Object

Representation ID: 56015

Received: 05/10/2020

Respondent: Endurance Estates

Agent: Barton Willmore

Draft Policy 4c requires the implementation of a Sustainable Drainage System (SuDS) across NEC in accordance with the Cambridgeshire Flood and Water SPD in order to minimise the risk of flooding. The policy goes on to require priority to be given to the use of environmental improvements, with SuDS naturalised to enhance green and blue infrastructure.

The accompanying Cambridge Northern Fringe East Area Flood Risk Assessment confirms that pluvial flood risk will be a constraint on any development proposals and areas of open space will be required to manage this risk, which may have an impact on the deliverable density of any proposals. To address this, the separate report on Surface Water Drainage Space Allocation for Master Planning (2019) advises total storage requirements for the area of approximately 120mm per square meter of impermeable surface, depending on the type of feature. This would equate to between 10-15% of the overall development parcel with interception storage requirements met through green/blue roofs, rain gardens, permeable paving and other vegetated features. As the site has limited gradient, the majority of the features should be on the surface and swales used to convey the water long distances to minimise any pumping requirements.

Reliance on underground attenuation tanks will likely increase where densities are higher within the AAP and open space is limited. The overall quantum and density of development shown in the spatial framework raises the question of how the surface water demands of the AAP will be met satisfactorily when considering the preference shown by the LLFA on other sites for open surface solutions such as swales – an example being Land North of Cherry Hinton