For years the dilapidated greenhouse located just across the Barre, Vermont line beyond Hope Cemetery has been described as an accident waiting to happen. This week it will literally live up to its reputation as part of what is being described as “the largest emergency preparedness exercise in Vermont history.” The long-abandoned “Dufresne House” will be leveled this week in preparation for a statewide “catastrophic exercise” that has been a year in the planning. The old house is just one part of the scenarios that will face more than 750 emergency responders during an exercise that will be played out continuously for 30 straight hours starting early September 24 and wrapping up September 25. Precisely what will happen, when and where, is mostly a closely held secret. The exercise, which is being run under the auspices of DHS has targeted some two dozen locations throughout Vermont, including communities like Barre, Berlin, Waterbury, St. Johnsbury, Burlington and Jericho. The exercise will simulate a massive natural disaster devastating the state, according to officials. Responders will be asked to deal with “â­¦ mass casualties, tens of thousands of power outages, extensive damage, including thousands of downed trees, flooding, and the aftermath of these events.”