San Isidro, Peru
San Isidro, Peru

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Breitenbach A.,Ausenco Vector
Geosynthetics | Year: 2011

Allan Breitenbach explains how the underliner soil materials on his projects were typically tested at optimum moisture and 95% of standard compaction in combination with an overliner of clean sand and gravel cover fill. The test re-runs differed by several degrees of friction strength, along with variable apparent cohesion values, using the same test equipment, materials, and procedures. The purpose of the testing was to verify the reliability of the 4-inch direct shear box in determining accurate test strengths. The overliner soil material comprised clean sandy gravel placed in a single loose lift and wetted to simulate a protective drain cover fill above the liner surface. The more flexible PVC liner showed no significant increase in restricted liner strength due to its high elongation characteristics. The other point in the restricted versus unrestricted liner argument is that it is still an apparent common practice in landfills to place composite clayey soils wet of optimum to meet regulatory specified low permeability requirements.

Breitenbach A.,Ausenco Vector
Geosynthetics | Year: 2011

Allan J. Breitenbach, P.E. focuses on the factors that influence liner interface test strengths. The friction strength can approach zero degrees with the cohesion intercept at its maximum value for a relatively saturated and fine-grained soil approaching unconsolidated and undrained conditions with quick loading and fast shearing rates. Under these conditions, the apparent cohesion should be discarded for a conservative friction strength estimate or a retest can be conducted with a longer time for pretest load consolidation and dissipation of excess pore pressures. The mining project experience gained from conducting large pilot scale liner test fills using loaded rock haul truck traffic at mine sites, observations of liner drain fill cover and heap lift construction, numerous large-scale direct shear box tests performed at optimum or dry of optimum moisture content, and a review of known pad liner slope failures all point to only one conclusion.

The article details the current methods for assessing remaining service life and provides an explanation of why existing ponds may not be performing as predicted. The typical ageing process for HDPE geomembranes involves three stages. In modern meomembranes, the initial OIT value can be around 130 minutes, which represents the time it takes for the geomembrane sample to reach the exothermic peak when held isothermally at 200 C at the given pressure for the test method in an oxygen environment. The length of Stage III can depend on which physical property is measured. Albeit arbitrarily, the service life of the geomembrane is considered to be the sum of the time it takes the geomembrane to complete the three stages. Contaminant transport modeling was used in conjunction with the measured chloride leachate concentrations throughout the clay samples to assess when the geomembrane ceased functioning.

Leon A.S.,Oregon State University | Kanashiro E.A.,Ausenco Vector | Valverde R.,Oregon State University | Sridhar V.,Boise State University
Journal of Water Resources Planning and Management | Year: 2014

This paper presents a case study on the application of a dynamic framework for the intelligent control of flooding in the Boise River system in Idaho. This framework couples a robust and numerically efficient hydraulic routing approach with the popular multi-objective nondominated sorting genetic algorithm II (NSGA-II). The novelty of this framework is that it allows for controlled flooding when the conveyance capacity of the river system is exceeded or is about to exceed. Controlled flooding is based on weight factors assigned to each reach of the system, depending on the amount of damage that would occur, should a flood occur. For example, an urban setting would receive a higher weight factor than a rural or agricultural area. The weight factor for a reach does not need to be constant as it can be made a function of the flooding volume (or water stage) in the reach. The optimization algorithm minimizes flood damage by favoring low-weighted floodplain areas (e.g., rural areas) rather than high-weighted areas (e.g., urban areas) for the overbank flows. The proposed framework has the potential to improve water management and use of flood-prone areas in river systems, especially of those systems subjected to frequent flooding. This work is part of a long-term project that aims to develop a reservoir operation model that combines short-term objectives (e.g., flooding) and long-term objectives (e.g., hydropower, irrigation, water supply). The scope of this first paper is limited to the application of the proposed framework to flood control. Results for the Boise River system show a promising outcome in the application of this framework for flood control. © 2014 American Society of Civil Engineers.

Breitenbach A.J.,Ausenco Vector
Tailings and Mine Waste'10 - Proceedings of the 14th International Conference on Tailings and Mine Waste | Year: 2011

Tailings disposal practices in the mining industry have been changing in the last 10 years from high water content conventional slurry tailings disposal to more water efficient thickened tailings, paste tailings and dry stack tailings disposal in recent time. These changes are occurring in part due to more scarce fresh water resources to sustain the mill production operations, and in part due to more efficient thickener tank designs for removal of excess tailings slurry water for plant reuse. Tailings disposal storage practices are also changing to co-disposal of tailings in minewaste piles with the potential for end of operations reprocessing of tailings as backfill disposal into depleted mine excavations at closure. This paper discusses the recent changes in tailings disposal and storage practices and their impact on tailings dam construction in the 21 st Century. © 2011 Taylor & Francis Group, London.

