As urban environments become increasingly congested; designers, councils, and other stakeholders increasingly need Basement Impact Assessment and ground movement assessments. These are used to demonstrate that construction activities are well-planned and controlled, and will not result in an unreasonable impact on buildings, infrastructure, or the natural environment.
CGL is an industry leader in providing Basement Impact Assessment services (BIAs) and ground movement assessments to aid the geotechnical design process, reduce risk, and gain regulatory and stakeholder approval for construction projects.
CGL’s work includes:
- Deep Basements,
- Steep Retained Slopes
- Construction Over and Around Existing Sensitive Structures
CGL’s experienced geotechnical engineers use a broad range of design software packages to carry out Basement Impact Assessment and ground movement assessments. These include industry-standard packages such as PDISP (soil displacement), WALLAP (embedded retaining walls), GWALL (gravity retaining walls), and SLOPE (slope stability) to assess ground movements and develop impact assessments.
Where geometry, construction sequences, or ground conditions are complex, CGL uses finite element/finite difference techniques for sophisticated continuum analysis, using software packages including FLAC (2D) and PLAXIS (3D) to model the soil structure movement.
Basement Impact Assessment (BIAs)
CGL has been an early provider of Basement Impact Assessment services (BIAs) following the original guidance document by the London Borough of Camden, which has since been mirrored by other local authorities. CGL has completed over 500 Basement Impact Assessment and Ground Movement Reports since 2011 and its extensive experience within the London area means CGL can address queries and provide a holistic analysis to determine the potential risks accurately and support the planning process.
The Basement Impact Assessment process requires a comprehensive review of surface and groundwater conditions and incorporates geotechnical analysis, where appropriate, to establish ground movements arising from the basement development and therefore its potential impact on neighbouring properties. This is particularly relevant where party wall foundations are to be supported.
CGL increasingly supports its clients with complex soil and structure interaction modelling, using finite element/difference analysis to quantify and control the risks to adjacent or buried infrastructure in support of modern UK and European standards
Finite element/difference analysis represents the state of the art in geotechnical analysis and correctly applied, can generate significant savings in analytical time, effort, and construction costs. CGL’s specialist geotechnical engineers get the most out of the highly versatile PLAXIS software packages.
Slope Stability Assessments
Slope stability assessments are a component of Basement Impact Assessment when construction activities may have an impact on nearby slopes or embankments. The key to a successful slope stability assessment is a strong knowledge of soil behaviour coupled with an understanding of the analytical approaches necessary to balance safety with design efficiency. Successful infrastructure design can require the geotechnical engineer to push cost-effectiveness limits. Maximising slope angles often allows increased developable areas and the reduction of construction materials.
CGL has a long-established track record in the assessment of slope stability from works on road and rail embankments/cuttings as well as the design of reinforced earth slopes and platforms. CGL designs remedial works on failed slopes or emergency stabilisation measures and provides expert opinions in respect of the causes of failures.
CGL’s investment in analytical software allows the company to make detailed assessments of complex ground movements or use predictive modelling and implement the Observational Method to control structures during construction with significant cost savings.
Ground Engineering magazine awarded CGL ‘Best UK Project with a Geotechnical Value Between £1-£3m’ for our work using these techniques at the Subsea 7 headquarters in Sutton, Surrey.
By using targeted site investigation to understand realistic geotechnical design parameters and hydrology, CGL modelled the predicted ground movements in structured chalk. This enabled a pragmatic approach using observational methods with a cost-saving combination of open-cut excavation and King Posts with robust monitoring controls, avoiding a contiguous pile wall solution for a 20,000 cubic meter basement.
Why Choose CGL For Basement Impact Assessment Services?
We are industry-leading experts with a proven track record in providing Basement Impact Assessment services throughout the UK. We ensure accurate risk assessment and support in the planning process having carried out over 500 Basement Impact Assessment reports since 2011.
We offer a comprehensive range of Basement Impact Assessment services including deep basements, steep retained slopes, and construction. We pride ourselves on only using industry-standard design software to conduct all of our Basement Impact Assessment and ground movement reports.
We have a proven track record and well-established reputation in the UK and have received awards confirming our expertise in this area.