This lecture discusses backfilling procedures for excavated structures. It defines backfilling as the activity that occurs after excavation to fill the excavated area. The lecture outlines the objectives of learning about backfilling clauses and how to determine which clauses apply. It then provides examples of excavating and backfilling footings and foundations for a simple guard house structure. It emphasizes the need to carefully measure excavation depths and backfill quantities for different areas. Finally, it provides exercises for students to measure backfill quantities for given structural details and footing configurations.