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The use of GIS in the environmental assessment of the WW2 mustard gas factory at Ergethan in the former East Germany
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Case Studies? > WW2 mustard gas factory at Ergethan? >
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The Ergethan Second World War chemical weapons production site contains a complicated cocktail of contaminants (mustard gas, tear gas, arsenic, trichloroethane and zinc),which are present within the soil, soil gas and groundwater phases. Arsenic was the main raw material used, with values of up to 5% being found on the waste dumps, up to 800ppm found in the production area, and with local crops containing up to 3mg/Kg. The present day industrial usages of the site are for drycleaning (using Trichloroethane), and steel fabrication, both of which have also contributed to current site contamination. Risk assessment was carried out by stereoscopic interpretation of RAF wartime reconaissance photography. Site investigation and subsequent ground truthing permited the delineation of a range of hazards through the use of simple GIS techniques. After drilling and and subsequent soil analysis, it was recommended that a further detailed investigation be carried out to accurately delineate the extent of the contamination to be followed by encapsulation of the site and the implementation of long term monitoring. GIS techniques would play a central role in this.
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Layla Resources Ltd was commissioned by Trischler und Partner GmbH to carry out detailed airphoto interpretation to assist in the subsequent assessment of the extent of danger associated with the Ergethan chemical weapons factory, which produced "arsenic-oil" (from arsenic and phenol) during World War Two ("WW2"). The Ergethan site lies in the state of Saxony- Anhalt in what was East Germany ("DDR"), it occupies an area of approximately 5 hectares lying three Km to the NNW of the town of Stassfurt. The site (a former salt mine) has had varied usages during the 20th century, ranging from the manufacture of chemical weapons to the dry cleaning of carpets. After the reunification of Germany in 1990, an environmental assessment programme was initiated to assess potential contamination in the area.
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Advances in toxicological research have highlighted various environmental and health issues asssociated with military installations (both current and historic). These environmental problems occur not only during the production of munitions, but are also of a long term nature due to problems arising from disposal of effluents and waste products. The Rustungsaltlasten (Military Hazardous Waste) programme was initiated by the state of Lower Saxony in 1987, with the aim of assessing the extent of contamination still present from the military activities of the Third Reich. A systematic investigation of production, operational and logistical flow paths was carried out in order to identify areas where spillage of hazardous chemicals could have occurred. Contamination associated also with the militarisation of Germany during 1914-18, and the subsequent post war occupation by the Allies was also addressed. The war machine of the Third Reich was fairly evenly divided between "West" and "East " Germany. The western part had 75 known production sites, of which 14 were used for the manufacture of chemical weapons, and 61 were for conventional explosives production. In the Eastern part of the country there were 49 known sites, of which 22 were chemical and 27 were conventional. During the war an estimated 1.66 million tonnes of explosive were produced at these sites, of which over 0.8 million tonnes were TNT (giving rise to 31 million cubic metres of waste water alone). In addition around 60,000 tons of chemical weapons, and 300,000 tons of mixed chemical and conventional explosive warheads were produced. After the war, the four power agreement divided occupied Germany into four zones, Soviet (East), British (North), American (South) and French (Southwest). In what was to become Western Germany, the Allies occupied a number of military facilities and initially destroyed large quantities of explosive by burning it. However the sheer volume of material meant that large quantities of munitions were either landfilled or dumped at sea in the Baltic. In the DDR there was a concerted effort between 1946 and 1952, to destroy all military facilities, either by dismantling, demolishing or by blowing them up. However it was not realised until 1989 that quite often there were deep underground tanks that had been missed, which still held reactive ingredients, at some of the sites that had been used to manufacture chemical weapons. Military contamination of WW2 sites (varying in area between 0.5 to 4 sq km), usually falls into the following categories:-
- Explosive fabrication plants e.g. TNT - made from Toluene, Nitric Acid,
- Chemical / Nerve gas plants e.g. Mustard gas - made from Arsenic, Phosphorous,
- Munitions factories e.g. Bombs - made from TNT, Mercury fulminate, Copper,
- Munitions Bunkers storing Bombs, Explosives, Pyrotechnics, Mustard gas,
- Airfields, Barracks, Naval Bases with associated Bunkers, Underground fuel storage tanks.
- White Cross - affecting the eyes e.g. Tear Gas
- Yellow Cross - affecting the skin e.g. Mustard Gas
- Blue Cross - affecting the Nasal passages e.g. Clark 1
- Green Cross - affecting the lungs e.g. Phosgene
- Nerve gas - affecting the nervous system e.g. Tabun
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Environmental hazards arising from military activity are present in a variety of forms and are still polluting the environment through the classical vectors of Soil, Gas and Water.
- Munitions factories were operating under war-time conditions, hence basic operating proceedures, and health and safety measures, were often lax.
- The factories suffered considerable damage, either through bombing or accidental explosions which led to the release of toxic substances both during and after the war.
