Jared Deible, John Osterle, Charles Weatherford, Tom Hollenkamp, Matt Frerking
The original rockfill dike, constructed in 1963 to form the Upper Reservoir at the Taum Sauk Pump Storage Project near Lesterville, MO failed on December 14, 2005. The Upper Reservoir has been completely rebuilt as a 2.83 million cubic yard (2.16 million cubic meters) Roller Compacted Concrete (RCC) Dam in compliance with FERC Regulations. The project is the largest RCC project constructed in the USA and is the first pumped storage project to utilize an RCC water retaining structure. The project is owned and operated by AmerenUE and consists of an Upper Reservoir and a Lower Reservoir connected by a vertical shaft, rock tunnel, and penstock. The Powerhouse has two pump-turbines with a total generation capacity of 450MW.
A refill plan was developed to monitor the performance of the dam during the first refill. Because it is a pumped storage project with no natural inflow, the reservoir level can be raised and lowered with reversible pump turbines. The refill plan includes hold points when the dam s performance will be assessed at eight reservoir levels. Monitoring of the performance of the dam is done through instrumentation readings and visual inspections. Inspections check for alignment changes, leakage, seepage, cracking, or any other unusual or changed conditions. Instrumentation monitored during the refill program includes piezometers, seepage weirs, survey monuments, and joint meters. The level control system for the project was also evaluated during the refill program. This paper summarizes the monitoring and inspections conducted during the refill and the performance of the dam during this period, and the performance of the dam during the initial period after the refill program.
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Graeme Maher, Richard Herweynen, Martin Mallen-Cooper and Stuart Marshall
Increasing awareness of the environmental impact of dams means that fish passage is emerging as a critical issue for both existing and new dams in Australia.
The fish passage and outlet works for Wyaralong Dam, a new dam currently under construction, required accommodation of large ranges of head and tailwater levels. The solution that has been adopted, a bi‐directional fishlift using a single hopper with trapping for downstream fish movement occurring within the intake tower, is a world first. The solution required the innovative integration of a number of existing technologies to create a system which is necessarily complex, yet reliable and effective.
The paper incorporates discussion of the critical design constraints, the biology of fish passage, the process adopted to reach the concept solution and a description of the final design including its integration with the outlet works. A number of design issues and their solution are discussed in detail, particularly those associated with dealing with the complexity of the design constraints and how the components of the solution were integrated into a seamless design.
The paper will be of use to those involved in the process of providing fish passage on both existing and new structures that obstruct river flow.
A Bi-Directional Fishlift – An Innovative Solution for Fish Passage
Hamish Smith, Graeme Maher
In order to achieve environmental sustainability it has become standard engineering practice to include a fishway on all new or refurbished large dams in Australia.
As regulators expand their understanding of fishways, project approval conditions associated with these complex engineering structures are changing. Regulators now increasingly wish to participate in the development and selection of the final fishway to be adopted.
This paper describes the process developed and implemented at Queensland’s most recent dam under construction, the Wyaralong Dam, to ensure that the views and opinions of regulators and stakeholders were sought and considered during the fishway selection and design process.
With no written guidelines available on “how to select and design a suitable fishway”, all associated parties entered into the process without a full knowledge of how it would unfold and what the final outcome would be.
This paper demonstrates that in an increasingly regulated environment it is possible to have regulators, proponents and stakeholders work cooperatively together to achieve a result that provides for sustainable development and is acceptable to all parties.
This paper will provide a model that could be adopted for the development of new fishways or the refurbishment of existing fishways on large dams in Australasia.
Changing Regulatory Environment – Large Dams and Fishways
Dr Adam Butler, Robert Rigg, Glen Hobbs
The cost of maintenance is a serious problem. Preventive Maintenance is a good strategy if implemented well, but can led to unnecessary costs if items are replaced unnecessarily. Predictive maintenance can augment preventative maintenance by using real time instrumentation to monitor conditions. These techniques have been effective at recognizing the symptoms of impending machine failure
Glen Hobbs and Associates (GH&A) recently analysed pressure and displacement data from hydraulically actuated hoisting equipment of a large emergency closure fixed wheel gate. Data analysis enabled GH&A to pin-point causes of the gate malfunction. Anomalies in the data waveform corresponded to impacts and squeeze points in the system. Furthermore, comparing recent test data with older data highlighted gate deterioration over time.
Testing, analysis and trending of data enables asset managers to better predict the point at which maintenance really needs to be performed and shows that careful analysis of relevant data can help solve multi-faceted problems.
Keywords: Operations, Maintenance, Asset Management, Gates.
David Ryan, Peter Richardson, William Steen
Ibis Creek Dam, a referable dam and classified as a mass concrete gravity structure, was constructed in 1906 to supply water for both tin ore processing and the local township of Irvinebank. Irvinebank is a small township near Atherton in North Queensland and is situated about 3 km downstream of the dam. The mill ceased operation in 1990 but the township of Irvinebank remains reliant on the dam for water supply.
In 1996 the dam was raised about 1 m and strengthened by the addition of mass concrete on the crest and downstream face.
One recommendation of the Safety Review conducted in 2009 was that an investigation be made of the strength of the lift joints and the shear capacity of the connection between the Stage I and Stage II concrete sections. The investigations revealed that the structure was not constructed as had been originally assumed and the overall stability of the structure had been overestimated.
This paper details the investigations and remedial works proposed to strengthen the structure so that it complies with current design standards.
Kristen Sih, Peter Hill, Susan Ryan, Siraj Perera
Although ANCOLD provides guidance on good dam safety practices, in Australia it is the State and Territory Governments’ role to protect the public from dam safety incidents and in many cases these jurisdictions have legally binding regulations in place that dam owners must adhere to. This paper presents a comparative analysis of the dam safety regulations currently in place for Australian states, as well as selected international jurisdictions. The limit of applicability of the regulations, number of dams regulated, content of the regulations and powers and responsibilities of the regulator are all compared. It was found that there is a large range within each of these categories with regulatory approaches varying from light-handed and objective based, to highly prescriptive. The extent to which risk management principles are used in the regulations for each jurisdiction has also been investigated. It was found that in jurisdictions where higher hazard category dams account for a higher proportion of dams being regulated, risk analysis is included in the regulations. Finally, the ANCOLD societal risk criteria and ALARP considerations have been compared and contrasted with those from international jurisdictions and other hazardous industries.