Littertrap progress

This piece was written for the Marina News and The Zandvlei Trust Newsletters and submitted to them on 17 August 2017. It was written by the ZPAAC chair at the time – Bernelle Verster, in a volunteering capacity.

The issue of litter is a highly emotive topic and a very difficult one to solve. The Zandvlei Protected Areas Advisory Committee (ZPAAC) has been trying to address this issue for some time.

Apart from the bigger problem of how we as a society live and dispose of waste, two more immediate issues make dealing with litter hard: As Councillor Aimee Kuhl reiterated in a ZPAAC meeting in October 2016, problems like litter management have to be balanced against the needs of the massive influx of people into the Cape Metropolis, who needed housing, water and sanitation. In short and as can be seen in this article, the City simply does not have the funding to build and maintain litter traps to the extent that it is required. Secondly, to the credit of members of the public who live, work and enjoy the vlei and its surroundings, many people are contributing in their private capacity through for example litter clean ups. This is, however, of limited value. Litter is an easy and visible thing for people to complain about, but it is also easy to misjudge the scale and scope of the interventions required. We are dealing with immense inequality issues and poor design decisions from the 60’s and 70’s which result in what we see in the waterways.

As a recently appointed chair to the ZPAAC, I had a look over the minutes of the ZPAAC since inception (mid 2015) to track the progress towards better litter management. It is important to note here that ZPAAC is a statuary advisory body to the City Council and that as such it does not deal with members of the general public. The ZPAAC is not obliged to furnish any information to individuals but connects with the public through the organisations represented on ZPAAC.

Note: the minutes of ZPAAC meetings are available on this website.

The timeline of addressing the litter problem since June 2015:

June 2015:                    Bob Crask of Marina da Gama Association (MDGA) tables the state and future plans of the litter traps in Sand River canal. Heavy rain results in the litter bypassing the existing litter traps. It is acknowledged that funding is a challenge. MDGA would like cities backing to retrofit the existing litter traps.

September 2015:           Abdullah Parker (City of Cape Town) met with Bob Crask, and supports the initiative.

February 2016:              The meeting discusses the repair, cleaning and maintenance of litter traps along the river(s) feeding into the vlei. More traps were needed, and an awareness campaign was ongoing. The incidents of dumping were increasing. Dredging and rubbish collection were ongoing. A long term solution to improving the river was proposed of proactive environmental education. Currently approximately 6000 children per year attend environmental education at Zandvlei. It was also noted that the cleaning of litter traps is not always done correctly, resulting in litter escaping over the top or through the bars.

April 2016:                    Abdullah Parker provided a feedback email about the litter traps

May 2016:                     This is the first meeting I attended. Litter traps were not being maintained due to insufficient funding.

August 2016:                Litter Traps were still ‘not working’; in the absence of Bob and Abdullah there was no further feedback. In this meeting I agreed to look into options for sediment removal, which in my view was the most pressing need. Through discussions about the management of the vlei I became aware that all the matters are related, and thus became more involved in the litter trap discussions.

During this time the Zandvlei Trust received an anonymous donation to investigate an improved litter trap.

November 2016:            No specific mention of litter traps. At this meeting the Friends of the Liesbeek were invited as it was hoped to learn about their strategy, seeing the success in managing to rehabilitate the Liesbeek river. They have also more recently suffered from funding shortfalls.

During this time Anchor Environmental did a report for the Stormwater and Sustainability Branch Planning Department – Transport for Cape Town, which is to be appended to the Integrated Reserve Management Plan (IRMP).

January 2017:               Litter traps feedback had been received from Abdullah Parker.

March 2017:                  Joshua Gericke, the Zandvlei Reserve Manager, had a preliminary design for a litter trap and needed a pilot study done. He had spoken to two students, but there had been little interest shown.

May 2017:                     An emotional discussion about the litter traps ensues, but with not enough personpower to address. A few people had a workshop and worked through Prof Neil Armitage’s 1998 WRC report as well as Kyle Kriel’s 2014 report (a student of Neil Armitage). From this it was established that the ground work has been done, but that a student is not appropriate for the final design. The next step is to obtain quotes/expression of interest from consulting engineers.

Litter reduction upstream: The conversation then went towards reducing the problem at source, either through recycling or through global initiatives. Peter Kruger has looked at this at a local level with a nearby recycling depot and Angus Hemp was advised to get in touch with him.

At this meeting I am also elected chair of the ZPAAC.

July 2017 (the most recent meeting):     Following the last meeting and working with Prof Neil Armitage (Future Water Institute and Urban Water Management Group at the University of Cape Town) (who has been contributing pro bono) quotes were sent to several engineering companies. Two companies replied with quotes, JG Afrika and ZAA Engineering Projects & Naval Architecture. ZAA then met with Joshua and myself discussing the project scope and limitations. Following this ZAA revised their quote and informed us that they have selected the Sand River Litter Trap as a ZAA Corporate Social Investment Project, to be executed as a  team effort between all parties involved.

