The Ponds Project has now come to an end, with the exception of the restoration of some of the work compounds. We won’t be updating this blog anymore, but you can keep up to date with activities on the Heath in various ways:
On Twitter: @CityCorpHeath
On facebook: https://www.facebook.com/hampsteadheathofficial
On our web pages: http://www.cityoflondon.gov.uk/hampsteadheath
During the construction of the Model Boating Pond dam we had a time-lapse camera taking a photo every few seconds during working hours. We’ve put these altogether, along with some of the drone footage which we’ve published on this blog before, to create a short film showing the progress of the large scale works.
You can view the 3.36 min video here.
After the success of our writing competition for young people last year, we’ve decided to run a series of three competitions (art, science and writing) related to the Ponds Project.
Our writing and science competitions are for secondary schools students (years 7 to 11), and are both themed around ‘Hampstead Heath of the Future’. The closing date for both is 6 April 2017.
We are also running an art competition for school children of all ages, in partnership with the Affordable Art fair and Anscombe and Ringland. The challenge is to create an artwork entitled ‘Wildlife on the Heath’ using the Heath as your inspiration.
If you know any young people who might be interested, please contact us on 020 7332 3738 or email ponds.education@cityoflondon.gov.uk for more information on the rules of the competitions and how to enter. You can also check out our website for information about this, and free education sessions that we run: www.cityoflondon.gov.uk/pondsprojecteducation.
Nearly two months after construction completion, nature’s amazing ability to regenerate is evident in the work sites and compounds.
Model Boating Pond
The hill-side next to Model Boating pond is beginning to look green as grass and wild flower seed establishes.
The island and pond are also looking good in the winter sun.
Grass on the Sports Field is also shooting back to life.
Sports Field
The haul road and work compound at Pryor’s Field were seeded slightly later, but green shoots are visible.
Haul road
Pryor’s Field
South of the Catchpit dam a new channel has been dug allowing water to flow down towards the Mixed Pond. Previously, this water would have flowed through a pipe under the ground. The benefits of having it above ground are: it becomes a wetland habitat and provides feeding and habitat for wildlife, including birds, insects and amphibians. Plants which like marsh habitats will also be able to grow around the new stream.
North of the Catchpit, the silt trap has filled up with water flowing down the chain.
Last week, BAM planted more trees to replace some of those removed at the beginning of the project.
Two semi-mature London Plane trees were planted by the deck at Hampstead No. 2 pond, to replace the two mature trees removed to allow the culvert to be built. These are in slightly different locations to the removed trees but will still be part of the existing avenue of trees.
Planting has also taken place at the bottom of the weir at Hampstead No. 1. Ivy has been planted to help camoflage the concrete as well as a few yew trees.
Hampstead No. 1
Over on the Highgate Chain, a new hedge has been planted in the place of the former path which was removed to protect the veteran oak tree.
Hedge planting
This hedge is made up of a mixture of shrubs including blackthorn and hawthorn. This will become a good habitat for nesting birds.
The Heath team will be carrying out more planting work over the winter months and into spring.
Last week we commissioned a drone flight to get some pictures of the Model Boating Pond now the construction work has been completed. Below are the new images and also similar images taken previously to compare the pond and landscape, during and after the Ponds Project.
Model Boating Pond – August 2015
Model Boating Pond – November 2016
Model Boating Pond – April 2016
Model Boating Pond – November 2016
Regular Heath visitor, David Cole, has been kind enough to send a selection of photos he has been taking from the same position on Hampstead Heath, as the works have progressed. David swims in the Men’s Pond daily and has been taking these pictures of the new dam at Model Boating Pond on his visits.
Earlier this week the tree planting programme began at the Model Boating Pond. Approximately 186 trees and shrubs are to be planted across the Heath to replace trees which were removed in February 2015 to build the scheme. These are all native species and include varieties such as oak, elm, black poplar, willow and hawthorn. Their locations have been selectecd by the Heath’s ecology and conservation team.
