Construction World January 2018

Beams installed on the uMhalazi bridge.

it is not generally safe for heavy vehicles to travel on the existing carriageway in order to reach the working areas. Careful planning has therefore gone into the use of smaller back roads for this purpose, requiring ongoing engagement with farmers and regular monitoring of the extra travelling Pearce also highlights the importance of minimising the project’s environmental impact in the light of sensitive areas such as mangroves being very close to the project’s pathway. And this is particularly relevant bearing in mind that about 800 000 cubic metres of bulk engineered fill is to be conducted as well as 240 000 cubic metres of layerworks. “A range of environmental studies were carried out and remedial strategies were developed, allowing the necessary permits to be obtained from the various relevant authorities,” he says. “We worked closely with KZN-based environmental consultancy Enviropro in this process, as well as making a number of adjustments to our plans to further mitigate our impact on the sensitive areas alongside the highway.” These zones included riverine woodland forests, swamp forests and seral dryland forests. The protected vegetation was marked, and wherever possible this was avoided or relocated. Discussions were also distances that may be incurred. Environmental impact

Concor Infrastructure constructed a causeway to facilitate work on the uMhlalazi bridge.

conducted with the client on how swamp forest areas could be recreated in other suitable locations, as an off-set strategy. Concor Infrastructure’s careful adjustment of plans reduced the construction footprint as the road went through the larger forest sections, leading to fewer trees having to be removed and relocated. “We have also minimised how much siltation flows from the works through the culverts and into the rivers, by installing bidim geotextile traps,” he says. “Care has

been taken to use geotextile sandbags on the edges of causeways, so that fine material is not washed into the river during the bridge building stages, which could affect water quality and river life.” Weekly testing of the rivers – upstream and downstream of the works – is conducted to ensure that the mitigating

measures are effective. The social legacy

In addition to the environmental impact, the social impact of the project is also a →

37

CONSTRUCTION WORLD JANUARY 2018