. A site approximately 2,600 m² in area would be required. 6.7.6 Construction equipment An indicative list of construction equipment/plant that would be used during construction is provided in Table 6.2.
Table 6.2 Indicative construction plant/equipment
Task Location Equipment
Excavation • Pipeline • 45t, 30t and 20t excavator • Side booms • Dump trucks • Road trucks • Rollers • High lift pump station • 30t, 20t, 8t, 3t excavators • Intake/low lift pump station • Small plant • Outlet • Road trucks • Articulated dump trucks Piling • Intake/low lift pump station • Piling rig
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Task Location Equipment
• Trucks, bobcat hydraulic power pack Rock hammer • Structures and pipeline route various • 30t excavator with hammer locations Formwork • Structures and pipeline route various • Small tools locations • Generators • Trucks • Utes Building • High lift pump station • 20 – 80 t cranes works • Concrete boom pump • Tool handler Blasting • High lift pump station • Drilling rigs • Various locations along pipeline route • Utes • Explosive truck
6.7.7 Storage of flammable liquids or dangerous goods A small tanker (for example, 5,000 L in capacity) would transport fuel along the corridor as needed by machinery. Some 200 litre drums would be located at the site office in a bunded area to refuel the tanker. Other materials would be small amounts contained in 200 litre drums or smaller located in temporary bunds. The use and storage of chemicals and dangerous goods would be in accordance with relevant legislation, manufacturers instructions and the material data sheets. Transport, handling, storage and application methods would be established with the relevant method statement to prevent chemical, fuel and lubricant spillage on or around the site. Adequate quantities of emergency response materials such as oil spill kits, absorbent materials, sand bags, flocculating agents and pH buffer solutions would be readily available and kept in designated compounds. Oil spill kits would also be kept in emergency response vehicles, superintendents vehicles, environmental managers vehicle and vehicles that carry substantial quantities of chemicals. Chemical, fuel and lubricant storage areas would be suitably located and bunded to minimise the impact of any spillage or contaminated on or around the site. Stockpiles not located within the designated site compounds would be located along the pipeline construction easement. Class 1 explosives No explosives would be stored on site; explosives would be transported to the site as required by licensed vehicles. All surplus explosives would be returned to the supplier’s licensed magazine at the end of the day. 6.7.8 Lighting during construction Night works are not planned as part of the construction phase, therefore task lighting would only be required during unplanned events at night. In winter, some task lighting may be required to assist completion of tasks towards the end of the working day due to less daylight hours. Security lighting would be used at site compounds for the duration of construction. 6.7.9 Crossing of waterways The route of the pipeline crosses a total of 17 drainage paths.
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These have all been assessed in terms of estimated flood event flows and their corresponding flow velocities. These velocities have been used as a basis for selecting the type of scour protection over the trenching where the pipeline would be installed. The largest flow occurs where the pipeline crosses Burra Creek, near the Burra Community Hall and associated facilities. Figure 9.1 shows a total of six crossings which represent the largest six catchment areas, with Crossing No 6 representing the Burra Creek crossing. The next two largest catchment areas are Crossings No 5 and 4 respectively 310 and 190 ha. In the case of Crossing No 4, there has been some significant upstream farm dam work, and with the pipeline being located downstream of Williamsdale Road there is minimal evidence of the water course in these paddocks. The remaining 11 crossings have catchment areas less than 50 ha. The pipeline would be installed using open trenching techniques. In the case of Crossings 5 and 6, the top of the pipe would be approximately 2 m below the bed of the channel. The erosion protection would incorporate an 800 mm layer of rip rap material overlain with approximately 1,000 mm of the natural materials that would be excavated from that zone in the river channel. In other cases the depth of cover would generally be controlled by the geometry of the drainage path, but normally a minimum cover of one metre would be maintained. In the more channelised crossings a layer of scour protection rock would be incorporated similar to Crossing Numbers 5 and 6 and in the areas where lower velocity sheet flow conditions are likely to occur normal trench construction procedures would be applied. All drainage crossings of the pipeline are ephemeral (flows for short periods) except for Crossing Number 6 where the methodology for the crossing would involve temporary sandbagging and bypass pumping. The flows during the dryer periods are very low, and hence bypass pumping would be quite feasible. The banks of all water crossings would be restored by compacting and grading to natural contours. Special bank protection measures such as stabilised sand bags would be employed where required. The proponent will consult with the NSW Department of Water and Energy with regard to watercourse crossing methodologies and site-specific mitigation measures for watercourses that can then be incorporated into the construction environmental management plan. 6.7.10 Public utility adjustments Telecommunications The pipeline would cross Telstra services along Williamsdale Road in several locations. Specific work methods would be written to detail the protection requirements and construction steps required in order to minimise risk of damage to these services. Transport infrastructure Construction of access roads Access to the outlet structure would be via a bitumen sealed single lane gated road from Burra Creek Road adjacent to Burra Creek Bridge. Road crossings The pipeline would need to cross the Monaro Highway. It is proposed that the crossing be undertaken using an open trench method of construction. This would involve a part road closure during construction hours (managed by appropriate traffic control). The trench would be covered outside of construction hours, and both lanes of the Monaro Highway re-opened to traffic. Justification for this construction methodology is discussed in section 7.3.3.
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There would also be approximately 18 other road crossings (including Angle Crossing Road, rural roads and access roads). Construction would involve open trenching and restoration of the road surface. Work within the road reserve would also be required for sections of the pipeline. Vehicular access to properties would be maintained, either by keeping one lane open or through the use of diversions and/or steel plates over sections of the trench. The construction of pump stations may require road closures of Angle Crossing Road for short periods when, for example, large pieces of equipment such as the pumps are being delivered and unloaded by crane. Tight working conditions on Williamsdale Road may mean that to ensure public safety, a short section of the road would need to be closed when trenching and pipelaying is taking place within the road reservation. Arrangements would be made with property owners to ensure access to their properties is possible at all times. It is intended that Williamsdale Road would be open to traffic outside of construction working hours. The length of time during which work would be undertaken in the road reservation and closures may occur is one month. Such closures would be a last resort and would only be used when lane closures and traffic management would not be adequate to address public safety. At the end of construction, roads would be returned to their original state. Railway crossing The pipeline corridor would cross the Goulburn to Cooma Railway line. Construction in the vicinity of the railway line would involve lifting the sections of track, trenching through the railway corridor, and replacing the sections of railway track. 6.8 Rehabilitation The rehabilitation plan is recognised by the proponent as the most important part of the post construction environmental process. The proponent would dedicate the resources needed to rehabilitate to a high standard. The rehabilitation plan would be developed, with specialist input, to describe the rehabilitation management, objectives and activities necessary to assess and rehabilitate areas impacted by construction works. The majority of rehabilitation would be undertaken after hydrotesting of the pipeline. However, reinstatement of disturbed areas would be undertaken progressively during the construction period where possible, with ongoing discussion with the project and construction managers to explore the options for early rehabilitation in areas of the construction corridor that may no longer required during the hydrotesting period. The rehabilitation plan would include recommendations of the terrestrial flora and fauna impact assessment. Outcomes of consultation with landowners would also be included in the rehabilitation plan. This is discussed further in chapter 27. 6.9 Operation of the project 6.9.1 Modelled scenarios for possible operational regimes The project would have the capacity to transfer up to 100 ML/day of water, subject to maintaining environmental flows in the Murrumbidgee River. However, a number of factors would influence the actual amount of water that would be transferred per day. ActewAGL has developed a monthly timestep bulk water resources model of the Canberra water supply system using REALM software. The model considers various factors, such as: • Which source(s) would supply Canberra’s demand; • What restriction level would apply, if any; and • The environmental flows that is required in each river. The model decides how to operate in each month on the basis of factors such as: • Storage levels in each dam;
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• River flows; • Town demand; and • Time of year. The following lists the proposed operating rules, which would be adjusted as more data from monitoring becomes available: • Availability of water in the Murrumbidgee River: – The availability of water in the Murrumbidgee River would be determined by the environmental flow requirement of the river (see section 6.9.3); – In periods when additional transfer is desired, and water availability in the Murrubmidgee is below the environmental flow requirements, Tantangara Dam water could be released to increase supply. This arrangement is yet to be agreed with Snowy Hydro Limited (operator of Tantangara Dam) or approved by the NSW Department of Water and Energy. Consequently, releases from Tantangara Dam are not included in this assessment; • Capacity of Googong Dam: – Water supplied from the Murrumbidgee River to the Googong Reservoir would be relatively expensive, more costly than supplying water gravity fed from Bendora Dam or natural inflows to Googong. While the Murrumbidgee River water source would be very useful when water storage is low, it would not be desirable to run it if the Googong Dam is likely to spill in the near future; – In consideration of the above, the transfer scheme is likely to operate when Googong Reservoir is less than 80% of its total operating capacity (this figure was considered in the model). This also allows for natural flows to be captured rather than spilled; – This number was developed by assigning a cost to each level of water restrictions, and finding the storage trigger that produced the lowest combination of operating cost and water restrictions cost; • Discharge into Burra Creek: – There are no restrictions proposed related to discharges to Burra Creek. Discharge could occur at any time of the year for varying lengths of time; – Discharge would be gradually increased and decreased over a 48 hour period to minimise impact. 6.9.2 Water supply Based on the model conducted by the proponent, the average supply rate from Angle Crossing to Googong is expected to be 8 to 10 GL/year without Tantangara. However, this rate would change significantly from year to year, to the point where the project could operate virtually all year or not at all. It is unclear in what time of year the project would operate most frequently. The demand for water is typically highest in the first half of the year, however recent years have contained low Murrumbidgee flows during this period. If this trend occurs, the project may be used more frequently during the second half of the year. Some indication of variability in the first 10 years could include: • More than a 31% chance that the pipeline would not be used at all in a calendar year; • A 10% chance for the projection operating both one and two months of the year and a reasonably even likelihood of operating the project between three and nine months of the year; • The likelihood drops off as the number of months increases to 10, 11 or 12; • A 25% chance that the pipeline would supply more than 14 GL/year; and • A 5% chance that the pipeline would supply more than 23 GL/year.
