The first day of interviews I had four 30-minute interviews. They asked the typical "Tell me about yourself". They also asked for general questions such as "Why GS?" and "Why Operations". They then asked for specific examples relating to Operations, such as examples of improving a process, or compliance/auditing, etc. They got back to me fairly quickly and I had my second round interviews a week later. The format was the same, consisting with four 30-minute interviews with very similar questions.