Beck A.,Ausenco Vector
Geotechnical Special Publication | Year: 2011

After five years of private research, the Dipole Method (ASTM D7007) has been vastly improved with technology that allows for superior quality control. Many companies performing the dipole method take exception to the ASTM requirement to record the voltage potential data, instead locating holes in real time as the survey progresses. The only commercial dipole equipment currently available does not include data recording capabilities. Per ASTM D7007, ASCII data files can be requested by the client, but the files would simply be a log of voltage potential measurements, which is not meaningful to a layperson. Recent advances in the Dipole Method equipment include a GPS-based data recording system and software in order to download the data and create an iso-potential map throughout the survey area. Potential hole locations are clearly shown as a bull's eye pattern in the voltage potential field. In addition, the equipment uses a proprietary technology, which allows the operator to greatly reduce the background noise. When the background noise can be reduced, the signal produced by a hole is not only amplified, but it can be seen more easily and from further away. The increased sensitivity of the new technology is presented in this paper through calibration curves produced for a given hole size using both the existing and the new technology. The new technology shows that the Dipole Method can be performed with both increased sensitivity as well as the production of survey documentation, which can ensure the quality of the survey and provide a means for quality control documentation. The abilities of the new technology presented in this paper will be increasingly important as national standards develop. This paper presents the capabilities of this dipole equipment for the first time. © 2011 ASCE.

Leon A.S.,Oregon State University | Kanashiro E.A.,Ausenco Vector | Gonzalez-Castro J.A.,South Florida Water Management District
Journal of Hydraulic Engineering | Year: 2013

This paper presents a new model for unsteady flow routing through dendritic and looped river networks based on performance graphs. The model builds on the application of a hydraulic performance graph (HPG) to unsteady flow routing introduced in a previous study and adopts the volume performance graph (VPG) introduced in another study. The HPG of a channel reach graphically summarizes the dynamic relation between the flow through and the stages at the ends of the reach under gradually varied flow (GVF) conditions, and the VPG summarizes the corresponding storage. Both the HPG and VPG are unique to a channel reach with a given geometry and roughness and can be computed decoupled from unsteady boundary conditions by solving the GVF equation for all feasible conditions in the reach. Hence, in the proposed approach, the performance graphs can be used for different boundary conditions without the need to recompute them. Previous models based on the performance graph concept were formulated for routing through single channels or channels in series. The new approach expands on the use of HPG/VPGs and adds the use of rating performance graphs for unsteady flow routing in dentritic and looped networks. The applicability of the proposed model to subcritical unsteady flow routing is exemplified through a looped network, and its simulation results are contrasted with those from the well-known unsteady Hydrologic Engineering Centers River Analysis System model. The results show that the present extension of application of the HPG/VPGs appears to inherit the robustness of the HPG routing approach in a previous study. The unsteady flow model based on performance graphs presented in this paper can be extended to include supercritical flows. © 2013 American Society of Civil Engineers.

Leon A.S.,Oregon State University | Kanashiro E.A.,Ausenco Vector | Gichamo T.Z.,Oregon State University | Valverde R.,Oregon State University | Gifford-Miears C.,Oregon State University
World Environmental and Water Resources Congress 2012: Crossing Boundaries, Proceedings of the 2012 Congress | Year: 2012

This paper presents a new framework for the intelligent control of river flooding. This framework links two components: river system routing (simulation) and optimization. The river system routing component builds upon the application of Performance Graphs (precomputed hydraulics under gradually varied flow scenarios), while the optimization component uses the popular second generation multi-objective evolutionary algorithm Nondominated Sorting Genetic Algorithm-II (NSGA-II). The use of hydraulic performance graphs for river system routing results in a robust and numerically efficient model as most of the computations for the system routing only involves interpolation steps. The proposed framework allows controlled flooding in the event that the capacity of the river system has been exceeded. This controlled flooding is based on weight factors assigned to each reach of the system depending on a hierarchy of risk to losses associated with flooding. Naturally, river reaches that are less prone to flood losses are assigned smaller weight factors and reaches that are more prone to flood losses are assigned larger weight factors. For illustration purposes, the proposed framework was applied to the Boise river system in Idaho. The results show a promising outcome in the application of this model for flood control. © ASCE 2012.

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