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The seasonal distribution of supply from the Murrumbidgee River would be determined by the following factors: • Seasonal distribution of Googong Dam storage and natural inflows; and • Availability of water in the Murrumbidgee River. Table 6.3 shows the estimated average monthly supply through the pipeline. The supply rates show a loose inverse correlation with the Googong Reservoir storage, which is typically at its lowest at the end of summer and highest during spring. This relationship develops because of the 80% storage trigger applied in the model. A storage trigger that changes during the year would produce a different seasonal supply distribution. Further information on possible transfer securities is provided in Appendix C.
Table 6.3 Estimated average monthly supply from Angle Crossing to Burra Creek
Month Average supply (ML/month)
January 884
February 881
March 966
April 746
May 606
June 595
July 532
August 569
September 406
October 474
November 396
December 606
6.9.3 Environmental flows Environmental flows are modelled as per the current Licence to Take Water (ACT EPA 2008) (refer Appendix C), with the following exceptions: • The environmental flow in the Murrumbidgee at the Cotter Pump Station is set to 20 ML/day in any level of water restrictions and the 80th or 90th percentile flow when water restrictions do not apply. The licence proposes a lower flow requirement in unrestricted conditions, but it is believed that this more lenient rule may not be maintained in later licences; and • The environmental flow in the Murrumbidgee at Angle Crossing is not specified in the licence because Angle Crossing is not currently subject to any abstractions. The environmental flow has been modelled as the 80th percentile flow between November and May and the 90th percentile flow between June and October. No reduction is applied in drought conditions (see Table 6.4).
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In conjunction with the ACT EPA the proponent is currently implementing a comprehensive environmental monitoring program in the Murrumbidgee River which would evaluate the effectiveness of this flow requirement at Angle Crossing. As such an adaptive management approach will be adopted should the existing environmental flows not be considered adequate to protect the river environment downstream of Angle Crossing. Table 6.4 shows the environmental flow volumes for Lobbs Hole, upstream of Angle Crossing.
Table 6.4 Environmental flow at Lobbs Hole
Month Flow (ML/day)
January 80th 34.5
February 80th 25.2
March 80th 18.4
April 80th 35.4
May 80th 56.7
June 90th 67.9
July 90th 84.5
August 90th 129.3
September 90th 181.8
October 90th 133.6
November 80th 164.5
December 80th 58.0
6.10 Maintenance of the project 6.10.1 Low lift pump station Yearly inspection of the pumps for oil, wear ring and general condition would be required. Pumps would be lifted out and hosed down at the low lift pump station. Oil would be changed. A visual inspection of the wet well and internal screens would be undertaken at least annually. This would need to be pumped out to a tanker and taken away for disposal. Periodic cleaning of refuse from the course screens - organic and in-organic waste disposal would also be required. 6.10.2 High lift pump station Maintenance would involve routine inspections where wash down of hydrocarbons and waste with degreasers would be undertaken. External painting would also be undertaken when required. Routine maintenance would also be undertaken on the oil/grease sediment trap. 6.10.3 Pipeline Operations staff would periodically remove silt that has built up in the low points of the pipeline. This would be done by draining water through the scour valves sited at each low point. It is anticipated that this operation would be undertaken during suitable weather periods when the easement is dry and would require a suitably sized tanker to traverse the alignment from the nearest access point to enable the scoured water to be collected.
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Small vehicle access along the easement would be required to inspect all accessible assets such as air valves, scour valves and any above ground infrastructure approximately every 6 to 12 months. The timing is negotiable subject to operational needs. During the first years of operation, maintenance crew may drive along the whole route on a monthly basis. This would be in accordance with a commissioning / early operational plan that would be developed. Larger vehicle access may be required along the route if any significant repair work is necessary. This would be a rare event. 6.10.4 Outlet structure Yearly inspections of the outlet structure would be undertaken. When necessary, sediment would be removed by backhoe and/or labour. Such material would be removed to landfill for disposal. 6.11 Project timing 6.11.1 Project timing The project would take approximately three years to complete, including planning approval time estimated to be 18 months, and construction time estimated for 18 months. 6.11.2 Decommissioning The design life of the main components of the project is between 50 to 80 years. Mechanical components would need to be replaced at approximately 20 year intervals. The project would be maintained so that it could be operated for longer if needed, depending on climate conditions and water availability at the time. At the end of its operating life the intake, pump stations and outlet structure would be dismantled and materials recycled, where possible. The pipeline would be left in the ground, access points would be locked off and/or covered over and easements would be removed from property titles. 6.12 Incorporating sustainability into the project The proponent uses the term ‘sustainability’ (as detailed in ACTEW Sustainability Framework and Assessment Plan 2005) in accordance with the policy document ‘People Place Prosperity: a Policy for Sustainability in the ACT’ (2003), which relates the commitments of the ACT government to sustainability. There are 13 guiding principles in the ACT Sustainability guiding policy (which incorporate the five principles of ecologically sustainable development as set out in the Environment Protection and Biodiversity Conservation Act 1999) and represent a balance in environmental, economic and social outcomes. This is also reflected in the ACT’s ‘Statement of Direction’ in the context of the principles for sustainable development. The proponent has committed to using the infrastructure industry developed Australian Green Infrastructure Council (AGIC) sustainability assessment categories as the platform on which the Bulk Water Alliance sustainability program is based. The Australian Green Infrastructure Council sustainability assessment categories align with the ACTEW, ACT and Commonwealth sustainability policies and objectives. The categories also align with the sustainability elements of the Alliances Charter commitments. The Australian Green Infrastructure Council categories and sub-categories are listed in Table 6.5.
Table 6.5 Australian Green Infrastructure Council categories and sub-categories
Categories Sub-categories
Project management and • Purchasing and procurement governance • Reporting and responsibilities • Climate change and vulnerability • Making decisions • Knowledge sharing and capacity building Economic performance • Value for money
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Categories Sub-categories
• Due diligence • Economic life Using Resources • Energy use • Water • Materials selection and use Emissions, pollution and waste • Greenhouse gas management • Discharges to the air, water or land • Land management • Waste management Biodiversity • Functioning of ecosystems • Enhanced biodiversity People and place • Health, wellbeing, safety • Natural and cultural heritage values • Participatory processes • Positive legacy for current and future generations • Enhanced urban and landscape design aesthetics • Knowledge sharing, shared intellectual property Workforce • Safety, health and wellbeing of workforce is optimised • Capacity building • Increased knowledge of applied sustainability • Equity
Table 6.6 provides a list of some of the opportunities for enhanced outcomes identified for the project (these are described throughout Part C). The opportunities have been aligned with the relevant Australian Green Infrastructure Council sub-categories and are a snapshot of the potential sustainability benefits provided by the project.
Table 6.6 Opportunities for enhanced outcomes
Issue Enhanced outcomes Australian Green Infrastructure Council category
Water quality Runoff captured in constructed erosion control Using resources settlement dams could be reused for dust Emissions, pollution and waste suppression spraying to augment river water usage.
Terrestrial ecology Biodiversity offset plan. Biodiversity
Landscape character and The vegetation rehabilitation plan would Biodiversity visual amenity consider the local character and opportunities Using resources to enhance local biodiversity and habitat value. The detailed design would consider building materials and treatments to minimise the
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Issue Enhanced outcomes Australian Green Infrastructure Council category
potential visibility of the project. These include, for example, low profile fencing, planting vegetation, and siting the access road within the existing topography.
Spoil handling and waste The waste avoidance and recovery strategy Using resources management encourages avoidance, minimisation, Emissions pollution and waste reduction, treatment and, as a last option, disposal.
Climate and air quality The mitigation methods include measures not Economic performance only suppressing dusts but also reducing Using resources particulates entering the atmosphere in the Emissions pollution and waste first instance (at source). Workforce
Greenhouse gas Energy efficiency measure - the installation of Economic performance assessment mini-hydro system at the outlet location would Using resources recover some of the energy required for Emissions, Pollution and pumping. Waste In addition to the proposed offsets, potential options for reducing construction and operational greenhouse gas emissions are currently being assessed by the proponent.
Social and economic The proponent would work with Palerang Economic performance Council and community members to identify People and place potential community benefits in recognition that benefits derived from the project (including secure water supply and a stable economy) are not directly related to the local impacted community.
6.12.2 Ecologically sustainable development The project has been assessed against the following principles of ecologically sustainable development. ACT principles of sustainable development The project is compatible with the principles for sustainable development in the ACT Territory Plan Statement of Strategic Directions. The relevant principles for sustainable development and how the project is compatible with each are summarised in Table 6.7.
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Table 6.7 Principles for sustainable development in the ACT Territory Plan relevant to the project
Principle Compatibility of this project
General principles
1.1 Planning processes and decisions will be focused The project planning has incorporated extensive on the combined achievement of economic vitality, community and stakeholder engagement and a number community wellbeing, and environmental quality. Broad of consultation methods are proposed during the community involvement will be a key element in the assessment, exhibition and the construction periods. pursuit of sustainable development, as will complementary regional strategies and agreements.