The approach was further discussed, including approaching the litter from multiple interventions, and modifying the current trap to only capture large items, allowing another litter trap downstream to be designed to capture smaller items with less potential for damage. Neil considers the cascade of interventions as a good idea, but expressed concern that the current litter trap is bad design. Neil kindly offered to advise during the project.

At this meeting the concerns expressed by some members of the public of an ‘over-engineered approach’ was also discussed. There was some concern that the litter trap is expensive and will take long to build, which does not address the immediate problem. I took input from all members attending. Neil’s response “If you are not going to do it properly you can’t do it at all” and that “it will have to be an engineering solution as we can’t deal with the social source of the challenge”, was met with agreement all round.

The committee further agreed that “You are not going to solve the problem in one go, it needs to be an iterative solution” particularly as it relates to larger and windblown litter.

Litter reduction upstream

A social approach to litter reduction around the Blue Route mall involving the Keysers river, a WESSA project in the 1990’s were mentioned. While it was noted that there is very little in that river that contributes to the litter in the Sand area, it was lauded as a good approach that we should consider for the catchment at large.

Neil also noted that the litter can be an order of magnitude higher than what we see. Nets can work but it really is about the maintenance and only works at low flow. The better litter traps is where a machine can empty it: it’s not a nice job, people start to ‘pretend not to clean it’.

As part of an integrated and iterative strategy, we need to find ways to reduce litter at source. One low hanging fruit is to get a working relationship with a recycling centre. There is apparently such an initiative underway in Noordhoek, and we are busy investigating this.

Dream Zandvlei: Meeting with Barry Clark

After the first Dream Zandvlei presentation (18 January 2017), Barry Clark from Anchor Environmental offered to discuss the merits of dredging the vlei, following work they did for the Department of Water Affairs, in collaboration with Aurecon and Southern Waters, on environmental flow requirements for the Zandvlei estuary along with several other systems in the Western Cape. Following this meeting some of the findings from that report was also presented at the Estuary Management Workshop, as reported at a Dream Zandvlei presentation on 15 March 2017.

As part of this work, Barry and his team looked at a number of options for restoring ecological health of Zandvlei including considering merits of dredging the vlei. Bernelle met with him on 27 February 2017.

Barry works in marine and estuary management. The work they were doing was required as part of a Department of Water Affairs classification study on the significant water bodies. The classification study broadly means to decide on a future desired state of health of these bodies, which takes into account its environmental, human, agricultural and industrial impacts. Significant bodies broadly fall along the Catchment Management Agencies (CMAs) and Zandvlei falls in the Berg/Steenberg area. This study will be publicly available once published.

The bodies are classified along 3 levels:
1. Natural
2. Moderately used
3. Fully developed.
Further, the bodies are classified along their current ecological health, where A corresponds to largely natural, and E being completely trashed.

“Zandvlei is probably the third most important estuary in the Berg catchment area”
(First Berg, then Langebaan, then Zandvlei, then Diep…)

“It is critically important that we conserve Zandvlei”
– Barry Clark, Anchor Environmental

Generally water abstraction is a large factor in water bodies, with about 60% of the Berg taken out for human use, for example. Zandvlei, in contrast, does not have a large water use, with it’s current runoff about 95% of the reference (or only about 5% of the water taken away). All the degradation seen in Zandvlei is human related, with a large portion recreational. But it is an estuary that is improving. In 1995 when Barry did his PhD on it, the vlei, especially in the Narrows, was filled with dark sludge. Now it has clean marine sand and an abundance of fish. This is due to good management, and specifically to Joshua Gericke’s input.

“Encouragingly, the transformation of Zandvlei from 1995 to now has been most amazingly good”
– Barry Clark, Anchor Environmental

As part of the classification study, reserve determination studies were done, which include water quality records. The present health of Zandvlei is classified as a ‘D’, about 50% degraded, and the best attainable state is advised as a “C”, given the pressures on the system. This is to acknowledge that the vlei will always have a large human component and cannot return to its natural state for a variety of reasons.

Improvement strategies included four scenarios (to be included in the Dream Zandvlei project):
1. Removing the weir
Removing the current rubble weir is desired for better tidal flow into the estuary. This is predicted to have a modest positive impact on water quality. The importance of water depth for recreational events are acknowledged, but Barry recommends that the weir be managed in a more dynamic way, similar to the mouth opening. It should be removed most of the time, for example in the week when people are less likely to be sailing. An option is to have a movable weir (like a sluice?). This would allow for (even) higher water levels when recreational activities take place, and extensive flushing more often per year, which would improve the water quality and reduce the silt buildup – it’s a potential win-win.
Another alternative to maintain a higher level constantly, especially for the rivets of the Marina da Gama residences is to install weirs where the Marina channels join the main water body.
One complicating factor is a sewer pipe that is currently protected by the existing rubble weir.

