A large dataset of water quality monitoring data from a diamond mine was cleaned, the data were collated into a robust database, and the data was interpreted. A comprehensive report was produced with data presented graphically and spatially, highlighting areas of risk. The cleaned database allowed for improved data and risk management going forward.
Data from water and waste material sampling and analysis from a shear-zone hosted gold deposit were analysed to assess the potential for ARD and metal leaching, and to determine source terms for the various waste facilities. A geochemical model was developed in PhreeqC using literature oxidation rates for the main sulphide minerals.
Foundry processes were reviewed to identify contaminants that could report to the spent foundry sand waste stream. Spent foundry sands were there assessed in terms of their total and leachable concentrations of these contaminants to determine the waste type and appropriate disposal.
Mills Water has provided technical review services coupled with mentoring of client staff to improve their geochemical assessment skills. Mills Water has also provided in-house training on monitoring program design, water sampling methods, and geochemical modelling for several mining clients.
A quality management system for environmental sample analysis was updated and implemented for the local branch of an international environmental laboratory. The laboratory achieved SANAS accreditation on the basis of the quality management system.
Arsenic was detected in soils and groundwater in the footprint of an old landfill site which was planned to be redeveloped for low cost housing. A quantitative human health risk assessment was undertaken to assess whether there would be any risks to the health of residents within the proposed low cost housing development.
A Monte-Carlo style approach was utilised to assess the appropriate change-out rate for GAC filters in a system to remove contaminants from tap water. An initial comprehensive desk top review was undertaken of the controls on adsorption potential and selectivity of the GAC in order to design an experimental set-up for measuring the break-through time for the contaminant. This was to ensure that there was no risk to the health of workers in buildings who were consuming tap water.
Available mine geochemical data were combined with information from previous environmental geochemical studies to assess whether it was preferable to separate out sulphidic material from mine waste. The conclusion was that, although the sulphidic material represented a small component of the mine waste, the other waste did not have sufficient neutralising potential to prevent acid rock drainage, and that waste separation was preferable.
Groundwater data from an extensive monitoring program for CBM were collated and reviewed. Protocols for updating the monitoring program to include organic parameters were developed, and baseline organic monitoring was undertaken. Groundwater quality fingerprints were used to assess whether deep production water was impacting shallower groundwater used for domestic supply.
A comprehensive field investigation was undertaken to assess the partitioning of inorganic contaminants into solid (immobile), particulate (sometimes mobile) and dissolved (mobile) phases in water and sediments within stormwater ponds. The relative risks of mobilisation of contaminants into the water were considered for various remedial scenarios. The greatest risks were found to be ongoing inflow of dissolved contaminants, particularly metals and nutrients, to the ponds, and baseflow of contaminated groundwater into the ponds.
The potential for co-disposal of fly ash and coal mine discard was assessed through laboratory experiments. The ratio of fly-ash to discard was established through geochemical modelling, and the results of the investigation indicated that co-disposal was worthwhile to consider to save on future rehabilitation costs.
A comprehensive assessment of soil and groundwater impact was undertaken for a cobalt mineral processing facility with the view to establish the extent of remediation required. Groundwater fingerprinting was used to assess the connection of the contaminated groundwater from the site to local surface water bodies.