Lesa Delaere, Dr Natalie Clark, Dr Shayan Maleki
Waterway barriers, such as dams and weirs, have the potential to impact aquatic fauna species through the restriction of fauna movement and direct injury and mortality of individuals. Without suitably designed aquatic fauna passages and features to minimise injury and mortality, these barriers may adversely affect the viability of local and regional populations, through disruption to critical behaviours (e.g. breeding, dispersal).
The Lower Fitzroy River Infrastructure Project comprises of two weirs on the Fitzroy River in central Queensland. Two threatened turtle species, the Fitzroy River turtle and the white-throated snapping turtle, and a range of fish species needed consideration of species-specific requirements and development of targeted design solutions.
This paper discusses the ecological needs of these species as well as features incorporated into the design to reduce the impact of the weirs. The design incorporated modular fishlocks, gate, spillway and stilling basin features, an innovative turtle passage, special considerations for outlets and operational aspects. The design was further subject to complexity due to the variation in river flows, zero flow to approximately 9,000m3/sat bank full, and needed to account for a wide range of operational scenarios with respect to the species impacts.The paper also includes a discussion on computational fluid dynamics modelling (CFD) which was used to validate the design of fish passage structures.
Richard Herweynen, Jamie Campbell, Mohsen Moeini
Hydropower storage plays an expanding role in integrated power systems internationally and can enable increased use of intermittent renewable energy sources such as wind and solar.With an increased amount of renewable energy within the Australian grid, pumped storage has gained increased focus in the past 2years. Entura have been working with Genex Power Ltd. to investigate, evaluate, optimise and design the Kidston Pumped Storage Project, located at the old Kidston gold mine in Northern Queensland. Through this design process, the final arrangement developed included an upper reservoir turkey’s nest dam to be built on the existing waste rock dump on the northern side of the Eldridge Pit, using the existing waste rock dump material and lining it with an HDPE liner. The original waste rock dump was formed during the mining operation by progressively dumping the waste rock predominantly from the Eldridge Pit excavation, with the haul truck traffic being the only compaction that occurred. Since the closure of the mine about 20 years ago, some consolidation of the waste rock dump has occurred.As a result, the key risks identified for the construction of the turkey’s nest dam on top of the waste rock dump were: (1) the stability of the slopes of the waste rock dump, which were generally at the angle of repose for the rockfill material; (2) the absolute settlement of the waste rock dump as the final dam crest level requires a settlement allowance in excess of the flood freeboard requirements; and (3) the differential settlement as excess differential settlement could cause fatigue stress cracking within the liner.This paper presents the investigation and modelling undertaken to confirm the feasibility of constructing this turkey’s nest dam on top of the existing rock waste dump, utilising the historical data on dumped rockfill dams. The paper also presents the feasibility design developed for the upper storage.
C.Jolly and J.Green
New rare design rainfalls were released for Australia in February 2017, for durations from one to seven days and probabilities from 1in 100Annual Exceedance Probability (AEP) up to 1 in 2000 AEP.The differences between the previous rare design rainfalls using estimated Cooperative Research Centre –FOcussed Rainfall Growth Estimation (CRC-FORGE) method and the new rare design rainfall estimates vary with location, duration and probability. In this paper, these differences are explored spatially through the use of national maps, comparing percentage change between the two datasets for selected durations and probabilities. Before this comparison with the new rare design rainfalls could be completed, the State-basedestimates had to be resampled and aggregated to form a national data set for Australia.For rare design rainfalls, it is often the catchment values that are required to determine the gross rainfall for design purposes. The impact of the revised areal reductions factors and rare design rainfalls is explored through case study catchments in Tasmania.
Andrew Balme, Dan Forster, Tim Logan
The MW7.8 Kaikōura earthquake on 14 November 2016, ruptured over 20 faults during the initial shaking,which lasted nearly two minutes. A complex series of fault ruptures propagated northeast for nearly 180 km from the initial rupture location. Instrumentation from dams across New Zealand shows that whilst most dams did not suffer physical damage, piezometric responses were measured in dams and their foundations. Earthquake related changes in seepage regimes are not unusual and depend on the characteristics of the ground motions,and site specific characteristics that influence how a dam and its foundation respond to ground motions. The ability to measure a piezometric response in a dam or foundation is heavily influenced by the instrumentation network and method of monitoring. Data collected during events such as the Kaikōura earthquake provides valuable information for both characterising performance of a dam during the event, and assisting future analysis such as failure mode assessments. Careful consideration must be given to the scope of installed instrumentation and the frequency of monitoring in order to provide these benefits,and the robustness of the system to ensure it adequately survives the event.
Zerui Lu, Behrooz Ghahreman-Nejad, Mahdi M. Disfani
Particle characterisation like size distribution and shape can greatly affect the mechanical behaviour of granular materials, and is closely related to the economics for engineering projects. For rockfill material in embankment dam construction, the particle size distribution (PSD) is fundamental to the design, quality control and numerical modelling. Traditionally, particle size distribution for engineering materials is obtained through physical sieving. However, with rockfill material, the size varies significantly and can range from gravels (+2mm) to cobbles (+60mm) and boulders (+200mm) with the maximum size usually limited to 1m, which makes the conventional sieving process considerably difficult to conduct as well as being time-consuming. Meanwhile, the advanced technology in computer image processing has created many possibilities in characterising particles within digital photographs, and therefore can be utilised as an effective alternative to the conventional sieve analysis. This method has been in use mainly in the mining industry over the past two decades to assist with rock fragmentation and process monitoring and control. Notwithstanding, the use of this technique in the dam industry for quality control of rockfill material has been rare. Thus, an innovative approach is proposed in this paper to estimate the PSD curves for rockfill material using image analysis along with the latest developments in aerial photography. The results of PSD analysis using the image processing software Split Desktop are presented and compared with the results from sieve analyses for verification. Recommendations are made to improve the process and increase the accuracy of the outcome. It is demonstrated that the proposed method has a reasonable accuracy and is a viable option for quality control in construction of rockfill structures such as rockfill embankment dams.