Ammunition depot Mitholz - when will it happen again?

During World War II, an underground military ammunition depot was built in Mitholz (municipality of Kandergrund BE). Since an explosion in 1947 (Dec. 19/20) with 9 fatalities, there are still about 3500 gross tons (editor's note: of about 7000 t) of ammunition with several hundred tons of explosives in the collapsed parts of the facility and in the rubble in front of it. Earlier assessments in 1949 and 1986 both concluded that only minor damage was to be expected in the event of a further explosion and that the plant could continue to be used.
In accordance with the Major Accidents Ordinance, the Federal Office for the Environment will now carry out an independent assessment of the risk analysis.

Full expert report confirms risk assessment

In the course of planning for a new data center at the facility, the DDPS commissioned a new risk assessment. The investigation was carried out by a team of external experts from the companies Risk&Safety AG and Bienz, Kummer & Partner AG, supported by various DDPS specialists. The interim report of the risk assessment by these experts was presented at the end of June. Their full risk analysis report of September 27 confirms the findings.

Some of the cleared ammunition was dumped in Lake Thun.

According to the report, the probability and the possible extent of an explosion of the ammunition residues is estimated to be higher today. than was assumed in previous decades. This could cause damage to the plant itself as well as to the nearby surroundings. The experts assume two scenarios and come to the conclusion that the Limit values of the regulations in force today in dealing with risks not complied with be

No immediate measures necessary for the population

According to the experts, based on these findings, there is no need to take immediate measures for the local population. For the access road to Kandersteg as well as the Mountain line of the BLS no measures are necessary at present. In the medium to long term, however, measures are needed to eliminate the risks as far as possible. To this end, the Federal Council has set up a working group for further action. This working group has been working since August under the leadership of Brigitte Rindlisbacher. Their tasks include, in particular, carrying out further investigations such as a geological survey, examining specific measures to reduce the risk to the surrounding area, or clarifying legal consequences.

In consideration of these findings and all other available files and facts, the expert group now assumes that major mass-reaction events in the railroad tunnel cannot be ruled out even today.

In parallel with this work, the DDPS has submitted the complete expert report on the risk analysis to the Federal Office for the Environment, as the federal agency responsible for accident prevention, for an independent assessment in accordance with the ordinary process in the enforcement of the Major Accidents Ordinance. In view of the complexity and the special situation with spilled ammunition, the Federal Office for the Environment will carry out the assessment with the assistance of external experts. It is expected to present the result of its assessment in spring 2019. In parallel with this assessment, the Mitholz working group is examining measures to eliminate the risk. The Federal Council was already informed about the first risk assessment at the end of June and now also about the complete expert report at its meeting on September 28, 2018.

Information of the population

The DDPS and the competent authorities informed on the evening of October 8, 2018 the population of Mitholz about the complete expert report. At the information event, the task of the working group was further presented. At the event, Government Councillor Philippe Müller, Police and Military Director of the Canton of Bern, also provided information about the expectations and support of the canton. In addition, representatives of the DDPS and the canton showed the current status of the work and answered questions from the population.

In order to address the concerns of the population, the already introduced consultation hours will continue to be offered. On these dates, residents and property owners can have their questions and concerns answered directly by those responsible. As new information becomes available, additional information sessions will follow. The full expert report will be made available to the public on the DDPS website. In addition to the report, other documents and reports reviewed in archives will also be made available on an ongoing basis for the sake of transparency.

• Expert report from 27.09.2018 (PDF, 2 MB)
• Appendix 1 to the expert report (PDF, 4 MB)
• Appendix 2 to the expert report (PDF, 5 MB)
• Appendix 3 to the expert report (PDF, 6 MB)

Text/Editor

Federal Department of Defense, Civil Protection and Sport
Defense group
Federal Office for the Environment FOEN

More info from the editors

The following quotation from the Eichenberger report of February 24, 1949 [7] shows how ignorant the authorities were of human life and the environment at that time: "Part (1402.5 tons!) of the cleared ammunition was dumped in Lake Thun." (Source. Ammunition balance according to the Eichenberger report [7] in the Final Report on page 19 of the Risk&Safety AG risk analysis dated 27.09.2018)

The military withdraws, the population is allowed to stay

Several thousand pallets of army medical supplies are currently still stored in Mitholz. "Today, Mitholz is the largest external storage location of the army pharmacy," explains Lieutenant Colonel in the General Staff Daniel Aeschbach, sub-project manager WEA Army Pharmacy in the administrative unit Sanitary. However, the Site to be vacated by the end of 2019 one way or anotherhe continues.

Report of the president of the municipality Eduard Kleinjenni to the catastrophe

Article "Mitholz remains dangerous"