Foss Basin Improvements

At Castle Mills Island in the centre of York, Keller Geotechnique have installed Pali Radice piles to stabilise the islands quay wall and bullnose walls at Foss Basin as part of a £0.75m improvement programme. The quay wall is originally built in the 18 century on a timber grillage foundation which has been deteriorating for many years as it has been subjected to alternating wet and dry conditions.

Working as Principal Contractor, Keller is repairing, grouting and installing some 80 No 220mm diameter Pali Radice mini piles designed to both reinforce and permanently stabilise the 47m long basin wall.

In York piles are being installed through the masonry walls up to 17m in depth and reinforced with both circular hollow sections and a full depth central bar
The Foss Basin is important because of it connects the higher level River Foss with the River Ouse via a lock forming one face of the triangular island. Thus the integrity of the basin walls to the island is crucial to control and maintain flood protection to this area.

Work started by installing concrete bags to seal the wall below the water line using divers. This provided containment to the voided quay wall substructure, allowing staged consolidation grout injection to follow. Scaffold platforms were then erected along the length of the wall against the wall, allowing piles to be installed safely through the fragile blocks. The quay wall movement was comprehensively monitored throughout the work leaving our Client pleased with our performance both in terms of time and environment.