Effective slope stability and retaining wall design in Swansea demands a deep understanding of the region’s complex glacial and post-glacial geology, governed by standards such as BS 8002 and BS EN 1997-1. Our approach begins with a comprehensive ground investigation, which is critical for identifying the Pennant Sandstone bedrock, overlying glacial till, and soft alluvial clays prevalent across the city and its outskirts. These site-specific conditions, combined with the high rainfall typical of South Wales, directly influence pore water pressure and the long-term stability of both natural and engineered slopes. A thorough desk study and intrusive CPT testing provide the baseline data required to assess shear strength parameters and identify potential failure surfaces.
The core of our analysis relies on robust UK methodologies to determine the engineering properties of local soils. We utilise a suite of In-Situ techniques to capture undisturbed soil behaviour, complemented by precise laboratory testing on recovered samples. For the cohesive tills and clays common in the Swansea valley, defining plasticity through Atterberg limits is essential for correlating with drained and undrained shear strength. Similarly, for the granular head deposits and weathered sandstone, a detailed grain size analysis using both sieve and sedimentation methods informs permeability and effective angle of friction assessments. These parameters are integrated into limit equilibrium and finite element models to produce a design in strict accordance with Eurocode 7, ensuring global stability and serviceability.
Slope and wall engineering in Swansea spans a wide range of projects, from stabilising coastal cliffs along the Gower Peninsula to enabling residential development on the steep valley sides of Morriston and Sketty. A key local application is the design of embedded retaining walls for basement excavations in the city centre’s regeneration zones, where the soft, compressible alluvium of the Tawe River corridor poses a significant challenge. For infrastructure works, we frequently design soil nail and reinforced slopes for road widening schemes, where rigorous on-site quality control is achieved through field density testing using the sand cone method to verify the compaction of engineered fill, ensuring the as-built strength parameters match the design assumptions.
Our process delivers a clear, verifiable design package that takes a project from initial feasibility through to construction sign-off. Following the investigation and analysis phase, we produce a Geotechnical Design Report containing detailed cross-sections, groundwater management strategies, and material specifications. The final deliverables provide contractors with clear earthworks and facing specifications, underpinned by the interpretative data from our physical testing programme. This integrated approach, combining local geological knowledge with precise measurement of soil properties from advanced laboratory and field techniques, delivers a value-engineered slope or retaining wall solution that manages geotechnical risk and provides long-term resilience for your development.