On the 23rd of April the Thames Waterblitz is taking place.
This is a great way of capturing a snapshot in time of water quality in the Thames and all its tributaries from source to sea. Run by Earthwatch, this will be the sixth Waterblitz and so far, they have collected nearly 1200 samples with the help of amazing volunteers.
The data they collect as part of the Waterblitz compliments the regular sampling already carried out by the Environment Agency and the Centre for Ecology and Hydrology. It allows extra information to be gathered from parts of the river that may normally be overlooked, helping to create a much better picture of what’s going on in one of the country’s most important rivers.
They would love as many people as possible to collect a water sample from their patch of the Thames basin on this one-day event. If you are interested in being involved, then follow thisregistration link to find out more and get involved. They will then send you all the details you need to take part.
In August we were very lucky to receive funding from the Coca-Cola Foundation to install a Downstream Defender (silt trap) at Richmond Park, which will stop pollutants (such as heavy metals and hydrocarbons) reaching the Beverley Brook and improve local water quality and the health of the river.
The project was one of three water management projects being managed by The Rivers Trust and WWF, in the Thames and South East River Basins, for the benefit of both people and wildlife. The wider initiative is funded by the Coca-Cola Foundation and contributes to Coca-Cola’s promise to safely return the full amount of water used in finished beverages and their production to communities and nature by 2020 – an ongoing commitment as they managed to reach this goal five years ahead of target. Globally Coca-Cola works in over 2000 communities and supports more than 248 community water partnership projects in over 71 countries – this being one of them.
If you wanted to find out more about how this project came about, you can read our Introduction Blog here.
Our first report left off at the point of the launch event – with the highlight being the arrival of the lower section of the Downstream Defender silt trap. When we all saw it arrive on the back of the low loader, I think it’s fair to say that we were all was a little shocked by the scale of it, including myself and Dave, the Site Manager.
Despite months of looking at the diagrams, seeing a number in the dimension box, and doing the calculations, the actual size only hits home when you are confronted by the scale of it in 3D. But that was nothing – the following week, the upper section arrived, and I’ll let the photos tell the story!
The bottom section seemed big but then…
the base section turned up
The Royal Parks had agreed to let us install this unit in Richmond Park, and they also very kindly allowed us to commandeer one corner of the Roehampton Gate car park for the five-week duration of the works.
Our occupation of the car park was appreciated by some more than others
To start with, a by-pass channel was installed around the point where the Downstream Defender would be located on the existing drain. This would to help accommodate peak flows and prevent surcharging the drain network.
Once the bypass was installed, it was time to dig the main excavation. The base of the Downstream Defender was big enough, but it was absolutely dwarfed by the upper section. This was going to have to be an impressive hole!
After much head-scratching, the Kenward Groundworks guys came to the moment of truth – lowering and offering up both sections of the chamber. The head-scratching had clearly paid off. The height of the inlet and outlet pipes were spot on, and running a spirit level over the unit verified that they’d done a very good job of getting it to fit.
The moment of truth
The bubble doesn’t lie. Great job!
A significant amount of concrete back-filling and some careful landscaping later, you would never guess what lies beneath. The only evidence on the surface is four inspection covers and some disturbed ground, and these too will soon disappear from view as the vegetation establishes.
But out of sight certainly isn’t out of mind. Simply knowing the Downstream Defender’s beneficial effects in improving the quality of water flowing from the A3 into the Beverley Brook is reassuring enough, but now we’re planning to demonstrate and quantify this too. Watch this space!
What Downstream Defender?
Once again a massive thank you to all involved. Thanks to…
The Coca-Cola Foundation for funding the work as part of their aim to help conserve water worldwide
The Environment Agency
The Royal Parks for your continued and much appreciated assistance and permission
Thames Water for all your contributions
Hydro International, WWF, The Rivers Trust and the Friends of Richmond Park
And a special thanks to all the guys at Kenward Groundworks who delivered a top job
And thanks for John Sutton from Clearwater Photography for the great photos
So you know that the roads can be pretty dirty. You see the direct effects of it on your car when you think it’s probably time to give it a clean. The dirt on the roads is also really well illustrated when it snows and soon the pure white snow changes to black slush. But where does all of this dirt come from?
