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Somerset: Durleigh WTW Secant Piling



Wessex Water


Wessex Water Engineering & Construction Services

Durleigh, Somerset

DAWSON-WAM was contracted by Wessex Water Engineering & Construction Services to install a 24.25 x 28.75m secant piled box, capable of retaining an internal excavation of 5.5m.

Durleigh Water Treatment Works, located on the outskirts of Bridgwater, Somerset, is owned and operated by Wessex Water. The major overhaul of the works coupled with ongoing maintenance to the local water network represent a significant investment to improve the quality of the drinking water within the Bridgwater and surrounding areas.

DAWSON-WAM installed 630mm diameter Cased CFA piles to a depth of 11.5m through firm mudstone, forming a robust hard/hard secant wall which, coupled with the construction of a capping beam and installation of temporary propping, supports the excavation and installation of internal structures.

In order to protect employees and reduce HAVS activities during the construction process, Wessex Water Engineering & Construction Services, in conjunction with consultants AECOM, proposed the innovative use of Ancon Shear Connectors within the steel reinforcement of the secant pile retaining walls to eliminate the requirement for post-installation dowelling of the secant piles. Typically used within traditional concrete wall/slab construction, Ancon Shear Connectors transfer shear loading and enable movement across construction joints.

Working with their supply chain, DAWSON-WAM proposed construction details to ensure sufficient shear capacity within the connection and developed installation methods to enable the shear connectors to be carefully installed to the correct position and orientation.