Comment

Representation ID: 22206

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 in present day Flood Zone 2, but once climate change is added to the flood levels, the entire site lies in Flood Zone 3a High Probability. Therefore the more vulnerable residential development 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 new built development or land raising within the 1% (1 in 100) annual probability flood outline with 35% climate change to ensure no increase in flood risk elsewhere. This will require lowering of higher land in Flood Zone 1 to provide the compensatory flood storage, which may be difficult to achieve, as the entire site is within Future Flood Zone 3a.
However we note that there is an extant permission on the site, and that the development has been designed not to impede water flow, and allow flood storage across the ground floor levels.