On March 23, an errant 105mm Howitzer round went over a hill and into the backyard of Lori and Scott Connors' Pleasant Grove home.
The explosion sent shrapnel through their house, damaging the homes of several neighbors and leaving a gaping crater in their yard.
The Army shell was pre-packed with seven bags of propellent, and the avalanche safety workers were supposed to remove two of those bags before firing. The round was supposed to go less than 4,000 yards, but instead flew about 9,000 yards.
''What we found wasn't a breakdown in procedure but a breakdown of the human element of the procedure,'' UDOT spokesman Tom Hudachko said.