We all drive over them, complain when they go missing, but seldom realise the crucial role manholes play in the construction of underground pipelines. Rocla, who is the leading manufacturer of precast concrete in Southern Africa, designs and manufactures standard and customised manholes.
Precast concrete manholes provide a working chamber for an easy and cost-efficient access for technicians and their equipment needing to inspect or conduct maintenance.
Placed at regular intervals along the pipeline, used as a junction where stormwater pipes meet up, or where stormwater flow needs to be redirected as well as for ventilation along sewerage systems, precast concrete manholes are still the preferred choice for infrastructure projects due to their durability (lasting up to 100 years). Assembled at site, they are quick and easy to install.
Rocla’s precast concrete manhole with an interlocking joint profile together with the application of a sealing material makes for a simple yet effective solution.
The Manhole chamber sections are supplied in lengths of 1000mm, 500mm and 250mm, and are available in diameters of 750mm, 1000mm, 1250mm, 1500mm and 1800mm and 1950mm but special sizes can be accommodated. Manholes may be manufactured with step irons to facilitate a safe, steady and easy entry and exit.
Special intermediate or larger sizes can be designed and manufactured subject to a feasibility study, and Rocla engineers can assist in this evaluation process.
Cover Slabs are available for sealing the manhole chamber. Rocla also manufactures Reducer Slabs for use in deep manhole chambers, enabling the diameter of the chamber to be reduced in order to make it more cost effective. Step Irons can be cast into the wall of the chamber whilst concrete lids are also offered as an alternative to the conventional cast iron lid.
Reported high theft rates of the cast iron lid option often leave numerous manholes open and exposed, resulting in a health and safety risk. The heavy nature of precast concrete lids, combined with the zero-resale value of the precast concrete lid reduces the temptation for theft.
Manhole components can be used with both storm water and sewer applications. In the case of sewer applications, Rocla will make use of dolomitic aggregates. Precast concrete manholes are ideal where maintenance-free, high quality solutions are required.