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Sewerage works taken over by a plant

16 Sep 2009 Posted by in Environment, News and Events | 3 comments

Hyacinth flower - pretty but pretty awful ecologically

Hyacinth flower – pretty but pretty awful ecologically

A very important birding area on the Peninsula is under siege from water hyacinth, the Strandfontein sewerage works. This very invasive weed is originally from South America and is known to have caused billions of dollars worth of damage throughout Africa.

The City of Cape Town has confirmed that they just don’t have the resources to solve or even control the problem themselves. They are however trying various techniques to keep the waste water side of the sewerage works weed free, this isn’t being made any easier by having Zorro as a resident in one of the pans. Zorro is a hippo that escaped in February from Rondevlei nature reserve next door and has made Strandfontein sewerage works his home.

A birder John Graham said he was “sad to see that the nature reserve portion of the works seems to be in a state of deterioration”.

“Four of the ponds I drove past are totally choked with hyacinth and it seems to be ringing most of the shoreline of (pan) S2 and so presumably will shortly also be choking this pan. There also appears to be a significant volume of hyacinth on Pan 5, north of the main works.”

He also expressed concerns about the fishermen using 2 of the pans saying they were “very important” for wading birds and waterfowl.

Wastewater treatments city manager, Kevin Samson, said the excessive growth of water hyacinth was not a new problem.

“It is a problem throughout the city and requires specialist intervention and assistance. The wastewater section currently spends R2 million per annum to remove the hyacinth and has not succeeded in controlling its spread.”

“The hippo in S1 pond is still a problem. The pond is fenced in but until the animal is removed hyacinth cannot be removed from the pond.”

The southern area manager for the city’s environmental resource management department, Dalton Gibbs, said the hyacinth at Strandfontein was well established in two large ponds.

“The extent of the infestation is presently beyond the resources that are available to eradicate the invasive plant in these pans.

“Hyacinth was detected on a further five ponds and has been removed. Weekly monitoring is done on these ponds to ensure no re-infestation takes place”

an article from ‘Simply Green’, for your interest

  1. Meredith Saul10-02-09

    Deeply concerned to hear about the Hyacinth infestation. Not exactly sure what the effects are, but if you guys in the know call it an infestation it can’t be a good thing. Of more concern, is that the city claims it is under-resourced to deal with the problem. Could manual intervention by way of civic mobility be any help ? Possibly person-power by way of schools in the area ? Please let me know, as i am involved with Environmental Education and could possibly help.

    Regards,
    Meredith Joseph Saul (Head of Geography at Fairmount Secondary School and Zeekoevlei resident)

  2. MoonDance10-19-09

    I have forwarded your Details on to Asieff Kahn, the Manager of the False Bay Ecology Park as this is his area and hopefully he will contact you soon.

  3. John Hofmeyr05-15-10

    In case this thread is still open:
    During 2009 I was in contact with Working For Water(WfW) about disposal of Water Hyacinth infesting (inter alia) the Hartebeespoort & Roodeplaat Dams in Gauteng. The concept involves co-processing the hyacinth simultaneously with terrestrial invasive & alien vegetation such as sickle-bush, Port Jackson Willow, Black Wattle, Rooikrans etc , as well as feral pine & Eucalypt and chipped sawmill waste. The process involves carbonisation at >300degrees C. Therefore seeds, and any residual viable plant structure would be destroyed.
    WfW expressed interest but later backed off claiming “no funds” to support even the transport of sun-dried hyacinth for test carbonisation.
    Over the past 2 weeks I have been trying to contact the responsible person at Working for Energy (WfE), which is housed within the South African Energy Research Institute (SANERI). No response there yet, either.

    QUESTIONS:
    1) I think the moisture content of freshly-collected hyacinth is around 98%? Can this be reduced to <25% before delivery? Sun-drying may be viable in summer but I don't know about winter.
    4) What tonnage of hyacinth (dried to <25% moisture) can be delivered to a processing plant if it can be disposed of without charging City of Cape Town any disposal fee. (Tonnage separately for each month of the year to establish seasonality of the arisings. In Gauteng it develops predominantly in summer).

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