At Model Boating Pond eight of the trees have come from our own nursery at Kenwood so have been grown from seed on the Heath.
Planting a black poplar
These trees include:
One lime, three hawthorns and three osier willows will also be planted at this pond. We also intend to plant a further eight oak saplings in the Tumulus Field along the line of a former ancient hedgerow.
Now that the construction element of the project has finished, I thought a post describing what has happened at each pond, along with an explanation of how these works improve dam safety, might be useful. In this post I will concentrate on the Highgate Chain and I will then go on to describe the Hampstead Chain in a future post.
There are five ponds in the Highgate Chain which come under the management of the City of London. A further two ponds are in the Kenwood estate and are managed by English Heritage. The Highgate Chain has a big catchment, which means water from a large area ends up in the pond chain – this is due to the geography of the Heath and the fact that water flows off the hills around the ponds.
Stock Pond
Stock Pond
Stock Pond is a relatively small pond and receives water from the two ponds in the Kenwood Estate, as well as run off from the surrounding hills. There had been flooding issues at this pond in the past, and during a flood in 2010 the dam was damaged when the pond water came over the top of the dam (overtopping) and caused some erosion to the downstream side of the earth dam.
The work carried out here as part of the Ponds Project includes raising the dam by half a metre. A spillway was also constructed. A spillway is a construction which allows water to leave a pond safely and in a controlled way so that it does not flow over the top of the dam and cause damage. At the Stock Pond the spillway is a large grassy area, and was designed so it would fit in with the surrounding landscape. The spillway is lower than the new raised dam so if water levels do rise then water leaves the pond via the spillway and flows over ground down to the next pond, in this case, Ladies Pond. The final piece of work at this pond was to add a culvert, or a large pipe, which allows water to flow out of the pond and then down a stream into the Ladies Pond. This replaces an existing pipe which often used to get blocked with silt. Water will flow down this pipe continuously, except in dry periods when the flow stops.
Several trees were removed from the edge of this pond, including some oaks, to allow for the spillway to be constructed. We have planted some additional aquatic plants in the pond which will help with water quality and will also provide a good habitat for birds, fish and invertebrates. Aerators have also been added to all of the ponds, which add oxygen to water to improve water quality. Finally, silt was also removed from the bottom of the pond which will also help improve water quality.
Stock Pond
Kenwood Ladies Bathing Pond
Part of the works at this pond have included replacing the building which sits on the dam. This had to happen for two reasons. Firstly the building was on the dam, which needed to be raised slightly, and secondly when we got the results back from survey of the concrete deck it was found to be in very poor condition. The old changing rooms have been replaced with two buildings. One provides changing facilities and toilets, and the other is the lifeguards facility. The building was prefabricated in a warehouse and brought to the Heath in five sections. You can see photos of this process in this post. This method of construction was chosen to shorten the construction period so that the pond was closed for the shortest time possible.
The other works included building a spillway, so like Stock Pond, water could leave the pond safely and flow down to the next pond (Bird Sanctuary).
Ladies Pond building, with incomplete spillway in foreground
The spillway at Ladies Pond is also grass lined and at the bottom it has a concrete stilling basin. The pipe which allows a flow of water from Ladies Pond to Bird Sanctuary was also replaced and enlarged. Some additional aquatic plants and an aerator were also added. Silt has been removed from the pond. All of these factors will contribute to better water quality and we’ve already had reports from swimmers that the situation is much improved. At the top end of the pond some wetland scrapes were also added to naturally filtrate the water, and remove silt as it flows down from Stock Pond.
Several trees were removed from the spillway area and we will be planting some replacement trees in this location, but we have also received positive feedback from swimmers on the additional light in the pond as well as a more open view thanks to the tree removal.
