Design of ground improvement by dry deep mixing to increase the stiffness of soft soil under embankmentsis critical in many infrastructure projects. To ensure high quality in the constructed embankment, the drydeep mixing columns need to be designed with respect to both ultimate and serviceability limit states.Because of the substantial geotechnical uncertainties that affect this design work, we propose the use ofreliability-based design approaches to ensure sufficient reliability in the column design. This papercontributes to the development of a reliability-based design methodology for the relevant serviceability limitstates of ground improvement by dry deep mixing. A common serviceability limit state for dry deep mixingunder embankments is analysed with respect to affecting geotechnical parameters and their associateduncertainties. Challenges on the way toward a full reliability-based design verification methodology for theserviceability of the ground improvement are also discussed.