The dam at Lake of the Woods is under state scrutiny. file/ROBERT A. MARTIN/THE FREE LANCE-STAR Visit the Photo Place

State says LOW's dam repair plan insufficient

State sends back LOW proposal to upgrade dam, saying it is insufficient

BY ROBIN KNEPPER

Date published: 8/23/2008

BY ROBIN KNEPPER

State officials have rejected several plans and processes proposed by Lake of the Woods that might have justified a lower standard for the dam on the Orange County subdivision's main lake.

Department of Conservation and Recreation spokesman Gary Waugh said Division of Dam Safety staff analyzed and found unacceptable LOW's proposal for a reduced spillway capacity and an evacuation plan for people in the inundation zone of the dam.

"Both of these might be a step in the right direction," Waugh said, "but neither is sufficient."

DSS Director William G. Browning said in a telephone interview this week that LOW needs to do further analysis and respond to his staff by Sept. 10.

The state Soil and Water Conservation Board will meet Sept. 24 and 25 and is expected to vote on LOW's plans to refit the existing spillway with a hydraulic gate. Such a refit is expected to cost about $3 million.

State regulations require that the spillway discharge water equal to a full Probable Maximum Flood (PMF), which in the LOW area is 37 inches of precipitation in 24 hours, if failure of the dam would result in loss of life or serious property damage.

LOW's proposed plan for the existing spillway would only discharge two-thirds of the PMF.

If the SWCB follows the dam safety division's recommendation and turns down LOW's proposal, the homeowners association could be forced to build a new 750-foot roller-compacted-concrete spillway over the top of the existing earthen dam. That is estimated to cost between $6 million and $8 million.

Part of the LOW submittals to the state was an incremental damage analysis that showed the number of homes that would be inundated if the dam failed. DDS staff engineers questioned some of the technical work used to determine how many occupied houses would be affected.

"The initial indication from both sides was that the IDA would work," said LOW General Manager John Bailey. "But when the numbers were crunched, it didn't. We think the DDS staff should consider other factors.

"The state has always said that the spillway needed to meet the full PMF," Bailey said yesterday. "But we will continue to work toward a reduced PMF."

Bailey said that the LOW board of directors will hold a special meeting to discuss its options and their implications before responding to the state by Sept. 10.

Robin Knepper: 540/972-5701
Email: rknepper@earthlink.net

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Date published: 8/23/2008