4.96

Increase the distances

We consider the distances from fluvial waters and tidal waters (8m and 16m) to be insufficient.

WGPC supports this policy intent.

A contingency should be made as a fallback position should these WwTW improvements not be delivered in time

We do have concerns in relation to Policy NE16 (Water Management and Water Quality) and the potential overreliance on necessary improvements to the wastewater treatment works (WwTW) to support residential development. The emerging plan makes it clear that that upgrades to wastewater infrastructure will be necessary to manage the increased wastewater from housing growth over the plan period. The emerging plan relies on the upcoming Southern Water Drainage and Wastewater Management Plan (DWMP) to provide solutions for conveyance and treatment of wastewater over the next 25 years yet there is no fallback position should these WwTW improvements not be delivered in time. Southbourne currently drains to Thornham wastewater treatment works, which is heavily constrained, with the SoCG between CDC, the Environment Agency and Southern Water stating, “whilst no definite showstoppers to treating wastewater from new homes across the plan period have been established, it is clear that providing significant additional capacity at Thornham WWTW is dependent upon significant infrastructure improvements”.

Please see our comments on this policy.

The following amendments are recommended for Policy NE15.

- We recommend an amendment and addition to the sentence regarding the 8 metre and 16 metre set back:

“Elsewhere, new development should be set back at least 8 metres from the top of the bank of fluvial watercourses (including culverts), and 16 metres from tidal watercourses to allow for easy access for maintenance and repair. Ideally, a buffer greater than 8 metres from any fluvial watercourse (10 metres plus) without any significant equipment or buildings present in it should be provided to provide additional biodiversity benefits alongside flood risk management.”

To reflect the above, paragraph 4.96 should also be amended:

“The policy includes a setback requirement to ensure there is a suitable buffer access strip free from development between watercourses, culverts and sea defences. Such buffers allow for access for maintenance and repairs. Environment Agency consent is required for any works within 16 metres of sea defences and 8 metres of the top of the bank of classified main rivers or a culvert in line with the Environmental Permitting Regulations 2016. ”

- Point 4 requires amending as follows to be in line with the national Flood Risk Standing Advice:

“For vulnerable development, finished floor levels should be a minimum of whichever is higher of 300mm above the:
• average ground level of the site
• the adjacent road level to the building
• predicted significant fluvial/tidal flood level (Fluvial 1 in 100 year / Tidal 1 in 200 year plus latest climate change allowances) for the lifetime of the development.

- We recommend an additional requirement to be added to the list for development in flood risk areas as follows to reflect the Planning Practice Guidance for Flood risk and coastal change (as updated in August 2022):

"Development will only be allowed in flood risk affected areas where, in light of this assessment, and the sequential and exception tests as applicable, it is clear that:
…
f. Where applicable, any loss of flood storage from any source of flooding in the fluvial floodplain is being should be compensated for on a level-for-level basis, ideally on-site. Compensation should be hydraulically and hydrologically linked to the floodplain, but not within it. The loss of floodplain storage is less likely to be a concern in areas benefitting from appropriate flood risk management infrastructure or where the source of flood risk is solely tidal."