Our team provided a dam breach study and prepare an Emergency Action Plan for Ioni Lake Dam in Elkhart, Texas. Ioni Lake Dam receives runoff from a watershed
area of approximately 10 square miles. Ioni Lake is a recreational lake with a surface area of approximately 60.5 acres and a maximum storage capacity
of 1,334 acre-feet. Ioni Lake Dam is under the dam safety program of the Texas Commission on Environmental Quality (TCEQ) and is classified as an intermediate-sized
significant hazard dam per Title 30 Texas Administrative Code (TAC).
Hydrologic and hydraulic modeling was performed using the U.S. Army Corps of Engineer’s HECHMS and HEC-RAS computer model. The Probable Maximum Precipitation
(PMP) was determined using the National Weather Service HMR-51 and HMR-52. A full dam breach analysis was performed for the following hydrologic scenarios:
sunny-day breach, barely overtopping breach, and design-flood breach. The HEC-HMS model was used to compute the outflow hydrographs for the dam breach
analysis. CivilTech also prepared a qualitative risk assessment to document the hazard potential and downstream impacts to property and infrastructure.
CivilTech also prepared the emergency action plan to reduce the risk to lives and property from the consequences of a dam failure.