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2006 Papers
2006 – A Summary Of Major Dam Safety Deficiencies Identified By The Initial U.S. Army Corps Of Engineers’ Screening Portfolio Risk Assessment Program
Learn moreJeffrey A. Schaefer, Ph.D., P.E., P.G. and David M. Schaaf, P.E.
In 2005 the U.S. Army Corps of Engineers (USACE) developed and implemented a Screening Portfolio Risk Assessment (SPRA) process for Dam Safety. The screening process considered loading frequency, an engineering rating to estimate a relative probability of failure, and both human life and economic consequences of failure. The results were utilized as a tool to help prioritize funding for dam safety modification projects and required studies. Three multidisciplinary cadres evaluated what was considered the worst 10% of the USACE’s dam projects in 2005 and the next worst 10% in 2006. The dams evaluated included flood control, navigation, and multi-purpose dams. Approximately seventy facilities were evaluated each year.
As a result of the aging of the USACE’s dam portfolio and the state of the art at the time of design and construction (mostly 1940’s-50’s), significant dam safety deficiencies exist at many USACE dams. This paper summarizes the major deficiencies identified from the SPRA process. Examples, including foundation seepage, karst development, embankment stability, gate deterioration, liquefiable foundations, and inadequate spillway capacity are provided along with discussion on which deficiencies contribute the greatest risk.
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2006 Papers
2006 – Accessing Deep Storage at Warragamba Dam
Learn moreB Simmons, N Mudge
In 2004 the NSW Government released its Metropolitan Water Plan (MWP). This plan detailed the government’s initiatives to secure Sydney’s water needs during the current drought and into the future. The MWP outlined a range of both demand and supply side measures. These included modification to Warragamba and Nepean dams so that the water at the bottom of the dams that is currently unavailable for water supply can be accessed.
Accessing this deep water will increase the available water supply by an additional six months in the immediate drought and will provide, on average, an additional 40GL/annum to our long term available water supply.
The Warragamba Dam Deep Water Access Project involves accessing and transferring water from deep in Warragamba Dam to the existing water supply system.
Phase One of the project saw an abandoned underground pumping station 1.5km downstream of the dam wall, being enlarged and upgraded to pump water from the low level pipeline into the existing water transfer pipelines.
Phase Two of the project involved making a penetration low on the dam wall, some ninety metres below full storage level to access the deep water. This enabled the water to flow into the new pumping station, through an existing underground pipeline.
This project and in particular Phase Two was extremely unique due to the saturation diving systems and specialist tooling systems needed to create the penetration in the dam wall. The project provides a reference point for the water industry for future similar works.
This paper describes the project that was initiated at Warragamba Dam to access the deep water and is focused on the extremely difficult and unique works associated with creating the low level penetration in the dam wall.
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2006 Papers
2006 – Achieving Benefits From Instrumentation And Survey Measurements Of Dam Behaviour
Learn moreJohn D Smart
The paper presents the recent trends in the use of instrumentation and survey measurements at Bureau of Reclamation (Reclamation) dams. The underlying philosophy that has influenced those trends is presented and discussed. Based on experience at Reclamation, several factors that are considered key to the effective use of instrumentation and surveys are discussed. Several conclusions are offered.,
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2006 Papers
2006 – ALARP Considerations for Dam Safety – Are We There Yet?
Learn morePeter Allen, Malcolm Barker, Shane McGrath and Chris Topham
Are we there Yet? The question we all ask in Tolerability of Risk. The answer is in the journey, which we are all on as owners, regulators or designers.
A number of authorities in Australia are applying risk assessment for the evaluation of dam safety upgrades in accordance with the October 2003 ANCOLD Guidelines on Risk Assessment. A fundamental requirement for the evaluation of risk below the limit of tolerability is the use of the As Low As Reasonably Practicable(ALARP) principle. In making a judgement as to whether an ALARP position may have been reached, ANCOLD suggest the evaluation of a Cost to Save a Statistical Life, good practice, level of existing risk, social concerns, affordability and duration of risk. ANCOLD also suggests consideration of the USBR Criteria for evaluating risk. Recent guidelines on the Acceptable Flood Capacity for Dams developed by the Queensland Dam Safety Regulator provide further insight into the application of ALARP.
The objective of the paper is to make dam owners, regulators and designers aware of some current practice regarding the evaluation of ALARP in Australia, highlight the challenges of applying this principle and to encourage further discussion.
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2006 Papers
2006 – An Overview of the U.S. Army Corps of Engineers’ Screening for Portfolio Risk Assessment for Dam Safety Program
Learn moreDavid M. Schaaf, P.E., Jeff Schaefer, Ph.D., P.E., P.G
The United States Army Corps of Engineers (USACE) has an inventory of over 600 dams. The main purpose of many of these dams is for flood control, but there are a significant number of dams primarily used for navigation. Additional benefits at many of these projects are provided through hydropower generation, recreation, and irrigation for farmers. Many of the dams are quite old and represent an aging infrastructure across the inventory. In addition, leaner budgets relative to the need for repairs across the aging system require that USACE invest wisely in order to efficiently use available funds to reduce the greatest risks across the inventory. Previously, individual projects with perceived deficiencies were evaluated separately by the responsible district. This evaluation was not compared in any programmatic way to other USACE dams being evaluated for deficiencies.
