Cremorne Wharf drop-shaft excavation complete

Excavation of a 45m-deep shaft at Tideway's Cremorne Wharf Depot site has been completed. 

The giant drop-shaft will be an integral part of the new sewer system as it will transport intercepted sewage to the depth of the main tunnel being constructed deep below the River Thames. 

Two methods of excavation were used to construct the shaft. Intersecting concrete piles were installed around the shaft perimeter to a depth of approximately 16m and the area within was excavated.

The remaining 29m were completed using sprayed concrete lining. This technique involves digging down 1m before spraying the exposed ground below the existing structure with concrete to stabilise it. 

To complete the structure, a 2m base slab was constructed by continuously pouring concrete, ensuring a consistent quality. 

From this base slab, a 145m-long tunnel will be built to connect the shaft to the main 25km super sewer tunnel currently being constructed deep below the River Thames.