Final DN 1200 pipeline connecting the DN 1470 diameter pipes that were pipejacked crossing Macassar Road to the Macassar Waste Water Pump Station .
Laying a new sewer line comes with multiple challenges , more so when in the midst of a developed area : environmental concerns , traffic , and inconvenience to communities , and more . The Black-Mac project in Cape Town had a multitude of professional players to ensure that carrying out the necessary work considered all of these . The main contractor for the construction of the new Black-Mac Outfall Sewer was Afriline Civils .
Stephan Kleynhans , Aurecon technical director in the company ’ s water unit and project manager for the Black-Mac Outfall Sewer project , explains the motivation behind installing the new pipeline .
Project motivation
The Black-Mac sewer runs for a few kilometres upstream of the Macassar pump station , says Kleynhans , and , “ It picks up some of Blackheath , Blue Downs , Croydon , and Macassar ’ s sewerage . It was constructed in the 1980s and it discharges at the Macassar pump station .
“ Along the Black-Mac sewer , there was a screening station that was in a state of disrepair , so what happened was that the City diverted flow from the Black-Mac sewer to the Zandvliet Waste Water Treatment Works ( ZWWTW ).
But this resulted in the ZWWTW becoming overloaded , as the population increased ,” Kleynhans explains .
When Aurecon was appointed for the upgrade of the overloaded ZWWTW , it was also tasked with recommissioning the Black-Mac screening station and to undertake a condition assessment of the existing outfall sewer .
From the screening station to the Macassar pump station comprises about 8km of pipeline . After conducting CCTV inspections of the entire length of the pipe , structural techniques were used to assess the remaining life of the existing sewer .
“ It ’ s roughly 4km from the screening station to where we crossed the Eerste River with the siphon ,” Kleynhans explains and adds , “ That length of pipe still had a reasonable remaining life , so it was agreed that we will just reline that section . The section from the Eerste River to the Macassar pump station , however , was problematic in terms of remaining life , as the wall thickness of the old asbestos cement pipes had eventually eroded or corroded . Along with this , future developments were planned in the area that would feed into that sewer , so increasing the hydraulic capacity was required .”
For this reason , the 4km section from the Eerste River to the Macassar
While the project started during the peak of the Cape drought , in November 2016 , imposing water restrictions on the project that also required dust control in the Cape winds , Kleynhans believes that the drier conditions made it easier for pipe installation . contributor innovations industry debate environment infrastructure municipalities
Photos by John Reed , Afriline
DN 1200 diameter pipeline constructed nine metres deep between the ‘ Big Rock ’ along Macassar Road and the adjacent houses in Macassar . networking
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