You see trucks and lorries leaking oil and busses belching out thick clouds of exhaust fumes when pulling away from traffic lights. You see gulley pots full of litter, cigarette butts and sand that has run off the nearest building site. Or the paint that is dripped out of vans or has been poured into the curb. You walk along the street dodging ‘dog eggs’ which litter the pavement. Then in winter the roads get spread with grit and salt during cold snaps.
You may consider of all of these things as unsightly or unpleasant when on the roads, but within a short period of time and with a bit of rain, all of these substances are washed away and are out of sight and out of mind. But where does it disappear to?
The answer: often the nearest watercourse.
The initial runoff, known as the ‘first flush’, runs black especially in urban areas. In turn with many other outfalls also discharging the entire river turns black.
First flush on the River Wandle, South East Rivers Trust
So what is in this run-off?
Basically it consists of a nasty cocktail containing pieces of the road surface, tyres, brake pads and other material from engine parts from regular wear. Throw into the mix some fuel, gear oil, grease, brake fluid and antifreeze. Then for good measure add some pesticides, fertilisers, plant detritus, some illicit dumping of substances, inputs from misconnected drains and in winter de-icing grit and salt.
Unsurprisingly road runoff can be detrimental to the receiving watercourse, whose impacts on riverine ecology can be acute or chronic. The sediment smothers gravels vital for invertebrates and fish. The turbid water reduces light penetration so plant communities suffer due to limited photosynthesis. Furthermore, the sediment blocks the feeding mechanisms of filter feeders and gills of other aquatic organisms.
The Poly Aromatic Hydrocarbons (PAHs) (oils) and heavy metals are both known to be toxic to aquatic fauna. High concentrations of heavy metals associated with the ‘first flush’ can ‘shock’ aquatic environments as the water is polluted with levels several times higher the normal concentration. Multiple studies have shown that heavy metals can also cause long term impacts as they bio-accumulate within the food chain.
So what can we do?
It is well known that these contaminants freely bind to sediment. It therefore follows that if the sediment is removed, so too will many of the contaminants. This is the plan to protect the Beverley Brook in Richmond Park.
The Rivers Trust and WWF are managing three water management projects in the Thames and South East River Basins, for the benefit of both people and wildlife. The wider initiative is funded by the Coca-Cola Foundation and contributes to Coca-Cola’s promise to safely return the full amount of water used in finished beverages and their production to communities and nature by 2020 – an ongoing commitment as they managed to reach this goal five years ahead of target. Globally Coca-Cola works in over 2000 communities and supports more than 248 community water partnership projects in over 71 countries – this being one of them.
A schematic of how a Downstream Defender works
We are delighted to announce that the South East Rivers Trust is delivering one of these three projects which will see a large (and I mean very large) silt trap, known as a Downstream Defender® supplied by Hydro International, installed onto a surface water drain. The drain currently carries run-off from the incredibly urban surrounding catchment directly into the Beverley Brook. The Downstream Defender will trap a large portion of the sediment and associated contaminants, preventing them from reaching the Beverley Brook. Intermittently the trap will be emptied with a gulley sucker and the toxic sludge removed to landfill. Consequently, the health of the river will improve making it a better place for both wildlife and people.
Last Tuesday we launched this collaborative project with the arrival of the Downstream Defender to Richmond Park. We’d like to thank our funders, the Coca-Cola Foundation, as well as all our partners including WWF, The Rivers Trust, the Environment Agency, The Royal Parks, the Friends of Richmond Park and Thames Water. Also a big thank you to Hydro International for supplying the Downstream Defender and for their much appreciated contributions to the launch event. Thank you to all the guys at Kenward Groundworks; Tony, Matt, Dave, Mark and Woody for all your efforts with installing the chamber. And finally thanks to John Sutton from Clearwater Photography for taking photograph of the launch and project.
