Comment

Representation ID: 22201

Received: 16/03/2020

Respondent: Environment Agency (Eastern Region)

There are many sites within Norwich which are adjacent to the River Wensum (GNLP2137, GNLP0409R, GNLP0360, GNLP0377, GNLP0401, GNLP0068, GNLP3053), firstly we need to ensure that SuDS within the development are sufficient to protect the water quality of the River Wensum and secondly any opportunities to improve riparian habitat to mitigate against the impacts of the development would help us to secure improvements necessary to meet good WFD status and help ensure that the development does not cause any deterioration.

This site allocation lies mainly in Flood Zone 1 currently, with very small areas of Flood Zones 2 and 3 adjacent to the river. Once climate change is applied to the flood outlines, Flood Zones 2 and 3 extend further into the site. The development must be sequentially sited in future Flood Zone 1 where possible.
If development is required to be sited within these future Flood Zone 3 (1% annual probability with 35% climate change) and Flood Zone 2 (0.1% annual probability with 35% climate change) flood outlines then the more vulnerable development, and ideally the less vulnerable development too, will need to be designed with floor levels raised 0.3m above the flood levels for the future 1% (1 in 100) annual probability flood event with 35% and ideally 65% allowances for climate change. Refuge will also need to be provided above the 0.1% (1 in 1000) annual probability 25% climate change flood levels. Compensatory flood storage will also need to be provided for any built development or land raising within the 1% (1 in 100) annual probability flood outline with 35% climate change.
The requirement to take account of the future flood risk on the site, and design the development to be safe and not increase flood risk elsewhere, as required in the NPPF, should be mentioned within the site allocation.