Flood Risk Assessments

Flood image

Flood Risk Assessments

Qualitative flood risk assessments undertaken for new single dwellings, basement or other extensions and for multi storey residential and commercial developments.

Flood risk assessments are required for major developments and for any development in an area at risk of flooding. The types of potential flooding to be considered include:

  • rivers and the sea
  • surface water
  • reservoirs
  • groundwater


New Basement for a Property in Chelsea

To the left is a property in Chelsea for which we undertook a flood risk assessment.

The project comprised an extension & refurbishment including construction of a new basement.

The Flood Risk Assessment determined that there was a low level of risk of the site from surface water, sewers and groundwater should a 1 in 1000 event occur.  The risk to the site from rivers, seas and reservoirs, canals and other artificial sources was determined as negligible, similarly the residual risk from overtopping or a breach of the River Thames defences.

The use of flood protection measures and water resilient and resistant construction will help to protect the development if the I in 1000 year event occurs and the other mitigation and management proposals will ensure that the site is safe from all sources of identified flooding without increasing flood risk elsewhere.

Four & Five-Storey Development in Deptford

To the right is a schematic of 73-79 Childers Street, Deptford SE8 5JR, our brief was to provide a phase 1 environmental report and a flood risk assessment.

The site is comprised the former British Legion building with its small service yards along Arklow Road. The site is in close proximity to a railway viaduct with immediate context made up of public open space, industrial and residential usage.

The development comprised 26 apartments distributed over a  block ranging from four to five storeys and including 348m² ground floor commercial floor space. Associated with these are amenity roof terraces, balconies and car parking.

The Flood Risk Assessment found that while the site lies within the flood plain of the River Thames and benefits from flood defences there is a residual risk of flooding at the site due to the possibility of either over topping or a breach of the these defences. In the FRA we were able to demonstrate that with appropriate mitigation there was no significant elevated risk posed to public health and safety.

If required drainage strategies and SuDS maintenance plans can be produced to accompany the flood risk assessment.

Schematic image

Need a Flood Risk Assessment