Marine UXO Target Investigation

Overview

The end client, RTE, required the site to be clear of all UXO targets prior to the installation of two 225 kV Cable Links connected from the landfall transition joint located at Bernières-sur-Mer to the Windfarm Offshore Substation.

Challenging Environment

The re-acquisition of pUXO targets at the marine and beach sites could not have been more challenging for the operations due to the heavy WW2 activities during the Normandy landings of June 1944.

Following the geophysical survey and target identification phase, seabed anomalies were assessed as potential UXO (pUXO) targets and earmarked for investigation. The main project challenge was to complete the work scope without causing disruption to the scheduled start date for the scallop fishermen.

Solution

The proposed solution was to divide the target areas into three separate locations which overlapped. For the offshore section the use of MV Relume fitted with a work class ROV and TS440, carrying out 24hr operations. For the nearshore section the use of the Diving Support Vessel (DSV) Susanne A carrying out 12hr operations and the beach section was completed by three two-man teams using hand-held magnetometers and plant for excavation.

The final target numbers investigated far exceeded the initial survey data – 421 across Offshore, Nearshore and Beach. Of these targets, the cUXOs and were safely destroyed by the French Navy.

Summary

For all areas the project was successfully completed and the end client furnished with ALARP certification for every investigated pUXO position identified by the survey.