PROJECT OVERVIEW
Nimbus Engineering Consultants were appointed to provide a Below Ground Foul and Surface Water Drainage Design for The Cloud House.
The London Borough of Camden granted planning permission for the proposed development, consisting of a pair of new semi-detached houses. Peter Morris Architects created a joyful design to bring an “element of fun” to the North London neighbourhood.
The planning permission for the ‘self-build’ project didn’t present any conditions relating to Sustainable Urban Drainage Systems (SuDS), as the original design featured a living wall and permeable paving.
However, we advised the client that Thames Water and Building Control will request a reduction in surface water runoff leaving the site via the inclusion of SuDS. Therefore, we discussed the idea of attenuation with restricted flow for each dwelling. This included the locations of the proposed attenuation and storage estimation to get some likely values for the required volume.
There was not much available space on the site for attenuation and other drainage assets. However, to ensure that our solution reduced the surface water runoff leaving the site and any future flood risk, our team looked at various scenarios to ensure that we would provide a viable yet cost-effective solution that would satisfy all relevant parties.
BELOW GROUND FOUL AND SURFACE WATER DRAINAGE DESIGN
Our experienced team advised that the sewerage system near the site would likely be combined. However, in accordance with Building Regs Part H, both Foul and Surface Water require separating until the final manhole before the flows are discharged into the receiving combined manhole.
Therefore, to provide the most cost-effective solution to the client, we proposed a gravity connection to one of the manholes within the site boundary. However, because of the levels at the site, we also had to propose one pumped connection to the main combined sewer on the main road.
The Nimbus team got to work once the client delivered the necessary information and plans. Our first step involved carrying out high-level calculations to understand what storage volumes were likely to be required in our design. We also engaged the clients in a conference call to review our outline proposal; we welcomed feedback and discussed any queries.
The site’s location meant that we also had to consider the foundations from the adjacent school, meaning there was even less available space than we initially thought.
DRAINAGE DESIGN CONNECTION APPLICATION
Further to the client’s approval of the design, Nimbus approached Thames Water to submit a S106 connection application for the proposed design.
In our experience, this procedure often includes extensive liaison with the technician reviewing our design. After a fair amount of correspondence, our skilled team secured the consent.
We successfully submitted the design to the client and eagerly await seeing The Cloud House come to life on Grand Designs. Peter Morris and Emily Kennedy have been delightful clients to deal with, and although this was a tight site, their consideration of source control Sustainable Urban Drainage Systems (SuDS) early in their initial design helped them understand the requirements and need for the attenuation required.
FURTHER ASSISTANCE WITH SURFACE WATER DRAINAGE DESIGN
We hope this project demonstrates how our approach to foul and surface water drainage design can help complete your development projects.
If you have questions about our surface and below ground drainage design services, please email us at info@nimbusengineering.co.uk, call 08000614916, or fill out our contact form.