Comment

Representation ID: 22200

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.

The majority of the May Gurney and Deal Ground Site (GNLP0360) is within the flood plain of the River Yare, any development of the floodplain would compromise the natural functioning of the river and the WFD no deterioration objective. There should be a significant buffer between the development and the flood plain. We are working with Norwich City Council on the Yare Valley Parkway green infrastructure corridor, to ensure that the River Yare around the south of Norwich is as good as it can be and to enhance the conservation value of the nature sites along the corridor. Any sensitive development of sections of this land parcel outside of the flood plain should also restore natural habitats within the flood plain.
As stated above, the majority of the site lies in Flood Zones 2 and 3, both now and with the addition of climate change. A significant majority of Flood Zone 3 is shown on our modelling to actually be Flood Zone 3b Functional Floodplain, with an annual probability of flooding of 5% (1 in 20) and classed as ‘land where water needs to flow and be stored in times of flood’. Residential and commercial development, classed as ‘more vulnerable’ and ‘less vulnerable’ development respectively, is not permitted in Flood Zone 3b so the majority of the site will need to be left undeveloped.
As with all development in Flood Zones, 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 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.
We note that there is an extant outline permission on the site, which met these requirements, although climate change allowances have since changed so the required floor levels may be different. This should be addressed as part of the reserved matters applications.