The Koralpe hydropower scheme is a major development on the Feistritzbach tributary of the River Drau to utilize water in a 50 MW powerhouse located in the south-eastern Carinthia, Europe. The Soboth reservoir is situated 735 m higher in a narrow valley and is created by the 85 m high Feistritzbach dam which was constructed near the border of Austria and Slovenia between 1988 and 1990. This rockfill dam is the latest addition to KELAG’s more than 15 structures and is sealed by an asphaltic core. The excellent deformability and impermeability of the asphaltic core is able to follow the deformation of the compacted rock-fill material best during construction, initial filling and operation period without any seepage. The asphaltic core was placed in three 20 cm layers per day by a specially developed placing unit from a contractor. The upstream and downstream filter zone was placed at the same time with the same machine and compacted carefully by vibrating rollers. The dam is curved in plan with a radius of 650 m and contains about 1.6 million m³ rock fill material. The surface of the downstream side was built exceeding the environmental standards of the time.The most important indicator of the normal function of a dam is the behaviour of seepage. A monitoring system of seepage, piezometers, earth pressure cells and deformation has been installed. The seepage water is monitored online at seven points of the dam base and at the access tunnel to the bottom outlet valve. Geodetic measurements on and inside the dam are done once a year. Several additional pieces of surveillance equipment were installed to observe the behaviour of the asphaltic core. The paper concentrates on the design, construction and performance of the dam with the asphaltic core.
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Legal and moral requirements necessitate an “equivalent to industry standard” approach to dam management by all dam owners. As an urban authority Central Highlands Water has a portfolio of dams with a broad range of classification and risk. ANCOLD Guidelines form the basis of our approach to dam management. Thus any guidelines developed can have significant affect on our budget and operation. Guidelines with requirements targeted at extreme and high hazard dams managed by large authorities with “deep pockets” may not be reasonable to impose upon low risk structures managed by lesser authorities. This does not mean smaller authorities want to do it on the “cheap” but budgets for such infrastructure can be hard to sustain. Consequently when guidelines are considered so too should the flow on affect to those who must implement them.
SunWater manages its portfolio of 29 major dams through 6 business centres each responsible for the Dam Safety Program for the dams under its management control.
The effectiveness of responses during an emergency depends on the amount of planning and training performed. Management must show its support for dam safety programs and the importance of emergency planning.
If management is not interested in community protection and in minimising property loss, little can be done to promote dam safety. It is therefore management’s responsibility to see that a program is instituted and that it is frequently reviewed and updated.
The input and support of all communities must be obtained to ensure an effective program. The emergency response plan should be developed locally and should be comprehensive enough to deal with all types of emergencies specific to that site.
SunWater is a responsible dam owner and has recently upgraded all its emergency action plans in consultation with emergency services of Queensland. This paper details the basic steps to handle emergencies of water infrastructure. These emergencies include inflow floods, rapid drawdown, earthquake, sunny day failure, changes in reservoir water quality and terrorist attacks including hoax.
This paper is intended to assist small dam owners that do not have dam safety programs in place. It is not intended as an all inclusive safety program but rather a provision of guidelines for planning for emergencies.
Ridges Basin Dam is part of the Animas-La Plata Project. When topped out in approximately 2008, it will be Reclamation’s newest dam. It will have a structural height of 273 feet and impound 120,000 acre-feet of water. This paper will discuss the design of the embankment and will detail the site geology, the general design considerations for layout and zoning, and other technical considerations. The construction, which began in 2004, is ongoing. This paper will also discuss foundation treatment and cleanup, the placement of the embankment material, grouting, and the unusual material processing for filters and drains, along with general construction details. Also included in the paper are the challenging arrangements for contracting by the American Indian Self Determination and Education Assistance Law, an overview of the dam safety risk analyses conducted on the yet-to-be-constructed embankment, and modern construction techniques being utilized to build the embankment.
G. Hunter, R. Fell, S. McGrath
The main embankment at Tullaroop Reservoir is a 42m high zoned earth and rockfill dam that was constructed in the late 1950s. The constructed embankment has a very broad, well compacted clay earthfill zone with dumped rockfill on the mid to lower upstream and downstream shoulders.
Over a two week period in April 2004 a diagonal crack of 60mm width and greater than 2m depth developed on the downstream shoulder of the main embankment. The crack was located on the left abutment and extended from the crest to the toe of the embankment. The diagonal crack terminated at the downstream edge of the crest. A continuous longitudinal crack extended along the downstream edge of the crest from the diagonal crack almost to the left abutment. Since April 2004 no further widening of the diagonal crack has been observed.
This paper presents the findings of a series of site investigations and analysis to understand the mechanism for formation of the diagonal crack, and the risk assessment process that culminated in the eventual construction of a full height filter buttress on the left abutment of the main embankment. Factors that influenced the cracking included the change in slope in the foundation profile, the temporary diversion channel on the left abutment, residual stresses in the dam abutment due to differential settlement during construction, a complex foundation geology and presence of shear surfaces in a Tertiary alluvial sequence that formed due to valley formation, an historic dry period and a prolonged period of drawdown. The presence of the crack and its assessed mechanism of formation presented a dam safety risk of piping through the embankment. The risk evaluation process was worked through with URS, Goulburn-Murray Water (G-MW), and G-MW’s expert panel, and eventuated in construction of the localised filter buttress in February – March 2006 to address the dam safety deficiency.
Karen Soo Kee
Strategic resource management has never been more important than it is today with the aging of the “baby boomers” and their ongoing exodus from the workforce. The vacancies they leave in professions such as engineering are just beginning to be felt and will exponentially escalate over the next few years. Specialised professions such as dam engineering and related professions will be hit the hardest as the knowledge and skills learnt over decades are depleted.
The lack of skilled staff and in fact the lack of interest of young engineers in entering the dam industry is one of the critical challenges for today. How do we attract professional staff into the field of dam safety before the exodus creates a “black hole” that can never be filled? And how can we ensure the knowledge transfer from existing skilled staff to newer staff to retain expertise within the industry?
Another issue for resource management is that tomorrow’s workers, the “X &Y generations”, will be unlike the current and previous generations of workers. These workers will be less likely to have a mortgage, will have fewer children and be more interested in lifestyle, not career. They will be extremely confident, well-educated and very mobile. The future will be a sellers market. The challenge here will not only be to attract and recruit talented workers but also to retain them.