- Raw materials and end product were often stored in an unsafe manner, with process water and effluents often being disposed of improperly.
- Preparation of an inventory, listing all sites known or suspected to have been used for military purposes, (initial datagathering, archive searches).
- Initial assessment of potential hazards by means of witnessess and RAF wartime air- photography, followed by a walk-over survey and a desk-top survey of the geology and hydrogeology of the site from a regional perspective (ground-truthing).
- Site survey and sampling (soil, water, gas phases), using geochemical, geophysical and hydrological sampling to determine the extent of contamination and the associated risks to the ecosystem, water supply and local population (orientation investigation).
- Detailed investigation to identify areas affected, perform detailed risk assessments, and delineate volumes of contaminated material (definition of site parameters).
- Remediation of the site and long-term monitoring of ground water and aquifers(clean-up).
- - high risk (e.g factories) - 74 in total
- - medium risk (e.g. airfields) - 191 in total
- - low risk (e.g. housing) - 87 in total
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Colour and infra-red photography (in conjunction with a site plan and a topographical map) is one of the main tools used in the environmental interpretation of contaminated sites. Features such as railways, streets, buildings, drainage and dumps can be ground truthed, thus assisting in the interpretation of other features observed on the photograph. The use of multitemporal stereoscopically overlapping aerial photography allows a geometrical depiction of the site, and accurate photogrametric measurement of the various site usages. Unfortunately, although detailed site plans often existed in wartime Germany, most were destroyed when the sites were overun, and often only a very cursory plan or record was made immediately prior to the site's subsequently demolition. Wartime reconnaisance air photos, (usually taken before a bombing raid, often under extremely hostile conditions), are the best records now available of the layout and development of German WW2 munition sites. Some 4 million of these photographs still exist, although it was not until 1987 that their true value as a unique record of wartime industrial facilities was realised. Users of war-time photographs, however, frequently encounter the following problems:-
- Photograph scale often smaller than 1:10,000, (high altitude flights to avoid flak activity)
- Poor clarity of image, (unsharp, poor contrast, due to sub-optimal weather conditions)
- Uneven coverage, (time, space and scale, concentrated primarily on major industrial areas)
- Processed under war-time conditions, (over/under developed, present day picture quality poor)
- Black and white panchromatic film stock, (little infra-red, difficult to separate out camouflage)
- Camera characteristics and focal length often unknown, (difficult to carry out photogrammetry)
- Photos distorted, (pitch, roll and yaw due to evasive maneouvres)
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The site was originally a pre-war potash mine and was used during WW2 to manufacture 12,600 tonnes of chemical weapons. The site which covers an area of 5.14 hectares ( roughly in the shape of a kitchen knife blade), is currently used by two enterprises, an industrial dry cleaner to the north, and a steel fabrication company to the south. After 1945 only two chimneys, two mine headframes and one watertank were left standing after the Soviets had demolished and levelled off the site using demolition rubble as hard core. The main chemical weapon produced was known as Clark 1 (Diphenylarsinechloride) which was made from arsenic, chlorine, and benzene, this was then mixed on site with Chloracetophenone and used as a filling for bombs and grenades.
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A total of 489 photos were available for the immediate area around Stassfurt, but only 12 of them covered the area of Neustassfurt and the Ergethan site. From these, a total of 7 (taken during 1944) were suitable for interpretation, in turn only 3 had full stereo coverage ( one in October , at a scale of 1:9,000 with poor contrast, and two in February at a scale of 1:11,800 with excellent contrast) The basic purpose of the site investigation was classify the site according to usage into either industrial (contaminated), transport (sometimes contaminated) or residential (uncontaminated), permitting the determination of sources of contamination, potential pathways for transportation, and the final resting point of the contaminats. In the case of Ergethan, the only site plan in existence dates from 1957, and depicts the state of the site after demolition, when very little was left standing. Ground truthing of individual features was thus rather difficult, and the site was interpreted in terms of category of feature. Both sets of photos were used to locate buildings and associated industrial usage. It was initially hoped that they could be interpreted using an image processing package running on a Apple Macintosh computer (Image 1.41 running on a Mac IISE, ). The photos were enlarged 200% and scanned in as grey-scale at 300dpi, to ensure that there was no loss of features. Conversion of the grey-scale image to pseudo- colours permitted density slicing of the image which allowed the identification and selection of the various "grey tones" in the photograph. Once the image had been enhanced in this manner, it was planned to export it in raster form, load it into a CAD package and after conversion to vector form, hold the attributes on a database for interogation at a later date. However this approach was unwieldy, as the images could not be examined stereoscopically on the screen, hence the Mac was used only to carry out density slicing and contrast / brightness enhancement of the photos. The photographs were interpreted using a mirror stereoscope with a magnifying viewer, with details being transferred by hand to acetates that were then scanned into the computer and processed with a CAD package (Minicad) to identify the following factors