Bird Sanctuary
Bird Sanctuary pond is a haven for wildlife thanks to being completely fenced off from the public. It is a home to many types of bird, including the kingfisher. It is because of this special status that works on this pond were kept to an absolute minimum, with the vast majority being focussed on environmental improvements, described here. Some very slight leveling of the dam took place, which in reality just looks like path resurfacing works. One of the pipes which connects Bird Sanctuary to Model Boating Pond was also enlarged.
Bird Sanctuary
Model Boating Pond
The vast majority of the works across the entire Ponds Project happened around the Model Boating Pond. The works were focussed here for a number of reasons:
A new dam was created using clay found in the borrow pits (located to the west of the pond within the large work compound) and from the western edge of the pond which has been excavated and re-profiled leaving an island (linked by a causeway) – which saves a group of mature trees.
A spillway has been created in the south-west corner of the pond. This is made of reinforced grass turf and in the event of a large flood, will allow water to safely leave the pond, and travel down to Men’s Bathing Pond, without over-topping and potentially causing damage to the dam. Aerators have also been added to replace much larger pieces of equipment which were there previously.
Model Boating Pond
Men’s Bathing Pond
At Men’s Pond the dam has also been raised but this time by a sheet metal wall with an oak capping. The wall runs the length of the dam except for the spillway in the south-west corner. Aquatic plants have been put in front of it to camouflage it from the pond-side, and also improve water quality.
The spillway is grass lined and allows water to safely leave the pond in the event of a large flood.
Men’s Pond spillway
Other environmental improvements include a small check dam in the north-west corner to filter water before it enters the pond, and the addition of two aerators. Silt was also removed from the pond last winter. Men’s Pond had issues with blue-green algae in the past and we hope these environmental enhancements will help with this.
Highgate No. 1 Pond
Highgate No. 1 Pond
The final pond in the Highgate Chain is Highgate No. 1, It is also the pond closest to a high density of residential properties. The dam has been raised by 1.25m with a sheet pile wall with an oak cap, similar to the work that took place at Men’s Pond. A grass lined spillway has also been created at the southern edge of the pond. This allows water to leave the pond safely in the event of a large flood. A timber retaining wall made of timber sleepers has been built along the eastern edge of the spillway (where the boundary of the Heath meet’s Brookfield Mansion’s boundary). A similar wall has been built at the other end of the dam, on the land of one of the adjoining landowners.
Highgate No. 1 spillway
Pipes which connect the Highgate No. 1 Pond to the sewers have been retained and in a normal flow water leaves the pond this way. If the Highgate No. 1 spillway ever does come into use, during a very large storm, the water flows down the spillway and down the hill, where it eventually finds its way into the sewers through gutters and land drains. Flood water is not retained permanently on the Heath but because of the extra storage incorporated at Model Boating Pond, it is temporarily stored and then released gradually after the peak of the storm. An aerator and aquatic plants were also added here to help improve water quality.
The works on this chain have eliminated the chance of uncontrolled overtopping of the dams and increased the standard of protection against flooding downstream.
If you are interested in more technical information on the design development and the basic principles of the scheme, the Preferred Solution Report might be of interest to you.
A concise history of the project can be found here.
As the construction element of the project draws to a close, we can now start to see grass shoots appearing in the areas which have alredy been hydro-seeded. This includes the area to the west of Model Boating Pond.
Grass begining to shoot
All around the newly landscaped Model Boating Pond there are beautiful views, made even more wonderful by the trees changing colour for autumn.
On the Hampstead Chain, BAM’s final compound on the Heath (at Pryor’s Field) is gradually shrinking in size as their kit is moved from site.
Viaduct Pond
Works have finished at all of the ponds on this chain, with the exception of the restoration of the work compound.
Hampstead No. 2
The last remaining works are the planting of various shrubs and trees to replace some of the trees that were taken down to allow for the construction of the scheme. Some of this work is being carried out by BAM, in the week commencing 7 November, and the rest will be taken care of by Heath staff.
Hampstead Heath Ponds Project 