Flood Risk and Drainage advice for Developers

Please refer to SEPA's Flood Maps (opens new window) . A Flood Risk Assessment (FRA) is required if there is a risk of flooding on or adjacent to the site. 

• All FRAs should consider all types of flooding. 
• All major development applications must include a FRA.

The Council's Supplementary Guidance requires a Self-Certification Process to accompany submitted FRAs:

• All submitted FRAs are required to include a completed Compliance Certificate - Appendix A (PDF, 169 KB)(opens new window)
• All Submitted FRAs for Major Applications are also required to include a completed Independence Check Certificate  - Appendix B (PDF, 191 KB)(opens new window)

All submitted FRAs must accord with the current guidance:

• National Planning Framework 4 (NPF 4) (opens new window) - Policy 22 Flood Risk and Water Management
• SEPA's Technical Flood Risk Guidance for Stakeholders (opens new window)
• Construction Industry Research and Information Association (CIRIA) Manual C624 - Development and Flood Risk Guidance for the Construction Industry (opens new window)

A Drainage Assessment (DA) is required, where applications are:

• greater than 5 houses for residential developments, or
• greater than 250 sqm for non-domestic developments

The DA should cover all aspects of the drainage strategy for the development including wastewater, surface water including SUDS, drainage of landscaped and garden areas and proposals for the management of run-off during construction.

The Council's Supplementary Guidance requires a Self-Certification Process to accompany submitted DAs:

• All submitted DAs are required to include a completed Compliance Certificate - Appendix C (PDF, 167 KB)(opens new window) 
• All Submitted DAs for Major Applications are also required to include a completed Independence Check Certificate  - Appendix D (PDF, 196 KB)(opens new window)
• All Submitted DAs should include confirmation of future maintenance arrangement of sewerage/SuDS  - Appendix E (PDF, 149 KB)(opens new window)
• Please also refer to the Developer Checklist for relevant discussion material for Pre-application, Outline and Full planning applications - Appendix F (PDF, 1 MB)(opens new window)

Post Development Discharge rate.

West Lothian Council aligns with Edinburgh Design Guidance (opens new window).  The proposed discharge rate from a development site should be no greater than the lesser of:

• 1 in 2-year return period (50% probability) greenfield runoff rate, or
• 4.5 l/s/ha of impermeable or positively drained area

Please note that the Council does not differentiate between brownfield and greenfield development.

All submitted Drainage Assessment's must accord with the current guidance:

• Sustainable Urban Drainage Scottish Working Party (SUDSWP) -  Water drainage assessment guide (opens new window)
• CIRIA SUDS Manual C753 - Appendix B: SUDS planning and design processes & The Simple Index Approach (SIA) - SuDS Manual (opens new window)