If you’re preparing to submit a planning application that includes basement development, you may receive a request from the Local Authority for a ‘basement impact assessment’ (commonly referred to as a ‘BIA’.) It may also be referred to as a ‘Basement Method Statement’ by some Local Authorities.
Basement development can raise some concerns – there is a potential for development to cause issues with groundwater levels and surface water/sewerage flooding, as well as the possibility of a loss of local environmental features such as gardens, trees and biodiversity.
You will need to ensure your proposed basement development is appropriate and that policies have been met where required.
It won’t just be your Local Authority you will need to appease – there are other regulations and policies that should be met, such as Building Regulations, Environmental Health standards and Utility Provider requirements.
So, what is a Basement Impact Assessment?
A BIA should justify your proposed development and consider its potential impacts. The assessment should be specific to the site and its proposed development.
It should be noted that there is no national guidance on how to produce a BIA, so you need to review your Local Authority’s guidance closely. Local Authorities will have their own requirements for the assessment – GeoSmart have worked on a number of basement impact assessments across the country, though London boroughs tend to be the most concerned and stringent when it comes to basements, no doubt due to space restrictions within the city.
What are the stages of a Basement Impact Assessment?
What kind of investigation may have to be carried out to support my Basement Impact Assessment?
Site Investigation will be required to present evidence on your findings. This could include:
Which Councils require a Basement Impact Assessment?
As mentioned earlier, London Boroughs make up much of this list. Research by Newcastle University has showed that Hammersmith and Fulham, Kensington and Chelsea, and Westminster have had the most basement developments on record in London, so it’s likely they will require a BIA to be submitted with your planning application.
Where can I get a Basement Impact Assessment?
GeoSmart can assist you with the initial screening stage required for a BIA – our report contains information on surface water features and uses flood risk data to provide context for the development and associated BIA. We will complete the assessment up to a stage as detailed as possible without a site investigation. We can then recommend a supplier to undertake the site investigation and further works. A Chartered Geologist (C.Geol) and a member of the Chartered Institution of Water and Environmental Management (CIWEM) always validates our BIAs according to the requirements set out in the widely referenced Camden CPG4 guidance.
Contact us today to see how we can help you.