Civil Designer Showcase

Meeting Sanitation and Water Service Delivery

The assignment: design and produce construction drawings for a network of more than 120 kms of sewerage lines and main collectors linked into 13 000 homes and fanning out over an area of more than 1 000 hectares.

The project co-ordination team consisted of Tiaan de Necker and Charles Marais, with Alphons van der Merwe acting as project manager. According to Alphons however, the venture had many challenges: "The first of the three projects entailed the construction of 595 toilet structures as well as the construction of a full waterborne sewer reticulation network. This encompassed a total of 7,9km of sewer mains and 5,7km of erf collector lines that had to be created," explains Alphons.

One of the challenges identified in the Bloemside phase 4 area was the topography. "The area was relatively flat, which from a design point of view made it difficult to keep excavation costs down. A further complication was the construction of an outfall line which had to connect Bloemside phase 4 to the Sterkwater outfall line still under construction. The depth of the reticulation network also affected the outfall line."

Designs were detailed on Civil Designer which has become an internal standard within Kwezi V3's branches. "The programme is used extensively and has been instrumental on this project. It has allowed us to provide cost effective design solutions despite the various project challenges. The software works really well," explains van der Merwe.

The second of the three ventures proved to be equally challenging. This phase entailed the construction of 620 toilet structures and full waterborne sewer reticulation networks in Bloemside phase 5. "The project required the creation of 7,0 km of sewer mains and 6,5km of erf collector lines. Extensive hard rock however, impeded progress. The team found that they had to blast through the rock while having to contend with a shortage of blasting contractors."

"Another challenge was that Bloemside phase 5 was established on land which was formally used for smallholdings. The water reticulation network which provided the smallholdings with water ran diagonally across the entire Bloemside area. A section of the network therefore had to be re-routed as three waterlines were running in the same street," notes van der Merwe.

This section of the Bloemside Phase 5's sewer network had to be diverted across the R702 to Chris Hani because the topography did not allow the section to join to the newly constructed outfall line. In order to ensure that traffic would not be disrupted, the crossing of the R702 was achieved by means of pipe drilling," he explains.
 
Bloemside Phase 5's sewer network | KV3


The last and probably most complicated of the three projects, was the construction of a 7,9km outfall sewer line connecting Bloemside Phase 4 and 5 to the Sterkwater outfall sewer line and which would connect to the Sterkwater Treatment works. In addition to this phase of the project, a section of a 150mm diameter vitro clay outfall sewer line had to be replaced with a 250mm diameter UPVC pipe in Pentagon Park in Bloemfontein.

According to Alphons, the challenging aspect of project three pertained to the outfall line. The depth of the sewer network in Bloemside phase 4 caused the outfall line for the section running past a filling station to be quite deep. This presented problems as the rock had to be blasted. This option was not feasible as it was in close proximity to the filling station which meant that the outfall line had to be rerouted. The rock itself posed other problems. It was too hard to excavate but soft enough to absorb some of the shock from the explosive. Certain sections therefore had to be blasted more than once.

Despite these challenges, Alphons is gratetful for his involvement on the project as it presented interesting problem solving scenarios. "One of my many project highlights was seeing the positive reaction from the community. It will make a real difference to the community and I am glad to be a part of that," says Alphons.

 
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