A requirement for excavation on tighter lots in Minneapolis is shoring.  This is a reinforcing line to prevent unwanted settling that could negatively affect immediate neighbors.  In this case, it's required on both sides.  Steel tubes are pounded down @ 24" o.c., with plywood set behind them as full excavation progresses.  Today was the set-and-pound down phase, with full excavation to follow.

After initial backfill, the excess pile height will be cut off a few feet below final grade.