Explosive Ordnance Threat Assessment in respect of RAF Alconbury for Buro Four 3870TA 19th April 2012 BACTEC International Limited 37 Riverside, Sir Thomas Longley Road, Rochester, Kent ME2 4DP, UK Tel: +44 (0) 1634 296757 Fax: +44 (0) 1634 296779 Email: [email protected] www.bactec.com Registered in England No. 2601923. VAT Registration No. GB 573 6627 13 Buro Four RAF Alconbury This document was written by, belongs to and is copyright to BACTEC International Limited. It contains valuable BACTEC proprietary and confidential information which is disclosed only for the purposes of the client’s assessment and evaluation of the project which is the subject of this report. The contents of this document shall not, in whole or in part (i) be used for any other purposes except such assessment and evaluation of the project; (ii) be relied upon in any way by the person other than the client (iii) be disclosed to any member of the client’s organisation who is not required to know such information nor to any third party individual, organisation or government, or (iv) be copied or stored in any retrieval system nor otherwise be reproduced or transmitted in any form by photocopying or any optical, electronic, mechanical or other means, without prior written consent of the Managing Director, BACTEC International Limited, 37 Riverside, Sir Thomas Longley Road, Rochester, Kent, ME2 4DP, United Kingdom to whom all requests should be sent. Accordingly, no responsibility or liability is accepted by BACTEC towards any other person in respect of the use of this document or reliance on the information contained within it, except as may be designated by law for any matter outside the scope of this document. Distribution Copy No. Format Recipient 1 Print Copy Buro Four 2 PDF Copy Buro Four 3 Print Copy BACTEC International Limited Date of Issue: 19th April 2012 Copy no. 2 Originator: OTB This Report has been produced in compliance with the Construction Industry Research and Information Association guidelines for the preparation of Detailed Risk Assessments in the management of UXO risks in the construction industry. Report: 3870TA ii BACTEC International Limited Buro Four RAF Alconbury Glossary of Terms AAA Anti-Aircraft Artillery ARP Air-raid Precautions BDO Bomb Disposal Officer EOD Explosive Ordnance Disposal (current term for “bomb” disposal) HE High Explosive HG Home Guard IB Incendiary Bomb kg Kilogram LCC London County Council LM Land Mine LSA Land Service Ammunition (includes grenades, mortars, etc.) Luftwaffe German Air Force m bgl Metres Below Ground Level MoD Ministry of Defence OB Oil Bomb PM Parachute Mine RAF Royal Air Force SI Site Investigation SAA Small Arms Ammunition (small calibre cartridges used in rifles & machine guns) USAAF United States Army Air Force UXB Unexploded Bomb UXO Unexploded Ordnance V-1 “Doodlebug” the first cruise type missile, used against London from June 1944. Also known as ‘Flying Bomb’. V-2 The first ballistic missile, used against London from September 1944 WWI First World War (1914 -1918) WWII Second World War (1939 – 1945) Report: 3870TA iii BACTEC International Limited Buro Four RAF Alconbury Executive Summary The Site: The site is located just north and east of the villages of Alconbury, Little Stukeley and Great Stukeley in Cambridgeshire. It is mostly bound by agricultural fields however a railway line is present immediately east and the A1 and B1043 border the site to the south-west. The majority of the study area, centred on the approximate National Grid Reference: 521572, 276540, is currently occupied by RAF Alconbury airbase. The site boundary currently includes runways, taxi ways, dispersal pans, numerous hangars, a WWII-era technical site, a post-WWII bomb dump, many other ancillary buildings and also a large agricultural area to the south-east of the airbase perimeter. Proposed Works: A large mixed use development is proposed over the entire site. Note however that many parts of the site will not require intrusive work as they will become open spaces or woodland. No precise details regarding the types and depth of the proposed intrusive works were available during the production of this report. Risk Assessment Methodology: In accordance with CIRIA guidelines this assessment has carried out research, analysed the evidence and considered the risks that the site has been contaminated with unexploded ordnance; that such items remained on site; that they could be encountered during the proposed works and the consequences that could result. Appropriate risk mitigation measures have been proposed. Explosive Ordnance Risk Assessment: BACTEC concludes that there are areas of Low/Medium, Medium/High and High risk at the site of the proposed development. This is based on the following factors: Allied Unexploded Ordnance Risk o The site is partially situated within the historic perimeter of RAF Alconbury, a WWII-era/Cold War-era airbase. Experience has shown