The Maine Department of Transportation began work Thursday on a project to further stabilize a roadside slope on Route 2. The slope first collapsed into the Penobscot River in July because of over-saturated soil, which continues to be a problem, according to the DOT. Work crews are building a trench designed to divert water away from the slope to prevent a repeat collapse. Traffic on the road was reduced starting Thursday to one lane. DOT officials expect that a detour will be in place for no more than a day, sometime between Oct. 31 and Nov. 2. A specific date will be announced as the DOT assesses the progress of the project. The road work is expected to last about three weeks.