What was projected before Aug. 30, 2012, to be a $1.4 million project to repair the dam at Percy Quin State Park grew to the $5 million to $6 million range after flooding from Hurricane Isaac threatened the structure through the first several days of September.
Dusty Myers, a dam safety engineer with the Mississippi Department of Environmental Quality, spoke to the McComb Rotary Club Wednesday about the emergency procedures at the lake, which impounds water from the Tangipahoa River, to prevent a breach of the dam.
Had it blown out, at least nine homes below the dam could have been wiped out, and others could have been affected by flood water.
Myers said a “combination of factors” contributed to the dam beginning to erode during and after Isaac, including water going over the clay core of the dam and eroding the slope on the downstream side.
“We didn’t have time to do a lot of planning,” he said as he recalled emergency measures to dig a bypass channel and also pump water from the lake.
Answering questions, he said “it’s hard to say” whether there would have been a breach if all the measures hadn’t been taken.
About $1.1 million was spent just on pumps, he noted.
Several state and local agencies pitched in to help, including the Mississippi Department of Wildlife, Fisheries and Parks which operates the park; MDEQ; the Mississippi Department of Transportation; the National Guard; and Pike County officials. The U.S. Corps of Engineers also assisted.
The lake has been drained now, and extensive repairs to the dam and spillway are under way.
Myers said the slopes are being made flatter, the lake drain is being replaced and a steel sheet pile wall is being installed on top of the dam core to prevent future seepage.
The state is financing the project, but Myers speculated some of the costs will be reimbursed by the Federal Emergency Management Agency because of the hurricane.