that the ‘housekeeping’ at historic RAF/USAAF stations was often poor with unwanted or unused ordnance sometimes buried, burnt, lost or otherwise discarded within or in close proximity to the airfield perimeter. Furthermore, the requirement for a swift post-WWII USAAF exit from England meant that some American military equipment was simply abandoned, poorly disposed of or buried within or close to their bases. o Previous BACTEC work on several former RAF stations has shown that the former bomb stores and dispersal pans/aircraft armament areas (where aircraft were loaded with weapons), have a higher risk of UXO contamination. As these features were/are located within the study area, the risk of encountering such munitions is elevated. BACTEC also recently exhumed WWII British HE bombs buried outside the perimeter of RAF Oakington, a WWII RAF Bomber Command base. o 1946 RAF Alconbury site plans show that several defence huts, pyrotechnics stores, armouries and gunnery ranges were positioned around the airfield, away from the bomb dump. The locations of these features will also have a slightly heightened risk of UXO associated with them. o Home Guard units and possibly regular army units are likely to have carried out guard duties and training within and in close proximity to the base. During such activities small arms ammunition and land service ammunition (grenades, mortars, etc) would have been issued to personnel, increasing the chance of UXO contamination. o If UXO remains at RAF Alconbury it is more likely to be of WWII-era because the frequency and intensity of operations during this period, coupled with a generally more relaxed attitude towards health and safety meant that items of UXO were more likely to be misplaced or buried. Although RAF/USAF rules and regulations regarding handling and storage of munitions have become increasingly more stringent in the post-WWII period, the possibility cannot be discounted that American UXO from the period 1953 – 1995 could be encountered on site, particularly in the current bomb dump facility, to the north. German Unexploded Ordnance Risk o Due to its rural nature, Alconbury was situated in an area of low bombing density throughout WWII. The only viable Luftwaffe targets in the region were several RAF airfields including that which occupied the site. The presence of this facility did locally raise the bombing density however. Records indicate that three small scale air raids were made on the airbase between 1940 and 1941. These attacks resulted in 46 HE bombs recorded on and close to the airfield. o Levels of access will have been variable across different parts of the site. Generally the main airfield site and communal area to the west would have been regularly frequented during the war. Furthermore, the buildings are likely to have been subject to checks for evidence of UXO, that would have been fairly obvious, following the air raids. During the raids it is considered highly likely that AA defences at the airfield would have engaged the attackers. This coupled with the small number of aircraft involved suggests it is likely that a UXB strike would have been observed. o The airfield peripheries and the agricultural area to the south-east will have been accessed to a much lesser degree. Therefore it is conceivable that a UXB strike could have gone unobserved and an entry hole would have been easily obscured; note that the entry hole of an SC 50 HE UXB, the most commonly deployed HE bomb, may have been as small as 20cm in diameter and therefore easily obscured by dense crops or soil debris (ploughed field). Report: 3870TA iv BACTEC International Limited Buro Four RAF Alconbury o Immediate post-WWII RAF aerial photography of the site does not exhibit any large scale damage or bomb craters within the study area. An anecdotal account also describes only minor damage to two aircraft during the three air raids. For the large part there has not been any significant redevelopment of the airfield since it became a non- operational base in 1995. There has however been some development within the airfield in the post-WWII period and therefore the risk of encountering shallow buried UXO (such as SAA, 1kg German incendiaries, AAA shells and USAAF munitions) in these areas will have been partly mitigated since any such items may have been discovered during excavations. However the risk from deep-buried German HE UXBs will only have been mitigated at the precise locations of and down to the depths of any post-war deep excavations or pile foundations. Note that the risk posed by these munitions is considered to be relatively low. Ploughing and re-working of farmland has been known to exhume shallow buried items of UXO, however purposely buried UXO has also been encountered at depths below that of normal ploughing methods. Therefore the risk of encountering UXO at any depth within the south-eastern part of the study area will not have been fully mitigated.