Envitech was appointed to carry out site investigations and to design a contaminated water management system for the silica sand washing operations to be located near Balmoral in the Mpumalanga Province. The operations wash silica sand for supply to a wide industry spectrum that includes construction, mining (as a flux), water treatment (filter sand) and glass manufacture. The sand washing process produces highly turbid slurry water which also contains other physical waste which may not be released into the environment. Activities around the plant site also potentially result in disturbed land highly susceptible to erosion with a snow-balling effect in surface water resource sedimentation. Surface water within the site must be managed accordingly to prevent pollution or contamination of nearby water bodies.
Envitech was responsible for carrying out the required investigations, design of all the works and supervision of the construction works. The key features of the project included:
- Geotechnical investigation to determine underlying soil conditions, excavatability of the soils, availability of clay materials and any potential perched water tables.
- Hydrogeological investigation to determine the underlying groundwater regime, existing groundwater quality and establishment of groundwater monitoring boreholes for long term monitoring.
1 in 50 year and 1 in 100 year flood line determinations for the adjacent stream and farm dam. - Delineation of the adjacent wetland to determine the required 500m buffer zone.
- Design of sand slurry dams to handle projected throughput of 120 tons/hour of silica sand and 240 000 liters/hour of water.
- Design of stormwater runoff drainage system separating clean and dirty water systems.
- Design of return water dam to be used for storage of runoff water to be used for sand washing process.
Supervision of construction works.
Site Layout Plan
PROJECT HIGHLIGHTS
Geotechnical investigation of complex geology
Protection measures for adjacent wetland
Recycling of process water and stormwater runoff
Containment Barrier System for Hazardous Waste Cell