Drainage Assessment, Darlington, County Durham
Jan 23, 2017

A Flood Risk Assessment report has recently been undertaken by RAB Consultants to support the development of land near Preston-Le-Skerne, near Darlington in County Durham. The planning proposal seeks to develop the land for holiday residence in the form of camping and caravanning.

The River Skerne is the closest river to the site, located to the north on the opposite side of the east coast mainline. The railway line is positioned on a raised embankment to protect it from flooding caused by the River Skerne.

As the proposed development will see the creation of car parking, hardcore access roads and toilet/shower block, there is a risk of increased surface water runoff from the site which will need to be managed. RAB Consultants therefore prepared a drainage design by:

  • Calculating the infiltration rate of the site.

  • Mapping surface water flow across the site using Flood Modeller Pro.

  • Providing a SuDS drainage assessment and detailed proposals to manage surface water discharge.

The design had to address the limitations of the site, including the geology and position of the railway embankment. A SuDS proposal was designed using:

  • Conveyance System – unlined narrow filter drains to intercept rain that falls on the site, allowing water to soak into the ground should conditions permit.

  • Permeable paving - the development will incorporate an area of hard standing for parked vehicles, this area should be constructed from permeable surfaces allowing rainfall the opportunity to infiltrate into the ground immediately below.

  • Open SuDS Feature – the northern boundary was identified as the preferred location for an open surface water attenuation basin. A geotechnical investigation will be needed along with Network Rail consultation to assess the most appropriate location for the basin.