Environmental Impact :: Flood Risk Assessments

Summary and Conclusions

9.1 Existing Conditions

This Flood Risk Assessment covers the area identified as the Seaton Regeneration Area comprising the Application Site and adjoining land alongside the River Axe.

The area is currently a defended site lying in a low lying category at risk of flooding from the River Axe Estuary.

The site is confirmed as being in a Flood Zone 3(a) high risk area, with significant areas lying within the once-in-200 year tidal flood plain.

9.2 Siting

It is proposed to redevelop the Regeneration Area for residential housing and flats with some areas allocated for retail and leisure employment (i.e. shops, hotel, public houses etc).

The reuse of the holiday camp and adjoining areas offers substantial potential for positive economic, social and environmental development enhancement in Seaton.

Whilst residential uses are a sensitive land use, existing flood defences can be enhanced together with proposed raising of levels to above

required 1 in 200 year flood levels to accommodate such a sensitive land use.

9.3 Proposed Conditions

A scheme is proposed which features -

• a design lifetime of 75 years for the residential development;

• a design life of 50 years for the commercial & retail development;

• increased ground levels, raising the site above the once-in-200 year extreme event tidal flooding level;

• residential building ground floor levels (75 year design life) 4.11m AOD;

• external paved areas generally at 3.96m AOD (to provide escape to residential property;

• commercial & retail buildings ground floor levels at 3.96m AOD;

• external paved areas generally at 3.81m AOD around retail / commercial areas;

• appropriate ‘SUDS’ techniques consisting of a widening of the Rhyne by means of a berm to provide surface water attenuation, supplemented by soakaways where practicable;

• new or improved flood escape routes from Harbour Road and The Underfleet;

• the provision of sea defence walls alongside the River Axe to defend the Axe Riverside development;

• an early warning system and evacuation management plan to facilitate emergency escape, together with the provision of refuges within the site.

9.4 Impacts

The site will remain a partially defended site but should these defences be breached the land raising behind the defences will adequately keep water away form the habitable areas. This also removes the risk of the tide-locked surface water flooding.

The foregoing proposals do not increase flood risk offsite.

The foregoing proposals achieve or exceed the minimum level of defence recommended by PPG 25, and accord with the proposals contained in draft PPS 25 (December 2005).

9.5 SUDS

There will be a nominal reduction in surface water discharge due to some roof water harvesting for on-site use, together with some infiltration drainage where this is environmentally appropriate and sustainable.

9.6 Conclusion

The scheme proposed adequately meets the standard criteria for acceptable flood risk and satisfies and exceeds the requirements of PPG 25.

 

 

The following Appendices can be viewed as part of the Outline Planning Application lodged at the offices of East Devon District Council:

Appendix A

Site Location Plan/ Topographic Survey

(Ref: P8877/G203/A)

Appendix B1

Pegasus’ Indicative Master Plan

(Ref:T.0129_08_24)

Appendix B2

Proposed Surface Water and Proposed Foul Water Drainage Strategies

(Jubb Consulting Engineers’ Drgs

P877/H100/D & P8877/H101/D)

Appendix B3

Contoured Plans of The Underfleet and Harbour Road

(indicating low points and flood water escape routes):

Key Plan Drawing No P8877/G304/A

plus “tiles” 1 to 14

Appendix C

Environment Agency Indicative Flood Map

Appendix D

Detailed Sea State and Drainage Calculations

* Application Site: pages 1 – 93 plus supplementary pages 94-97 and 112-177

* Axe Riverside site: pages 98-111

Appendix E1

Survey of Sea Defence Wall levels

(Jubb Consulting Engineers’ Drg No P8877/G204/A)

Appendix E2

South West Water’s Drainage (SWIMM) Plans for Seaton

(2 plans + 4 legend sheets)

Appendix E3

Catchment Plans

(Jubb Consulting Engineers’ Drgs P8877/G202/C and P8877/G205/B)