Lack of proper maintenance and repair of Detroit Salt Mine, during the life of the 90-year old facility and an aggressive subsurface environment, presented many unusual design issues. The technical note describes how the mine stabilization and closure design addressed the issues and ensured that ground water was controlled at all phases of the construction. It introduces the design challenges for the stabilization and the closure of the Salt Mine which includes design of the stabilization measures in the mine to ensure long term stability, and concrete plugs in two mine shafts to prevent long-term leakage into the mine and subsequent solution of the salt. The design includes grouting in and around the shaft plugs including two-state cement and chemical curtain grouting in the rock surrounding the plug and high-pressure contact grouting at the concrete-soil and concrete-rock interface. The paper addresses the selection of plug locations, plug geometry, concrete mix design, cooling of the concrete and grouting of the rock and rock/ concrete interface. © Nigerian Mining and Geosciences Society (NMGS).