Asse II salt mine

The Asse II shaft was sunk between 1906 and 1908 to 765 m; potash was mined until 1925 and rock salt until 1964. From 1965 the research centre now called Helmholtz Zentrum München used it to test disposal of radioactive waste in salt.

Between 1967 and 1978, 125,787 drums of low-level waste were placed in thirteen chambers at 725–750 m depth, and between 1972 and 1977 another 1,293 intermediate-level containers at 511 m. The inventory also lists 497 kg of arsenic, plus mercury and lead.

The rock above the mine subsides by about 15 cm a year and since 1988 thirty-two new water entry points have opened. In 2007 an expert report concluded that an uncontrollable inflow would make it impossible to keep the mine dry. A test borehole in 2017 found damaged and rusted containers.