Tag Archives: Friends of Richmond Park

Water quality improvements are on par at Richmond Park

Shortly I will post another blog updating you on how the river improvement works in Richmond Park are settling in one year after they were completed. Although the river habitat works have been completed (for now!) work has by no means ended. In addition to improving the habitat, our attention is also focused on addressing the poor water quality entering into the Brook.

Upstream of the Richmond Park golf course, rain water pours off the surrounding urban catchment and notably down the incredibly busy and often choked A3 at Roehampton Hill. It then flows down the gulley pots, into a surface water drain before this opens out into a ditch which flows across Richmond Park Golf Course before discharging into the Beverley Brook. Such road runoff is known to cause detrimental effects to the aquatic environment, not only from the significant quantities of sediment carried in it, but additionally from the contaminants bound to it. These include Poly Aromatic Hydrocarbons (PAHs), hydrocarbons and heavy metals. Our aim was to therefore capture the sediment and the contaminants before they reach the Brook. This was achieved with a two pronged attack.

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Oil from the A3 covering the surface of the pond in the golf course. Thick black sediment covers the bed

First of all, mid-fairway at the upstream end of the golf course we opened the ditch out to create an on-line pond, known to us as a silt trap but to golfers as a feature water hazard. With help from Rob McInnes, the pond’s size was calculated so that all coarse sediment down to 0.1mm would drop out as a consequence of lowering the velocity of the flow. A shallow marginal ledge was incorporated along the length of the pond, which has been planted with a mix of wetland plant species to promote deposition, whilst providing species and habitat diversity. By emptying the pond regularly, the silt is removed from the system and the effectiveness of the trap is maintained.

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Starting to open the ditch out

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A few months after completion, the pond is trapping plenty of silt (and plenty of golf balls)

The second measure took place a few hundred metres further down the ditch where an existing online pond, in the shape of a ring doughnut, provided an excellent opportunity to be modified to create a wetland. The plan was to re-jig it so that the doughnut became a U-shape. This prevents short-circuiting, therefore increasing retention times, reducing velocities and again promoting a depositional environment.

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The pond before works start

The pond was too deep to plant straight into, so we needed to find spoil to fill it in. What better way to produce the spoil than dig a second wetland immediately upstream of the first, which will increase the treatment capacity further.

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Re configuring and filling in of the pond

Six thousand plants consisting of over 20 species were planted in the wetlands. The dense structure created by the plants results in even finer sediments being captured than in the silt trap upstream.

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The wetlands newly planted with 6000 plugs and fenced off

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August and the plants have established

Furthermore, this has now created a fantastic wetland habitat full of dragonflies, damselflies and frogs to name a few. Both the silt trap and wetlands have been fenced off and have bird twine strung over them to prevent the large population of geese from nobbling the plants before they had the chance to establish. The total area of both is approximately 800 metres square.

A simple water level control structure was created at the outlet of each wetland. As sediment accumulates and reduces the depth of water over time, another drop board can be put in, allowing the water depth to be increased, therefore reducing maintenance requirements and prolonging the life of the wetland.

The effectiveness of the installed measures is currently being monitored, however a coincidental site visit during a pollution event helped to anecdotally demonstrate the effectiveness. Run-off from a presumed building site was bringing significant quantities of sand rich water into the ditch. After the silt trap, the turbidity of water flowing out was visually improved. Walking further down the ditch network, after flowing through both wetlands, we were incredibly impressed to see that the water flowing out and into the river was clear to the eye. Although this was always the theory behind why we created these features, to see it work first hand to such a great effect was brilliant and hugely satisfying. With contaminants generally being bound to sediment, this clearly demonstrates not only a reduction of sediment input to the river but indirectly of contaminants too.

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Thick sandy water flowing into the sediment trap

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Water in the ditch downstream of the sediment trap and both wetlands

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Significantly improved water clarity entering into the Beverley Brook

Job done!! (for now anyway). I am now working up the next phase of water quality improvements. Updates will follow shortly.

As always, the success of this project is down to the valuable contribution of many people and organisations.

Big thanks to the ongoing project partners; the Environment Agency, Defra, The Royal Parks and Friends of Richmond Park. Thanks to Jon Dummett and Gary Stewart at Glendale Golf Course for surprisingly being so willing in allowing us to dig up their course and for their continued support since. Thanks to Rob McInnes at RM Wetlands & Environment Ltd for guiding the designs, Ben and the guys at Aquamaintain for braving the cold February days delivering the work and again for planting it up. Thanks to Thames Water for providing the flow meter which was installed in the ditch network to inform the design and finally, to Layla at Queen Mary University for monitoring the work.