1.2 Matters of broader National Capital, metropolitan The project forms part of the ACT Government’s Water and regional significance will be carefully considered Security Program, a matter of broad National Capital, when formulating Territory Plan policies and when metropolitan and regional significance. making decisions about development proposals and sequencing.
1.3 Economic, social and environmental objectives will The project would assist in securing the ACT’s water be pursued in a balanced and integrated way, having supply. This would provide ongoing economic and regard to both short term and long term factors, such social benefits through increased diversity of water that present needs can be met without prejudicing the sources in the ACT region resulting in less dependence welfare of future generations, and without serious or on rainfall, resulting in reduced application of water irreversible loss of life-supporting natural resources or restrictions and not exceeding the Murray Darling Basin damage to the environment. cap on water diversion. This would be achieved while also protecting the health and ecology of the Murrumbidgee River, Burra Creek and Googong Reservoir.
1.4 Wherever appropriate, the broader global and This assessment has considered the potential regional context and potential cumulative impacts of cumulative impacts of the project (chapter 26). Chapter decisions will be taken into account. Where there are 21 considers climate change risks and impacts of the threats of serious or irreversible damage, lack of full project and its relationship with the broader global and scientific certainty should not be used as a reason for regional cumulative impacts of climate change. failing to prevent environmental degradation.
General principles environmental sustainability principles
1.5 Planning policies will seek to ensure the efficient The project incorporates measures to minimise use of all resources and to reduce consumption of non- resource consumption and waste generation, and renewable resources. Waste minimisation, reuse and encourage reuse and recycling (for example, the spoil recycling will be encouraged, whilst energy-rating and reuse strategies and waste management measures conservation measures will be applied wherever detailed in chapter 19). appropriate, particularly in transport, subdivision planning, and building design and construction.
1.6 The pattern of development is to reflect land The project has been carefully designed and proposed capability constraints resulting from topography, soils, management measures have been developed to geotechnical factors, drainage, natural hazards, minimise potential environmental impacts and to reflect microclimate and the sensitivity of ecosystems. land capability constraints. This includes the planning of Particular attention will be given to the need to the pipeline route, design of ancillary structures and conserve soil, water and vegetation; maintain biological operational management techniques. diversity; safeguard important ecosystems and ecological processes; and provide and protect wildlife corridors.
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Principle Compatibility of this project
1.7 Land and water resources will be planned in The project would assist in securing the ACT’s water accordance with the principles of integrated catchment supply by transferring water from the Murrumbidgee management and water sensitive urban design. Policies River to Googong Reservoir via Burra Creek. It would will seek to protect identified environmental values, do this in a sustainable manner, which: whilst focusing on opportunities for multi-purpose use of • Protects the health and ecology of the Murrumbidgee resources. Special attention is to be given to protecting River, Burra Creek and Googong Reservoir; sources of the Territory’s water supply and to • Does not cause significant impact in the pipeline maintaining environmental flows in rivers and streams. corridor; and • Does not significantly impact local communities. The project would require the incorporation of Burra Creek management in the Draft Googong Foreshores Catchment Management Plan.
Economic sustainability principles
1.17 In planning future development and The project would generate long term positive impacts redevelopment, particular emphasis will be placed on relating to security of water supply which help lay the cost-effective provision and management of existing foundation for the continued growth of the region. and new infrastructure and services, taking into account The project is expected to generate a net economic whole-of-life and whole-of-system costs, including the benefit as a result primarily of savings due to reduced ecological footprint of proposed developments and application of water restrictions. activities.
Social sustainability principles
1.25 Heritage and cultural values will be safeguarded, The proponent has committed to a number of measures including in particular those of the Territory’s Aboriginal to safeguard heritage and cultural values, as described peoples and those derived from both its rural history in chapter 28. and urban development as the National Capital. The distinctive qualities of residential areas and other places, as well as elements of community heritage, will also be recognised and their conservation promoted.
1.26 Identified places of heritage significance will be Indigenous and non-Indigenous heritage assessments protected in accordance with requirements for their were carried out as part of this environmental conservation contained in the Heritage Register and assessment to identify places of heritage significance. any relevant heritage guidelines under the Heritage Act Identified places of heritage significant would be 2004. Special provisions are included in the Heritage protected in accordance with the ACT Heritage Act Act for the recognition, registration and conservation of 2004. Aboriginal heritage.
Compatibility with the principles of ecologically sustainable development in NSW The Environmental Planning and Assessment Act 1979 adopts the definition of ecologically sustainable development contained in the Protection of the Environment Administration Act 1991. Clause 6 of Schedule 2 of the Environmental Planning and Assessment Regulation 2000 lists the principles of ecologically sustainable development as: • Precautionary principle; • Inter-generational equity; • Conservation of biological diversity and ecological integrity; and
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• Improved valuation, pricing and incentive mechanisms.
An assessment of the project against these above principles is provided below. Precautionary principle A range of environmental investigations, as described in Part C of the assessment, have been undertaken as part of the development of the project and the environmental impact assessment process, to ensure that potential impacts are understood with a high degree of certainty. The assessment of the potential impacts of the project is considered to be consistent with the precautionary principle. It is considered that the assessments undertaken are consistent with accepted scientific and assessment methodologies, and have taken into account relevant statutory and agency requirements. The project has evolved to avoid impacts where possible and to reflect the findings of the studies undertaken. A number of safeguards have been proposed to minimise potential impacts. These safeguards would be implemented during construction and operation of the project. No safeguards have been postponed as a result of lack of scientific certainty. The selected construction contractor would be required to prepare a construction environment management plan prior to commencing construction. This requirement would ensure that the project achieves a high-level environmental performance. Principle of inter-generational equity It is recognised that the construction of a project of this scale has the potential to lead to some environmental and social disturbance. This includes the clearing of vegetation and some disturbance to private properties during construction of the pipeline; potential loss of some Aboriginal sites; and localised impacts at the sites of the intake, high lift pump station and discharge structures. However, the potential for environmental and social disturbance as a result of construction has to be balanced against the long term benefits of increasing the security of the ACT’s water supply. Should the project not proceed, the principle of intergenerational equity may be compromised, as future generations of ACT and Queanbeyan residents would inherit a lower level of water security and higher economic cost. There has been a demonstrated increasing decline in long term average inflows to the ACT’s water storages. The medium to long term outlook is for a further significant deterioration in inflows. Hence there is a real demand for construction of additional water supply assets that can cope with substantially reduced inflows as well as more frequent and longer droughts. Improved utilitsation of the Googong Reservoir and Water Treatment Plant would enhance inter-generational equity, through extension of the period in which the assets and investments continue to contribute a positive community benefit. The project would benefit future generations by helping to ensure that the ACT and Queanbeyan’s water supply is secured, which would be a positive benefit affecting all residents of these areas. Conservation of biological diversity and ecological integrity Ecological studies have been undertaken to identify potential adverse impacts on flora and fauna. Where potential impacts have been identified, mitigation measures would be implemented to reduce the impact as far as possible. There is the potential for some impact to threatened species and communities to occur within the study area. However, a number of mitigation measures are proposed that would reduce the impact of the project on native vegetation and flora and fauna, including amongst other things, vegetation offsets. Improved valuation and pricing of environmental resources The assessment has identified the environmental and other consequences of the project and identified mitigation measures where appropriate to manage adverse impacts. The construction and operation of the project would be in accordance with relevant legislation and the construction and operation environmental management plans. Requirements imposed in terms of implementation of these measures would result in an economic cost to the proponent. The implementation of mitigation measures would increase both the
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capital and operating costs of the project. This signifies that environmental resources have been given appropriate valuation. The concept design for the project has been developed with an objective of minimising potential impacts on the surrounding environment. This indicates that the concept design for the project has been developed with an environmental objective in mind. The economic costs of the project, including environmental works and management, would be reflected in water pricing policies. Water diverted through the project would be subject to a water abstraction charge reflecting the value of the environmental resource.
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Chapter 7 Alternatives considered
7.1 Overview This chapter describes the alternatives to the project. The alternatives to the project as a whole are described in section 7.2 while the project components (the pipeline, intake and outlet structures and pump stations) that were considered as part of further development of the project are described in sections 7.3 to 7.6, with the reasons for selecting the preferred option for each project component described. Further detail on the preferred option is provided by the project description in chapter 6. In the past few years, the proponent has been reviewing options for a secure water supply for the ACT and surrounding region, with a considerable amount of work undertaken in the last four years. The proposal to extract water from the Murrumbidgee River has been considered as part of these investigations. All the options identified between 2004 and 2007 have been the subject of community consultation, and the reports in which they were considered were made available to the public. The options identified in these reports are outlined below. 7.1.1 ACT water security investigations, 2004 In April 2004, the ACT Government released Think Water, Act Water - a strategy for sustainable water resources management (ACT Government 2004). The strategy defined actions to achieve sustainability objectives for water use in the ACT to 2050, including to: • Increase the efficiency of water use; and • Provide a long term reliable source of water for the ACT and region. As a result of the commitments made in ‘Think Water Act Water’, the ACT Government requested the proponent to provide advice on new water supply options to complement demand and water conservation measures being implemented by the Government. 7.1.2 ACT water security investigations, 2005 In 2005, the proponent produced the ‘Future Water Options’ series of reports, which identified a range of measures necessary to secure water for the ACT region (ACTEW 2005a). This work was based upon the following six key assumptions: • Climate variability and climate change; • Impact of bushfires on inflows to ACT reservoirs; • Future population growth in Canberra and Queanbeyan and the possibility of servicing additional areas; • Reduction targets in per capita water use set by the ACT Government in ‘Think Water, Act Water’ (ACT Government, 2004); • Environmental flow requirements; and • Acceptable levels for the duration, frequency and severity of water restrictions during times of drought. The main recommendations arising out of the ‘Future Water Options’ series of reports included: • A transfer system from the Cotter to the Googong catchment, called the Cotter to Googong Bulk Transfer Option, which was implemented in 2006/07; • The immediate construction of a transfer pipeline from the Murrumbidgee River near Angle Crossing to Googong Dam, called the Angle Crossing Option; and • Continued studies and annual reviews of water planning assumptions and security of supply.
