Ulu Jelai project is a recently completed 372MW hydroelectric peak – power project located in the Cameron Highlands of Malaysia. A combination of power generating and reservoir operating conditions together with the site topography, existing road infrastructure, geology and hydrogeological conditions pose a significant risk to the viability of the project during operation. As a result, significant reservoir rim stability treatments were designed and constructed along a 3.5km section of the right abutment of t he Susu Reservoir to reduce the risk of instability to acceptable levels. This paper describes the methods of investigations, stability assessment and design aspects of the reservoir rim stability treatments that were constructed.
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Recent advances in communication technologies have made available an array of new systems and functionalities that dam operators can use to improve automation and centralisation in the daily surveillance tasks of their portfolios. These functionalities include real-time monitoring, target-oriented video surveillance and the remote management of PLCs and data loggers.
The present paper aims to outline some integration possibilities using TCP/IP technologies for remote operations and video surveillance.
The case study features a comprehensive dam instrumentation upgrade, in which the acquisition systems were complemented with a series of IP cameras designed to be triggered by local and remote events.
For hydropower dam projects, design and construction of the temporary works including cofferdams are very important. Improper selection, design and/or construction of temporary works may cause delay of major construction works and increase construction cost.
The authors worked on the preparation of the Engineering, procurement and construct EPC tender (based on International Federation of Consulting Engineers (FIDIC) contract-yellow book) for a 20 MW Hydro Power Plant (HPP) project in the Balkans Region. The scheme involved the design and construction of three cofferdams to enable construction of the main dam, intake and powerhouse. The basis for tendering, as a part the contract documents, was the preliminary design of the HPP scheme. The tenderers were allowed to deviate from the solutions presented in the preliminary design as long as the proposed solutions fulfilled the Employer’s Requirements.
As a part of a winning strategy, the preliminary design cofferdams were changed and modified, providing significant saving and facilitating quicker and safer construction. This paper presents the development of the design and challenges faced during construction work.
Melbourne Water (MW) has historically seen dam safety management as a civil discipline and has focussed on understanding and managing the civil assets at its dam sites. The recent addition of a mechanical engineering resource to the team responsible for the dam safety management has refocused attention on the mechanical and electrical (M&E) assets and provided a more holistic asset management approach to MWs large dams.
This paper discusses the process MW has developed over the past two years to improve their understanding and management of M&E assets. It centres on key process points for how MW has prioritised the development of M&E asset management programs on the basis of an autogenous ‘asset criticality’ rating system and has utilised ANCOLD comprehensive inspections to plan and implement new inspections and tests on dam M&E assets. The two case studies of Sugarloaf and Upper Yarra Reservoirs’ outlet works demonstrate the the benefits of the process to gain operational and technical knowledge of M&E assets, strategic importance to the water supply network, identifying risks therein and reallocate significant funding to address these risks as prioritised by asset criticality.
On February 7, 2017, the gated service spillway (also known as the Flood
Control Outlet or FCO Spillway) at Oroville Dam was being used to release water
to control the Lake Oroville level according to the prescribed operations plan.
During this operation, the service spillway’s concrete chute slab failed, resulting
in the loss of spillway chute slab sections and deep erosion of underlying
foundation materials. Subsequently, as the damaged service spillway was
operated in an attempt to manage multiple risks, the project’s free overflow
emergency spillway was overtopped for the first time since the project was
completed in 1968. Significant erosion and headcutting occurred downstream of
the emergency spillway’s crest structure, leading authorities to evacuate about
188,000 people from downstream communities.
For intraplate regions such as Australia, identifying and quantifying activity on tectonic faults for inclusion in probabilistic seismic hazard assessments can be challenging due to the typically long return period for ground-rupturing earthquakes associated with these structures. Return periods of 10,000’s to 1,000,000’s of years mean that surface displacement evidence is prone to degradation through erosion and burial, and paleoseismological ‘trench’ excavations may not uncover geology old enough to reveal previous events. As a consequence, there is often little or no preserved evidence of past ground rupturing events on these structures. Rather than ignoring faults which show no evidence of neotectonic displacement, we present an alternative approach; in addition to considering active faults (movement in the last 35,000 years) and neotectonic faults (movement in the last 10 Myr) in seismic hazard assessments, we also consider faults which otherwise show no evidence of neotectonic activity but which are aligned favourably with the current stress regime and are therefore potential sources of earthquakes and accompanying strong ground motion.