Tree Planting in Richmond Park

I am sure you have all been following the progress in Richmond Park with our Beverley Brook Restoration Project. Well now that the main channels works have been completed, we were ready to move on to the next stage: tree planting.

Tree Planting

Adding the right number of trees along the channel is crucial to restoring the habitat. Trees provide excellent cover for fish from predation, the shade they create helps to keep the river cool in the summer months, they provide habitat for birds and insects and the seeds as a food source. However too much shade can prevent marginal, emergent and submerged plant growth, so a balance has to be struck.

On a sunny February morning we were joined by seven volunteers from Friends of Richmond Park to plant nearly 200 trees along the two restored sections on the Beverley Brook.

To ensure we got it right, Toby (Senior Projects Officer at SERT) had worked closely with Royal Parks’ Julia (Head of Ecology) to map out where each species should be planted and how many.

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Tree species planted included several types of willow (white, grey, osier and goat) as well as alder, black poplar, blackthorn, hawthorn, hazel, birch and elm. All trees were given a protection from grazing and from high flows to give them the best chance at establishing. Given the flashy nature of the Beverley Brook, those trees planted closer to the channel were given some extra protection from strong flows with a large stake providing cover.

More trees

Next on the agenda for this project is to add plants to the marginal habitats in April. Watch this space and come and get involved!

Big thank you to our volunteers from Friends of Richmond Park: Brian, Ian, Janet, Jed, Mike, Roger and Simon.

Lovely gravels

River Restoration in Richmond Park

Richmond ParkWe’ve started our latest restoration project in Richmond Park, working to enhance the Beverley Brook in partnership with The Royal Parks, The Environment Agency, the Friends of Richmond Park and the Beverley Brook Catchment Partnership.

Richmond Park is well known for its deer and its nationally important terrestrial habitats, e.g. acid grassland. Given this high status you would be forgiven for thinking that the river was also in good shape.  However, it’s actually not and its wildlife is relatively impoverished.

About 14% of the length of the Beverley Brook runs through the Richmond Park and so restoring the river through the park, presents an excellent opportunity to make a real difference to the whole river ecosystem.

Why is restoration needed?

The Beverley Brook, like many of London’s rivers, has been heavily modified in the past leaving a highly uniform river channel lacking in habitat diversity. The river channel has been over-widened and in places deepened along most of its length with all natural woody material and instream features being routinely removed from the channel for decades. Due to these reasons there is little variation in flow and depth and subsequently there is little habitat diversity for fish and aquatic invertebrates.

RP Before 2In addition to this the banks are very steep and the river is incised (if you stand on the top of the bank the river is quite a long way down!) and the banks have been subject to increased erosion due to the intense grazing of deer. The deer enjoy eating the succulent river bank plants. This means there is little vegetation left and there are no root structures to hold the soil on the river bank in place and so it washes into the river.  You may have seen a sandy bottom on the river bed: this isn’t actually what it’s meant to look like and is a result of the soil washing in and smothering the natural gravels on the river bed. This is a problem for the river ecosystem as many of the plants and animals that would naturally live in the Beverley Brook need the gravelly river bed habitats to survive.

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A natural river system has the ability to self-regulate but when it becomes modified, the processes can get out of kilter and we may need to intervene to kick start them again.  All of the modifications to the Beverley Brook have left the river with little power, taking away the opportunity for the channel to naturally fix itself with geomorphological processes.

RP Before 1What we are doing

A large river restoration project in the Park has been developed and funded in partnership with the South East Rivers Trust, the Royal Parks, the Friends of Richmond Park, the Environment Agency and the Beverley Brook Catchment Partnership. The aim of this project is to naturalise 600 m of the Beverley Brook through the park using a number of simple restoration techniques. These include:

  • Adding Large Woody Material to increase flow variation and provide a greater complexity of habitats for aquatic wildlife.
  • Re-profiling the incised and steep banks to enhance marginal habitats.
  • Narrowing and remeandering the channel to create a diversity of different flow patterns and produce marginal wetland berms.
  • Erecting fencing and river gates to temporarily exclude the deer to allow the banks to stabilise and for vegetation to recover.
  • Creating slower flowing areas as refuge for animals during the high flows which are typical of urban rivers such as the Beverley Brook. This is particularly important to help fish establish and not be washed downstream (and possibly right out of the river) in heavy rains.
  • Address the contaminated road run-off input into the river from the A3 by creating a siltation pond and wetland to trap and clean the silt from the road.

So it is going to be a busy couple of months on site and we are all excited about the results this project will bring!

You can read more about the project and how Richmond Park access will be affected during works on the Royal Parks website here.

RichmondGrid