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Surface water management projects

Have a look at some of the surface water management projects we've completed across London and the UK.

Architect on Building Site
Diagram of high water table

Purley Avenue, London

This project was a development for 7 new flats on a site that had been previously occupied. The challenge with this site was that the whole of site was being developed, without any room for drains outside of the main building. The other challenge we had to overcome was a very high water table above London clay, which meant that normal SuDS solutions were not able to be installed.

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We designed a foul and surface water drainage system which satisfied the requirements of Thames Water. The drains had to be low enough to pass underneath the beam and block floors, which meant that we had to design a large attenuation tank, together with pumping stations for both the foul and surface water drains. We eventually received permission to connect to the existing sewers in December 2023

Throckley Marsh, Northumberland

This was a relatively simple development using existing farm buildings, however the discharge point was a ditch in the highway verge. The difficulty with this design was that although the ditch was located close to the last manhole on the system the invert levels did not allow us to connect in that vicinity.

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In order to get the surface water drainage system to work we had to design a ditch in the adjacent field to transfer the water to a point where the invert levels were similar and we could connect into the highway ditch.

Plan of Throckley Marsh, Northumberland

Kirkley Hall, Northumberland

This project was an extension to an existing classroom at Kirkley Hall agricultural college in Northumberland. The foundations for the extension to the building can be seen on the plan to the left shaded in yellow. As this was a working college it already had an extensive drainage network which we were required to connect to. Therefore, this involved a survey to establish the location and depth of all of the existing drainage together with a CCTV survey to ascertain the condition.

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Once we had the survey we liaised with the Local Authority to provide a drainage strategy report before we could start the actual design.

Unfortunately, the existing drainage network had been laid too shallow in an area where tractors were running over the drains, so all of the drainage network was cracked and blocked in a number of places.

This meant that we could not use the existing network and we had to design a new system with the necessary cover above the pipes.

We still had to limit the discharge to 5l/s which meant we had to design a hydrobrake at the outlet, together with a large attenuation tank.

This drainage system was designed and completed in 2020.

Plan of Kirkley Hall, Northumberland

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