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7.1.3 ACT water security investigations, 2006 The proponent implemented the Cotter to Googong Bulk Transfer option (ACTEW 2005a) in 2006/07. Further analysis resulted in the deferral of the Angle Crossing option and the implementation of the Extended Cotter to Googong Bulk Transfer option, which could be implemented earlier and at less expense. The Extended Cotter to Googong Bulk Transfer option involved pumping water from the Murrumbidgee River, near the Cotter Pump Station, to the Mount Stromlo Water Treatment Plant to supplement supply to Canberra. Any excess water could be pumped to Googong Reservoir for storage via the water reticulation system. The Angle Crossing option, involving extracting water from the Murrumbidgee River at Angle Crossing, was deferred as pumping from the Cotter Pump Station was possible by the end of 2007, whereas pumping from Angle Crossing could not be implemented within this timeframe. Additionally, in its 2006 annual review, the proponent identified that there had been a fundamental change to the assumptions on climate variability and climate change (ACTEW 2006). Based upon CSIRO assessments it was predicted that by 2030, inflows into storages would decrease, on average, by 30%. Over the past six to seven years, inflows have decreased by more than 60% and by nearly 90% in 2006. This prompted a review of the options recommended by the ‘Future Water Options’ series of reports. 7.1.4 ACT water security investigations, 2007 In response to ongoing drought and the lowest inflows to storages on record, ACTEW’s 2007 report to Government (ACTEW 2007a) undertook another review of water supply options for Canberra. The review assumed that demand management targets would be met and considered all the previous water supply options (including those outlined above and the findings of ‘Future Water Options’ 2005), including: • The ‘do nothing’ option; • Enlarged Cotter Dam; • Tennent Dam; • Tantangara transfer; • Angle Crossing option; • Seawater desalination; • Groundwater; • Water purification scheme; • Stormwater; • Rainwater collection (private tanks); • Greywater re-use; • Other non-potable reuse options; • Cloud seeding; • Water mining; and • Evaporation control on reservoirs. These options are the alternatives to the project as a whole, and an overview of these options is provided below. The project was included as one of the options (described as the Angle Crossing option).
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7.2 Alternatives to the project as a whole 7.2.1 The ‘do nothing’ option A key aspect of the Future Water Options study was an assessment of the need for an additional water supply. The report ‘An Assessment of the Need to Increase the ACT’s Water Storage’ (ACTEW 2004) determined that new scientific knowledge of the potential combined effects of climate change and bushfire impacts meant that additional water storage would be needed sooner than was previously expected. Future conditions were predicted using the six assumptions described in section 7.1.2. This indicated that reservoir storage levels would become low to very low in periods of drought. The report identified that ACT would not run out of water, as long as severe and onerous water restrictions were applied or unless some unforeseen event occurs. The report also identified that water restrictions would be increasingly detrimental to the community and at the same time, would become less effective. This is because restrictions would come on top of a substantial reduction in per capita water use through meeting the water efficiency targets, which themselves would require permanent water restrictions. As a result, it was concluded that unless the ACT community was willing to accept the regular recurrence of water restrictions of a severity and frequency unprecedented elsewhere in Australia, then additional water storage would be required. The economic costs of doing nothing (that is, relying on restrictions for water security) are substantial (the project is expected to generate a net economic benefit in excess of over $500 million as a result of savings due to reduced water restrictions). This means that the ‘do nothing’ option is not feasible. 7.2.2 New dam in the Cotter catchment As part of the Future Water Options studies in 2005, four alternatives involving the Cotter catchment were considered (ACTEW 2005a): • Construct a new Coree Dam, with a 73 GL storage capacity, upstream from the existing Cotter Dam; • Retain the existing dam, plus make greater use of environmental flow releases from Bendora Dam; • Enlarge the existing dam to a storage capacity of 45 GL; and • Enlarge the existing dam to a storage capacity of 78 GL. Enlarging the existing dam was identified to be the preferred option and the Enlarged Cotter Dam project was developed. The 2005 studies also recommended that the proponent review existing infrastructure associated with these options, such as pipelines, pump stations and water treatment plants, to determine the upgrading that would be required to distribute water to various locations within the Canberra and Queanbeyan water supply system. In this review, the Cotter Dam options were refined and it was determined that the best option would be to construct a separate dam wall downstream of the existing dam wall as opposed to incorporating the existing structure in a new one (raising the existing dam wall). The ‘Future Water Options Review’ (ACTEW 2007b) included a detailed review of the Enlarged Cotter Dam project which led to the ‘Enlarged Cotter Dam: Update Report’ (ACTEW 2007c). This report reconfirmed the Enlarged Cotter Dam as one of the preferred options to secure the ACT’s water supply. The advantages and disadvantages of the Enlarged Cotter Dam option are presented below.
Advantages Disadvantages
• Existing dam site on ACT land • Requires pumping • High yield at relatively low cost • No increase in diversification • Minimal environmental impacts • Management of endangered fish
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The draft environmental impact statement for the Enlarged Cotter Dam project (‘Enlargement of the Cotter Reservoir and Associated Works – draft environmental impact statement’) was placed on public exhibition in October to November 2008. 7.2.3 Tennent Dam One of the dam options considered as part of the Future Water Options project was construction of the Tennent Dam on the Gudgenby River in the Naas Valley (ACTEW 2005a). The construction of this dam would also require building a new water treatment plant onsite, or pumping water to the existing Mount Stromlo Water Treatment Plant. The proposed dam included a number of issues that would need further assessment: • The Naas Valley has an existing community of rural lessees who would need to be relocated if a dam was built; • The site has an existing road linking Tharwa with the Boboyan Road, which would need to be entirely relocated; • The site has areas of Yellow Box Grassy Woodlands, which have national significance (EPBC listed communities). The woodlands are also home to several threatened species of birds; and • The site has a number of Aboriginal and non-Aboriginal heritage sites. The key issue associated with this option is the uncertainty of flows in the Gudgenby River system. This river has long term average flows of about 57 GL per year, compared to 138 GL per year for the Cotter River. Over the last six years the Tennent catchment inflows have reduced by 70% compared to 40% in the Cotter Reservoir and 35% for Tantangara Reservoir. This indicates that the Gudgenby River flows are potentially much less resilient to drought than the other river systems considered. Had the Tennent Dam been in place in 2006 it would have received inflows of less than 6 GL in total. This option is also the most expensive dam option. The advantages and disadvantages of the Tennent Dam option are presented below.
Advantages Disadvantages
• Diversification through a new catchment • Uncertainty of future inflows • Largest dam option available • Longer timeframe to build and fill and high capital cost • Endangered yellow box woodlands • Leaseholder relocation • Road relocation • Heritage
7.2.4 Tantangara transfer As discussed in section 5.3.4, the Tantangara transfer option would involve transferring water from the Snowy Mountains Scheme, most likely via the Tantangara Reservoir in NSW, to the ACT (most likely to Googong Reservoir). This would involve: • Purchasing water licences from irrigators downstream of the ACT; • Storing purchased water in Tantangara Reservoir, a reservoir located well upstream of Angle Crossing; • Transferring that water from Tantangara to the ACT via the Murrumbidgee River; and
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• Transferring the water from the Murrumbidgee for storage in Googong Reservoir. Alternatively, the water from Tantangara releases can be pumped from the Murrumbidgee River to the Mount Stromlo Treatment Plant via the Cotter pump station, although this is unlikely to be a frequent occurrence. This option was initially evaluated under the Future Water Options project and has been further developed since then. In light of the recent changes to national water management, this option appears to be more realistic than when it was when last considered by ACTEW in 2004/2005. However, there are a number of issues associated with this option that remain unresolved including: • The purchase of about 20 GL of general security water entitlements and conversion to about 11 GL of high security water entitlement; • Intergovernmental arrangements to allow water trade to occur between NSW and ACT; and • A commercial agreement between ACTEW and Snowy Hydro Limited for use of infrastructure to store and release water purchased by ACTEW to the ACT when required from Tantangara reservoir. Work is still progressing on this option. The advantages and disadvantages of the Tantangara transfer option are presented below.
Advantages Disadvantages
• Provides added diversification of water supply sources • Changing Snowy Hydro Limited’s operating licence • Improves use of Googong Reservoir and water • Protracted negotiations treatment plant • Losses in run of river delivery • Quick to implement • Requires pumping • Cost effective
7.2.5 Angle Crossing option (Murrumbidgee to Googong) The Angle Crossing option was a key recommendation of the Future Water Options study (ACTEW 2005a). This option is aimed at better utilising Googong Reservoir by transferring water from the Murrumbidgee River. The transfer of water would involve pumping water from at or near Angle Crossing to Burra Creek where it would flow into Googong Reservoir. This option was further developed to become the project which is the subject of this assessment. The recent agreement for a regional approach to water management has helped in obtaining better regional support for this option. The advantages and disadvantages of the Murrumbidgee to Googong option are presented below.
