When undertaking a program of quantitative surveillance of dams the potential to make expensive decisions based on inaccurate and/or inappropriate data always exists. The implementation of a ‘quality’ based system of quantitative surveillance as identified in the ANCOLD Guidelines On Dam Safety Management 2003 can reduce the likelihood of making these inappropriate decisions.
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Now showing 1-12 of 59 2970:
G.L. Sills, N.D. Vroman, J.B. Dunbar, R.E. Wahl
In August 2005, Hurricane Katrina made landfall just east of New Orleans and inflicted widespread damage on the Hurricane Protection System (HPS) for southeast Louisiana. Subsequent flooding was a major catastrophe for the region and the Nation.
The response to this disaster by the U.S. Army Corps of Engineers included forming an Interagency Performance Evaluation Taskforce (IPET) to study the response of the system and, among many lines of inquiry, to identify causes of failure of levees and floodwalls. Beginning in September 2005, the IPET gathered geotechnical forensic data from failed portions of levees and floodwalls. Major clues discovered at the 17th Street break, including clay wedges dividing a formerly continuous layer of peat, led to an explanation of the failures. Field data from the failure sites were interpreted within the regional geologic setting of the New Orleans area to identify geologic and geotechnical factors that contributed to the catastrophe. The data gathered provided a method that resulted in the “IPET Strength Model.” This strength was used in analyses of the I-walls and levees using limit equilibrium stability analyses, physical modeling using a powerful centrifuge, and finite-element analyses. The results of all three types of studies revealed a consistent mode of failure that included deformation of the I-walls and foundation instability. The IPET also studied non-failed I-walls at Orleans and Michoud Canals, to identify geotechnical, structural, and geologic distinctions between failed and non-failed reaches.
Performance of the HPS during Hurricane Katrina offered many lessons to be learned. These lessons learned include: the lack of resiliency in the HPS; the need for risk-based planning and design approach; the need for the examination of system-wide functionality; and knowledge, technology, and expertise deficiencies in the HPS arena. In addition, understanding of the failure mechanisms and related causes of the levee and floodwall breaches provides a new direction for future designs of hurricane protection systems.
Ensuring compliance with the Regulator’s requirements is a cornerstone consideration for any water corporation in planning its risk minimisation strategies against dam failure. With the increased focus on due diligence and corporate governance however, there are emerging themes that are of equal importance for a water corporation in planning protections against its core risks to dam safety.
These considerations include:
• documenting and implementing plans and strategies to ensure corporate compliance with the
Regulator’s requirements and updating these in line with legislative and policy changes;
• Documenting and implementing the corporation’s defences to the common law duty of care for
public liability, including keeping up to date with the latest case law development locally and
internationally in interpreting implications in respect of damage to property and injury and loss of
life in relation to dam failure.
• Adopting behaviours and practices that bear out a compliance culture – is the current dam safety
assessment and training “best practice” and is this enough to defend a claim? What is reasonable
in economic and practical terms to ensure defensibility?
• ensuring the Board, Executive and other Officers are informed of operational decisions and
incidents and their advice is implemented;
• arranging and maintaining appropriate insurances if available for public liability and property
damage, as well as protections for directors and officers, both past and current.
• Developing and implementing a policy for disclosure, document management and retention that will support investigation for legal proceedings purposes; including providing privilege for relevant
Roger Vreugdenhil, Joanna Campbell
The dams industry is immersed in a changing environment. It is one of many industry sectors in Australia becoming acutely aware of the impacts of ageing practitioners and a competitive labour market. Shortages of skills and labour are impacting on all participants. The constraints around recruitment and retention are further amplified for dam owners in some States by increasing expenditure regulation and accountability.
People choosing to leave or retire from the dams profession per se does not necessarily pose a problem. Instead, problems arise if insufficient transfer of valuable knowledge has occurred prior to their departure, if the rate of replenishment is inadequate to cope with current and future industry workload, and if there is no innovation around what workforce is involved. Future work will likely be characterised by remedial works for existing dams rather than new dam construction, with an increased focus on environmental restoration, and optimisation of operations and maintenance to minimise losses and maximise productivity. These tasks require a great level of skills in leadership and innovation, equal to any level previously applied to this industry.
Organisational goals and decisions have to be realised through people and it appears that many people are taking up their roles differently than in the past. The authors, both Generation X, contend that the core issue is as much a challenge of imagination as it is a crisis of human resourcing. Greater imagination is required around: the image presented by the profession; retention and replenishment of personnel; appropriately connecting people of different generations to their individual roles; developing leaders comfortable with the sentient aspects of organisation life and capable of collaboration; and sustainable management of knowledge.
As one of Australia’s largest dam owners, Hydro Tasmania maintains a comprehensive Dam Safety Program. The Program makes use of industry Guidelines in combination with complementary processes to form a decision framework. This framework drives dam improvement initiatives, one of which is the development and operation of survey and instrumentation programs. It is Hydro Tasmania’s belief that the ANCOLD Guidelines on Dam Safety Management currently provide adequate descriptive guidance with regards to survey and instrumentation and it is questionable if more prescriptive Guidelines are prudent or required. Hydro Tasmania believes that a Guideline presenting a decision framework from which targeted Survey, instrumentation and inspection programs and other initiatives can evolve would be a welcomed document to the Australian dams community.
The paper describes the methodology, operative techniques and organizational aspects that are used for dam safety assessment procedures. Kelag owns 15 larger dams with wall heights up to 110 m. It is necessary to monitor the aging of the structures and to check all safety equipment regularly. The manned control centre is situated at the KELAG Headquarter in Klagenfurt, which is the capital of Austria’s southern-most Province, Carinthia. KELAG is the principal electricity supplier in Carinthia, and owns several reservoirs in the Austrian Alps. The whole hydropower system has a capacity of 434 MW with an annual production of 1000 GWh. During the last century KELAG employees designed, supervised and constructed most of the structures in cooperation with the authorities. Most of the rock-fill dams have a bituminous concrete sealing on the upstream face. KELAG owns one concrete arch dam with a height of 30 m. A pendulum monitors the movement of the dam crest. This information is transmitted to both the power house and the manned control centre in Klagenfurt. Seepage is monitored at all rock-fill dams. In case of an alarm a skilled engineer has to be informed by the staff of the manned control centre. This dam safety engineer starts to check the reasons on site and manages the emergency action plan. Data has been collected since 1998 and special software is used to handle this information, carry out interpretation and safety assessments. One aim of data collection is to develop a decision support system performing online evaluation, explanation and interpretation of dam behaviour. Normally, once a year geodetic measurements are carried out at all dams.
KELAG’s experience gained in the use of automatic monitoring and risk assessment of dams is covered in this paper. The monitoring systems show the state of the structures and those showing anomalous situations requiring human intervention can be identified as soon as possible. Although the repercussions of the free market system have led to substantial staff reductions, the quality of dam surveillance has had to remain unaffected. Dam safety is guaranteed by new types of instrumentation, data transmission and data assessment. A special software has to be updated constantly.