The Siltex is in!

Have you walked past Carshalton Ponds today? If you have, you may think it is looking a little different…

The White Carshalton Ponds

The ponds have turned a milky-white colour. But do not fear, this was intentional! Working with the Environment Agency, we have just added two tonnes of Siltex to the ponds.

Siltex is a natural chalk-like substance which helps to increase the speed of silt breakdown by stimulating natural processes. (Click here to read more about why we are doing this).

We had eight dedicated and brave volunteers join us at 8am on chilly Tuesday morning. Everyone was kitted out with waders, goggles and masks – Siltex isn’t dangerous but we wanted to be extra careful.

Siltex Volunteers

Steve stepped up as Captain Siltex to join Olly in the boat, throwing Siltex overboard in the deeper waters. For the morning, our vessel was kindly lent to us by Sutton Council. In the afternoon, Olly and Steve commandeered a smaller boat from the Sutton Ecology Centre. Without these boats, we wouldn’t have been able to apply the Siltex at all so we are extremely grateful to Dave Warburton, Ian Hudson, Warren Chapman, Collin Franklin and Mark Featherstone for loaning and delivering these boats on the day.

Captain Siltex

While Steve and Olly sailed the open seas, the rest of us were adding Siltex from the shore, showing off our throwing skills. This allowed us to get a good coverage over the shallower parts the boats could not access.

Adding Siltex by hand

Throughout the day, the Environment Agency were taking readings further downstream to ensure everything was working as it should.

Olly will be monitoring this regularly for the next few months to determine if it is a cost effective solution to the management of silt at Carshalton Ponds. Last week, Olly and I took some pre-Siltex water samples on a chilly and damp morning.

The Water Samples

Why are there four different bottles I hear you ask?

The reason for this is that there are several different substances which are of interest in the ponds. We are interested in what effect the Siltex might have in speeding up the breakdown of several contaminants (e.g. car exhaust particles) as well as reducing the overall volume of mud. Different tests are required for different substances – for instance hydrocarbons (oils and fuels) stick to plastic, so must be stored in a glass bottle if they are to be extracted and analysed. So different bottles are needed for each different test!

While we were out we rescued Woody from the Wandle – he is now our unofficial Mascot for the project! He even joined us for the Siltex event, although came out a little worse for wear….

Woody Before and After

Keep your eyes peeled for more updates!

2 thoughts on “The Siltex is in!

  1. Barbara

    Please can you let me know if you think this has worked. Looking at using Siltex on a smaller pond would be grateful to know if it has been a successful experiment.

  2. Polly Post author

    Hi Barbara, in our case the Siltex did not work however that is not to say it has not, and would not, work in other locations. We only had funding to monitor for 4 months, so we have no way of knowing whether there were any longer terms changes which was also a possibility.

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