Smith Lake Dam Repair

S&ME provided engineering design and construction support services for the rehabilitation of Smith Lake Dam at the Fort Bragg U.S. Army Base near Fayetteville, North Carolina (U.S. Government Project No. W91247-17-C-0063). The project was a military design-build project with Up-Side Management Company (U-SMC), the general contractor.

Smith Lake was originally constructed in the 1940’s for U.S. Army training during WWII and is currently used as a recreation lake for the Smith Lake Recreation Area. The dam was overtopped and breached during Hurricane Matthew in October 2016. The Fort Bragg area received approximately 14 inches of precipitation over a 24-hour period during the storm.
Smith Lake covers 67 acres and has a contributing drainage area of 3,353 acres (5.2 square miles) including several upstream dams. Smith Lake Dam is classified as a Class C, High Hazard Dam by the North Carolina Department of Environmental Quality. The new dam spillway system was designed to safely pass a 1/3-PMP storm event. Calculated peak outflow for the spillway is 1,900 cubic feet per second.

Our design services included preparing a design report including construction drawings and technical specifications. Our services included geotechnical assessment including hand auger borings and Cone Penetration Test (CPT) soundings, seepage and stability and analysis, hydrologic and hydraulic modelling, spillway structural design and uplift analysis, embankment re-construction design, and temporary cofferdam design for construction.

The principal spillway consists of a 3-cycle concrete labyrinth spillway with sheet-pile cutoffs walls and an underdrain system for seepage and uplift control. A pedestrian bridge was incorporated to provide access across the spillway. An earthen emergency spillway was designed along the right abutment. A 42-inch low level slide gate was designed to allow the lake to be lowered.

S&ME provided submittals review, site observations, and construction certification services for the dam construction. The project was completed in March 2021.