Advantages Disadvantages
• Provides additional diversification • Inter-jurisdictional approvals required • Quick to implement • Land owner easement requirements • Improved use of Googong Reservoir
7.2.6 Seawater source Desalination of seawater to serve Canberra and Queanbeyan was also considered as a potential water source as part of the Future Water Options assessment (ACTEW 2004). This option would consist of: • A seawater reverse osmosis process plant located on the NSW south coast;
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• The intake and outlet located in water depths of approximately 20 m offshore to optimise dispersion and intake water quality; • Construction of a desalination plant with a capacity of 50 ML/day. A one pass reverse osmosis process would be required if the water is to be delivered to the Queanbeyan River. A two pass reverse osmosis process would be required if the water is to be delivered directly to the existing water supply network to match existing water quality; • An intake which would draw approximately 140 ML/day to produce 50 ML/day of potable water; • Discharge of reject water to the ocean; • A 750 mm diameter pipeline approximately 100 km long, connecting the plant to the existing ACT supply system; • A main pump station at the plant site and three more along the route; and • Electricity sourced from the grid. This option was not considered appropriate at this point in time, based on the potential complexity in obtaining approval to construct a project of this scale as well as the estimated cost for construction and operation. The advantages and disadvantages of the seawater source option are presented below.
Advantages Disadvantages
• Proven technology • Higher cost • Rainfall independent • Higher energy use • Inter-jurisdictional approvals
7.2.7 Groundwater use Groundwater use was examined in the Future Water Options studies and was not considered to be a viable option. Groundwater use can provide benefits on a small localised scale and is already being extracted and used at various locations in the ACT. The advantages and disadvantages of groundwater use are presented below.
Advantages Disadvantages
• Potentially provides diversification • No large aquifers in or near the ACT • Transfer costs to the ACT water network • Sustainability of extraction
7.2.8 Water purification The proponent has investigated adoption of existing technology to treat used wastewater to a standard that is safe for human consumption. Membrane filtration and reverse osmosis is the preferred combination of treatment processes that provides a multi-barrier approach to water purification. Membrane filtration uses hollow fibre membranes with fine pores to filter particles and micro-organisms. The membrane surface acts like a screen to retain the micro- organisms; similar to a screen door that retains insects. This step removes microscopic particles, contaminants and pathogens. Reverse osmosis is the process of pushing water through a membrane or filter that traps almost all suspended and dissolved substances and micro-organisms to one side and allows water
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to come out the other side. The membranes have very small pores, small enough to trap more than 99% of sodium and chloride ions. This step removes pollutants such as salts, organic compounds and viruses. A further process (as part of a multi barrier approach) is the inclusion of ultra violet disinfection and advanced oxidation. Ultra violet light is used to disinfect water. UV light is effective at destroying micro- organisms such as Giardia and Cryptosporidium and other pathogens. Oxidation is effective in destroying chemical compounds. Strong oxidation agents such as hydrogen peroxide are commonly used to remove trace organic constituents. This option could also involve taking advantage of natural water treatment processes by letting the purified water flow into the natural environment (wetland). The ACT Government recently announced it had agreed with the proposal to defer the construction of this option providing the Tantangara Transfer along with the Enlarged Cotter Dam and the Murrumbidgee to Googong Water Transfer proceed and there is no further deterioration in dam inflows. The advantages and disadvantages of water purification are presented below.
Advantages Disadvantages
• Less directly dependent on rainfall than a dam • Higher cost • Proven technology • Higher energy use • Assist in avoiding restrictions under extremely dry future • May not be used in wetter periods climate scenarios
7.2.9 Stormwater harvesting Stormwater harvesting is promoted in the ACT Government's ‘Think Water, Act Water’ strategy, as it can assist towards meeting the target of a 25% reduction in potable water consumption per person by 2023. It is also factored into the ACT Government’s ‘Waterways: Water Sensitive Urban Design General Code’ (2008a), which targets a 40% reduction in potable water use for all new developments and re-developments. The ACT Government carries out stormwater harvesting from most urban ponds and lakes for use on community parks and ovals. Golf courses, nurseries and other large water users also use stormwater. The ACT Government is currently undertaking the ‘Canberra Integrated Urban Waterways Project’ with assistance from the Australian Government Water Fund. This project would implement stormwater storage, harvesting and use up to 3 GL per year by 2015 as well as providing stormwater improvement benefits. A feasibility study is currently underway to determine what level of use is feasible. The project would cost $17 million (excluding ongoing operations, maintenance and monitoring costs). The advantages and disadvantages of stormwater harvesting are presented below.
Advantages Disadvantages
• Local use of existing storages can be cost • Poor water quality as a source of supply for potable water effective • Highly variable quantities • Provides some stormwater control • Large storages required • Provides fit for purpose supply and substitutes • The most cost effective systems are already implemented for demand for potable supply
7.2.10 Rainwater collection (private tanks) Rainwater tanks can store runoff from the roof for garden watering and other household uses, contributing towards reducing residential water demand and serving as a water conservation measure. The ACT Government's ‘Rainwater tanks: Guidelines for residential properties in Canberra’ (2008b) provides information on this subject.
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Rainwater tanks are promoted in the ACT Government's ‘Think Wwater, Act Water’ strategy, as they can assist towards meeting the 25% target reduction of drinking water consumption per person by 2023. The strategy recognises the benefits of installing a rainwater tank in terms of water saving and stormwater reduction. The ACT Government has provided household rebates for the installation of rainwater tanks to assist the community contribute to water conservation. The use of rainwater tanks is also promoted in the ACT Government’s ‘Waterways: Water Sensitive Urban Design General Code’ (2008a). It is estimated that the cost for installing a tank in all households in the ACT would total about $330 million to $550 million and deliver approximately 8 GL per year. Rainwater tanks are also dependent on rainfall, thereby reducing the benefit of rainwater tanks during drought periods. There is limited opportunity for citywide rainwater tank use at levels above what is already being put in place. Although rainwater tanks are dependent on rainfall and they can be expensive to install, they represent a means to reduce dependence on mains water. The assessment found this option to be a costly solution that would not translate into the storage required to secure the ACT’s future water needs. At best this could be a supporting solution. The advantages and disadvantages of rainwater collection are presented below.
Advantages Disadvantages
• Supplement existing drinking water use • Higher cost • Can be used in toilets and laundry • Rainfall dependent • Reduce stormwater runoff • Difficult to obtain large enough storage
7.2.11 Greywater re-use Greywater is wastewater from hand basins, showers, spas, washing machines, laundries, (but not from the toilet or urinal, which is known as blackwater). The use of greywater varies from bucketing or siphoning, connecting the outlet drain to a diversion pipe or installing an appropriate greywater treatment system. Greywater use is promoted in the ACT Government's ‘Think Water, Act Water’ strategy, which includes a target to increase reclaimed water from 5% to 20% by 2013. Ways to encourage the take-up of greywater use are being considered, including incentives and rebate schemes. Greywater use is also promoted in the ACT Government’s ‘Waterways: water sensitive urban design general code’ (2008a). Greywater use can replace some drinking water use and contributes to water conservation measures. In addition, it also reduces wastewater flows, which reduces treatment costs and discharge volumes to waterways. Due to poor water quality however, untreated greywater can only be used for irrigation and cannot be stored for more than 24 hours unless an appropriate treatment system is used (ACT Government 2007a). The advantages and disadvantages of greywater use are presented below.
Advantages Disadvantages
• Replaces drinking water use on gardens • Higher cost • Reduces sewerage flows (and treatment costs) • Care needed in handling due to potential health issues • Ongoing maintenance
7.2.12 Other non potable reuse options – large scale irrigation Non-potable reuse options involve the extension of the existing ACT water reuse schemes for irrigation purposes from water supplied from the Lower Molonglo Water Quality Control Centre. This provides additional reuse of water for irrigation of open spaces, parks, ovals and golf courses through Central Canberra, Belconnen, Woden and Tuggeranong, reducing the use of potable water for these uses by
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approximately 3 GL/year. This option involves a capital cost of more than $100 million. Additional capacity beyond this option becomes even more expensive. To implement this option, approximately 100 km of new pipelines would need to be constructed through largely existing urban areas. Several pump stations would also need to be constructed and connection to decommissioned reservoirs. The demand for non-potable reuse is mostly limited to seasonal demand during warm and dry periods. It has the advantage of allowing use of sports ovals through periods of drought, but does not reduce the probability that severe restrictions will be required for larger Canberra, particularly in current and future droughts. The scheme could only be implemented in some parts of the city, resulting in a potential inequitable distribution of the resource, with some areas benefiting by having access to playing fields during drought whereas other areas of the city would not. This scheme provides only limited additional flexibility to the water supply system, as it provides non-potable water to limited areas of Canberra only through the summer months. It does not supplement the drinking water supply during years with low inflows to reservoirs (like 2006) and only provides limited offsets to the drinking water supply during periods of water restrictions. The proponent is examining ways to further expand non-potable reuse where it is viable, including assessment of storage options, seeking suitable winter demand and water pricing. The advantages and disadvantages of other non potable reuse options are presented below.
