For Researchers

A serviced outfall net is a flux-measurement instrument that runs all season.

South African stormwater plastic flux is badly under-measured, and the reason is mundane: nobody is standing at the outfalls with a scale. We intend to be. If you are working on marine plastics, urban hydrology, waste flows or EPR policy, we would rather build our measurement programme around your protocol than invent our own.

What we can offer

  • Fixed-point access to instrumented outfalls with known catchments, for sampling, deployment of your own equipment, or observation during events.
  • Systematic capture data — mass per service, service intervals, rainfall context, sorted composition, brand counts — released raw, not just as summary statistics.
  • Sampling to your protocol. If your study needs a specific sub-sampling scheme, sorting taxonomy, preservation method or event-based regime, we will train crews to it and run it, provided it is safe.
  • Material. Physical samples of intercepted debris, characterised by site and date.
  • Longitudinal continuity. The scarce thing in this field is not a single survey; it is the same site measured the same way across seasons.
  • Local knowledge and access — municipal relationships, site permissions, crew, and the practical experience of what can actually be done at an outfall in a KwaZulu-Natal summer.

What we ask in return

  • Help us make our measurement defensible. Tell us where our protocol is weak; we would rather be corrected than published.
  • Let the data be open where your funder and institution permit it.
  • Authorship follows contribution, in whichever direction that runs. We claim nothing by default.
  • No exclusivity. We will not sign an arrangement that prevents another group working at the same sites.

Open questions we think are worth someone's time

These are the gaps we keep hitting, offered freely as potential student or thesis projects. We will support any of them with site access and data.

Seasonal yield per outfall

What mass of gross pollutant does a single South African urban stormwater outfall actually deliver over a wet season, disaggregated by catchment type? Nobody can currently answer this, and it is the number every funder and municipality asks for first.

First-flush plastic loading

How much of the seasonal litter load arrives in the first hours of the first significant rainfall events? If the concentration is as high as field observation suggests, servicing strategy should be built around forecasts rather than calendars.

Capture efficiency and bypass

What fraction of gross pollutant passes an installed net — through overflow, around the hub, or in suspension — and how does that change as the net loads? This is the credibility question for the whole method.

Cost per kilogram, compared honestly

Full lifecycle cost per kilogram of plastic intercepted at the outfall, against beach cleanup, river boom and improved collection in the same catchment. We will publish the result whichever way it goes.

Brand audit at the outfall

Does the brand and item composition of stormwater-intercepted debris differ systematically from beach-collected debris? If it does, beach audits — the basis of most producer-responsibility argument — are measuring the wrong sample.

The EPR gap, quantified

What share of intercepted material falls outside the categories EPR schemes are measured on? A defensible figure here would be directly useful in policy review.

Our measurement principles Wet and drained mass reported separately and never conflated. Organic fraction separated from plastic before any plastic figure is quoted. Service interval and rainfall reported alongside every mass. Sub-sampling fraction stated explicitly. Missed services and overflow events published, not omitted. Raw records retained and available. We would rather publish a small, honest dataset than a large, flattering one — the sector has quite enough of the latter.

Reference reading

  • Verster, C. & Bouwman, H. (2020). Land-based sources and pathways of marine plastics in a South African context. South African Journal of Science 116(5/6). Link
  • Impacts of marine plastic on ecosystem services and economy: state of South African research. South African Journal of Science (2020). Link
  • Addressing plastic pollution and waste flows: insights from South Africa's experience (2024). Link
  • The economic impacts of marine plastic debris in South Africa: a preliminary estimate. Marine Pollution Bulletin. Link
  • Identifying and addressing challenges in gross pollutant trap maintenance: perspectives from the Australian stormwater industry. Link — essential reading on why these systems fail in practice.
  • WWF South Africa. EPR for plastic packaging: synthesis report. Link
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