Weston Dam Repair

Repair Weston Dam consisting seepage mitigation repair and emergency spillway repair. The repair for seepage mitigation consists of construction a toe berm to collect through-seepage and control the migration of soil particles occurring in boils. The components of the toe berm repair include a horizontal drainage blanket, a trench drain, toe drain collection system, and extension of the existing 36 reinforce concrete outfall pipe. The horizontal drainage blanket will placed along the existing downstream face of the dam and extending approximately 150 feet downstream of the toe. This horizontal drainage blanket will collect embankment through-seepage and any foundation under-seepage and provide for a filter exit that prevents movement and migration of soil particles. The trench drain will be excavated near the toe of the new horizontal blanket and will relieve hydrostatic pressures in the foundation, reducing likelihood of boils forming. A toe drain collection system consisting of perforated pipes, manholes, and pipe outfalls will collect the seepage and direct it away from the dam. The existing 36 reinforced concrete outfall pipe needs to be extended due to the required length of the toe berm. The repair for the emergency spillway to reduce the risk consists of armoring the emergency spillway to reduce the potential of erosion, this reducing the risk associated with failure. The components of the emergency spillway repair consists of high-performance turf reinforcement mat (HP-TRM), riprap, and a diversion berm. The HP-TRM will be placed along the graded emergency spillway to armor it. Sod will be placed on top of the HP-TRM as the vegetation cover. Riprap will be placed were the HP-TRM is terminated at the downstream end of the emergency spillway to reduce the potential for erosion and head-cutting to progress upslope. A diversion berm will be constructed along the left side (looking downstream) of the emergency spillway to direct the flow of water toward Cedar Creek.