Detailed Unexploded Ordnance (UXO) Risk Assessment

Detailed Unexploded Ordnance (UXO) Risk Assessment

Project Name Client

Aerodrome Road, Hawkinge Enzygo

Site Address

Hawkinge, Folkestone CT18 7AG

Report Reference Date

DA5936-00 6^thMarch 2018

Originator

JM

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1^stLine Defence Limited

Unit 3, Maple Park, Essex Road, Hoddesdon, Herts. EN11 0EX
Tel: +44 (0)1992 245 020 [email protected]

Company No: 7717863 VAT No: 128 8833 79

www.1stlinedefence.co.uk

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 1^stLine 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, 1^stLine 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 www.1stlinedefence.co.uk

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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 27^thOctober 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



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Glossary

Abbreviation Definition

AA

Anti-Aircraft

AFS AP

Auxiliary Fire Service Anti-Personnel

ARP AWAS DA

Air Raid Precautions Air Warfare Analysis Section Delay-action

EOC EOD FP

Explosive Ordnance Clearance Explosive Ordnance Disposal Fire Pot

GM HAA HE

G Mine (Parachute mine) Heavy Anti Air High Explosive

IB

Incendiary Bomb

LAA LCC LRRB LSA MOL OB

Light Anti Air London County Council Long Range Rocket Bomb (V-2) Land Service Ammunition Molotov (Incendiary Bomb) Oil Bomb

PAC PB PM

Pilotless Aircraft (V-1) Phosphorous Bomb Parachute Mine

POW RAF RCAF RFC RNAS ROF SA

Prisoner Of War Royal Air Force Royal Canadian Air Force Royal Flying Corps Royal Naval Air Service Royal Ordnance Factory Small Arms

SAA SD1000 SD2 SIP U/C UP

Small Arms Ammunition 1000kg high explosive bomb 2kg incendiary Self-Igniting Phosphorous Unclassified bomb Unrotated Projectile (rocket) United States Army Air Force Unexploded

USAAF UX UXAA UXB UXO V1 V2 WAAF X

Unexploded Anti Air Unexploded Bomb Unexploded Ordnance Vengeance Weapon 1 Vengeance Weapon 2

Women’s Auxiliary Air Force

Exploded

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Contents

1.

Introduction ................................................................................................................................... 2

Background....................................................................................................................................... 2

Method Statement ......................................................................................................................... 2

Background to Historic Records...................................................................................................... 3