Author Archives: Tim

Silt trap project: Update 4

The silt trap in Mill Lane is now in and functioning!

All that can be seen of it is a nice smooth patch of new tarmac and a manhole cover that will be used to clean the chamber every 6 months or so.

Here is  a picture of Councillor Hamish Pollock checking out the site of the chamber with Wandle Trust Director Bella Davies last week.


The second chamber on Denmark Road is now well under way and in fact our contractors F.M. Conway will be finished work on Thursday!  In contrast to the first chamber everything has gone smoothly with no surprise pipes emerging to slow us down!

This site has an important extra addition in that we have included two monitoring chambers into the design.  The surface water pipe first feeds into one inspection chamber then into the silt trap before passing into the second monitoring chamber and then on towards the river.

IMG_9070 (1)

The silt trap in the ground with the surface water pipe shown in the foreground.   This area of open pipe is where the upstream monitoring chamber is located.

The chambers will allow us to monitor the effectiveness of the traps by taking samples before and after the silt trap.  This will be carried out using automated sampling apparatus to allow analysis of the water quality and any particulates present.


The access chambers  (Two monitoring chambers and one for the silt trap) being built up to road height ready for the manhole covers.

The third and final chamber project which will be located on Butter Hill will start on 17th June.

Silt trap project: Update 3

The mystery pipe has been identified as a redundant water pipe that was first laid in 1868 and has now been removed.  All systems are now go, and the silt trap is being fitted as we speak!

A 3.5 metre hole has been dug:


A concrete slab laid:


The collection chamber inserted:


The hydrodynamic separator inserted:


The road should all be back to normal by Friday, and then it’s on to the next site in Denmark Road on Tuesday!

Silt trap project: Update 2

After some detective work involving a number of utility companies the mystery pipe has now been identified as a redundant water main.

This was removed on Friday 17 May but means we are now behind schedule with the works. Currently the aim is that Mill Lane works will be complete by Friday 24 May and we will be ready to start on Denmark Road on Tuesday 28 May.

Silt trap project: Update

As you may have seen, work started on the silt trap project on Mill Lane, Carshalton on Monday 13 May.

While digging up the road the contractors have found a gas pipe that is in a different location than was shown in the ground radar survey.

This has implications for the location of the silt trap chamber and will result in some delay to the project while this is resolved. There will likely be knock on delays to the work on Denmark Road and Butter Hill as a result.  We are working hard with Conways, Southern Gas and the London Borough of Sutton to minimise any  potential delay or disruption.  We will keep you informed as work progresses.

Pollution Assessment Volunteers Needed!

Fed up with seeing pollution in the River Wandle and wish you could do something about it? 

Then why not get involved with our exciting new  Pollution Assessment Volunteer Scheme?

What is the scheme?

The Scheme is a pilot that is being run by the Wandle Trust in collaboration with the Environment Agency.  Minor (category 3) incidents will be assessed by volunteers to determine the seriousness, source and type of pollution and ensure a fast, efficient and effective response from the EA. If successful it would be rolled out across London and maybe even beyond!

What would I need to do?

  • We will provide training in pollution assessment and provide you with pollution assessment forms.
  • When we hear of an event in your local river stretch we would call you and ask you to go down to the river and assess the pollution.
  • The assessment will then be fed back via the Wandle Trust to the EA and ensure that their response is efficient and effective.

How will it help the river?

  • It will ensure pollution incidents are responded to quickly and more efficiently
  • Hotspots and long term trends will be identified and allow a targeting of pollution prevention schemes.
  • Ultimately it will mean a cleaner, healthier river for wildlife and people!

Want to get involved?

Contact Tim at to register your interest and await news of training events in the near future!

Our first Pollution Assessment Volunteer Workshop!

On Friday a group of six keen Wandle Trust Pollution Assessment Volunteers attended our inaugural training workshop.  They learnt more about the Pollution Monitoring Scheme and were trained in how to carry out assessment of  Category 3 (minor) incidents.

The scheme, which we are running in collaboration with the Environment Agency, is the first of its kind in the UK.  If successful, similar schemes could be rolled out across London and beyond.

Our friends from the EA’s Environment Management team, Richard Maile and Eleanor Pratt, came along to meet the volunteers, and offered good insight and information about pollution in the Wandle and London’s other waterways.

If anyone who cares about the Wandle is keen to be involved in this scheme then we would love to hear from you.  Please contact Tim at  for more information.

Thanks to: Abi, Henry, Jane, Mike, Per and Sue for attending and becoming our first trained volunteers!

Wandle Trust and Environment Agency work together to monitor pollution on the Wandle

20120709_151413 (1)

We’re delighted to announce that the Wandle Trust will be working in collaboration with the Environment Agency to help monitor pollution on the Wandle.

The collaborative project will be led by the Wandle Trust with the Environment Agency helping to train Wandle Trust staff and volunteers so that they are able to attend minor incidents on the river.

When notified by the Environment Agency, the Wandle Trust volunteers will provide a first line of response to assess the situation and report back to the Environment Agency who will then react accordingly. It is hoped that this newly established partnership will enable local Wandle Trust volunteers to keep an eye on the river, facilitating a more efficient response to all pollution incidents.

Lord Chris Smith, Chairman of the Environment Agency, said:

“Working with community groups is crucial in ensuring the vitality of our rivers and waterways, and the Wandle Trust is a superb example of residents taking an active interest in the health of their local environment. 

Rivers in England and Wales are the healthiest they have been for 20 years, but it is important that we do more to continue this improvement and meet stringent new EU standards. I’m confident that our work with the Wandle Trust will enable us all to do just that.”

 Click here to read the full press release

Anyone interested in getting involved in this exciting project please contact Tim at

Update: this story has now been picked up by the Wimbledon Guardian and the Surrey Comet.

Pollution Alert: Oil in the Wandle, Wandle Park (Croydon)

Oil was seen in the Wandle this morning at Wandle Park (Croydon) coming from the culvert.  It has been reported down as far as Mill Lane industrial estate and Bridges lane.  I cycled up the river to this area at 1pm but saw none below that point.  Although the oil is still coming from the culvert Thames Water have boomed off the area and are currently tankering the oil away.  Investigations as to the source will continue tomorrow. Many thanks to the Environment Agency (EA) and Thames Water once again.  This area of river is very problematic and there have been a number of pollution events recently.

Please be vigilant and call the EA on (0800) 807060 if you see any pollution in the river.  

If you are interested in helping to monitor pollution on the river watch this space for an exciting new initiative we will soon be launching with the EA.

Trout spawning in the Wandle!

Now for a bit of good news after the last pollution post:  Trout are spawning on the Carshalton arm of the river again!

The picture shows  a trout redd (nest of trout eggs).  The redd is the light coloured gravels made by the hen fish with her tail.  She scoops out the gravel by fanning her tail and then lays the eggs which when fertilised by the cock fish are covered with more gravel in the same way.  Trout eggs need lots of cool, well oxygenated water flowing over them to mature and hatch.

Note, this is in the Butter Hill stretch which until our works last year was behind a weir.  Notice the fast flow and healthy growth of marginal iris and watercress.  And of course none of this would have been possible without removing the weir with the help of the Wild Trout Trust, and all the work of our marvellous volunteers!