Long-term Stabilization of Disturbed Slopes Resulting from Construction Operations

Abstract

Highway construction disturbs soil, which must be stabilized to prevent migration of soil particles into water bodies. Stabilization is enforced by law, regulation, and a permit system. Stabilization is most efficiently attained by reestablishment of vegetation, and permits sometimes specify this method of stabilization. Revegetation is difficult in northern Alaska, and seeded grasses often die in a year or two, while reestablishment with native vegetation takes several years. A literature search and interviews with experts indicates that simply extending this “establishment period” has many practical difficulties. Field investigations and interviews indicate that in northern Alaska little erosion occurs at slopes with failed vegetation, which implies that vegetation was not critical to reducing contamination and the expense of revegetation was unnecessary. However, when revegetation is specified in standard permit language, and contractor, owner, and regulator must close out projects, grasses are utilized. This research supports the recommendation that the Alaska Department of Transportation and Public Facilities work with the Alaska Department of Natural Resources and the Alaska Department of Environmental Conservation to develop special standards for projects north of the Brooks Range and between the Brooks and Alaska ranges, that recognize the low erosion potential of clean road fill – embankments.