Thursday, September 9, 2010

Erosion–Control Project

The river has been severely eroding into the Miskowic property for years, taking away soil, fencing and trees.

Now, a major shoreline restoration, erosion-control project has been nearly completed on the Miskowic property and it shows promise in checking the erosion, according to Mille Lacs County Soil and Water Conservation District conservation technician Lynn Carter.

The project was made possible with the help of:

• A Minnesota Clean Water Fund matching grant of close to $39,007, in which the Miskowics had to put up 25 percent of that in money or in-kind contribution.

• Organizing by the Mille Lacs County Soil & Water Conservation District (SWCD), with input from the Department of Natural Resources.

• Engineering by a Joint Powers Board of Engineers.

• A week of labor by a youth group from the Conservation Corps of Minnesota and Iowa. Also labor from master gardeners and people involved with conservation agencies during the afternoon of Aug. 2. The latter had attended a workshop on shoreline restoration during the morning of Aug. 2 at the Princeton Area Library. Part of the mentioned grant funded the workshop.

• Labor by the Miskowics and use of their equipment, which counted toward their 25 percent grant share.

The erosion at the Miskowic property has been occurring where the Rum River makes a sharp U-turn, typical of rivers in a mature age. When moving water makes a turn, the water speeds up on the outside part of the arc and that causes erosion of the river bank.

The shoreline is also at the bottom of a slope that had been devoid of deep-rooted vegetation.

The anti-erosion plan for the Miskowic property was developed over late 2009 and into the spring of this year. Joint board of Engineers/Technical Service 3 engineer Michelle Sternquist and engineer technician Al Bernhardt came up with the plan with input from the DNR, Carter said. The engineering group was established to help with such projects at a lower cost than what private engineers would usually charge, according to Carter at the Mille Lacs SWCD office.

Here’s what was done in the project:

• Excavation work was done in late July this year to reduce the steepness of the slope and build terraces on it. Terraces are flat, bench-like plateaus to slow the advance of draining water.

• Posts were sunk deep into the toe of the slope, around which uprooted trees and shrubs were attached with cables to make what is called a tree/shrub revetment. That breaks up the energy of the current as it passes by the bottom of the slope.

• Willow wattles were installed on the first bench at the bottom of the slope. Willow wattles are made by twisting long branches of willow together and tying them end to end. The two longest willow wattles were about 100 feet long. They are designed to help keep river water from pulling away embankment soil as the river level rises and falls.

• The entire slope was also seeded with native grasses and flowers and some oats, the latter to begin immediate growth to check erosion until the permanent plants can take over.

• A landscape fabric was laid out over the whole slope and then native plants that grow deep roots (some as much as 15 feet long) were planted. Holes were punched through the fabric and the roots placed through them and into the soil. In all, 6,400 native plants and 325 native shrubs were planted.

• This fall dormant willow stakes will be planted just behind the tree/shrub revetment with the idea they will become willow trees to also help check erosion along the river bank.

Attention was also paid to the lawn that lies atop the slope. About 10 feet back from the top of the slope, the shallow-rooted turf grass that has been growing there, was replaced with prairie grass and native vegetation.
The city of Princeton, as part of the state permit rules for its planned expansion of the Princeton wastewater treatment plant, must reduce a certain amount of bank erosion along the Rum River in the Princeton area. The purpose is to reduce phosphorous going into the river, which happens when river bank soil goes into the river, according to wastewater project engineers. A project like this could help work toward that end. Whether or not the city would ever use this particular plan, it did check it out, with Princeton Public Works Director Bob Gerold visiting the Miskowic site to look it over.

Comment from landowner

“I hope it works,” said Randy Miskowic last Thursday. “We spent a lot of time and money. If it doesn’t stop the erosion, we’ve enhanced it.”

Miskowic explained what he meant about enhancing it. He stated that when excavation was done to redo the slope, a lot of sand was removed from the slope’s toe. Enough sand was removed from the slope that it sits in a pile 30 feet high and 100 feet wide on the property, Miskowic said.

But the angle of the slope was improved so it now isn’t nearly as steep, Miskowic said, explaining that originally it dropped 33 feet vertically over a horizontal span of 25 feet.

Miskowic said he thinks the project “turned out really well,” and talked about how it withstood for the most part, the heavy rains during the second week in August. And that was before the planted vegetation had much chance to grow, he said.

Miskowic is likely looking forward to not having reruns of what has been going on along the river next to their residence during the 23 years the Miskowics have lived there.

The bank has eroded anywhere from six inches to three-to-four feet per year, he recalled. “I had been planting grass and throwing logs and any kind of trees and anything I had to hold the soil,” he said, referring to the area of the erosion.

But when the spring floods arrived, they would just wash it all away, and he came to realize, he said, that a solution would take more expertise than what he had.

Read this and more newsworthy erosion articles

1 comment:

Laharia group said...

Sewage treatment plant and equipment- Delhi India based manufacturer and supplier of sewage water treatment plant and sewage waste water treatment .