Partners with the Downstream Defender Silt Trap
Celebrating the launch of the project with partners and volunteers
Our lucky Pollution Patrol volunteers were treated to a FIN-tastic day with our local Environment Agency team, learning all about fish.
It may come as a surprise to some people, but the Hogsmill, Wandle and Beverley Brook all contain a variety of different fish species. Common species across all three rivers include chub, dace, roach, barbel, stickleback and European eels.
But how do you tell the different between these species? For some, it is easier than others. The European eel is quite distinctive compared to the others for example. But as to the rest, it’s a bit more difficult.
Tom Cousins, a local EA Fisheries Officer, started the day for us with a presentation on the different fish species and the key identifying features.
The diagram below shows the external morphology of an average fish, and the features that help us distinguish one species from another.
For example: Roach and Rudd
These two fish are quite similar in appearance, both large-bodied with reddish fins. So how can we tell them apart? The answer is by looking at the mouth.
The roach is a bottom feeder, and its mouth points downwards, with the upper lip over-hanging the bottom lip – whereas a rudd feeds from the surface, and therefore the bottom lip overhangs the top lip.
The presentation from the Environment Agency is available below for you to download, with many more tricks and tips for ID.
As part of the training day, we also got to witness the Environment Agency’s electrofishing survey at Morden Hall Park on the River Wandle in South London.
It was amazing to learn about the fish in the classroom, and then come outside and see some in the flesh. Each fish caught was measured, and scale samples from some were taken in order to age the fish.
Once they had been recorded and had recovered, they were returned safely back to the Wandle.
Many thanks to Morden Hall Park for hosting us and to the Environment Agency for running the event!
The Hogsmill gauging station is an Environment Agency flow monitoring structure, essential for water resources planning and regulation. It is the furthermost downstream weir in the catchment and poses a significant barrier to fish passage, preventing the recolonisation of fish to the river from the Thames below. Addressing passage at this key site has been discussed for several years but due to the sensitivity and importance in the recorded flow-gauging data, in combination with the unconventional structure it has resulted in a complicated and extensive process to identify and develop a suitable solution. JBA have helped inform the positioning of the upper baffle and through a programme of spot gaugings will update the rating of the gauging station.
The impassable Hogsmill Kingston gauging station
The selected approach is a variation on the Low Cost Baffle (LCB) Solution as we have used elsewhere, whereby rigid baffles are put on the downstream weir face in a specific geometry and spacing to slow the water, deepen the flow and provide a distinct passage route on the weir face. However, due to the significantly steeper gradient at the site in comparison to that the design was developed for, the Trust and EA have modified the arrangement to help promote the correct hydraulics to enable fish to pass. The maths aside, in essence this meant that each line of baffles is incrementally taller than the last, starting at 120mm and ending at 288mm at the downstream end.
With this novel approach the Trust and the Environment Agency are keen to establish how efficiently the pass/easement operates, as the principle could be adopted at other similar challenging sites. In order to get a comprehensive assessment, an exciting opportunity arose to work with Durham University who will use the project as part of a wider study looking at fish passage past human made barriers. That’s the good news. The bad news being that in order to be ready for the dace spawning season I was committed to delivering for three weeks through the bleak days of January and February. The summer would have been far too pleasant.
Due to the non-standard design the baffles were manufactured as a bespoke commission carried out by Northwood Forestry & Sawmills, made of oak as opposed to the standard recycled plastic. Once complete, myself and Norm spent the first week of the year huddled in his workshop drilling and bolting the stainless steel angle to each baffle which would enable them to be securely fixed to the concrete weir. All 36 pieces of the jigsaw were complete, coded and stacked in the lockup ready for installation.
