The Camden Local Plan 2017 includes policy A5 on basement development which updates and expands former basement policies. It places specific restrictions on the scale of basements and their impact. You can object and the Basement Impact Assessment is a good place to start.
Where the proposed development includes a new or extended basement a detailed technical statement must be submitted by the applicant assessing the impact of the development on drainage, flooding, groundwater conditions and structural stability. This information should be contained within a Basement Impact Assessment (BIA) which is specific to site and proposal.
Updated guidance 2018
- Planning Guidance: On 26th March 2018 the Council formally adopted Camden Planning Guidance : Basements. The Guidance was prepared to support the policies in the Camden Local Plan 2017. It should be read in conjunction with the relevant policies in the Local Plan. The Guidance replaces Camden Planning Guidance 4: Basements and Lightwells (July 2015).
- Audit review: Basement Impact Assessments are technical documents which must be prepared in accordance with planning policies and guidance and submitted with planning applications for basement development. The Council obtains independent audits of BIAs from Campbell Reith Consulting Engineers in order to ensure that they meet the technical policy requirements.
- Camden has produced a ‘BIA pro forma’ and a help note on ‘Defining the Scope of Engineering input to preparing BIAs’ in order to help applicants who are preparing planning applications for basement development.
The BIA will be submitted to an independant technical audit by Cambell Reith and covers the following details:
The soundness of :
a) the conceptual model with regards to ground and groundwater conditions
b) the consideration given to structural condition of neighbouring properties
c) identification of the likely impact on land stability and the structural integrity of the neighbouring properties
d) identification of the likely impact on hydrogeology
e) identification of the likely impact on hydrology
f) the scope of completed ground investigations with the presumption that invasive ground investigation should take place in all instances
g) appropriately conservative modelling used in reaching the BIA assumptions including anticipated structural damage categorised according to the Burland Scale, and conclusions (mindful that Campbell Reith shall use professional judgement in respect of calculations in the audit material and are not required to carry out any detailed calculations or checking of specific figures)
h) proposals for ongoing monitoring of groundwater levels
i) measures to ensure the on-going maintenance and upkeep of the basement and ground water management measures
j) temporary works methodologies, requirements and recommendations for construction contractors
k) the inter-compatibility of the assessments, findings and conclusions of all BIA
l) an outline methodology for monitoring and responding to ground water levels and structural movement
m) Identification of relevant cumulative impacts on land stability and local ground and surface water conditions arising from the basement development