Chelsea Self / Post Independent A major rock and debris flow down the Devil’s Hole drainage in Glenwood Canyon last week was largely unexpected in terms of its impact on Interstate 70, state transportation officials said Wednesday. The massive debris flow caused by a rainstorm the evening of July 22 dumped piles of large rocks and trees into the Colorado River, damming the river and forcing it out of its channel up against the highway’s eastbound deck structure. Concerns about the water and debris compromising the highway structure ultimately closed I-70 for the better part of two days as a result. Westbound lanes weren’t reopened until early Saturday morning, and the eastbound lanes remained closed until later that day.