High Density Polyethylene (HDPE) Lined Steel Band Jacking Pipes specifically designed for a new bulk outfall sewer project in Montague Gardens in the Western Cape has won Rocla, part of the Infrastructure Specialist Group of companies (ISG), a Concrete Manufacturers Association (CMA) Award for Excellence in the Engineering Category.
Rocla partnered with CSV Construction to supply HDPE Lined Steel Band Jacking Pipes for the construction of the new bulk outfall sewer project. Rocla designed and manufactured these products in accordance with very strict specifications as set out by the tunnel boring machine requirements. The combination of Micro-tunnelling and pipe jacking is a process which is very different to conventional jacking methods, making this a first for Rocla.
Rocla Technical Executive Muhammad Bodhania, said “Rocla is delighted and honoured to have received the Award of Excellence: Engineering from the CMA. This was a project like no other we have been involved with in terms of the stringent design requirements due to the utilisation of the two innovative tunnel boring systems. Our design and manufacturing teams at Rocla worked hard to ensure that our Lined Steel Band HDPE pipes were constructed to standard and delivered on time”.
CSV, a construction company with a substantial footprint in SA, approached Rocla to develop these specific HDPE pipes to work in conjunction with their AVN (Slurry) machines. Within very tight deadlines Rocla managed to design and fabricate moulds and produce sample test units for scrutiny and testing by council and project engineers. With satisfactory results and the go-ahead on this historical project, Rocla started manufacturing the required products, which, when completed, were delivered within the required timelines.
Montague Drive Bulk Sewer is a major collector for the Koeberg Road Pump Station with a catchment area of approximately 3,320ha. The original 4km long system, installed 50 to 60 years ago, comprising asbestos, cement and reinforced concrete pipe materials is unable to accommodate current and future requirements. It was also established that line is exhibiting significant deterioration from sulphuric acid corrosion and infiltration with areas of exposed reinforcement, obstructions and partial collapse. Construction of the new gravity main comprises approximately 3,800m of 970mm and 1000mm and 300m of 1350mm ID concrete sewer.
Due to relative close proximity of commercial and industrial businesses requiring access during the entire construction period and the high installation depth, the entire section of new sewer is to be installed using the unique micro-tunnelling trenchless construction.
The exciting combination of micro-tunnelling with pipe jacking is becoming increasingly important world-wide for the installation of service and sewer pipes, offering numerous advantages, especially in urban city areas. Bodhania said “Rocla has made a commitment to venture into this industry to supply the required precast elements that conform to the specified high levels of quality required by those involved with the micro-tunnelling process. We are known for our technical excellence and focus on service delivery”.
Micro-tunneling is safe with un-crewed underground operations in nearly all geologies with minimal traffic disruptions and conservation of protected landscape areas. Construction is not affected by poor soils and high water tables with fewer stoppage periods due to weather conditions. Inclined jacking and 3-dimensional curves are also possible.
AVN machines are closed, full-face excavation machines with a hydraulic slurry circuit. The cutter head excavates soil that passes through a cone shaped crusher, crumbling stones and other obstructions to a size conveyable via a slurry line to settlement tanks where solids are removed and the water returned and recycled. A hydraulic jacking frame advances the drilling head and trailing jacking pipes forwards. Computer controlled guidance systems and lasers provide the high degree of accuracy required to ensure perfect installation.
Rocla has an extensive network of factories throughout South Africa, Namibia and Botswana. They are able to design and manufacture customised special products that will meet the requirements of the customer. This is made possible as a result of Rocla’s technical expertise and quality controls. Rocla has over 107 years of experience in the pre-cast concrete sector and is part of the ISG of companies that includes Technicrete.
