The effects of chrome mining activities on the water quality of the Hex River in the Rustenburg area: case study on Kroondal chrome mine

• Main Author: Mavunda, Alter Nyiko
• Format: Others
• Language: en
• Published: 2016
• Subjects: Water quality > Effects of mining on; Water quality > Rustenburg > Hex River; Chrome
• Online Access: Mavunda, Alter Nyiko (2016) The effects of chrome mining activities on the water quality of the Hex River in the Rustenburg area: case study on Kroondal chrome mine, University of Witwatersrand, Johannesburg, <http://wiredspace.wits.ac.za/handle/10539/21030>; http://hdl.handle.net/10539/21030

Research Report Submitted in Partial Fulfilment of the Requirements for the Degree of Master of Science in Environmental Sciences Date: May 2016 === This study assesses the water quality status of the Hex River downstream of Kroondal Mine (KMS15, sampling point located downstream of Kroondal Mine) and the effects of mining activities (Kroondal Chrome Mine) on the water quality of the Hex River in Rustenburg, which is in the North West Province of South Africa. Potential pollutants were identified, quantified and their distribution was determined over seven years (2007 to 2013) along different sampling points upstream and downstream to the mine. Water quality-monitoring data was obtained from the mine. The surface and underground water was sampled on a monthly basis and analysed by Aquatico, (a water quality service provider of Kroondal Chrome Mine) at SANAS Accredited Testing Laboratory (No T0374). Data was collected for the Hex River and its tributary; the nearby discharge from Crocodile Farm and Farm Dam; as well as mine containment dams, slimes dams, run-off from the processing plant and water dams within the mine. Descriptive statistics (mean/average, minimum and Maximum) and box plots are used to explain the water quality at all sampling points. Water quality from sampling location points was compared against the Total Water Quality Guideline Range (TWQGR) for irrigation, livestock watering, ideal domestic use, aquatic ecosystem limits and the exemption permit issued to the Kroondal Chrome Mine by the Department of Water Affairs and Forestry (DWAF) in 2007, now Department of Water and Sanitation (DWS). The water quality of the Hex River, downstream of Kroondal, was described as neutral, alkaline, saline and very hard with a high pH, and a high concentration of Electric conductivity (EC), Total Dissolve Solids (TDS), Chlorine (Cl), Sulphate (SO4), Nitrate (NO3), Ammonium (NH3), Hardness (CaCO3) and Orthophosphate (PO4). Pollution sources and pathways were identified using the study area layout and by conducting an impact pathway analysis using annual descriptive statistical (annual mean or average values) of water quality tables generated by SAS enterprise 6.1 (a software used to analysed descriptive statistics of the mine water quality data) for a period 2007 until 2013, and box pots graphs showing monthly water-quality data for pH, EC, TDS, Cl, SO4, NO3, NH3, CaCO3 and PO4 at 15 monitoring localities between Kroondal Chrome Mine, the Hex River and its tributaries (Kroondal tributary and Sandspruit) over seven years. It was concluded that the surface/groundwater of the Kroondal Chrome Mine process – such as seepage from slimes dams, plant run-off and the vent shaft underground water dam – had an influence on the water quality of Hex River with regard to the discharge of pH modifying pollutants, EC, TDS, Cl, SO4, NO3, NH3, CaCO3 and PO4. Other pollution sources were discharge from Crocodile Farm and Hex River, as well as the Sandspruit upstream sources such as mining (platinum and chrome), industries’ municipal sewage treatment works, agricultural activities and informal settlements activities. Mine pollutants or constituents were identified as a unique example of the compound impact of weathering, hydrologic and anthropogenic processes such as the increased use of explosives containing NO3 and NH3 underground. The chemical compositions of surface water in the mine sampling location were strongly influenced by rock water in tractions, dissolution and dilution, as well as anthropogenic inputs. Key insights drawn from the study is that, cumulative impacts in the Hex River catchment present different issues, roles and responsibilities for industries, government/ regulators and community stakeholders. Practical and cooperative management of cumulative impacts by catchment stakeholders can benefit regional environments and communities of Rustenburg and the North West Province at large. This study demonstrates the usefulness of descriptive statistical techniques for analysis and interpretation of complex data sets, water quality status of the Hex River catchment, influence of the Kroondal Chrome Mine (KCM) waste water to the Hex River catchment, pollution sources and pathways from different activities around Hex River catchment. Best practice water management was recommended to form part of the Kroondal Chrome Mine environmental objects, target and management plan as well as the mine risk profile. Cumulative management dimensions, approaches and/or methods were recommended for all Hex River catchment stakeholders including Department of Water and Sanitation (DWS), mines, farmers, industries and disadvantage communities along the catchment.