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Dam repairs this summer

MDEQ OKs village DPW fix to watergates in August, sedimentation may be next obstacle in long term repairs

June 12, 2013 - Goodrich-On Wednesday morning, engineers from the Department of Environmental Quality, Water Resources Division, WadeTrim engineers, and village council members gathered for a discussion regarding the necessary repairs to the village dam.

The meeting stems from an inspection in the spring of 2012 when the MDEQ evaluated the century-old village dam and required some significant repairs to the structure. Currently, only three of the five wooden flood or watergates, which move up and down to regulate the amount of water and the level of the mill pond, are operational. Two of the gates remain stationary. The state inspector required the village to remove the two stationary gates and replace with moveable gates.

However, on Wednesday Pete Morey, village council member and street administrator, proposed an alternative to the moveable gates.

Morey's concern is that if all five gates are opened, the down river areas north of the dam could be flooded. Therefore, he suggested to alter the two gates so they can be removed only if necessary.

"The three moveable gates are enough to contend with future rain events," said Morey. "We've had seven- and-a-half and nine inches of rain in two storms—the three gates worked just fine."

Morey and the village DPW proposed to the MDEQ drawing down the level of the mill pond over a three to four day period in August during the dry season. Then, Morey proposed cutting about three feet off the top of the two eight foot stationary watergates, which will allow the necessary flow over the dam in the event of a major water event. Those top sections of the watergates can then be put back in place and removed if necessary.

The need, say MDEQ officials, is to allow sufficient water to pass through if heavy rains were to occur.

"Our number one concern is the public safety," said Lucas Trumble, MDEQ dam safety engineer. "We are not asking to open the gates; however, if necessary we have the ability to deal with the water with the gates."

Morey and WadeTrim engineers will provide a plan for the modification to MDEQ. No exact costs for the village were discussed.

Christopher Clampitt, MDEQ quality analyst, along with Trumble tentatively approved the plan proposed by the village.

"If the dam can be modified to meet the requirement for water flow is our concern," he said.

It is essential to be able to remove the stoplogs and lift gates from all five spillway bays in order to safely pass the design flood, MDEQ engineers added. In addition, within the next five years the village should develop a long-term plan for the future of the dam including a structural analysis for the long-term stability as well as a feasibility study for repair, replacement, or removal of the spillway.

Councilmember Mark Baldwin proposed leaving the dam in place, but moving the water flow around as a long term plan.

"As long as the long-term plan is safe and done in accordance with state statues," said Trumble. "The real negative is the deconstruction of the dam—during the removal itself bad things can happen."

"Consider, too, that a river, like the Kearsley Creek, naturally moves sediment— particulate matter that can be transported by fluid flow and which eventually is deposited. That sediment has been building up for the past 100 years—as long as the dam had been in place. Our major concern is sediment management—to control the release of the material downstream."

Trumble added that often contaminants often build up in the sediment.

"Some contaminants like arsenic, which is naturally occurring, may be in the build-up of sediment," he said. "Other contaminants coming upstream from the Ortonville area may also have entered the water and now are part of the sediment. Our concern is controlling the release of the sediment if the dam is removed."

Trumble said testing the sediment, which could be many feet deep, is a major cost in dam removal or modification.

"Any project is going to cost money," he said. "A lot depends on the amount of contamination and volume that has been deposited by the dam."

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