Citi-Con continues to deploy its extensive skills and experience to help rehabilitate critical services-delivery infrastructure. This includes the rehabilitation of waste-water treatment works, the concrete of which operates in harsh environmental and chemical conditions and is subject to the penetration of water and or other corrosive liquids from all directions.
The company’s corrective methods include permanent concrete protective coatings that penetrate the concrete surface so that it can resist extreme hydrostatic pressure from either positive or negative surfaces. These liquid resistant qualities become an integral part of the concrete substrate. They are highly impervious to aggressive chemical attack, while also sealing hairline shrinkage cracks and enabling the concrete to breathe.
More recently, Citi-Con completed major concrete repairs to a water purification plant in the Mpumalanga coal fields on behalf of a leading coal miner.
This state-of-the-art facility treats contaminated underground mine water to pristine quality. The bulk of this water is supplied directly to municipal reservoirs and the balance used by the mine for its own purposes. It still serves as a stellar example of private sector involvement in service delivery, supplementing stressed municipal water supplies.
Over the years of treating corrosive mine water, the concrete of the water-purification plant had fallen into a poor condition and required extensive repairs.
Greene Consulting Engineers designed and supervised the remedial work. This was an extensive undertaking that entailed repairing the two concrete tanks and the interconnecting pipe, as well as the water purification plant’s clarifier and thickener.
Citi-Con has nurtured a long professional relationship with Greene Consulting Engineers, having successfully completed many concrete repair projects working alongside this leading consulting engineering firm. This includes undertaking extensive concrete repairs to elevator lift shafts at a hospital in Alberton. It used a similar concrete repair method that was deployed at the water purification plant. Based on the company’s quality workmanship on these projects, the specialist contractor was appointed to undertake the repairs to the water purification plant.
Work commenced with the repair of the bases of the two concrete tanks, with workers lowered down the 6m-high structures using rope-suspended platforms.
“We first drilled a hole into the damaged areas of the bases of the two water-retaining structures. An acrylic reinforced cementitious, flexible waterproof coating was then used to plug these areas. Forming a hard wearing, seamless, waterproof membrane, the liquid was poured directly into the damaged areas via a conduit that was inserted into the various holes that we drilled in the damaged areas of the base of the reservoir,” Andre Vermeulen, Director of Citi-Con, says.
One of the challenges on this project was repairing the 1m diameter pipeline between the two tanks, with the team having to work in an extremely confined space to seal areas that were leaking.
The damaged areas of the clarifiers were repaired using epoxy-injected grouting methods and Hypalon bandage, which was also deployed to repair concrete defects on the thickeners.
Rope access systems were used by the specialist contractor to gain access to various damaged areas. All of the company’s rope access practitioners have completed their Rope Access Level 2 training and have, therefore, undertaken many thousands of hours working in the field.
Notably, it also provides a safer method of working at heights. Working for a mine, the company had to ensure that it complied with very strict mine health and safety protocol, and there were no major incidences during the entire duration of the project.
“We are known for delivering high quality workmanship on all of our projects. Our recent work on the water purification plant is just one more example of the extent of our skills and capabilities repairing critical civil-engineering infrastructure,” Vermeulen concludes.