Advantages Disadvantages
• Provides irrigation water during droughts • Higher cost • Disturbance during installation of pipes • Seasonal use of water
7.2.13 Cloud seeding Cloud seeding is a form of weather modification. It involves changing the amount or type of precipitation that falls by dispersing substances into clouds to serve as cloud condensation or ice nuclei. The usual intent is to increase precipitation, but hail suppression is also commonly practiced with these methods. Silver iodide and dry ice are the most commonly used substances in cloud seeding. Seeding requires clouds to contain liquid water colder than zero degrees Celsius. The introduction of a substance such as silver iodide, which has a crystalline structure similar to that of ice, then induces freezing and promotes precipitation. Clouds can be seeded from the air or ground level. Snowy Hydro Limited embarked on a six-year research project of winter cloud seeding to assess the feasibility of increasing snow precipitation in the Snowy Mountains. As there have been no cloud seeding studies in the Canberra region, preliminary investigations of seeding types and frequency of suitable atmospheric conditions are required, followed by a four to six year experiment. The correct cloud formations are required for cloud seeding to be successful, therefore research into the types and abundance of clouds over the Canberra water catchment areas needs to be undertaken to determine the usefulness of cloud seeding in the region. ACTEW, ActewAGL and Snowy Hydro Limited are cooperating to understand the potential of cloud seeding for the ACT. A proposal is being developed that builds on the expertise that Snowy Hydro Limited has obtained in the cloud seeding operations to assist with meteorological research into the appropriateness of cloud seeding for the ACT. While cloud seeding has shown to be effective in altering cloud structure and size and converting cloud water to ice particles, it is more controversial whether cloud seeding increases the amount of precipitation at the ground. This is partly problematic given the difficulty associated with discerning how much precipitation would have occurred had cloud seeding not taken place. Nevertheless, there is more credible scientific evidence for the effectiveness of winter cloud seeding over mountains (to produce snow) than there is for
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seeding warm-season cumuliform (convective) clouds. Cloud seeding essentially makes the wet times wetter and has minimal benefits in dry times. Benefits of cloud seeding will generally only become tangible over a long term period, following a trial period to assess effectiveness. On this basis cloud seeding was ruled out as a reliable future water source for the ACT. The advantages and disadvantages of cloud seeding are presented below.
Advantages Disadvantages
• May increase rainfall • May not increase rainfall • Ongoing research by ACTEW • Uncertain • Several years to test and prove
7.2.14 Sewer water mining Water mining is a process by which wastewater is taken from a sewer system and treated for reuse in the local vicinity, such as for irrigating ovals, parks and playing fields. The proponent currently undertakes water mining at its Watermining® facility at Southwell Park (Lyneham), which supplies irrigation water for the adjacent Southwell Park playing fields. The plant was commissioned in 1995 as a demonstration facility of new technology. In 2005, the proponent investigated localised water mining opportunities for the ACT including facilities in areas including Kambah, Stirling, Isabella Plains, Condor, Melba and Charnwood. Investigations highlighted that water mining facilities were expensive and even if a number of facilities were built, they would provide little benefit to the overall security of the ACT water supply. Although water mining may benefit individual sites, it does not have the potential to provide sufficient water at a reasonable cost to meet the ACT’s water security requirements. The advantages and disadvantages of water mining are presented below.
Advantages Disadvantages
• Reduces drinking water demand • Higher cost • Further locations being investigated • Seasonal use • Not a major supply option
7.2.15 Evaporation control on reservoirs The proponent also investigated techniques for reducing evaporation from existing water supply reservoirs. None of the options examined provided a cost effective solution. The options were only suitable for the smaller reservoirs, Bendora and Cotter, which have relatively insignificant evaporation losses compared to Googong and Corin reservoirs. It would also not provide any significant increase to the ACT’s water supply. However, the proponent will continue to review new products and techniques that become available. 7.2.16 Preferred options The ACT Government announced a range of projects that will be implemented to secure the ACT and regional water supply. The projects endorsed by the ACT Government include: • Enlarging the Cotter Dam from 4 GL to 78 GL; and • The Murrumbidgee to Googong Water Transfer. The proponent has been refining the project since the announcement by the ACT Government in 2007. This has involved considering the location of the intake, determining the pipeline route and the location of the outlet structure. Other alternatives considered included the type and location of pump stations (high lift and
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low lift), types of intake structures, pipeline materials, and energy requirements. A description of the main alternatives considered is provided below. 7.3 Pipeline alternatives 7.3.1 Initial corridor options Three broad options for the pipeline corridor were initially assessed including a northern, central and southern pipeline corridor (refer to Figure 7.1). Four variations of the Southern corridor were assessed, making a total of 6 route options with various extraction and discharge points. The northern and central options involved extracting water at Point Hut approximately 500 m upstream of the Point Hut Road crossing. Point Hut was considered to be a good potential location for the intake as a natural rock barrier across the river at this location negated the need for an impounding weir. Both the northern and central options traversed the Queanbeyan local government area to discharge at Googong Reservoir approximately 2.5 km from the Googong Reservoir intake tower. The longer northern corridor (approximately 28 km in length) mostly followed an existing 10 m wide easement over the existing pipeline conveying water from Googong Reservoir to the ACT. The central corridor (approximately 20 km in length) followed a more direct west–east corridor and passed just south of the proposed Googong township. The southern options involved extracting water from near Angle Crossing just inside the ACT border. These options traversed the Palerang local government area in NSW to various discharge points including Burra Creek at Williamsdale Road (approximately 13 km in length); Burra Creek at Burra Road (approximately 15 km); and to the top end of the Googong Reservoir (approximately 22 km in length). A high level assessment using a multi-criteria assessment exercise was done. The criteria used are listed in Table 7.1.
Table 7.1 Assessment criteria
Environmental Social Economic
Endangered and threatened Cultural heritage (Aboriginal and Net present value (capital and species/ecological communities historical) operating costs)
Greenhouse gas emissions Public health (drinking water quality) Implementation timing (design, approvals, land acquisition, procurement, construction, cost of delay)
General aquatic and terrestrial General landscape and amenity Net economic benefit (benefits less ecology costs)
Higher weightings were applied in the assessment to the total cost and timing criteria to reflect ACTEW’s prioritising of the criteria. As a result of this assessment, the shorter southern options (referred to as S3 and S4 and discussed in Table 7.2) emerged as the better options, mainly due to benefits associated with cost and time for delivery. Option S1 was ranked third, as it includes a greater number of private landholders. The rankings are shown in Table 7.2. Compared to the northern and central options (options N and C), the main potential environmental issues associated with the southern options were those associated with discharge into Burra Creek. These potential issues are assessed within section C this report.
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10Kilometres 5 0 o GOOGONG RESERVOIR ALIGNMENT N ALIGNMENT C ALIGNMENT S1 ALIGNMENT S2 ALIGNMENT S3 ALIGNMENT S4 QUEANBEYAN JERRABOMBERRA
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Table 7.2 Ranking of options
Rank Option Rationale for ranking
1 S4 Least stakeholders / least issues / lowest net present value / highest net economic benefit
2 S3 Adds pump site issues (recreation amenity and water quality perceptions) and increases risk of delay
3 S1 Adds Burra Creek private landholding issues and increases risk of delay for small cost saving
4 C Adds pipe length, cost, commercial stakeholders, urban proximity, noise, visual impact and higher greenhouse gas emission issues and increases risk of delay
5 N Adds pipe length, more cost, easement ownership, construction complexity, natural and cultural heritage issues and further increases risk of delay
6 S2 Adds more pipe length, more cost, Googong Foreshores ownership issues (Commonwealth land) and higher cost for small benefit (i.e. avoids Burra Creek potential management issues)
Note: S-southern; C-central; N-northern
The S4 intake was located in a relatively isolated former sand mining around 2 km downstream of Angle Crossing without road access through leasehold land. Although this site offered lower cost than S3 (shorter pipe length), a more detailed assessment revealed other impacts would be greater due to: • No natural weir/intake location (instream works required); • Past evidence of highly mobile sand bars; • Lengthy roadwork required across EEC and steep slopes; and • Closer proximity to more sensitive areas of the Gigerline Nature Reserve. Consequently, S3 was adopted for the more detailed evaluation as outlined in the following section. 7.3.2 Refining the ‘Angle Crossing’ option The process undertaken to refine the S3 option is described below. Method for identifying and assessing options for the pipeline route The identification and assessment of further (refined) southern route options involved the following tasks: • Assess and confirm connection points; • Develop route identification criteria; • Identify construction and hydraulic considerations; • Identify key location constraints via a desktop study; • Identify alignment options; • Undertake field investigations to further identify potential social and environmental constraints associated with each option; • Confirm criteria used to assess options;
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• Assess alignment options using a multi-criteria/triple bottom line approach; and • Identify and further develop the preferred option. Connection points In a more detailed assessment, the location of the intake/low lift pump station and discharge point provided the start and finish points for the proposed pipeline. The pipeline also needed to pass through the proposed high lift pump station. These location constraints were important drivers for the route selection. An additional major constraint on pipeline route selection was the terrain. The Gibraltar Ranges divide the Googong and Queanbeyan River/Burra Creek catchments from the Murrumbidgee River. The lowest point of the Gibraltar Ranges is a saddle where Williamsdale Road crosses the ranges. It was preferable that the pipeline route passed through this saddle point to avoid the need for a more powerful and larger high lift pump station. Identification criteria The following criteria were used to identify further route options: • The hydraulic operability of the pipeline; • Avoiding physical constraints such as buildings and dams; • Avoiding environmentally sensitive areas; • Route alignment to minimise length of pipeline; • Maximising use of existing road reserves (where not environmentally sensitive); and • Constructability. Construction and hydraulic considerations Construction considerations that influenced the location selection included: • Hydraulics, high and low points (pumping requirements); • Overall system efficiency to minimise the carbon footprint; • Construction width and safety; • Geology, blasting impacts and construction methods; and • Operations and long term maintenance. The hydraulic grade represents an operational cost and as a result, the objective then is to minimise the lift required and balance this against the length of the pipeline. Key location constraints Potential constraints identified included: • Major land use considerations (for example intensity of land use); • Significant flora; • Riparian (fauna) movement corridor and connections; • Proximity to local sensitive receivers (for example houses); • Steep gradient and long term environmental and operational issues; and • Construction safety and right-of-way requirements. In order to verify the alignments, investigations included extensive field surveys; desktop investigations; and drive-overs with specialists across a range of disciplines including pipeline and construction engineers,
