Monitoring of heavy metal contamination at the Norwegian Armed Forces munitions demolition facility in Lærdal municipality – results from 2020

In Øyradalen southeast of Lærdal center, the Norwegian Armed Forces has a demolition facility, where munitions are demolished by open air detonation. This area was established in 1976, and has since been used for demolition of munitions. From 1991 until today, soil samples from Øyradalen have been analyzed to monitor the concentration of heavy metals. In 2008, the Norwegian Defence Research Establishment (FFI) carried out an evaluation of the results from this monitoring, and some adjustments of the monitoring program were recommended. In addition to the facility in Øyradalen, a destruction facility for small arms munitions and propellant is localized in Tønjumdalen. The destruction of such munitions takes place in an incinerator connected to a treatment plant. The contamination in this area has not been regularly monitored. In 2008 FFI recommended that this area should be included in the monitoring program. This report present results from the monitoring of the munitions-related contamination in Øyradalen and Tønjumdalen in 2020. The concentrations of copper in the demolition area in Øyradalen were higher than at the reference station in the valley. The mean concentration of copper in the demolition area was 461 mg/kg in 2020. This concentration was similar to the concentration measured in 2019 (516 mg/kg). Zinc and lead levels were also above background levels, while the concentrations of other heavy metals were equivalent to background levels. The lead concentrations have shown a small increase during the last years (since 2016), but there was no increase from 2019 (108 mg/kg) to 2020 (104 mg/kg). The concentrations of the other metals in the demolition area have not changed significantly during the last years, and the contamination levels in Øyradalen are within the national limits for recreation areas. It is unlikely that the animals grazing on the demolition area is at risk for poisoning, but due to locally high copper concentrations, it cannot be totally excluded. In the river Nivla, which runs through the demolition area, the concentration of copper and lead did not exceed the limit value in any of the sampling points (7.8 μg Cu/L and 1.2 μg Pb/L). Based on metal values measured in Nivla in 2018, effects on aquatic organisms is negligible. The concentrations of lead in soil near the destruction facility in Tønjumdalen were above background levels, while the concentrations of other heavy metals were comparable with the background levels. The lead concentration in the soil in this area was on the same level in 2020 as previous years. Still, the contamination level in Tønjumdalen was within the national limits for recreational areas, and no risk for grazing animals is expected. The content of munitions-related metals in the river Kuvella in Tønjumdalen were below effect levels for aquatic organisms, and below drinking water standards. The concentration of metals in soil and water at the demolition areas in Tønjumdalen and Ørjadalen pose a low risk to humans and local fauna. However, it is uncertain whether the risk will change in the future, as these areas are still in use. FFI therefore recommends further monitoring.