In order to improve the process of making risk-based decisions across the entire spectrum of USACE dams, the Screening for Portfolio Risk Assessment (SPRA) for the USACE Dam Safety Program was initiated during the summer of 2005. This effort represents the first level of a multiple phased effort to bring full scale risk assessment to the decision-making regarding making investment decisions associated with dam safety by linking engineering reliability with economic and life loss impacts on a relative scale. The SPRA effort involved the development of a tool for evaluating the relative life and economic risk of dam failures for a variety of deficiencies across the inventory of USACE dams. This paper will focus on the basic aspects of the evaluation tool as well as the process by which the screening was completed.
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2006 Papers
2006 – Contemporary Issues Concerning the Instrumentation/Survey of Dams from the Legal Perspective
Learn moreDermot Armstrong
This paper reviews the general principles of duty of care which assist in the understanding of responsibilities that may exist for surveillance of dam safety, including the inter-play of the common law and statutory law. Only when there is a foundation in the general principles can obligations upon dam owners/operators with respect to surveillance and instrumentation be interpreted. Some legal issues around the development and use of industry guidelines are also explored.
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2006 Papers
2006 – Corporate Governance For Dam Safety
Learn moreS. Frazer
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 legal advices
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2006 Papers
2006 – Corporate Governance for Dam Safety
Learn moreS. Frazer
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 legal advices.
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2006 Publications
2006 – Dam Instrumentation or Damn Instrumentation – A South African Perspective
Learn moreChris Oosthuizen
A brief overview of dam surveillance is given from a South African perspective and more specifically the perspective of the Department of Water Affairs and Forestry (DWAF). DWAF’s Ten Commandments for the design of dam monitoring systems serve as introduction and this is followed by a summary of the design steps. The various parameters that can be measured and the South African preferences are discussed briefly followed by a synoptic description of crack and joint monitoring in South Africa. This provides the background for DWAF’s recent developments in 3-D Crack-Tilt gauges. Some of DWAF’s achievements as well as some of the blunders made by the author during the past 30 years are illustrated by means of a few case histories.
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2006 Papers
2006 – Dam Monitoring at Verbund – Austrian Hydro Power
Learn morePius Obernhuber
Verbund – Austrian Hydro Power (AHP) is the owner and operator of 27 large dams. The highest dam is the 200 m high Koelnbrein arch dam and the highest embankment dam is the 83 m high Durlass-boden dam. Instrumentation of the dams of AHP comprises almost all kinds of instruments employed in dam monitoring. Manual measurements are carried out with the help of portable terminals. Auto-matic monitoring with an early warning system is implemented at all dams. Besides a description of the monitoring system and some “interesting” measurement results the article also deals with organisational aspects of dam surveillance.
The case study of Koelnbrein arch dam is appended to the article. It contains a brief description of the original dam and the encountered problems as well as of the main elements of the remedial works. Dam surveillance and the performance up to now are also dealt with.
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2006 Papers
2006 – Dam Safety Management in Austria
Learn morePius Obernhuber
In Austria, special procedures for ensuring dam safety apply to dams higher than 15 m or reservoirs with a capacity of more than 500,000 m³. There are at present about 90 dams which belong to this category. The largest one is the 200 m high Kölnbrein arch dam.
In general, it is the task of the dam owner to provide for the safety of a dam. For that, he has to appoint qualified engineers, the “Dam Safety Engineers”, which are in charge of dam surveillance and maintenance. The Water Authority verifies that the owner makes the necessary provisions for dam safety. Water Authorities are the Provincial Governor and the Federal Minister of Agriculture and Forestry. The Water Authorities are supported by a governmental advisory board, the “Austrian Commission on Dams”.
Projects for new dams or for reconstruction of existing dams are examined by the Austrian Commission on Dams. Approval by the Water Authority is based on the findings of this commission. A group of a few experts of the commission accompanies the project during construction, first impounding and the final acceptance procedure. In normal operation, dam attendants carry out visual inspections and measurements. The most important instruments are measured automatically and the data are transmitted to a permanently manned control centre. The Dam Safety Engineer has to inspect the dam at least once a year. His annual report to the Water Authorities must contain an assessment of the safety of the dam. The Federal Dam Supervisory Department of the ministry checks the annual reports and carries out an in-depth inspection of the dam at least every five years.
In the case of extraordinary events, the Dam Safety Engineer has to assess the situation and he has to set appropriate measures. An Emergency Action Plan is available for all dams of the said category.
