Issuu on Google+

MILNERTON Email: Now more English! B u r g e r Wednesday 28 March 2012 WEST COAST VILLAGE OPENING END APRIL Tel: 021 910 6500 Fax: 021 910 6501 ) Alien plant species to be cleared Goodbye to hyacinth The Black River, which becomes the Liesbeek Ri­ ver by the N2, is overgrown with water hyacinth. The city is in the process of removing it at huge cost. Insert: The removed hyacinth is left next to the river to dry out before it is transported to the landfill site. Photos: André Bakkes ANDRÉ BAKKES One of the Black River’s tributaries starts in Langa and then it snakes past the Athlone Waste Water Treatment Works. On its winding journey through urbanised Cape Town, the polluted river collects “nutrients”, which is food for the alien plant known as water hyacinth. These hyacinths grow uncontrollably downstream and the City of Cape Town’s roads and stormwater department spends approximately 30 percent of the total annual cleaning budget of all rivers, canals and catchpits on the removal of these plants. Which makes one ask; why remove it at all? Duncan Daries, acting director of the roads and stormwater department, answers: “One of the reasons, from an engineering perspective, is to improve the hydraulic functioning of the river. In other words, it improves the flow dynamics of the river.” The Black River, which becomes the Liesbeek River north of the N2, is currently undergoing one of these cleaning operations. Rugby resident Pincus Sanzul accompanied TygerBurger to the riv- er this weekend just to show how bad the hyacinth situation really is. Next to the M5 it literally looks like a river of luscious greenery. Daries says the reason for this is the fact that the river is in a “continuous state of eutrophication”. He explains: “That means it has high levels of nutrients due to the discharge of the Athlone Waste Water Treatment Works as well as the discharge of grey and black water from the informal settlement in Langa.” He adds that this plant has no predators in the country to control growth. As a result, the city must clean the river once a year by means of a specialised excavator to remove the bulk of the growth. It is followed up by a hand crew (on a boat or raft) to clear the hyacinths that the excavator could not reach or was unable to remove. The crew also sometimes works in conjunction with the excavator to draw the floating hyacinths towards it. Sanzul wonders why the piles of dead hyacinth is left next to the river to rot, but Daries responds by saying that it is only left to dry and will be transported to the landfill site in good time. Daries elaborates: “Water hya- cinths consist of about 80 percent of water. If it is left to dry, it reduces to about 20 percent of its mass. It would, therefore, be about 80 percent cheaper to cart the dry hyacinths to the landfill site.” Jan Odendaal, the CEO of Green for Life, feels very strongly about achieving cleaner rivers. “Every single river in South Africa is polluted and they have become an embarrassment for the country. God’s creation is in our hands, but our greediness has a lasting effect on our rivers. People must know that when you pollute a river then you are really just shooting mankind in the foot!” he exclaims.

Tygerburger Milnerton 28 Maart 2012

Related publications