10th Anniversary of the Percy Quinn Dam Incident - Two Slides, Two States, One Big Mess!

ABSTRACT ONLY - Percy Quinn State Park Dam is a 34 ft. tall earthen embankment dam located on the Tangipahoa River in the Southwest part of MS. Lake Tangipahoa, formed by the dam, covers an area of approximately 550 acres at normal pool. The dam was originally constructed around 1940 and at the time of the incident on August 30, 2012, the 2300-foot-long embankment dam had a low level outlet, a 145' wide concrete primary spillway, and a 300' wide asphalt covered auxiliary spillway at the left abutment.
On the morning of the 30th around 6:30 am, the park manager performed an inspection of the dam as part of enhanced surveillance and monitoring being done due to the heavy rainfall occurring in the area as a result of Tropical Storm Isaac. During the inspection, he noticed two slides on the downstream slope of the embankment that progressed to the edge of the downstream crest. The park manager immediately notified the state dam safety program and local emergency management. Prior to the state dam safety program arriving on site to assess the situation, the National Weather Service issued a flash flood watch due to potential failure. The watch was issued, in part, due to uncertainty about the condition of the dam and how it might fare since water levels were still rising. The dam is only located about 15 miles from the Louisiana border and the State of Louisiana issued evacuation orders for approximately 60,000 people because of the flash flood watch. This presentation will provide an overview of the ensuing 10-day primary emergency response effort and the coordination that took place between the two States and multiple stakeholders to address this emergency. Details will also be provided on the longer-term response and remediation of the dam that occurred after the incident.