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.