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2006 Papers
2006 – Design and Construction of the Gattonvale Offstream Storage
Learn moreNerida Bartlett, David Scriven, Peter Richardson
The failure of a number of consecutive wet seasons has resulted in storage levels in Eungella Dam being at dangerously low levels such that supply could be exhausted by June 2007. Eungella Dam supplies bulk water to the Bowen Basin coal fields as well as the Collinsville power station and the Collinsville township.
The Collinsville township, power station and coal mine as well as the Newlands mines take water from the Bowen River Weir which is supplied from Eungella Dam some 95 kilometres upstream. Transmission losses of the order of 25 to 50% have been experienced for releases from Eungella Dam to Bowen River Weir.
The Eungella Dam catchment area is 142 square kilometres. Significant flows occur in the Bowen River downstream of Eungella Dam, the catchment area above Bowen River Weir being 4,520 square kilometres. The topography in the surrounding area (near Collinsville) is not suitable for dam construction.
The opportunity existed for the construction of an offstream storage adjacent to the Bowen River Weir so that the downstream flows could be captured reducing the demand on Eungella Dam thus making more water available for upstream users.
A 5,200 ML offstream storage, associated pump station and rising main was designed, constructed and filled within a period of 12 months.
Foundations at the site are highly permeable sands. Marginally suitable clay for a seal was in short supply as was suitable rock for slope protection. A fixed price budget had been set by the contributing customers.
This paper describes the hydrology, site conditions, design and construction of the project.
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2006 Papers
2006 – Design and Construction of the Ridges Basin Dam
Learn moreJohn Cyganiewicz
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.
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2006 Papers
2006 – Developing Techniques for New Dam Design and Construction Management – Recent New Zealand Experience
Learn moreR. Dawson, J. Grimston, R. Cole, D. Bouma
The authors have been involved in the design and construction of several embankment dams in New Zealand over the past decade, and have considerable corporate knowledge from dams designed by the company in its 47-year history. This paper examines four dams which are relatively small to medium, ranging in height from 10 to 19 m with moderate storage volumes. Three of the dams service landfills and the fourth a wood processing mill. Such dams may provide the designer with considerable challenges due to their relatively low capital cost resulting in limited investment in geotechnical investigation at the front end of the project, with varying levels of change often required during construction due to unforeseen conditions as a result of the limited investigations.
The general arrangement and conceptual design principles for each of the dams is described followed by the field investigation and laboratory testing undertaken for each dam, together with the interpreted ground conditions.
The experiences from construction have helped to develop techniques for a balance between preliminary design, investigation, and evolution of the design and specification during construction. It is imperative to develop a sufficiently detailed preliminary design, on the basis of readily available information such as visual and geological assessment, to allow the investigation to be thoughtfully designed to allow the major assumptions to be verified. This needs to be followed by a skilfully executed geotechnical investigation with the designer advising on findings and changing direction as necessary through the investigation. An investigation trench along the full alignment of the cutoff trench (if envisaged in the design) is warranted. Earthworks specifications should be evolved early in the construction phase through compaction trials using specific plant for the site, and backed up by insitu and laboratory testing.
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2006 Papers
2006 – Development and Application of a Risk Analysis and Prioritisation Tool (RAPT) for Dam Safety Management
Learn morePeter Hill, Rory Nathan, Phillip Jordan, Mark Pearse
This paper outlines the development and application of the Risk Analysis Prioritisation Tool (RAPT) which has been developed as an interactive tool to aid dam safety risk management. RAPT allows the risk profile and prioritisation of upgrades to be incrementally updated as inputs are refined. The paper outlines some of the requirements of a risk management tool and the resulting functionality of RAPT and the lessons learnt from its application to more than 75 dams.
Issues covered include:
- importance of understanding and tracking the reliability of the inputs;
- requirements for incorporating staged upgrades and non-structural risk reduction measures;
- impact of different approaches to prioritising risk reduction measures; and
- approaches for summarising and conveying risk results
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2006 Papers
2006 – Effect of Geology on Dam Construction Projects in Iran
Learn moreA. Uromeihy, P.G. Ranjith
In response to increasing potable water need and in order to control and collect precipitations, many dams have been constructed and many more are under construction in Iran. Due to the complex geology of the country, many of the dam sites face serious geological problems both during construction and in operation phases. The most predominant types of problems are water leakage and sediment deposition in the reservoirs. In order to define and classify the type of problem with regards to geological condition, the country is divided into eight zonesin whicheach zone demonstrates similar problem on the dam site location. It is found that the water leakage is related directly to either the presence of soluble carbonate rocks in the abutment or the presence of thick permeable material in the foundation. It is also shown that the sediment deposition in the reservoir is related to many factors but the geology of the watershed area has a major effect. Therefore it can be concluded that the geology has a great role in the construction of dams.
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