Draft Local Plan-Part 2 Site Allocations

Comment

Representation ID: 22203

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.

GNLP0377
The very east of the site allocation, adjacent to the river, lies in the present and future Flood Zones 2 and 3. Therefore there should be no development within this small section of flood zones, and the development should be sequentially sited in Flood Zone 1.
As with all development in Flood Zones, the 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 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.

Comment

Representation ID: 22204

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.

GNLP0401
The site lies in present day Flood Zone 2, but once climate change is added to the flood levels, the majority of the site lies in Flood Zone 3a High Probability. If possible the development should be sequentially sited on land to the south in Flood Zone 1.
If development is required to be sited within these future Flood Zone 3 (1%cc) outlines then 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 the south to provide the compensatory flood storage.

Comment

Representation ID: 22205

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.

GNLP0409R
The site lies almost entirely in Flood Zone 2 present day, however once climate change is applied to the flood levels, the site lies mainly in future Flood Zone 3a.
The development should 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.
We note that there is an extant planning permission for the site, to which we had no objection, so these requirements should have already been taken into account.

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.

Comment

Representation ID: 22207

Received: 16/03/2020

Respondent: Environment Agency (Eastern Region)

GNLP0415R-E and GNLP0415R-F
Allocations adjacent to the River Yare of a nature reserve and Country Park (GNLP0415R-E, GNLP0415R-F) are welcomed, especially if we can secure riparian habitat improvements for this often overlooked chalk stream. In Marlingford just downstream we have been working to undertake natural flood management works, we could build on this partnership work to restore a better connection with the flood plain, plant trees and slow the flow.

GNLP0415R-A, GNLP0415R-C
There are two sites adjacent to the River Tud another chalk stream (GNLP0415R-A, GNLP0415R-C), we need to ensure that any water discharging from the development is as clean as possible and that SuDS are sufficient, a WFD compliance assessment must be undertaken. The River Tud has a population of white-clawed crayfish, an endangered species. If there is any opportunity to improve the river habitat to compensate for the additional run off then this would be welcomed.

GNLP0415R-E
The south of this site allocation, adjacent to the river lies in Flood Zones 2 and 3. Our detailed modelling shows that much of the area covered by Flood Zone 3 is actually 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’. As a county park would be classed as ‘water compatible’ development in Table 2 under ‘Amenity open space, nature conservation and biodiversity’ then this would be an acceptable land use within the flood zones, including Flood Zone 3b, providing that it is designed to: ‘remain operational and safe for users in times of flood; result in no net loss of floodplain storage; and not impede water flows and not increase flood risk elsewhere’
Therefore it would be preferable if any associated built development is located within Flood Zone 1, and all development within the flood zones meets the above requirements.
GNLP0415R-F
The north of the site adjacent to the river lies in Flood Zones 2 and 3. Our detailed modelling shows that quite a lot of the area covered by Flood Zone 3 is actually 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’. As a nature reserve would be classed as ‘water compatible’ development under ‘Amenity open space, nature conservation and biodiversity’ then this would be an acceptable land use within the flood zones, including Flood Zone 3b, providing that it is designed to: ‘remain operational and safe for users in times of flood; result in no net loss of floodplain storage; and not impede water flows and not increase flood risk elsewhere’ Therefore it would be preferable if any associated built development is located within Flood Zone 1, and all development within the flood zones meets the above requirements.

Comment

Representation ID: 22208

Received: 16/03/2020

Respondent: Environment Agency (Eastern Region)

GNLP0133-E
The very south west of the site allocation, adjacent to the Broad, is in Flood Zones 2 and 3, both now and in the future with climate change. As this is only a very small part of the site then all built development must be sequentially sited outside of the flood zones in Future Flood Zone 1.

Comment

Representation ID: 22209

Received: 16/03/2020

Respondent: Environment Agency (Eastern Region)

It appears that the site boundary has been drawn to exclude the current and future flood zones just to the east of the site, and therefore the sequential approach has been correctly applied.

Comment

Representation ID: 22210

Received: 16/03/2020

Respondent: Environment Agency (Eastern Region)

It is not clear what is being proposed at Salhouse Broad (Tourism GNLP0157) near Woodbastwick, if there are to be any changes then a WFD compliance assessment must be undertaken to assess the impacts on ecological elements.
The east of the site adjacent to the river is Flood Zone 3 and Flood Zone 2. Part of Flood Zone 3 is also shown to be Flood Zone 3b on our modelling. Ideally all new built development should be sequentially sited to be located within the large area of Flood Zone 1 on the site. However if the tourism uses were classed as ‘water compatible’ then this would be an acceptable land use within the flood zones, including Flood Zone 3b, providing that it is designed to: ‘remain operational and safe for users in times of flood; result in no net loss of floodplain storage; and not impede water flows and not increase flood risk elsewhere’.

Comment

Representation ID: 22211

Received: 16/03/2020

Respondent: Environment Agency (Eastern Region)

It appears that the site boundary has been drawn to exclude the current and future flood zones just to the north of the site, and therefore the sequential approach has been correctly applied.

Comment

Representation ID: 22212

Received: 16/03/2020

Respondent: Environment Agency (Eastern Region)

Many other sites intersect water courses (e.g. GNLP0264, GNLP3024, and GNLP0132), they should undertake a WFD compliance assessment for the watercourse receiving the runoff, maintain a buffer of 20 m between the watercourse and gardens and secure opportunities for riparian habitat restoration.