Sandsend, Whitby, North Yorkshire - Excavation Support

Feasibility studies by others indicated an expensive anchored double row large diameter bored pile wall would be required to stabilise and support a 5m deep excavation at the base of a sea-side slope to enable construction of a terrace of houses on a gap site in Sandsend, North Yorkshire. Byland Engineering were approached by the housing developer and commissioned to value engineer the retention system which was both over budget and impractical to construct. 

The site was previously occupied by low rise masonry garage structures. Following partial demolition, the slope to the rear was temporarily retained by the former garage walls and floor slab with additional screw props at close centres. Closely adjacent to this gap site to the north and south are other residential and community building structures. Thus access for large and heavy piling equipment, such as is necessary to construct CFA piles, was not feasible.

Discussions were held with a number of piling contractors to identify the plant and techniques that were both suitable and practical for the site conditions.  A solution was devised comprising a main single row bored wall using 600mm diameter hollow stem sectional flight auger (SFA) piles at 750mm centres plus self-drill tie backs built into a capping beam at the rear of the site.  Flanking retaining walls were designed as grouty structures using mass concrete. 

Byland Engineering undertook the Eurocode compliant design of all the walls preparing drawings, specifications and bar bending schedules for construction.  In addition, the difficult temporary works piling platform design was undertaken by Byland Engineering, providing a one-stop shop for the client. 

Following installation of the retaining wall, the developer quickly constructed the 3 storey residential properties from a convenient flat street level base.