Hampstead Heath ponds upgrade

Year:2016

Duration:18 months

Cost:£22m

Country: London, UK

What did this project achieve?

Repair, strengthen and upgrade the ponds on Hampstead Heath in north London

There are around 30 ponds on Hampstead Heath in north London. Fed by the waters of the river Fleet, they were dug in the 17th and 18th centuries as reservoirs.

Three of the ponds are used as freshwater swimming pools. Popular all year round, 2 of the pools are single sex with the other used for mixed bathing.

The City of London Corporation which is responsible for the heath announced in 2011 that it was planning extensive work on the ponds to make their dams and overflow structures safer.

The proposals included measures to improve water quality as well as overhauling some of the pipes and weirs that allow water to cascade from one pond to the other.

The proposed measures faced strong opposition from swimming clubs and the Protect our Ponds campaign. Protestors – who later united under the banner Dam Nonsense – claimed the work was unnecessary and would cause irreparable damage to the heath's landscape.

The corporation argued that the engineering work was required by reservoir laws to prevent the heath's dams collapsing and triggering a flood if a major storm hit the area.

The 18 month project finally went ahead after 5 years of consultation, reports and protests.

Difference the scheme made

The scheme has protected the heath's dams from collapse.

There were also ecological benefits. More than 1,000 bulbs and plants have been added at 3 ponds. Around 40 native trees and 140 shrubs were also planted.

The project team improved habitats for some wildlife. New log pile 'homes' were created for grass snakes and 20 bat boxes installed.

How the work was done

The main work for engineers on the scheme was to raise and stabilise the heath's existing pond dams.

Around 7 million people visit Hampstead Heath every year so the project team had to find ways to work in a busy public space that would stay open during the programme.

Engineers found all the material needed to raise the dams on site – 30,000m³ of London clay. Workers dug 2 borrow pits to get the clay they needed. A borrow pit is the excavation left after material has been dug up for building an embankment.

Using the pits meant the team didn't need a fleet of trucks to bring clay to the site. This helped reduce pollution.

Workers used a new suction technique to remove silt from ponds. The process now took weeks rather than months as the ponds didn't need to be emptied. The silt was buried in the borrow pits.

Another advantage of the new suction method was that it caused less disruption to wildlife.

"​‌

Wild swimming… is a sensible response to the pressures of modern life, especially the isolating effects of life online.

Isabel Berwick

Financial Times journalist on why she loves swimming on Hampstead Heath, April 2017.

Fascinating facts

Dredging one of the ponds revealed a Mark 3 Ford Cortina lying on the bottom. The car may have been there for up to 25 years. The find was reported to police.

One of the swimming pools makes an appearance in the 2011 movie 'Tinker, Tailor, Soldier, Spy'. Intelligence chief George Smiley – played by Gary Oldman – takes a break from hunting down a traitor in MI6 with a morning dip in the pond.

The Hampstead Heath scheme won a 2017 ICE London award.

People who made it happen

  • Client: City of London Corporation
  • Landscape design: Atkins
  • Contractors: Bam Nuttall

More about this project

Explore more civil engineering projects

I want to become a civil engineer.

See how your studies lead to a civil engineering career

The job you end up with in civil engineering is likely to link back to what you studied at school, college or university. Here you can see your options at any age.

At school

Up to 16 years

School / college

16-19 years

College / university

18 years +

Change career

Any age