A geotechnical and geoenvironmental site investigation was carried out in connection with the redevelopment of West Suffolk College campus in Bury St Edmunds. The project involved the demolition of some of the existing education facilities and the construction of four multi-storey buildings, associated car parking and site access roads.
A site investigation was carried out by RSA Geotechnics, under the directions of Pick Everard, the architects and consulting engineers for the project.
The college campus occupies the site of the former Gibraltar Barracks which was built in 1878. The barracks was the military training depot for the Suffolk Regiment until 1959. Despite the military history no evidence was found to suggest any risk due to unexploded ordnance. However, old chalk workings were known to exist within 100m of the site. The ground investigation was designed to check whether these extended into the proposed development area.
During the investigation the site was accessible to the public and college users. Particular attention had to be given to the safety by careful planning and fencing around the exploratory positions. Although utility service drawings were available surface scanning with a cable avoidance tool and precautionary inspection pits were hand dug to ensure no local services supplies were interrupted or damaged.
Previous investigations by others provided evidence of the old chalk workings. These were reviewed and supplemented by our local knowledge. The investigation was then extended and modified to concentrate exploratory holes in the area where the risk of workings was greatest. One exploratory hole revealed ground conditions which were considered possible evidence of a working. Further intrusive investigation and dynamic probing in the vicinity allowed the risk to be assessed in more detail with the conclusion that no workings were present.