The increase in residential and commercial developments in the Walmer area of Port Elizabeth in addition to the estimated increasing needs requirement by 2020 was a crucial factor for the Nelson Mandela Bay Municipality to increase the capacity of the existing Driftsands Collective Sewer Augmentation.

The construction of a 1400mm of concrete HDPE lined sewer of 1850m in length

forms part of Phase One of this four-phase project which commenced in the second quarter of 2017. Rocla were selected to supply Class 75D high-density polyethylene (HDPE) lined pipes and manhole access pipes. The sewer starts from the Driftsands Waste Water Treatment Works and terminates at the ACSA boundary.

The existing sewer was constructed in 1983, and is a gravity sewer which is not able to be upgraded from a technical perspective, therefore a realignment of the line route is currently being undertaken. The first 1460m is parallel to the existing 1050m Driftsands Collector sewer and then branches off to by-pass the planned ACSA extension of the Port Elizabeth Airport runway.

Rocla Sales Consultant in Port Elizabeth, Graham Howell said “We started manufacturing the 780 lengths of 1400mm diameter Class 75D HDPE lined pipes in May 2017 at an average rate of eight pipes per day. We achieved this by double stripping our four available moulds, and we delivered the first pipes to site in July 2017”.

“We made minor improvements to the product after numerous on-site visits and we continued with production for the remainder of the year. Ten manhole access pipes were also ordered and these were cut in the Rocla yard to specification, which allowed the laying of pipes to continue uninterrupted, thus giving the contractor the opportunity to achieve good production on site” said Howell.

Rocla made further design changes during the manufacture of the manhole rings and offered rings and cover slabs with internal HDPE liners. This could become the accepted and required standard for all future Outfall Sewer Projects.

“With Phase One completed, the second phase is due to start during 2018 which will most certainly present Rocla with new and interesting challenges as the conditions include rock and very deep trenches, but we are more than confident in our ability to overcome these as well as in our manufacturing capabilities” concluded Howell.

The value of the Phase One project is R52.8 million and consists of 1850m of 1400 concrete HDPE lined sewer, 26 manhole structures, one diversion chamber and one diversion chamber and bulk earthworks.

On completion, the 4.2km four-phase project will have addressed the sewerage requirements for existing and future developments for the western suburbs of the Nelson Mandela Bay Municipality.

Rocla is Southern Africa's leading manufacturer of pre-cast concrete products for infrastructure, including pipes, culverts, manholes, poles and various other related products. The IS Group of companies also includes Technicrete and Ocon Brick.

ISG Group