In the workshop with Norm fixing the stainless steel angle to the baffles
Half of the baffles with angle attached and coded ready to go
The baffles would have to wait, as first we needed to help fish of the anguilliform variety, eels, to also be able to successfully navigate past the weir. With the eels having already made the 6000+km epic journey from the Sargasso Sea we were keen to ensure this weir would not be an abrupt dead-end. Although there was an eel pass on the weir, it has been largely ineffective for some time. A new and improved pass was called for, so out with the old and in with the new.
Out with the old…
and in with the new
With the eel pass installed, preparation to fix the baffles was underway. This primarily revolved around creating a dry working area, not necessarily an easy task when working in a river but with the temporary coffer dam supplied from RN Inspection Services this was achieved with unbelievable effectiveness.
The coffer dam installed providing a manageable working area behind
For the next two weeks, Roo and I lugged baffles, drilled holes, spaced, chocked, clamped, injected resin, removed then re-erected the dam and battled the elements. As the jigsaw slotted together the theoretical schematic drawing I was now well familiar with became a reality.
The baffles being clamped into position before the stud secured to the concrete with resin
Getting into the flow of things
Time to move the dam and install the second half of the baffles
Finished! The notch bisecting the baffles to allow a deeper channel for fish to pass
Once complete, the time came to remove the dam and allow the water to flow over and through the baffles. With this action the Hogsmill became re-connected to the Thames once again.
The time lapse of the build conveniently summarises the full 3 weeks into 1 minute video can be seen here:
About to ‘pull’ the dam
Flow and fish passage returned to the channel
Over the coming year JBA (hydrology experts) will undertake a spot flow-gauging program, to ensure that the weir continues to gauge accurately with the modifications. Meanwhile Angus at Durham University and ourselves will monitor the LCB fish pass/easement aiming to understand its performance for coarse fishes such as chub, dace and roach.
One aspect of the monitoring is a camera looking across the upper notch
A BIG thanks to: All those involved in the various teams at the Environment Agency, partners in the project especially those in Hydrometry and Telemetry and Fisheries. Angus, Martyn and Jeroen at Durham University for bringing their wealth of monitoring experience and expertise to the project. JBA for carrying out the hydraulic assessments associated with the project. Bedelsford School who kindly agreed to us hooking up to their electricity supply to power the monitoring equipment. Rob Waite at the Royal Borough of Kingston for helping us to secure access and parking at the site. The Thames Anglers Conservancy, especially Will, for getting involved and helping to install the eel pass. Norm Fairey for your continued help with all things fishy and manufacturing. And my good mate Roo for the long hours, hard graft, permanently cold hands and near permanent good humour.
Last week I was lucky enough to visit the Hogsmill River twice with some of our dedicated Pollution Patrol volunteers.
From left to right: Geoff, Me (Polly), Steph, Peter, Bill and Jan
Our Pollution Assessment Volunteers (PAVs) work hard to track down and monitor polluted outfalls on the river, sending reports to the Environment Agency for action.
On Wednesday we were joined at a particularly bad outfall by our local Environment Agency Officer Steph to take some samples.
Sewage fungus at the outfall
Steph sampled for ammonia, which is used as an indicator of raw sewage entering the river, and for oxygen available to river invertebrates and fish. Oxygen is a good indicator of how polluted an outfall is, as bacteria use up oxygen to break down organic pollutants, which reduces oxygen available to other species which can sometimes result in fish kills.
For this week, both readings were fine.
This is one of many outfalls we’ve been looking at. You can find Steph’s updated report here.
On Friday I was invited along to the monthly Riverfly Monitoring session at the same outfall with the same dedicated team. Every month they get together at this location and take a kick sample of invertebrates as an indicator of how healthy the area is.
Some invertebrates such as caddis flies are very sensitive to pollution and are therefore an excellent indicator of water quality. If this is something you might be interested in, check out the website here!
Thank you to all our volunteers working on the Pollution Patrol scheme – we are making progress!