Sniper Elite: Resistance

This is another optional objective that will crop up on your map, and requires you place a satchel charge on the pump in the dam's pump room to weaken it for a bombing run during Mission 4 'Collision Course'. The objective is marked on your map as a blue diamond and the pump room is in the basement of the marked building. Once you've done what's necessary to cause the dam to crack, this will unlock.