CDC Compaction at Berth 9 Quay Extension Felixstowe, UK

In February 2015 Cofra Dynamic Compaction (CDC), a heavy Rapid Impact Compaction (RIC) technique to compact granular subsoil, was performed on the Berth 9 Quay Extension project in Felixstowe, UK. The extension consists of a 15.000m2 reclamation between sheet pile walls. The compaction of the reclamation was required to reduce future settlements and improve the properties of the sand behind the quay wall. An extensive compaction trial was performed before the start of the project to assess the compaction procedures and work method in relation to the specifications but also to assess the impact of the compaction on the Quay wall. Compaction effort was monitored during compaction with the use of the crane monitoring system which registers the (induced) settlement with increasing blows. The effect of the compaction has been measured with the use of pre- and post-compaction CPT's. The main quay wall displacements were continuously monitored by a manual station and a robotic total station. During the trial an inclinometer was used to gather more data. The paper focusses on the gathered data, findings and observations during the project and the compaction trials.