Project Lead: Joel Eadie, Senior Associate Engineer
Team Members: Natascha Kotze (Research and Design), Georgia Greening (Research and Design), Phillippe Garneau (Project Reviewer), Glen Burton (Design and Laboratory Assistance)
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Joel, how did the innovation project idea originate?
Erosion management is a key consideration for landform design in mine closure. Erosion and landform evolution modelling is undertaken to understand the magnitude of erosion, identify problematic areas and optimise landform designs prior to construction.
Deriving modelling input parameters for erosive materials is challenging due to the lack of published literature for Australian soils, particularly in the context of mine rehabilitation. Historically, inputs have been determined using empirical formulas which rely on basic material characterisation such as particle size distribution, permeability and soil density. These formulas, however, are generally developed for agricultural soils in the US, and therefore poorly represent the diversity of materials and landform geometry used in mine closure.
Flume testing removes the reliance on empirical formulas and allows us to derive and directly measure the erodibility parameters for the tested soils. Flume testing is not commonly available from geotechnical laboratories and is only available from specialist engineering firms specialising in mine closure or educational geotechnical laboratory facilities.
This project focuses on building that laboratory testing capability so the team can generate the data needed to support erosion modelling for mine closure projects.
Above: Erosion on the embankment of a rehabilitated TSF
What problem does your project solve?
The project addresses the limited availability of published erosivity parameter values in Australia, as well as the specialist nature of the testing required. The testing is not widely undertaken in geotechnical laboratories in Australia, which can make it difficult to access when project teams need timely, fit-for-purpose data.
Developing an in-house laboratory test will give our teams a practical way to generate the data needed to support erosion modelling and closure-related projects.
Can you explain your approach?
The lack of a defined method and industry standard highlights the importance of developing a robust, repeatable testing approach that can produce defensible results for mine closure projects. The team began by reviewing academic papers and examples of similar testing methods, as there is no single approved method or Australian standard for this type of laboratory erosion test. This research helped the team develop a fit-for-purpose design that provides a reliable way to determine the soil parameters needed for erosion modelling.
The testing apparatus comprises a soil bed approximately three metres long and one metre wide, with rainfall applied over the surface so erosion can be measured under controlled conditions. The soil bed will allow different material types, slopes and compaction levels to be assessed in a consistent way. At the same time, the rainfall simulator will provide repeatable rainfall intensity across the test area. Runoff and eroded sediment can then be collected and measured, allowing the team to calculate material-specific erodibility parameters for use in landform evolution modelling.
What stage is the tool at now, and what is planned in the future?
The project is currently in the design and build stage. The team is finalising the design, with some construction activity already underway in the Newcastle Laboratory (shown above). The goal is to have a working flume completed by the end of the year.
In the new year, the team will identify suitable opportunities and sites where the test can be trialled, refined, and improved through practical use.