Paddling in poluted water not on

Mike Ryder, Marina Da Gama

I am writing to you again in my personal capacity as a concerned resident of Marina Da Gama and frequent user of the vlei. The views I express are not necessarily those of the Marina Da Gama exco.

I am sure you are aware of the recent outcry in the marina after the heavy rains a couple of weeks back.

On Sunday May 7 I went for a paddle from the canoe club around the perimeter of the vlei passing the various river entrances, the entrance into the reserve and round to park island.

The amount of litter blown up against the reeds everywhere is astounding and quite unacceptable. The smell of the rotting garbage and scum is overpowering in places.

But what is most distressing is the vegetable soup nature of the water in that area. So bad, in fact, that in places it was difficult to paddle without lifting some item of rubbish out of the water with a paddle unintentionally.

This rubbish cannot be seen from afar as it is in suspension in the water, or semi submerged, but it is palpable when close; tyres, tvs, computer carcasses, umbrellas, mattresses, clothing, packets of litter, plastic bottles and all sorts of other general detritus.

You will be aware that most of this enters via the canal and indeed at the last rains the quantity of rubbish that was swept into the vlei was horrific.

I sent a letter back in January warning of the state of litter in the canals and requesting that they be cleared before the rains, but nothing was done, would you be able to shed any light on why not?

As I said then, clearing the canals is far easier and cheaper than trying to clean the vlei. Meanwhile one can see the litter building up again in the canals. Is there any plan of action to pre-empt another environmental catastrophe besetting the vlei at the next heavy rains?

Such as repair of existing nets; installation of additional nets; clearing of the two litter traps or clearing of the canals.

To allow another similar deluge of filth and rubbish into the vlei,unabated, is nothing short of an environmental crime.

I look forward to a positive and encouraging response,

* Joshua Gericke, manager of the Greater Zandvlei Estuary Nature Reserve, responds:

Firstly, Mr Ryder is quite right about the severity of the problem. Unfortunately the solution is just not as simple as he seems to think.

Zandvlei is fed by three rivers, but the Sand River is the main problem and the one he is referring to. It has an entirely urban catchment that finds its origins near Wynberg Hill. It is canalised for its entire length and is subjected to vast amounts of direct littering and dumping, but it also receives every chip packet and bottle top dropped in the streets in its catchment. Thanks to the low summer time flows in the Sand River, most of this remains in the dry canals, storm water drains and streets until removed or until the first rains.

Just above Zandvlei, both the Sand River and the Langevlei Canal (a tributary) have litter traps in place which have been recently repaired and are functioning as well as can be expected. They catch almost all of the litter coming down the estuary during low flow conditions. Unfortunately however, under even light rain, the Sand River starts to flow really strongly.

The litter load in this catchment is such that both litter traps become entirely chocked with litter within a few minutes during such a rain event. They then form a dam that can cause severe flooding upstream. This is dealt with in the design of the trap by the presence of a large spill area adjacent to the trap that allows the river to flow around the trap. This then renders the trap wholly useless during a high flow event.

The litter nets (originally downstream of the traps, adjacent to the Wildwood Island causeway, nearer to Marina Da Gama) are unfortunately even less effective during a high flow event. They clog up even faster than the formal trap above them and simply break after relatively little rain, and this is in fact essential. I once made the mistake
of strengthening a
trap to the point where it could withstand mild flood conditions. During a rain event similar to the rains last week, it clogged up, formed a dam and caused the river to start flowing over the Wildwood Island causeway. The causeway was severely damaged and all of the litter was introduced directly into Marina Da Gama.

Litter nets are therefore less than useless during high flow events. Those who suggest otherwise simply do not grasp the volume of litter that we deal with nor the shear destructive force of a river in spate. Since the vast majority of Zandvlei’s litter flows in from the Sand River under high flow conditions, the litter nets will have no discernible effect on the litter load entering the estuary but will take up a lot of our time with repairs after every rainstorm.

The other point made by Mr Ryder regarding clearing of the litter traps and canals before the rains start is quite logical. Unfortunately this was implemented, so it also offers no solution. Many of the residents I’ve spoken to about the litter issues blame a lack of cleaning in the canals and litter traps, but the litter traps were in fact cleaned to a polish by the stormwater contractors shortly before last week’s rains, as per usual. The canals are also almost continually being cleaned at one point or another in this catchment. We therefore have to look elsewhere for solutions and mitigation measures. The real problem is two-fold.

Firstly, people in our catchment and indeed countrywide don’t understand or don’t care about the damage done by littering. This we have addressed through our environmental education programme that reaches about 6 000 people a year, primarily within our catchment.

Secondly, packaging manufacturers don’t recognise or take responsibility for the destructive nature of their products. Here a major, nation-wide campaign is needed and some have been tried, but this falls largely outside of our ambit.

Addressing the social causes are long-term propositions and there is plenty of effort already being channelled in those directions. The only other options that I can think of, apart from getting more staff to clean up, are to find point sources and solve them; and create a litter trap that can handle high flow rates and high litter loads.

Preliminary investi-gations have revealed only one major point source which is a
garage that was dumping tyres. We threatened to take legal action and publicly humiliate them and the problem promptly ceased. There don’t seem to be any more that we can really get a handle on though.

At present I have a sum of money to work with to find a solution given by a member of the public through the Zandvlei Trust in order to find a litter trap design that works during high flows.
Many have tried and failed in the past, so we’ll see if this exercise is actually worth anything.