Specifications include, but are not limited to: Work includes implementing the remedial action plan for Bank Stabilization at Double Ditch Indian Village State Historic Site. To stabilize the riverbank toe, a rock filled trench was selected because rock of sufficient size and quality is readily available and is routinely specified by North Dakota Department of Transportation. To stabilize the slope, removing the mass on the upper slope, adding mass to the lower slope, and installing pipe pile walls to provide strength across the failure planes is the selected solution. The pipe pile walls include driving 12” diameter steel pipes located approximately 70 feet from the toe of slope. The pipe piles are estimated as 25’ long and spaced 3’ apart, located approximately 15 feet below the ground to intercept the failure surface and to allow vegetation to grow on the slope above the pipe piles. Two rows of the pipe piles are required to provide enough strength across the failure planes to stabilize the slope. Native vegetative plantings will be included to help stabilize the soil.
