Case Study Colchester

The RMPA consortium are currently redeveloping Colchester Garrison to provide serviced accommodation for over 3,500 army personnel and 700 civilian staff. Over 110 buildings are included in the contract, which is expected to be worth around ?2 billion to the consortium over its 35-year life.

The redevelopment covers an area of some 185 hectares of land that has been used by the military since the Roman era. Colchester Garrison was an important barracks during the Napoleonic Wars, throughout the Victorian era and played a prolific role in both world wars preparing and training British and allied troops for combat. Consequently Colchester was heavily defended as it was seen as a significant target and bombed by the German Air Force on numerous occasions during World War Two (WWII). The defence of Colchester during this time included 2,000 volunteers of the Home Guard who possessed over 20 types of weapon including the Vickers machine gun, flame throwers, grenades and 2-pounder anti-tank guns and it is known that anti-aircraft batteries were established on Abbey Field.

With such a broad military history it is unsurprising that historic activities have left a legacy of munitions contamination on the garrison land and in the surrounding area. The RMPA consortium was aware of the risk that unexploded ordnance (UXO) may be encountered during their works and recognised that some form of remediation would be required.

In 2003 RPS Group were appointed as principal contractor for the complete alienation of the new Colchester Garrison, which included consideration of the UXO risk. Due to the size of the project and the level and nature of risk identified a number of different mitigation techniques had to be deployed and the approach has had to evolve over the years that RPS have been working on site. This initial mitigation included proactive clearance and was undertaken in the following phases:

• Initial Risk Assessment & Health & Safety Plan. An initial risk assessment was undertaken to identify the types of munitions that may be encountered and the levels of risk on site. This risk assessment has continually been revised and modified as the development has progressed in order to tailor the mitigation required to the works currently taking place.
• Geophysical Survey. A proactive approach was undertaken to clear as much land as possible by means of geophysical survey. Different methods of survey were deployed dependant upon the ground conditions and the type of munitions the survey was expected to detect.
• Anomaly Investigation. The survey alone cannot identify whether ordnance is present it will only locate ferrous and magnetic items located in the ground. Each item identified by the survey needs to be investigated by an Explosives Engineer to determine whether it is ordnance or ordnance related. During the investigation phase numerous items of ordnance such as Land Service Ammunition and live chemical weapon training units from World War Two were found.

This proactive clearance was undertaken between April & Nov 2003 with BACTEC International acting as the clearance contractor and RPS EES providing the Quality Assurance and consultancy aspects of the project. During this phase of works the following items were identified and removed:

• 131 various types of grenades (71 Live)
• SAA.
• PIAT Bomb.
• Anti Gas Ointment.
• Lachrymatory Training Agents (BBC & Liquidised Adamsite).
• Fire Extinguisher inserts containing Concentrated Sulphuric Acid.

Once the clearance phase of works were completed RPS EES were further successful in winning, by tender, the continued Explosives Engineering support contract, which was put in place by the MOD to facilitate a safe working environment during the construction phases. This aspect of the works is projected to continue for at least 5 years and is due to complete in 2009. RPS EES are currently managing all of the Explosives Engineering support for the main contractor and are ensuring a safe working environment for some 2,500 site personnel.