Robert Kingsland, Andy Noble and Dr Eric Lam
Engineering design is necessarily context specific. However, engineering design produced in industrialised nations often comes encumbered with design methods, standards and construction process familiarities that can result in inappropriate design solutions for developing nations. This is no more apparent than with the design of small hydropower projects where budgets are small and the implications of poor decisions can easily threaten the viability of schemes.
In this paper we explore the challenges and opportunities for the scheme’s developer and designer, in striking an appropriate balance on engineering solutions that remain appropriate for the local construction practices. In most cases, based on our experiences from small, run-of-river developments, the available methods for feasibility study data collection, including geotechnical investigations and hydrology assessments, are in themselves a challenge. Consequently, the designer needs to work with what is readily available and often has to reset the established thinking to incorporate practical constructability into the designs, while giving special attention to the operation and maintenance aspects. More labour-intensive methods are not uncommon.
The stakeholders in small hydropower schemes are many: the community, the approval agencies, the lenders, the developers, the local construction industry, the government. Design decisions cannot be made in a vacuum. However, designers are often distant from the social, political, environmental and commercial context of their project. This separation can present significant challenges which, without due attention, can result in poor design outcomes.
This paper will, with reference to examples of good and poor design, discuss various facets of small hydropower development from a civil engineering perspective including, the scale of development, design methods, stakeholder engagement, local content involvement, constructability and financing. The paper concludes with suggestions for improving design outcomes for small hydropower projects.
Peter Allen and Kevin Bartlett
One of the recommendations of the Queensland Flood Commission of Inquiry was for the introduction of a legislative requirement for all referable dams in Queensland to have Emergency Action Plans (EAPs) formally approved by the Dam Safety Regulator. Prior to this EAPs were required under the dam safety conditions applied to each referable dam and they were not formally approved. This recommendation has now been implemented as a requirement of the Water Supply (Safety and Reliability) Act 2008. This paper summarizes the emergency action planning system now applicable to Queensland’s referable dams and details the actions involved in implementing this system. It involves significant consultation between dam owners and local disaster managers and gives local disaster managers an opportunity to formally comment on EAPs prior to them being submitted for approval. Development of associated regulatory guidelines to cover all aspects of EAPs was done in order to make EAPs more consistent and more readily understood by users and other stakeholders in emergency situations. Once the guidelines had been developed, the Regulator undertook a state-wide series of seminars to raise the level of awareness of local disaster management groups and dam owners of the new requirements. The legislation also requires the publication of the approved EAPs on the department’s website to raise the public’s awareness of the risks involved and improve their responses in advance of emergency events. This represents a challenge from a public relations perspective because people will become more aware of the risks to which they are exposed. The paper summarises the Regulator’s experience in reviewing and considering the EAPs submitted for approval and it indicates some of the benefits and challenges of the ongoing program.
Michael Ashley and Robert Wark
The construction of service reservoirs has been an integral part of the development of water supply systems throughout Western Australia, and many such developments have occurred in coastal regions. The porous and highly soluble limestone foundations that are found in coastal regions pose specific challenges and risks for the long term management of these structures. Minimising leakage rates has been traditionally driven by economic losses. However, it has become apparent that the leakage has caused long term structural damage to the foundations of the structures.
Based on four case studies from south west Western Australia, this paper describes the extent of the problem, investigation and testing methods, design challenges and construction issues to be considered when constructing water storages on porous foundations.
Dennis C. Green
Current good practice for risk management as represented in ANCOLD guidelines emphasises risk reduction beyond tolerable risk levels to As Low As Reasonably Practicable (ALARP). Risk reduction reflected in key design parameters such as the spillway design flood is monitored on a quantitative basis, while the guidelines also draw attention to a number of non-quantifiable measures.
Recent work health and safety legislation in Australia does not at first appear to relate to dam safety, but it mandates elimination of risk, and, if that is not possible, then it mandates reduction of risk So Far As Is Reasonably Practicable (SFAIRP). It is tempting to believe that this is equivalent to ANCOLD’s approach to ALARP, but the devil is in the detail of the legislation. This paper argues for a change to a more systematic presentation of recording of decisions on dam safety risk management, lest the legislation expose dam owners unwittingly to liability when they thought they were following good practice. In particular, the re-focussing of ANCOLD Guidelines to align more recognisably with the new legal paradigm, including preparation and adoption of a Safety Case, is recommended.
Marius Jonker and Dr Radin Espandar
This paper provides a summary of the current state of practice for arch dam design criteria that have been adopted by some international dam organizations, and where relevant, compares that with the criteria provided in the updated ANCOLD Guidelines on Design Criteria for Concrete Gravity Dams, with the view to provide a basis for consistent and unified design criteria for arch dams in Australia.
The paper draws on the authors’ experience with arch dams, including recent experience with a number of arch dam safety reviews in Australia, their past experience with arch dams over 200 m height, as well as their involvement with the development of the mentioned updated ANCOLD Guidelines.
Since the last arch dam was constructed in Australia, a number of international publications have been released on arch dam design practices, providing general information and guidance for the design of new dams and evaluation of the safety and structural integrity of existing arch dams. This paper compares these publications and proposes criteria that are aligned with the ANCOLD gravity dam guidelines.
S. Suter, G. Singh, and M. Britton
Today, many organisations rely on hydrodynamic modelling to assess the consequences of dam break failure on downstream populations and infrastructure. The availability of finite volume shock-capturing schemes and flexible mesh schematisations in widely used software platforms imply that dam break modelling projects will be carried out differently in the future: Finite volume based platforms allow widespread application of shock-capturing methods and flexible mesh platforms can represent features in the study area more realistically and are more flexible thanks to varying mesh resolutions. Furthermore, the recent adoption of Graphics Processing Unit (GPU) technology in mainstream scientific and engineering computing will also significantly decrease computation times at relatively low cost.
This paper examines the application of finite volume, flexible mesh and GPU technologies to dam break modelling. One-dimensional (1D) modelling results are compared to those from two-dimensional (2D) finite difference and finite volume approaches. The results demonstrate that there are differences between modelling approaches and that the computational speeds of 2D simulations can be significantly reduced by the use of GPU processors.