Zandvlei weed harvester on track for delivery to remove pond weeds

The hull of the weed harvester under construction. | SUPPLIED

The hull of the weed harvester under construction. | SUPPLIED

Published May 11, 2023

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Cape Town - The City has confirmed that following months of delays in procuring a weed harvester for Zandvlei and subsequent construction delays of the harvester, without which the vlei risks becoming choked with vegetation, the project is on track for its delivery in November.

The community interest in the construction and success of this weed harvester comes after a number of delays which affected its procurement.

It was initially expected in August 2021, then December 2021, and was later postponed to early last year and then later in June.

In Zandvlei, the weed harvester will be used to cut pond weed and to remove excessive filamentous algae build-up in the marina.

The deputy chairperson of the mayoral advisory committee on water quality in wetlands and waterways, Alex Lansdowne, this week conducted an unannounced oversight visit to the factory in Paarden Eiland, where the new Zandvlei weed harvester is under construction, and provided updates to the Zandvlei Protected Area Advisory Committee (ZPAAC).

“After the awarding of the contract there were initial delays in the construction to finalise fine-scale design concerns. However, construction has commenced and there are no existing delays. Four pontoons have been assembled. The base of the hull has been assembled and is 50% complete. The construction is now moving to sequence welding,” Lansdowne said.

Deputy mayor and spatial planning and environment Mayco member Eddie Andrews added: “While we are waiting for the delivery of the new weed harvester, the old Zandvlei weed harvester is in operation.

“The City’s Environmental Management Department also employs expanded public works programme teams to remove weed by hand when the old weed harvester is unavailable or in for repairs.”

ZPAAC chairperson David Walker explained that the weed harvester was needed, preferably by next year, as Zandvlei continued to receive even more nutrients from the catchment due to the impacts of load shedding on sewage systems, leading to excessive algal and vegetation growth.

Rendering of complete Zandvlei aquatic weed harvester. | SUPPLIED

“Our two biggest issues are sewage spills and general solid waste getting into Zandvlei. We strongly support the mayor’s anti-littering and clean-up campaigns and urge everyone to become conscious of the negative impacts of littering and illegal dumping,” Walker said.

Dr Kevin Winter from the University of Cape Town’s Future Water Institute said that construction was indeed making good headway and that the weed harvester had an important role to play, but that the causes behind the weed growth needed to be dealt with just as urgently to properly manage the catchment.

The City in March this year received final assessment reports from specialist consultants on proposed remediation interventions for Zandvlei.

These related to the imminent dredging of Zandvlei to improve the water quality for recreational use, and practical remediation options to address pollution in the catchment.

Andrews said: “There are several considerations the City needs to take into account, among which are available funding and how we can use the budget that we have to achieve the best possible outcome.”