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Water and sediment analysis in Lake Neuchâtel

From 29 to 31 March 2021, armasuisse Science and Technology, together with partners, will be taking samples for analyses in Lake Neuchâtel at Forel (FR). Today, the lake contains around 4500 to 5000 tons of ammunition remnants from Air Force firing exercises. In addition to a new measurement of harmful substances and heavy metals in the water, specialised divers will also be collecting sediment samples.

30.03.2021 | Sandie Pasche and Anela Ziko, armasuisse Science and Technology

Today, Lake Neuchâtel still contains some 4500 to 5000 tons of ammunition remnants from Air Force firing exercises.
Today, Lake Neuchâtel still contains some 4500 to 5000 tons of ammunition remnants from Air Force firing exercises. @VBS/DDPS, Joddie Pasche

2015: First water samples for heavy metal analysis in Lake Neuchâtel at Forel 

In 2015, the DDPS performed an initial analysis of the lake water at Forel. The aim was to establish whether the Air Force firing practice which still takes place has an effect on the water. For this purpose, the concentration of heavy metals was measured before as well as after airborne shooting. The analyses have shown that the respective limit values of the Waters Protection Ordinance were not exceeded during the firing tests.

As live ammunition, in particular, was also fired for practice purposes almost 100 years ago when firing practice started, the remnants will not only contain ammunition without explosives but also blind shells. Their impact on the water and the sediment is now also to be investigated with explosive analyses.

2021: Extended water and sediment analyses in Lake Neuchâtel

Experts from armasuisse Science and Technology (armasuisse S+T) have developed an appropriate concept for the water and sediment analyses together with the Laboratory Spiez. The concept has also been discussed with the Swiss Federal Office for the Environment (FOEN), the cantons of Fribourg, Vaud and Neuchâtel as well as the conservation organisations Pro Natura and the Association Grande Cariçaie.

The goal of this year’s examination is to estimate the potential risk of possible harmful substances from the ammunition remnants as well as to analyse the content of explosives and heavy metals in the water and the sediment.

Water samples

Individual water samples will be taken from various points at Forel for the analyses. In addition to sample takings in the current shooting perimeter, where the Air Force has been firing at targets in the water since 1931, samples will also be taken in former presumed target areas as well as two reference samples a few kilometres away.

The samples will be taken by divers from the Explosive Ordnance Disposal and Mine Action Command (EOD Command) of the Armed Forces and by armasuisse S+T around 20cm above the bottom of the lake using sample bottles. In addition, temperature, electrical conductivity and the ph values will be determined. 

Sediment samples

To analyse the sediments, three primary samples will be taken in the prohibited area, three samples each in former presumed target areas as well as two reference samples for comparison purposes.

The EOD Command divers of the Armed Forces will use plastic tubes for this purpose, which they will place in the ground and thus extract the sediment cores to be examined. A special metallic core drill will be used for sample takings near the shoreline, as the subsoil is firmer here. The sampling points will be determined and recorded using GPS systems, both for the sediment and the water samples.

Analysis of water and sediment samples

The samples collected at Lake Neuchâtel will then be analysed for heavy metals by the Spiez Laboratory as well as by the company Bachema AG for explosives and organic carbon content. The results are to be evaluated and assessed together with the cantons concerned, the FOEN, Pro Natura and the Association Grande Cariçaie. It is also planned to define further steps jointly.

Air Force firing range Forel

The firing range in Forel (FR) has been used for firing practice with fighter aircraft since 1928. It is one of the last Air Force firing ranges which the Air Force uses for training air to ground shooting. Firing practice is currently taking place on around ten days a year in Forel. For some time, the location has also been used for the survival training of pilots in water.

Munitions in Swiss lakes (in German)