Detailed Unexploded Ordnance (UXO) Risk Assessment Project Name Aerodrome Road, Hawkinge Client Enzygo Site Address Hawkinge, Folkestone CT18 7AG Report Reference DA5936-00 th Date 6 March 2018 Originator JM Find us on Twitter and Facebook st 1 Line Defence Limited Company No: 7717863 VAT No: 128 8833 79 Unit 3, Maple Park, Essex Road, Hoddesdon, Herts. EN11 0EX www.1stlinedefence.co.uk Tel: +44 (0)1992 245 020 [email protected] Detailed Unexploded Ordnance Risk Assessment Aerodrome Road, Hawkinge Enzygo Executive Summary Site Location The site is located in Hawkinge, Kent. Aerodrome Road borders the site to the north, while Elvington Lane forms the eastern boundary. Areas of open ground border to the south and west. The boundary comprises areas of open ground and the foundations of previously demolished structures. The site is approximately centred on the OS grid reference: TR 2044639485. Proposed Works The proposed works are understood to involve the excavation of trial pits to a depth of up to 3m. Boreholes will also be drilled to a depth of 4m-6m below ground level depending on ground conditions. Geology and Bomb Penetration Depth The British Geological Survey (BGS) map shows the bedrock geology of the site to be underlain by the Pit Chalk Formation – chalk and sedimentary bedrock of the Cretaceous Period. The superficial deposits are comprised of Clay-with-flints Formation - clay, silt, sand and gravel of the Quaternary Period. Site specific geotechnical information was not available to 1st Line Defence at the time of the production of this report. An assessment of maximum bomb penetration depth can be made once such data becomes available, or by a UXO specialist during on-site support. It should be noted that the maximum depth that a bomb could reach may vary across a site and will be largely dependent on the specific underlying geological strata and its density. UXO Risk Assessment After considering the following facts, 1st Line Defence believes that there is a Medium Risk that items of Allied military ordnance were discarded or disposed of within the site and a Medium Risk that unexploded German air-delivered ordnance could have fallen unnoticed and unrecorded within the site boundary. Allied Military Ordnance The site is situated within the former grounds of RAF Hawkinge, a fighter aircraft base that saw extensive use during WWII. Hawkinge was the closest operational RAF base to continental Europe, and as such was situated on the frontline of the Battle of Britain subsequent to the capitulation of France. The base was extensively fortified with anti-invasion installations when the threat of a German landing seemed imminent. Hawkinge’s role shifted primarily to Search and Rescue operations over the channel subsequent to this threat, as well as the acceptance and maintenance of damaged aircraft. This was largely operated by WAAF personnel, who remained at the airfield until the 1960s. These personnel may have been housed on barrack blocks constructed within the site post-war. The site is shown to comprise of the Officers’ Mess and Quarters, open ground, a gun post and several trench positions within an RAF site plan and a map of defensive positions at the station. While the occupation of the mess and quarters is unlikely to have involved the usage or storage of significant amount of ordnance, the same cannot be said about the gun post and trench positions located in the more open areas of the site. These installations will have been constructed as part of anti-invasion measures, and may have been equipped with ordnance as a result. Moreover, the installations are likely to have been utilised during any of the many training exercises recorded at the station within the ORB. The exercises are recorded to have involved the RAF Regiment, the Home Guard, local army units, and station personnel. During such exercises, it was not uncommon for personnel to carry and store items of live LSA and SAA ordnance in the areas used. The gun-post recorded on site may have been utilised for Light Anti-Aircraft defence during one of the many Luftwaffe raids recorded at the station. The position may have been utilised for Hispano, Browning or Lewis Guns. LAA usage is recorded within the ORB. As such, the storage, transport, and usage of items within the site. A record set titled ‘Defence Measures in the Event of Invasion’ accessed at The National Archives, records RAF Hawkinge as being rigged with ‘pipe mines’ or demolition charges. It has not been possible to obtain any matrix loading plans showing the locations of any installed pipe mines at Hawkinge. Pipe mines were encountered and dealt with on the former aerodrome surface in two recorded UXO clearance operations in 1999 and 2000 Report Reference: DA5936-00 II © 