City flooding with chemicals (Dying Light 2: Stay Human)

At the very iron does not allow you to play, because I watch the passage. I can't find anywhere what happened to the central loop after the opening of the dam. It seems that according to the plot it is said that if the colonel opens the dam, he will flood the whole city with chemicals, but according to the plot it is not clear what happened to the city. None of the endings mention this event. Plot omission? Who played for the peacekeepers?