After further study, this appears to be the rubble foundation of a wall, packed into a foundation cut.

A cluster of tile, pottery, basalt, travertine, chalk and tufo that accumulated at the south side of wall SU480 and that, in the northeast corner, rested directly on top of bedrock, which seems to continue underneath a layer found below SU486. No cut discernible, therefore no cut number assigned. It is still possible that SU486 lay within a cut, however. Possible structural function related to wall SU541 which it abuts.