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Detailed Unexploded Ordnance (UXO) Risk Assessment Project Name Land at the Airfield, Earls Colne Client Green Earth Management Co. Ltd Site Address Land at the Airfield, Earls Colne, Essex, CO6 2NS Report Reference DA11807a-01 Date 10th November 2020 Originator AB 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 Land at the Airfield, Earls Colne Green Earth Management Co. Ltd Executive Summary Site Location The site is located near Earls Colne, Essex. The site area is occupied by a mixture of open grassland and vegetation, with no structures present on-site. The site is bound by open fields to the north and west, whilst the Earls Colne Airfield is located to the east. An aircraft hangar is adjacent to the site to the north-east along with a helipad belonging to the Essex and Herts Air Ambulance. Various industrial warehouses and commercial buildings within the Earls Colne Business park are to the site’s south-east. A footpath forms the site’s southern boundary. The site is approximately centred on the OS grid reference: TL 33419 46137. Proposed Works The scope of works at this stage are understood to comprise window samples with SPT (standard penetrating testing), five boreholes to 5.0m bgl, and trial pits to 3.0m bgl. Multiple haulage yards are to be constructed on-site and the excavation of an attenuation pond will also take place. Geology and Bomb Penetration Depth The British Geological Survey (BGS) map shows the bedrock geology of the site to be underlain by the London Clay Formation – clay, silt, and sand formed in the Paleogene period. The superficial deposits are formed of Lowestoft Formation – diamicton formed in 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 1st Line Defence has assessed that there is a Medium Risk from Allied military ordnance at the site of proposed works. The risk from German aerial-delivered ordnance has been assessed as Low. This assessment is based on the following factors: Allied Military Ordnance RAF Earls Colne was operational between 1942 and 1945. It saw extensive use as a heavy and medium bomber base for both USAAF and RAF units from May 1943 until the war’s end. Aircraft such as B-17, B-26, and Halifax bombers were involved in major wartime engagements, including D-Day and Operation Varsity. According to 1944 RAF site plans and WWII-era, aerial imagery the site was situated on the periphery of the original airfield footprint and was predominantly occupied by open ground. However, following the arrival of the USAAF in 1943 the airfield was significantly expanded and a number of hard standing dispersal pans, used for the re- armament and resupply of planes, were constructed in the centre of the site. During its time as an USAAF and RAF station, Earls Colne saw heavy operational use, with the 323rd Bomber Group carrying out 33 missions between July and October 1943 alone, for example. B-26 aircraft, which saw the most extensive use at Earls Colne, were heavily armed with 11 .50 Cal M2 Browning guns, and could carry 4,000lb (1,800kg) of bombs. Such munitions would have been loaded onto aircraft at dispersal areas across the station such as the ‘spectacle type’ dispersal pans located on-site. Due to the heavy usage of such areas it is possible that UXO in the form of LSA/SAA may have fallen or been improperly discarded in their environs. A number of crash landings and landing accidents are noted to have occurred at RAF Earls Colne within incident records from the American Aviation Archaeology website, although limited information is provided regarding these incidents. One more well-documented crash occurred on 22nd March 1944 when a German Ju 88 was shot down and landed at Earls Colne, causing a large explosion and destroying a B-26 parked within a dispersal pan. It was not uncommon for such crashes to occasionally result in ground contamination from explosive ordnance, as the aircraft involved such as B-26s were typically carrying ordnance. The official Air Ministry boundary surrounding the airfield is noted to cross through the northern portion of the site area, which was partially occupied by open grassland. Such areas, at the edge of airfields, were typically Report Reference: DA11807a-01 II © 1st Line Defence Limited www.1stlinedefence.co.uk Detailed Unexploded Ordnance Risk Assessment Land at the Airfield, Earls Colne Green Earth Management Co. Ltd UXO Risk Assessment considered to be prime locations for unwanted ordnance burial. Such burials often occurred at times when bombing groups left airfields suddenly following specific events – the 323rd USAAF bombing group are known to have left Earls Colne for France shortly following D-Day, so may have buried any ordnance which they were unable to transport. Furthermore, open areas within airfields were often used for training and exercises. Although no reference to exercises on site could be found, being a large important airfield, it is entirely possible that training exercises (such as defence and ‘mock invasion’ battle exercises) were carried out, and may have remained unrecorded. Should this have been the case there would be an elevated risk of contamination from Allied ordnance, owing to the SAA and LSA that troops undertaking training were issued. In summary, given the military history of the local area, the possibility that training exercises and/or ordnance burials may have taken place on-site, and the high number of crashes and landing accidents which occurred at RAF Earls Colne, the risk of UXO contamination from Allied military ordnance on-site has been assessed as Medium. German Aerial Delivered Ordnance During WWII, the site was located across two Rural Districts of Braintree and Halstead, which both sustained an overall very low density of bombing according to official Home Office statistics, with an average of 9.8 and 8.5 items of ordnance recorded per 1,000 acres respectively. Since RAF Earls Colne was only constructed in 1942, no specific references to bombing could be found within local air raid damage files or incident files prior to this date (though one UXB was recorded within the approximate vicinity of the site ‘within fields’ on 8th October 1940). The main period of German bombing across southern England occurred from 1940-41 and the fact that the airfield did not yet exist during this period means that the site area would not have been contained within a known Luftwaffe target, thus it is considered unlikely that the site and its vicinity were subjected to bombing at this time. However, once activity at the airfield increased following the occupation of the USAAF in 1943, bombing incidents affecting the airfield became slightly more frequent. Air raid damage files for the Rural District of Halstead note three raids in which the airfield’s vicinity was bombed, however only minimal damage is recorded at the airfield during any of these raids causing no operational delays. Additionally, no positive evidence could be found to suggest that the site area itself was subjected to bombing during any of these raids. Aerial photography from the WWII-era appears to corroborate the overall lack of damage recorded within these incidents. The structures within the southern portion of the site appear to have remained unchanged between images from 1942 to 1949, whilst remaining, open areas of the site also do not appear to show any obvious signs of damage, such as ground disturbances or cratering. Any ground disturbances shown in the site’s vicinity within early photography from 1942 are considered likely to be the result of planes travelling over soft ground, rather than any bombing incidents. Additionally, owing to the occupation of the site by the USAAF and RAF, it is anticipated that the site would have been regularly accessed. It is also likely that specific post-raid checks were carried out across the airfield, in order to maintain serviceability and security. Ground cover across the site is not homogenous, with the northern section of the site situated occupied by open grassland. Evidence of UXBs can become obscured within open, vegetated areas or areas under crop. It has therefore not been possible to absolutely negate the possibility that UXO could have fallen within the site area unnoticed, however this is thought unlikely, owing to the anticipated access of the airfield and the degree of resulting observation on site. Therefore, despite the recorded bombing incidents within the vicinity of the site, these are not anticipated to have affected the site area directly. Given this, combined with the anticipated frequency of access on-site, it has been assessed that the risk from buried UXBs on site is not considered to be elevated above the ‘background’ level for this part of the country. Post-war Redevelopment The structures located within the southern portion of the site during have been demolished during the post- war era, with the hardstanding dispersal pan also having been removed. However, the site area has largely remained undeveloped.