Kentucky’s State-Owned Dam Repair Program in Action: Bullock Pen Lake Dam Rehabilitation

Bullock Pen Lake Dam was constructed in 1953 for the Kentucky Department of Fish and Wildlife Resources
(KDFWR). Since its original use as a recreational impoundment, Bullock Pen Lake has become a water supply reservoir for the surrounding community. The high-hazard earthen dam has a maximum height of 50 ft, a crest length of 670 ft, and upstream and downstream slopes of 3H:1V and 2.5H:1V, respectively. A single ungated concrete weir in the right abutment was the only spillway. Analyses indicated that this structure was significantly undersized relative to current design storm requirements, passing only 24% of the probable maximum precipitation (PMP). Erosion of the soft bedrock exposed in the spillway outlet channel began shortly after initial reservoir filling and has continued headcutting toward the reservoir, along with significant seepage flows in the interbedded rock layers beneath the weir, increasing the likelihood of a breach through the right abutment. In response to these deficiencies, the Commonwealth of Kentucky ranked this project the first priority for rehabilitation among all state-owned dams, setting the stage for implementation of the Commonwealth’s now robust State-Owned Dam Repair Program. Through a decade-long collaborative effort between the Commonwealth, Engineer, and Contractor, Bullock Pen Lake Dam has been rehabilitated to current dam safety design standards with a 12½-cycle, 260-ft-wide, reinforced concrete labyrinth spillway over the dam embankment and closure of the previously existing spillway and outlet channel. The reservoir remained functional as a regional water supply during the 2.5-year long construction period.