1st Line Defence Limited www.1stlinedefence.co.uk Detailed Unexploded Ordnance Risk Assessment Aerodrome Road, Hawkinge Enzygo UXO Risk Assessment indicating that not all of them were removed post-war. It is likely that any pipe mines would have been placed under the runways, to prevent the enemy using it as a landing ground, but these items have been known to cover the majority of an airfield’s landing grounds. While it is unlikely therefore that the site itself, situated away from the landing area, was mined, these factors should be borne in mind. It has not been possible to discount that other infrastructure around the airfield was also subject to mining. German Aerial Delivered Ordnance During WWII the site was situated within the Elham Rural District, which sustained a moderate density of bombing according to Home Office statistics, with an average of 26 items recorded per 1,000 acres. The majority of bombing within the district is anticipated to have been targeted at RAF Hawkinge, which was situated on the front-line of the Battle of Britain, barely a seven minute flight from occupied airfields in Calais. Numerous raids are recorded at the airfield within a wartime Operations Record Book accessed at the National Archives. The site, which formerly comprised the Officers’ Mess and Quarters, is explicitly recorded as having been bombed on four occasions between August 1940 and March 1941, with another incident recorded on the area immediately adjacent. During one raid on the 27th October 1940, a bomb is recorded as having landed within an old bomb crater next to the Officers’ Mess, highlighting the density of localised bombing. The Officers’ Mess, Quarters and associated squash courts are recorded as having sustained damage within the wartime ORB, accessed at the National Archives. The ORB also states that two houses within the Airmen’s’ Married Quarter, on the sites immediate south-eastern boundary, were completely destroyed. Given the density of bombing in the vicinity, it can be assumed that the open ground throughout the site was also disturbed for periods as a result. Evidence of UXO can fall easily obscured within areas of open ground, or areas obscured by ruin and rubble. The lack of damage visible on site within acquired photography is likely a result of repair works, as the image is taken around four years since the most severe raiding on site. A 250kg German HE bomb was discovered at Hawkinge in the year 2000. This is recorded as having been found approximately 300m east of the site. The bomb was subsequently rendered safe. The presence of an item of this size which remained uncovered for around 60 years is testament to the fact that there is a possibility that further items may remain around the historic aerodrome site. Recommended Risk Mitigation Measures The following risk mitigation measures are recommended to support the proposed works at the Aerodrome Road, Hawkinge site: All Works Site Specific Unexploded Ordnance Awareness Briefings to all personnel conducting intrusive works Open intrusive works (trial pits, service pits, open excavations, shallow foundations etc.) Non-Intrusive UXO Magnetometer Survey and Target Investigation Where this type of survey is not practical (due to for example terrain or ground conditions), the following is recommended to support shallow intrusive works: UXO Specialist On-site Support and Site Specific Unexploded Ordnance Awareness Briefings to all personnel conducting intrusive works Boreholes and Piled Foundations Intrusive Magnetometer Survey of all borehole and pile locations/clusters down to maximum bomb penetration depth Report Reference: DA5936-00 III © 1st Line Defence Limited www.1stlinedefence.co.uk Detailed Unexploded Ordnance Risk Assessment Aerodrome Road, Hawkinge Enzygo Glossary Abbreviation Definition AA Anti-Aircraft AFS Auxiliary Fire Service AP Anti-Personnel ARP Air Raid Precautions AWAS Air Warfare Analysis Section DA Delay-action EOC Explosive Ordnance Clearance EOD Explosive Ordnance Disposal FP Fire Pot GM G Mine (Parachute mine) HAA Heavy Anti Air HE High Explosive IB Incendiary Bomb LAA Light Anti Air LCC London County Council LRRB Long Range Rocket Bomb (V-2) LSA Land Service Ammunition MOL Molotov (Incendiary Bomb) OB Oil Bomb PAC Pilotless Aircraft (V-1) PB Phosphorous Bomb PM Parachute Mine POW Prisoner Of War RAF Royal Air Force RCAF Royal Canadian Air Force RFC Royal Flying Corps RNAS Royal Naval Air Service ROF Royal Ordnance Factory SA Small Arms SAA Small Arms Ammunition SD1000 1000kg high explosive bomb SD2 2kg incendiary SIP Self-Igniting Phosphorous U/C Unclassified bomb UP Unrotated Projectile (rocket) USAAF United States Army Air Force UX Unexploded UXAA Unexploded Anti Air UXB Unexploded Bomb UXO Unexploded Ordnance