As part of their regulation duties a planning authority will need to be satisfied that a development proposal is justified and
that the consequences of flooding are acceptable.
TAN 15 is a technical advice note produced to provide technical guidance to supplement the policy set out in Planning Policy Wales
(PPW), in relation to development and flooding. TAN 15 advises on development and flood risk, and provides a framework within risks
arising from both river and coastal flooding, and from additional run-off from development in any location, can be assessed.
The general approach of PPW and TAN 15 is to advise caution with respect to new development in areas at high risk of flooding by
setting out a precautionary framework to guide planning decisions. The overarching aim of the precautionary framework (in order of
preference), is to:
1. Direct new development away from those areas which are at high risk of flooding.
2. Where development has to be considered in high risk areas (zone C) only those developments which can be justified on the
basis of tests (outlined in sections 6 and 7 of TAN 15), are located within such areas.
Development Advice Zones
TAN 15 contains a development advice map (DAM). Three development advice zones (A, B, C) are described on the maps, which are
attributed different planning actions. Zones A and B areas are areas of generally low risk (i.e. outside the main river flood plain).
Zones C represents the extreme flood outline (equal to or greater than 0.1% flood risk), and is further subdivided into two zones,
C1 and C2.
Zone C1: described as "areas of the floodplain which are developed and served by significant infrastructure, including flood
Zone C2: described as "areas of the floodplain without significant flood defence infrastructure".
Nature of Development or Land Use
As particular flooding consequences may not be acceptable for particular types of development, e.g. allowing residential development
in areas which are subject to high risk of flooding. The precautionary framework identifies the vulnerability of land uses to flooding
by sub-dividing land usage in three categories:
1. Emergency Services including hospitals, ambulance / fire / police / coastguard stations, command centres, emergency depots,
buildings used to provide emergency shelter in time of flood.
2. Highly vulnerable development including all residential premises (including hotels and caravan parks), public buildings
(e.g. schools, libraries, leisure centres), especially vulnerable industrial development (e.g. power stations, chemical plants,
incinerators), waste disposals sites.
3. Less vulnerable development including general industrial, employment, commercial and retail development, transport and
utilities infrastructure, car parks, mineral extraction sites and associated processing facilities, excluding waste disposal sites.
Justifying the Location of Development (Section 6)
Section 6 of TAN 15 provides detail in relation to justifying new development within zones C1 and C2.
TAN 15 states that:
'new development should be directed away from zone C and towards suitable land in zone A, otherwise to zone B, where river and coastal
flooding will be less of an issue'.
'...highly vulnerable development and Emergency Services in zone C2 should not be permitted. All other new development should only be
permitted within zones C1 and C2 if determined by the planning authority to be justified in that location'.
Assessing Flood Consequences (Section 7)
A development proposal meets the tests outlined in section 6 of TAN 15, the justification will be in the knowledge that those
developments will flood and will need to be planned accordingly.
Whether a development can proceed will depend upon whether the consequences of flooding of that development can be managed down to an
Further details on the assessment of flooding consequences is given in Section 7 and Appendix 1 of TAN 15.
Undertaking Flood Consequence Assessments
It is stated in TAN 15 that 'The first step in undertaking an (flood consequence) assessment must be for developers to consult the
Environment Agency about the objectives of the assessment'.
Appendix 1 of TAN 15 provides further guidance on what is required when producing a Flood Consequence Assessment.