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landscape architects, construction experts, town planners, valuers, ecologists, archaeologists and environmental scientists. Identify alignment options Two further route options, a northern and a southern route, were identified in the route refinement process. Assessment criteria The criteria used in the options assessment were as follows: • Costs: – Capital cost; – Net present cost; • Social impacts: – Recreation impacts; – Visual impacts; – Traffic impacts; – Private and public land impacts; • Heritage impacts: • Environmental impacts: – Climate impacts; – Flora impacts; – Fauna impacts; and • Water quality impacts. Selection and justification of the preferred pipeline route option A triple bottom line analysis based on a subjective comparative assessment was undertaken for the route options. This led to identification of the southern option as the preferred option. This route involved maintaining an adequate clearance from the 132 kV power line, and trying to achieve a more or less direct alignment from Angle Crossing to Gibraltar Pass. In developing this route, technical assessments were used to refine minor routing alternatives. The advantages of the preferred location option are that: • It would maximise the use of existing road reserves and government owned land; • It would minimise the need to place additional encumbrances on private freehold title; • There are minimal areas of hard rock, with resultant construction issues; • It is shorter in length compared to the northern route; • It passes mainly through areas of previously disturbed agricultural land, minimising the potential for disturbance to areas of remnant vegetation; • It traverses lower areas away from creek lines and fauna movement areas; and • It crosses fewer major roads and waterways and offers an acceptable traffic solution to the use of Williamsdale Road during construction. The location of infrastructure and the alignment of the pipeline have been chosen in consultation with local landowners and the broader community to minimise overall impacts. The proponent is currently in the
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process of negotiating with landowners over access to their land for the purpose of construction, including land rehabilitation, and operation of the pipeline. A more detailed assessment of potential impacts is considered in Part C of the assessment. Further information on the pipeline is provided in chapter 6. 7.3.3 Construction options considered Aboveground pipeline An aboveground pipeline would have resulted in a substantial visual and social impact, as the 1 m diameter pipeline would stretch across 13 km of landscape. As the pipeline would also traverse through a number of private properties, an underground pipeline was considered less intrusive in the long term. In addition, an underground pipeline would generally reduce the potential for tampering of the pipeline during operation. Micro tunnelling or boring the pipeline Monaro Highway As discussed in section 6.7.10 it is proposed to open trench at the location the pipeline crosses the Monaro Highway. The alternative considered for crossing the Monaro Highway was micro tunnelling or thrust boring. There are a number of reasons why this was not considered the preferred option: • Hard rock would result in a 2 to 3 week boring period. This would require establishment of launch and receival sites (for the boring machine) adjacent to the highway, with large open pits within meters of the road carriageway. Although the pits would be barricaded these would remain open at night, increasing risk to public safety. • There are concerns with the undulating nature of rock/soil interface at this location. If the rock dips away and re emerges, which is likely, then there is a high probability of having to send construction work force into the tunnel with jack hammers to create a face for the cutting head. The tunnel would be approximately 1.8 m diameter and confined space. • High strength rock would result in frequent cutter changes and could result a high incidence of break downs due to forces in action resisting forward movement of the bore. This would then increase the time required for the boring period and the time the open pits would be required. Crossing the Monaro Highway using the open trench method offers the following benefits: • Short duration of approximately 3 to 4 days; • No confined space; • Less hazards to construction work force; • Monaro Highway remaining open to the public (managed through lane closures and appropriate traffic management) with no hazards after hours like the open pits within meters of road that would be required for the boring methodology. Waterway crossings An alternative considered for construction of the pipeline where it crosses waterways was micro tunnelling or thrust boring. All drainage crossings of the pipeline are ephemeral (flows for short periods after rainfall) except for Crossing Number 6 where the methodology for the crossing would involve temporary sandbagging and bypass pumping. The flows during the dryer periods are very low, and hence bypass pumping would be quite feasible.
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Using the open trench method would minimise the duration of construction activities required at each waterway crossing. Boring activities would generally require concrete launch and receival sites of 20 m x 20 m with open pits, which would result in further disturbance at these sites. The amount of spoil generated by this method would also be increased. Therefore, it is proposed to open trench the waterway crossings (as described in section 6.7.9) and implement the mitigation measures (refer chapter 9) to minimise any impacts to waterway crossings. Other sections of the pipeline Consistent with the above justification for selecting trenching, in other areas trenching has also been considered to be the preferred construction method for the following reasons: • More efficient, thereby reducing the length of time the community is impacted by construction activities; • Provides better value for money; and • Involves a common construction methodology used in rural areas. 7.4 Intake/low lift pump station alternatives The overall route selection process for the project was driven by the selection of the preferred intake location for the extraction of water from the Murrumbidgee River. The intake location is particularly important, and needs to satisfy essential requirements, including: • Stable pool conditions for the intake; • Land availability for pump stations; • Bank conditions to facilitate construction of the low lift pump station; and • Suitable locations for the high lift pump station above the 1 in 200 year flood level for the Murrumbidgee River. Initially two general locations for the extraction of water from the Murrumbidgee River were identified based on the above criteria, being Point Hut and Angle Crossing. As Point Hut is located in close proximity to the Gigerline Nature Reserve and Angle Crossing has existing vehicular access, it was determined that Angle Crossing would be a more appropriate location to construct the infrastructure for the extraction of water from the Murrumbidgee River. As such, site investigations for the intake/low lift pump station structure focused on the Angle Crossing area and appropriate locations for the high lift pump station, pipeline and outlet structure were subsequently investigated based on this general intake location. Preliminary investigations of the Angle Crossing area identified a potential site and design for the structure as the intake site on the east bank of the river immediately north (downstream) of the Angle Crossing Causeway, with the intake design using an overflow ‘colander’ screen on the downstream causeway face with a separate pump station structure adjacent to the causeway. It was concluded that this location and intake form would not suit the design criteria formulated for this project. More detailed investigations were therefore undertaken to identify alternative designs and locations for the structure. The investigations were based on the following criteria: • The ability to operate in the widest range of conditions including flood and drought; • Avoiding of siltation and flotsam blockages during operation; • The requirement for the structure to be vandal proof; • Good maintenance accessibility; • Minimal physical and visual intrusion into the landscape and, where not possible, provision of a positive social feature; and
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• Minimal costs. The outcomes of this more detailed investigation are described below. 7.4.1 Design options Five alternatives were considered for the design of intake/low lift pump station. These were: • Fixed river bed; • Floating arms; • Pipes/pumps-on-pier; • Inclined draft tube pumps; and • Box in bank. A brief description of each option, together with an assessment of the option’s suitability for the project, is provided below. Option 1: Fixed river bed This intake form would comprise of a fixed structure in the riverbed. This could take one of three forms: • An open topped box in the river bed equipped with a safety grill; or • A slotted polyethylene (HDPE) pipe weighted to sit in the river bed; or • A fixed slotted pipe grid buried in a sand infiltration bed in the riverbed. For all fixed riverbed options, the low lift pump station would need to be located within a separate structure on the adjacent bank of the river. This requirement for separate structures and a mid river intake would result in high construction costs. It is also likely that the costs of sediment removal during high river flows, and possible system shut downs in major storm flows, would be high. It addition, it was considered that a hidden underwater intake could pose potential safety risks in the Angle Crossing area, which is used for recreational swimming. Option 2: Floating arms This intake form would involve a floating arm arrangement to ensure that the best quality water is drawn from the mid-stream surface layers into the intake. It could physically comprise of a hinged pipe with a float to locate the level of the intake, or a flexible HPDE pipeline from a mid stream anchor pile. This intake form would physically occupy an area of the river and the floating pipes would be visible at the surface of the river. There would be potential safety risks associated with the intake floating in the river. There would also be the potential for damage to the floating arms from river users. Option 3: Pipes/pumps-on-pier This intake form would involve mounting the pump and pipe work on a pier to locate the intake as close to mid-stream as practicable. As the pumps would be mounted on the pier, there would be no requirement for a separate structure for the low lift pump station. As such, sediment and fish egg filtration would need to take place within the high lift pump station. Wear and tear on the pumps would therefore be increased and there would be potentially significant costs and risks associated with disposing of captured sediment and filtrate materials to landfill. The pier structure would also have the potential to impact on use of the river and the visual amenity of the area. Option 4: Inclined draft tube pumps This intake form would comprise of draft tube mounted pumps with the tube position up the natural bank slope. Similar to the pier option, sediment and fish egg filtration would need to take place within the high lift pump station. Wear and tear on the pumps would therefore be increased and there would be potentially significant costs and risks associated with disposing of captured sediment and filtrate materials to landfill. The construction, operation and maintenance costs of this option would be high. In addition, there would be the potential for damage as a result of major floods, and the structure would be visually prominent.
