Laboratory & field services
We provide tailored sample preparation and analytical services to help our clients develop the right information to quantify potential environmental risk and develop tailored solutions.
Sample preparation area
Our general preparative laboratory provides ample bench space for sample preparation. Equipped with an analytical balance, drying oven, shaker table, rock mill, sample freezer and fridge. A variety of consumables and analytical equipment such as an agate mortar and pestle, deionised water, micropipettes and all the necessary consumables required for accurately weighing and preparing solids and solutions.
The humidity cell test is designed to model weathering of spoil / overburden, waste rock and tailings. The purpose of the test is to determine the rate and variation of acid generation, salt and metal release in leachate. They are often performed to reduce result uncertainty from static tests and to provide control options for acid rock drainage, neutral mine drainage and saline drainage.
One kilogram of sample is placed in the humidity cell and is wetted / flushed. Each humidity cell receives repetitive weekly cycles of three days dry air pumped continuously through the cell, then three days of humid / moist air and on the final day is flushed with 500 millilitres of deionised water. Leachate is collected, filtered before dispatch for further analysis.
Humidity cells normally run for 5-10 weeks, but in some circumstance, may be run for longer periods.
The leach column test is the most commonly used (compared to humidity cells) and also determines the rate and variation of acid generation, salt and metal release in leachate for spoil / overburden, waste rock and tailings.
Leach column operation is designed for a weekly wet-dry cycle and a monthly leaching cycle for a six month period. The 2-2.5 kilogram sample is wetted by applying deionised water to the sample surface and leachate is collected through the column base. Heat lamps are used to dry the sample between deionised water applications. Typically, deionised water is applied weekly and leachate is collected monthly; however, sometimes this regime requires modification depending on material characteristics and analytical requirements.
Soil water characteristic curves
A soil water characteristic curve, relates matric suction to volumetric water content. This information is important for describing water storage in soil / growth medium, spoil / overburden, waste rock and tailings. The soil water characteristic curve can be used to determine how much water is available for plants, and for predicting water and contaminant transport.
SGME uses a multiple porous plate extraction system capable of measuring up to 50 soil water characteristic curves at a time. It is one of the most popular lab systems, providing capabilities for a variety of materials and conditions. The 1500 and 1600 extractors provide ample flexibility and capacity for low or high-water content extraction routines (0-5 bar and / or 15 bar).
A soil water characteristic curve can typically be measured in three weeks, but may take up to months depending on the material texture. They are also needed for accurate unsaturated soil mechanics modelling (SVFlux) for cover design.
SGME can measure the water potential of samples fast and accurately using a WP4C in the range of 1-3,000 bar. We can also use the WP4C to measure the wetting soil water characteristic curve of a material as an alternative to the multiple porous plate extraction system.
Soil water characteristic curves measured using the WP4C can be measured rapidly (about one week), but are less accurate.
SGME can run laboratory rainfall simulator tests which provide accurate and cost-effective information for erosion assessment and modelling in a fraction of the time compared to relying on natural rainfall.
Rainfall simulator tests are used to:
Study the rill and interrill erosive properties of a material;
Assess the impact of management practices; and
Understand the relationship between infiltration, runoff and erosion.
Rainfall simulators can rapidly provide:
Sediment characteristics used in designing erosion and sediment control features
Impact of material mixing on erosion potential
Impacts of revegetation, consolidation and armouring on erosion potential
Testing the efficiency of surface stabilisation products
Rainfall simulator testing is required for calibration of Water Erosion Prediction Project (WEPP) and Siberia modelling and can be run rapidly with testing completed within two-three weeks of receiving samples.
We provide tailored in-situ testing to help our clients develop the right information to quantify potential environmental risk and develop tailored solutions.
SGME is able to measure the in-situ saturated permeability of soil / growth medium, spoil / overburden, waste rock and tailings using our CSIRO disc permeameters.
The CSIRO disc permeameter is an easy-to-use instrument that quickly and accurately measure in-situ hydraulic conductivity and sorptivity as a constant head test. It can be transported, assembled, and operated by one person and tests can be made in 0.5-2 hours, depending on the material type.
In-situ permeability is needed for accurate unsaturated soil mechanics modelling (SVFlux) for cover design.
SGME is able to measure the in-situ density of soil / growth medium, spoil / overburden, waste rock and tailings using our balloon density apparatus.
The balloon density apparatus is a water-filled, calibrated vessel fitted with a hand-operated pump to pressurize the chamber. A thin, flexible rubber balloon on the bottom displaces under pressure to fill a void. It can be transported, assembled, and operated by one person and a test can be made in under 0.5 hours, depending on the material type.
In-situ permeability is needed for accurate unsaturated soil mechanics modelling (SVFlux) for cover design and is also required for saturated permeability testing.
SGME is able to collect aerial imagery and multispectral imagery covering blue, green, red, red edge, and near infrared bands using our multispectral high-precision drone for our field sampling programs. Drone technology assists our field programs because:
We are able to collect up to date aerial imagery
We can develop digital elevation models and assess stockpile (soil / waste rock) volumes
We can assess vegetation health using the normalized difference vegetation index (NDVI)
We are developing techniques to use visible / infrared reflectance spectroscopy (VIRS) in combination with handheld XRF, pH and electrical conductivity to develop distinct mineral responses that will allow us to assess on-ground near surface geochemistry / salinity for soil, waste rock dumps and for abandoned or legacy mines
Electrical conductivity and pH
SGME is able to measure the following electrical conductivity types as part of our field sampling programs:
EC1:5 is the first of three steps to estimate soil salinity (ECe). It is determined by mixing 1 part soil with 5 parts distilled or deionised water. After mixing the sample and allowing the sediment to settle, the electrical conductivity of the solution is tested
ECe is the estimated amount of salt in the soil. It is estimated by multiplying the EC1:5 value by an appropriate factor related to the soil texture
ECse is the electrical conductivity of a saturated soil (paste) extract
SGME is able to measure field pH by two techniques:
A field pH test kit with a colorimetric indicator can be used. To use a field pH test kit, a small sample of soil is collected and an indicator solution is added to form a paste. The paste is coated with barium sulfate powder. The powder changes colour depending on the pH of the soil, and the colour of the powder is compared with a colour chart.
The laboratory pH method can be roughly imitated by shaking 1 part soil in 5 parts distilled or deionised water by hand and inserting a pH probe into the suspension.
Field measurement of pH and EC assists our soil survey programs and spoil / overburden, waste rock and tailings characterisation.
SGME is able to use handheld RXF to field map soil / growth medium, spoil / overburden, waste rock and tailings. Portable XRF provides an ideal tool to quickly collect and analyse geochemical data onsite and in real time.
SGME improves the quality of our field mapping by using a portable rock mill and sample palletisation tool to prepare uniform and dense sample prior to analysis.
Field measurement using handheld XRF assists our soil survey programs and spoil / overburden, waste rock and tailings characterisation.
SGME designs, installs, and manages monitoring systems for our mining and landfill clients. Our monitoring systems are designed to evaluate cover system, waste rock dump, tailing storage facility and landfill performance. Evaluating performance provides us with data that we use to develop management solutions and closure designs (cover and landform).
We also conduct rehabilitation, ground water, surface water, and stream sediment monitoring. We use this data to make sure our clients are compliant with regulation and / or achieve rehabilitation success.
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