2. Restoring habitat
The area most requiring this is the shallow intertidal salt margin, which is currently lined with concrete. Rehabilitating this is not expected to really have an impact on water quality, but it would contribute to the biodiversity of the region.

3. Improving water quality
Difficult because of diffuse urban water runoff, but we spoke about the potential for biological means, biomass cultivation rather than chemical or physical means, – and the importance of harvesting the biomass as a means to remove the nutrients from the system.

4. Dredging
Dredging did not have a positive outcome in this study, but the scenario that was considered was a deep, 1.5m channel through the middle of the water body. The main function of this is to entrain more salt in the system to reduce the growth of invasive grasses. But, through modelling this is predicted to cause stratification in this channel of the more dense salt water, leading to hypoxic conditions.
In retrospect, however, Barry comments that dredging 0.5m everywhere rather than a single deep channel should still invoke a tidal prism allowing for better flushing. This, in combination with a re-think of the weir may yield better results, but needs more hydrodynamic modeling.
A point to mention is the potential impact of dredging on prawn stocks. Dredging sections over longer periods of time would allow the prawns time to adapt and move to new areas. “Artisinal dredging”. – See Port Owen’s set up in the Bergriver.

“The Zandvlei estuary has huge potential as a fish nursery and in terms of biodiversity once the system is restored”

Closing remarks touched on monitoring stations, linking to nutrient inflows into specifically the Westlake Wetlands. The City apparently has about 20 monitoring stations in the Zandvlei catchment. – listed in Candice Haskins’s presentation at the Estuary Management Workshop (notes at the feedback meeting). From Josh, this data gives an indication on the concentrations, but not the total flows and hence total amounts of nutrients incoming. Flowmeters could be a good project here.

We then briefly discussed rehabilitation of the Westlake Wetlands generally, and Barry noted that the city’s preference for the concrete canals is to reduce the risk of backflooding. But he agreed on the need to have the wetland meander to remove nutrients and design for sediment traps, as the sediment holds most of the Phosphorous. Barry agreed that the nutrient levels are a large potential risk, and agreed that if the larger plants (polymechetons??) are successfully removed, this opens up opportunities for algal blooms which are potentially more dangerous. The nutrients need to be captured into biomass and then removed from the system (harvested). If this can be done with economic yield, even better. Bernelle mentioned her work on wastewater biorefineries.

About the Dream Zandvlei Group

The Dream Zandvlei Group is an informal, collaborative collective of individuals working together to improve the Zandvlei Estuary and the catchment leading into it, with specific projects of personal interest, and independent of imposed mandates.

The current projects are mainly focused on installing litter traps in the Zandvlei catchment and promoting awareness of the Estuary through sport.

The core individuals represent several groups, and actively maintain communication between these groups:

The Zandvlei Trust  aims to conserve the indigenous fauna and flora of the Zandvlei and
to enhance this natural resource for the benefit of all  since 1988.

The Zandvlei Protected Areas Advisory Committee (ZPAAC) is a government mandated body and made up of groups and individuals with a common interest in the ongoing management of the vlei.



Caring for Zandvlei: presentation to ZPAAC 18 January 2017

Presentation regarding initial research on managing nutrients, silt and flows in Zandvlei and Westlake Wetlands, prepared by Bernelle Verster and friends, and presented at the ZPAAC meeting on 18 January 2017.

The presentation covers the project background and dredging options. Because dredging would not make sense in isolation of an integrated nutrient management plan, the presentation touches on the need for nutrient inflow mapping as well as wetlands rehabilitation. A challenge on what to do with the dredgings made the presentation conclude on a way forward, and includes the request to ‘dream for Zandvlei’. Images used in the presentation is from the Zandvlei parkrun, and can be found on the Zandvlei parkrun Facebook page.

Continue reading “Caring for Zandvlei: presentation to ZPAAC 18 January 2017”

Dream Zandvlei: meeting 24 January 2017

This is the minutes of a meeting that forms part of a series of conversations to take care of Zandvlei. In 2017 the plan is to develop a ‘dream’ of what all the various stakeholders want to see or experience in and around the Zandvlei Nature Reserve, and wider, the Zandvlei catchment. Towards the later half of 2017 and into 2018 this dream will then be interrogated with feasibility analyses and shaped into a plan. This is a highly participative, somewhat informal, dynamic process. If this interests you, please get in touch:

Continue reading “Dream Zandvlei: meeting 24 January 2017”