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Option 5: Box in bank The box in bank design comprises an open sided concrete box structure built into the riverbank. Further information on this design is provided in chapter 6. The preferred design option Option 5 is the preferred design option for the intake/low lift pump station. The benefit of this structure is that the intake and low lift pump station, including sediment removal and fish egg and larvae filtration, would all be housed within the one structure and it would therefore have the smallest footprint of all the options considered. Other advantages of this are that it would: • Have less potential for visual impact than other options which require above ground structures; • Be less prone to damage, in particular from vandals; • Be better able to obtain all available water from the river, even in drought; and • Pose less risk to users of the river, as the intake would be visible. 7.4.2 Location options Following identification of the most appropriate design of the structure, four suitable locations for the intake/low lift pump station were identified and investigated along the riverbank in the Angle Crossing area. The advantages and/or disadvantages of each of the intake/low lift pump station locations considered are detailed below. Option 1: West bank immediately south (upstream) of the Angle Crossing causeway This location would require clearing of some vegetation from the riverbank and would be visually prominent when approached from the Monaro Highway along Angle Crossing Road. This location would also require river crossings for the pipeline and electrics, which would increase the cost of the project. Option 2: East bank immediately south (upstream) of the boat hole This location has the advantage of being located upstream of the area that is used for public recreation. A box in bank structure in this location would not impact on the recreational use of the river and would not be visible from the recreational areas. However, some vegetation would have to be cleared from the riverbank to accommodate the structure. Option 3: East bank 300 m north (downstream) of Angle Crossing causeway This location would require a weir to be constructed across the river immediately downstream of the structure to provide the stable pool conditions required. This would increase project costs and could cause potential impacts on the aquatic ecology of the river. Turbulence on the downstream side of the Angle Crossing causeway would potentially impact on the quality of the water that would be transferred. In addition, it was noted that in certain flow conditions (such as during flood), there is the potential for the river to divert from its normal course downstream of the causeway, bypassing the intake. Option 4: East bank immediately south (upstream) of Angle Crossing causeway An intake/low lift pump station structure at this location would require the loss of some vegetation from the bank of the river and would also be within the recognised recreational area of the river. However, it would reduce water flow over the causeway thus improving public access. Preferred location option It was determined that the preferred location would be on the east bank of the river immediately south (upstream) of the Angle Crossing causeway (option 4). The advantages of this location option over the alternatives are that it: • Would require less clearing than other options; • Would not require a river crossing for the pipeline and electrics; and • Has existing vehicular access.
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7.5 High lift pump station alternatives Following selection of the design and location of the intake/low lift pump station, alternatives for the nearby location and design of the high lift pump station needed to be identified. The location of the high lift pump station is constrained by particular technical requirements. The high lift pump station needs to be above the 1 in 200 year flood level for the Murrumbidgee River, which is approximately 20 m above river level, and within the pumping capacity of the low lift pumps, which is approximately 42 m above river level. The location of the high lift pump station in relation to the river and intake/low lift pump station is particularly important. As such, the location of the high lift pump station was determined in the first instance, and then the alternatives for the design of the structure were then considered. 7.5.1 Location options Three possible locations for the high lift pump station were investigated. Option 1 This site is located on a 1:4 slope below Angle Crossing Road with the eastern limit of the site against a gully line. The construction of a building platform at this site would require benching into the side slope and consequently, there would be space constraints. Retaining walls would be required to contain the earthworks within the site and only the building footprint would be available for construction activities. Furthermore, access to the site would not be ideal and could only be obtained by reversing around a double curve with an 8 m high embankment batter on one side. Option 2 This site is located on a 1:2.75 slope and would also require benching into the side of the hill with cut batters extending nearly to the top of the ridge. As with option 1, the resulting building platform would only be sufficient for the building footprint and access could only be gained by reversing up a steep section of Angle Crossing Road into the site. Option 3 This site is located (in part) on an existing rudimentary car park on the north side of Angle Crossing Road. Access is available at grade to the site from Angle Crossing Road and the building platform would be constructed by removing the eastern half of a knoll down to the required level. Preferred location option As a result of terrain and space constraints at locations on the southern side of Angle Crossing Road, it was determined that the only feasible location would be on the northern side of Angle Crossing Road. Option 3 was therefore the preferred location. Whilst this site is on higher ground and is, therefore, more visually prominent than the two potential sites on the south side of Angle Crossing Road, it would provide an easily accessible site with space available for construction activities outside of the building footprint. It is also considered that any visual impact could be minimised by the appropriate design of the high lift pump station structure. 7.5.2 Design options With the only feasible location being relatively elevated compared to surrounding land, it was considered that the design of the structure for the high lift pump station would need to integrate well with the surrounding landscape. Other important design considerations included: • Technical requirements of the structure; • Management of visual impacts associated with the structure in the context of the surrounding areas; • Consideration on recreation, heritage and general amenity values at Angle Crossing and surrounds; and • Minimising opportunities for anti social behaviour while ensuring high levels of public safety, access to recreation areas and successful mitigation of noise from the operation of the infrastructure. Three alternatives for the design were investigated and are outlined below:
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Option 1: Concealed structure This option involved locating the pump station underground. Option 2: Rudimentary structure Rudimentary structures are typically constructed from a lightweight metal portal frame system and prefinished profiled metal cladding. Rudimentary structures can be fabricated off site and are quick to erect and, as such, construction impacts and costs would be minimised. However, it is considered that such a structure located in the preferred location would be visually prominent. The structure would also provide little attenuation of noise from the pumps due to its lightweight nature. Option 3: Architecturally designed structure This option would involve input by an architect, and incorporation of more design features to minimise the potential for visual impacts. Similar to a rudimentary structure, this option would involve a steel portal frame system and could be fabricated off site and craned into position, thus limiting disruption to the surrounding landscape and reducing construction time. Preferred design option The preferred design option for the high lift pump station is an architecturally designed structure (option 3). An architecturally designed structure was considered to be more appropriate than the alternatives considered as it would: • Allow the use of materials with a wide range of finishes, colours and textures for better integration with the surrounding environment; and • Enable the use of heavier cladding systems than a rudimentary structure, thus providing better sound attenuation and protection from damage. Although the visual impact of a concealed structure would be potentially less than other above ground conventional structures, it was considered that given the characteristics of the location constructing this option would potentially lead to unacceptable adverse environmental impacts. Further information on the design of the high lift pump station is provided in chapter 6. 7.6 Outlet structure alternatives 7.6.1 Location options Following identification of the preferred locations and design for the intake/low lift pump station and the high lift pump station, the optimum location for the discharge of water to Googong Reservoir could be determined. Continue the water pipeline to Googong Reservoir The option of continuing the pipeline through to Googong Reservoir was investigated by the proponent as part of early project investigations. The multi-criteria assessment (ACTEW 2008b) concluded this option had significantly higher cost (over $30 million) and a much greater potential for delay arising from increased terrestrial ecological impacts and a greater number of private land-holder negotiations than other options. Preferred location option The multi-criteria analysis identified the optimal discharge point as being just east of Burra Rd. with Googong Foreshores (i.e. land owned by the Commonwealth, and managed by ACT Government). This location was preferred over the shorter upstream option as the land was managed by the ACT Government. 7.6.2 Design options As the preferred location for the outlet structure is in a rural residential area, the design of the structure would need to minimise the potential for visual impacts and impacts to Burra Creek. An overview of the options is provided below. Option 1: Open discharge This option would involve the pipeline freely discharging into the creek. The creek bed and bank at the discharge location consists of fairly large cobbles and silty sand. As such, it is likely that free discharge
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would result in scouring of the creek. Some protection for the creek bank and bed would therefore be required. This would take the form of gabion baskets and reno mattresses, which would intercept and distribute the flow smoothly into the creek without the erosion of bed or bank material. This option would be relatively cheap to construct compared to the other options. However, it is considered that the potential for visual impacts would be higher than the other options, and some excavation of the creek would be required. Option 2: Submerged discharge valve This option would involve incorporating a valve in the outlet structure. The valve would dissipate the potential energy from the pipeline by passing water through jets into a stilling basin. The stilling basin would need to be approximately 3 m3 in size. Discharge of water from the stilling basin would need to occur smoothly so that the flow enters the creek bed without erosion of the banks. Therefore, a weir would be required, approximately 10 m in length. This option was not considered further as a result of its potential cost, high levels of maintenance required, and visual impacts. Option 3: Weir box arrangement This option would consist of a rectangular concrete box built into the creek bank with a weir located on the side wall closest to the creek. The weir box arrangement would require a 10 m long weir and would also require rockfill to be installed on the creek bank surrounding the weir. Water would flow into the weir box from the pipeline and would discharge over the weir and run down the creek bank to the creek. Preferred design option The preferred design for the outlet structure is a weir box arrangement (option 3). As the weir box would be sunk into the creek bank it is considered that it would have less potential for visual impact than the other options, which would require above ground structures. In addition, vegetation would be able to grow through the rockfill with time to lessen visual impacts. Further information on the design of the outlet structure is provided in chapter 6. 7.7 Consequences of not proceeding The project forms part of the ACT’s water security planning. The consequences of not proceeding are described below: • The region’s future water security would not be assured, and it would be difficult to meet the water needs of current and future populations without extensive water restrictions. The ACT would not run out of water, but only if severe and onerous water restrictions are applied, or unless some unforeseen event occurs; • The need to plan for an adequate new water supply has been identified by various strategic planning documents and has been endorsed by the ACT Government; • Storage and water treatment capacity at Googong Reservoir would remain under utilised; • There would be less diversity of water sources and higher risk of more severe water restrictions; • Other water supply alternatives would need to be implemented at a higher community cost; and • The net cost to the community would be substantial due to the significant costs associated with water restrictions (see section 23.3.3). With the project implemented in isolation, reduced periods of water restrictions have been estimated result in a net economic benefit of more than $500 million.
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