- Transport links - (road, rail)
- Water courses - (lakes, ponds, canals, streams)
- Buildings - (administration, production facilities, chimneys, housing)
- Land usage - (industrial, agricultural, woodland, wasteland, dumps, quarries)
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Neustassfurt is underlain by Quaternary drift, Tertiary sands, gravels and mudstones and Triassic Buntersandstone, the last two sequences have several aquifers within them, with hydraulic flow being in a westerly direction. Contamination was known to exist in the old process plant (the Ergethan site), and a waste dump derived from pre-war mining operations (known as "deponie 29") lying 150 metres northwest of the site. Deponie 29 also contains 26,000 M3 of wartime production waste, as well as 30,000M3 of demolition rubble. Potential contaminants from the wartime usage of the site fall into four main groupings being:-
- Raw material (arsenic, chlorine, bromine, phenol, phosphorous, toluene)
- End products ( chloroacetophenone, dichlorodiethylsulphide, diphenylarsenocyanide)
- Byproducts and daughter products ( Polyaromatic hydrocarbons, arsenic phenylhydroxide)
- Other substances (sodium sulphate, trichloroethane, carbon tetrachloride, various catalysts)
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29 Percussion drill-holes ("RKS") were drilled (1.75 - 6.5m in depth) and sampled. Grab samples were also taken of agricutural soils and crops, together with water samples from boreholes in the local area. To counter public concern over the accidental discharge of still active chemical warfare agents into the atmosphere, drilling and sampling was carried out through a steel platform (fixed to the ground by partial vacuum) by personnel in full positive pressure suits. Standard German Atomic Absorbtion Spectroscopy (AAS) protocols were followed for arsenic (As), extractible organic halogens (EOX) and chlorinated hydrocarbons (CKW). The chemical weapon analyses were carried out in using Gas Chromatography / Mass Spectroscopy (GC/MSS). Problems arose as the usual analytical technique is based on fresh reference material, rather than on the low levels of concentration of 50 year old significantly decayed material actually present on the site. The main chemical warfare agent to be analysed for was Clark 1. As this is an organoarsenic compound, organic Arsenic was utilised as a pathfinder, allowing the use AAS to delineate those areas requiring more detailed analysis with CG/MSS.
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The trigger values for the clean-up of industrial land in Saxony-Anhalt are as follows
- Level I Background (geological values ,<50mg/Kg for As)
- Level II Further investigation necessary, (8 - 80 mg/kg for EOX)
- Level III Toxic (requiring clean-up , >200 mg/Kg for As)
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Based on investigations to date, approximately 20% of the site (covering 10,000 M2 to a depth of 6M), requires remediation to remove arsenic and associated contaminants, with deponie 29 containing another 26,000 M3 of material requiring remediation. Total excavation of the site (the classical remediation proceedure), would have to be carried out under full pressure suit conditions (costing around £ 10 million) , with subsequent burial as hazardous waste in a secure landfill accounting for another £ 25 million. Soil washing, using chemical detergents, is a relatively untried technique with chemical warfare material and may not be that sucessful, due to the fine nature of the material, clean-up using this technique would cost around £ 15 million. Whilst a variety of techniques do exist for making the site safe, the long term solution currently favoured is the total encapsulation of deponie 29 and partial encapsulation of the Ergethan production site. In conjunction with the implementation of a long term monitoring programme, this will cost around £ 2.5 million. Nevertheless a final decision will be based on further detailed investigation of the site.
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Theory The range of facilities available for the processing of spatial information within a GIS are varied, but generally include Data Input, Data Management, Data Transformation and Data Manipulation, permiting computerised mapping, database management and cartographical analysis and modelling. Data Input and Management Based on the air photo interpretation the site was classified into various zones of land usage - wetlands, residential, agricultural, infrastructure, and industrial. A GIS approach was used to examine the last two groupings, which were then divided up into four main geographical areas (based in part on interpretation of similar WW2 chemical warfare production facilities elsewhere).
- Northern zone - Administation buildings, steam and electricity generation
- Central zone - Production and Final storage of product prior to dispatch
- Southern zone - Primary storage tanks, loading and unloading of rail wagons
- Western zone - Waste disposal site
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Using the above information a series of percussion holes were put down at various of the old WW2 buildings. Several boreholes gave anomalous results indicating that significant contamination had occurred. In the final site report, maps, analyses and contaminated areas were presented separately in paper hard copy. The use of a GIS at the time was found to be unwieldy, being used purely for cartographic purposes. However this type of work is the very area where a GIS exhibits flexibility, not only in mapping areas warranting future investigation, but also in carrying out data analysis and data modelling. Using IDRISI the author recently reprocessed the Ergethan site data to carry out data analysis, determine contaminated areas, and finally to perform data modelling. These results that were achieved (50 years after the site photographs were taken) will form the basis of a short presentation to be given on at AGI 94 on the 17th November 1994.