In addition to its backfilling operations, GSES GmbH has also had planning permission since 1 January 2006 for the long-term, safe storage of waste materials in its underground class IV waste disposal site.

This underground waste site is separated by various barriers from the rest of the backfill field, and forms a separate, closed disposal site within the mining field.

This area is primarily used for storing waste materials from inorganic chemical and thermal processes, building and demolition wastes, and wastes from waste treatment plants. Materials are received packed in big bags, steel sheet drums, underground waste containers etc.