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Do I need a Flood Risk Assessment or Drainage Assessment?

Flood Risk Assessments UK

Do I need a Flood Risk Assessment or Drainage Assessment?

There are various reasons why you may be asked for or require a flood risk assessment or need to consider drainage. A useful first point of reference is the Environment Agency Flood Map which provides a national representation of areas considered to have an increased risk of flooding from fluvial (rivers) and tidal sources, surface water and reservoirs.

FLUVIAL AND TIDAL

This map is for land-use planning. If you are planning a development,.

Flood Zone 1 is the low flood risk area which is land assessed as having a less than 1 in 1,000 annual probability of river or sea flooding (<0.1%).

Flood Zone 2 the medium flood risk area comprises land assessed as having between a 1 in 100 and 1 in 1,000 annual probability of river flooding (1% – 0.1%), or between a 1 in 200 and 1 in 1,000 annual probability of sea flooding (0.5% – 0.1%) in any year

Flood Zone 3 the high flood risk area is land assessed as having a 1 in 100 or greater annual probability of river flooding (>1%), or a 1 in 200 or greater annual probability of flooding from the sea (>0.5%) in any year.

These flood zones refer to the probability of river and sea flooding, ignoring the presence of defences.

SUFACE WATER

The shading on the map shows the risk of flooding from surface water in this particular area.
The Environment Agency flood map for Surface Water divides England and Wales in to areas with a very low, low, medium and high risk of surface water flooding.

‘Very low’ means that each year this area has a chance of flooding of less than 1 in 1000 (0.1%).
‘Low’ means that each year this area has a chance of flooding of between 1 in 1000 (0.1%) and 1 in 100 (1%).
‘Medium’ means that each year this area has a chance of flooding of between 1 in 100 (1%) and 1 in 30 (3.3%)
‘High’ means that each year this area has a chance of flooding of greater than 1 in 30 (3.3%).

RESERVOIR FLOODNG

Reservoir flooding is extremely unlikely to happen. There has been no loss of life in the UK from reservoir flooding since 1925. All large reservoirs must be inspected and supervised by reservoir panel engineers. As the enforcement authority for the Reservoirs Act 1975 in England, we ensure that reservoirs are inspected regularly and essential safety work is carried out.

However, in the unlikely event that a reservoir dam failed, a large volume of water would escape at once and flooding could happen with little or no warning. If you live or work in an area that could be affected, you should plan in advance what you would do in an emergency. You may need to evacuate immediately. Consider where you would go to safety, and be ready to follow the advice of emergency services.

The shading on the map shows the area that could be flooded if a large reservoir were to fail and release the water it holds. A large reservoir is one that holds over 25,000 cubic metres of water, equivalent to approximately 10 Olympic sized swimming pools.

NATIONAL PLANNING POLICY FRAMEWORK

Where your property is identified by the Environment Agency’s national flood map as an area of increased flood risk a flood risk assessment will routinely be required as part of any planning application submitted to your local planning authority in accordance with the National Planning Policy Framework guidance.  Even when no risk of flooding to an area exists, the sustainable management of surface water remains a fundamental consideration of the planning application process.

CODE FOR SUSTAINABLE HOMES

For many developments benefitting from existing planning consent, it is a common planning requirement for residential development to be compliant with the Code For Sustainable Homes (CfSH) Design Standard. The Sur 1 and Sur 2 sub-criteria of the CfSH technical guidance consider the sustainable management of surface water and flood risk to a site respectively. Up to four credits are available under the combined Sur 1 and Sur 2 criteria often meaning that they are an invaluable component to achieve the required Code rating for a development.

BREEAM

New, non-residential development may be required to comply with the BREEAM design standard as a condition of planning consent or for prestige.

The Pol 03 sub-criteria of the BREEAM technical guidance consider the flood risk to a site and the sustainable management of surface water respectively. Up to four credits are available under the combined Pol 03 criteria often meaning that they are an invaluable component to achieve the required BREEAM rating for a development.

BUYING, SELLING, OR INSURING PROPERTY AND FLOOD RESILENCE

Where your property is identified by the Environment Agency’s national flood map or other sources as an area of increased flood risk, insurance companies, lenders and property buyers will often ask for more detailed assessment of both the probability of flooding and its severity when a generalised flood risk to an area is identified. The Association Of British Insurers acknowledges the benefit of a property-level flood risk assessment  but you should always check with your insurer before you commission this work to see if they are able to take surveys into account when assessing your application for insurance.

Sometimes, even when there is no direct requirement for flood risk assessment, the owners of property will seek to remedy existing or future flood risk issues regardless of buying, selling, or insurance matters.

About

We offer Flood Risk Assessment and Surface Water Drainage services. This is including Sur 1 and Sur 2 Code for Sustainable Homes Asssesments. This covers all types and scales of development throughout the UK where flood risk and surface water drainage information is requested by the Local Planning Authority.

Services

Flood Risk Assessments
Surface Water and foulwater strategy and design
Code for sustainable homes sur 1 and sur 2
BREEAM pol3 and pol 5
Basement impact assessments
Sewer diversion and build-over applications
Flood Defence consent applications
Sequential and exception test reports