In many parts of the Netherlands Unexploded Ordnance (UXO) from World War II, including aerial bombs, grenades, mines and ammunition, can still be found in the subsurface. UXO investigation maps the risks and the presence of explosives left behind in World War II.
T&A's approach of UXO investigation very often results in a considerable reductions of costs and time:
- High quality historical research limits the area to be surveyed in the detection phase.
- Use of innovative UXO detection techniques gives a 3D image of the objects detected and reduced the amount of objects to be removed.
- T&A is independent has no interest in extensive, superfluous digging activities.
- UXO investigation can be combined with geophysical, environmental or archaeological research.
- T&A has its own team of certified UXO divers.
If the historical preliminary research (fase 1) considers it necesary, the detection fase will be carried out. The goal is to determine the position (x, y and z coordinates) of the suspect unexploded ordnance (UXO) using geophysical techniques. We will advise the client about which (combination of ) techniques to use to achieve the best results. A solid and thorough UXO detection survey will prevent unnecessary expenses in the following phase.
During field activities parallel measuring lines are run across the investigation area, moving along the selected research equipment. In some cases, when the survey goes deeper than 4 meters, T&A uses boreholes for measuring or incorporates research equipment in a probe. In this phase, the investigation area will not yet face intensive surface-disturbing activities.
After the geophysical survey the location of metal objects, possibly UXO, in the subsurface is known. In some cases we can also give an indication of the dimensions of the objects. Other disturbing factors in te subsurface, like tubes, cables and layers of debris, will also result from the (combined) detection research. The results determine the further measures to be taken.
I - Work preparation for approach
A project plan and a project control plan are drawn up. The safety measures are established based on a risk evaluation. Besides safety measures, liabilities, authorizations, approach strategy and communication are established in the project plan, which needs to be formally approved by all parties involved.
II - Approach and identification
The suspect object will be dug up and identified by an explosives expert. In some cases protected excavators of civil engineering companies will be used. If the suspect object turns out to be an UXO, phases III and IV are carried out. If not, the area, will be restored in it's original state.
III - Temporary securing and/or storing of detected UXO
If an UXO is found during the approach activities, additional safety measures will often be applied. The explosive will, depending on the situation, be stored in a secured ammunition container or covered awaiting the arrival of the Explosives Clearing Service (EOD)of the Ministry of Defense.
IV - Hand over to the Explosives Clearing Service
The UXO will then be registered by the EOD and rendered harmless safely. Depending on the state of the UXO this can be done on the spot, on a location nearby that has been determined in advance or on a location elsewhere assigned by the EOD.
V - Delivery and Evaluation
A "Declaration Clear of Explosives" will be issued and the project will be evaluated together with the client.
Historical research and risk analysis
In order to determine the risk of finding explosives on or in the sediment, T&A Survey carries out a historical research. If this desk study shows that the area is suspect for UXO, the suspect areas can be narrowed down performing a risk analysis. This is a detailed inventory of post-war activities, location-specific circumstances and the types of explosives in relation to the planned activities. A substantiated advice is drawn for each sub-area. Depending on the types of expected UXO, the advise will be detection and/or secured dredging.
Prior to dredging a suspect area, detection of metal objects in the water bed will take place. After the detection investigation, certified divers will check whether these objects are actually explosives. Under water, they carefully remove the sludge around the object in order to identify it. Detection of UXO in the sediment is only effective for large explosives, such as airplane bombs.
Dredging in UXO suspect areas
On locations suspect fore the presence of smaller explosives, or where the larger explosives have already been approached by divers, dredging must take place according to current legislation. Secured dredging is always a customized operation. T&A Survey can organize the dredging process in several ways, making it fit in perfectly with your project.
References UXO investigation
|Ballast Nedam Infra|
|BAM Civiel Zuidwest|
|BAM Infra De Ruiter Boringen & Bemalingen|
|BAM Infratechniek Midden West|
|BAM Nelis De Ruiter|
|BAM Wegen - Regio West|
|Bedrijvenschap regio Gouda|
|Bohlen & Doyen|
|Bouwcombinatie Stadsbrug Nijmegen|
|Combinatie Sporen in Arnhem - Civiel|
|Dienst Infrastructuur Verkeer en Vervoer|
|Dienst Landelijk Gebied|
|Dura Vermeer Infrastructuur Midden West|
|Dura Vermeer Railinfra|
|Eneco Milieu - Business Development|
|Gemeente Alphen aan de Rijn|
|Gemeente Hollands Kroon|
|Gemeente Utrecht - Dienst Stadsbeheer|
|Grontmij Advies & Techniek|
|Hoogheemraadschap Hollands Noorderkwartier|
|Hoogheemraadschap Schieland & Krimpenerwaard|
|Hoogheemraadschap Stichtse Rijnlanden|
|Hoogheemraadschap van Rijnland|
|Ingenieursbureau Den Haag|
|Koenders & Partners|
|Kragten Civiele Techniek|
|Lankelma Geotechniek Almelo|
|Nuon Wind Benelux|
|OceAnco - Alblasserdam Yachtbuilding B.V.|
|Ontwikkeling Maatschappij Het Nieuwe Westland|
|Provincie Zuid Holland|
|PWN Noord Holland|
|Royal Haskoning DHV|
|RPS advies- en ingenieursbureau|
|Siemens AG - Energy Sector|
|Stadsdeel Amsterdam Noord|
|Strukton Rail (Zuid)|
|Temmink Infra en Milieu|
|Twentse Weg- en Waterbouw|
|UXO Offshore Services|
|Waal & Partners|
|Waterschap Aa en Maas|
|Waterschap Zeeuwse Eilanden|
|Witteveen & Bos|