An unloading system for a storage bin and related method are provided. The unloading system can have a sump configuration that includes a foundation having a floor and a foundation footing. A central tunnel can be formed in the foundation that terminates at a tunnel opening on a perimeter of the foundation. A primary sump can be formed through the floor at a location generally near a centerpoint of the storage bin and connected to the central tunnel. At least one radial sump can be formed in the floor at a location radially offset from the central tunnel and located generally between the primary sump and a sidewall of the storage bin.