Westminster

Basement Construction Method Statement

Planning is a legal procedure to which standard questions are applied.   Croft Structural Engineers has developed and continues to evolve its documents to ensure that they meet the Council’s planning requirements. 

Westminster Council require that at planning all Basement construction complies with their Development Management Development Plan document (DM DPD). 

Westminster Council requires that a Basement Construction Method Statement be prepared.  as part of the application.  This document clarifies:

• Details of subsoil
• Groundwater from a recent investigation
• Method of excavation formation including temporary supports and sequence of construction
• This Basement Construction Method Statement needs to be completed by a Structural Engineer

The purpose of this is to highlight that at planning adequate investigation has been completed on the site to demonstrate works can be undertaken without risk or that any risks can be mitigated.  This report is not adequate for building control or party wall, but should form the basis and underline any further work.
A construction management plan may also be required by planning condition:  This is outside the brief of Croft Structural Engineers Ltd.

Croft Structural Engineers provides a service and this covers:

• Site Inspection

• Meeting with an engineer to discuss the needs of the projects and specific requirements
• Walk over survey to determine what the requirements of the site are
• Review of local trees (not a full arboricultarlist report, but one can be commissioned)
• Review of adjacent buildings where access is available
• Are there signs of subsidence locally

 

• Testing

• Arranging soil investigation report

• Bore holes to confirm ground and water tables
• Reports by a geotechnical engineer

• Arranging Hydrology report

 

• Desk Study – This forms the bulk of the Basement Construction Method Statement and will cover

• Structural Schemes of internal layouts

• Proposed use and loadings
• Retaining wall designs
• Anticipate deflections of retaining walls.

• Local Stability

• Highway loadings
• Ensure that the scheme “Maintains Structural Stability of the building & Neighbouring Properties”.
• Suggestions for monitoring during the works of neighbouring buildings.
• Are there slopes that may slip?
• Are landslides a concern?
• Are there signs of subsidence locally?
• Is network rail of the underground near?
• Are there listed buildings close to the site that may be affected?

• Water Flow and Hydrology

• Review of local water tables.
• Will the development affect London’s Main aquifer
• Will drinking water supplies be affected.
• Local water course reviewed within 100m
• Are we close to drift deposits – springs are likely to occur near changes in ground from sands to clays.

• Flood Risk Assessment

• Review on flooding
• Comment on whether the development may affect the Hampstead Heath Swimmers.
• Avoid Adversely Affecting drainage and Run off.
• Review of environment agency information

• Loss of Open Space or Trees

• Review of local trees, their location and the affect the basement may have.
• Arrange appointment of Arboricultarlist if many or impart trees are to be affected.

• Construction Process

• Method statement on how the contractor should approach the work to safely complete the design.
• Recently added is the initial temporary design details for the basement.