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Jersey Valley
CLAY BLANKET REPAIR |
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This flood control dam needed to have the clay blanket covering one side of the lake replaced, due to the existing blanket allowing water to seep through the dam itself. Highlights of the repair to this flood control dam: |
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Ceres Environmental Services crew removes topsoil and trees from the rock abutment. 25 feet of rock will be removed to create a working platform for the deteriorated clay blanket removal. |
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Twenty cubic yard capacity, off-road, articulated dump trucks are needed to maneuver in the tight work-site conditions. |
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The rock abutment has been pulled back, and the old clay blanket has been removed. |
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During excavation, a long, deep crack was discovered at the base of the rock abutment. River City Concrete of Westby was contracted by the County to bring in the concrete to fill the crack. |
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This crack at the base of the rock abutment had to be filled before work could continue on the replacement of the clay blanket.
High slump (8 inch) concrete was pumped into the crack. Six cubic yards were pumped into this section alone. |
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Borrow material was determined to be "dispersive" and needed to be treated with quick lime to make it usable. The addition of quick lime also increased the stability of the material. Unstable, heavy clay in the original blanket brought about initial concerns over long-term stability of the dam. |
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The quick lime needs to be worked into the borrow material to a depth of 9 inches. This allows the lime to react with the soil and create the new 'super soil'. |
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The treated borrow is immediately loaded and transported to the work site. It is then spread into an 8 inch lift and then compacted. Contractor-supplied quality control keeps the borrow at 16% moisture and 95% of Provtor density (about 106 lbs./cubic foot). |
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Borrow has been placed maintaining a 1.5:1 slope. The total depth of fill will be about 3 feet. |
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Work is nearly finished. A decision was made to flatten the slope to 1.7:1 to increase stability. |
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The area where material for the blanket was removed is in the upper end of the lake/park. The County took advantage of this by creating a wetland scrape area. This will provide a small pool of water for wildlife. Native grasses were planted around the edges as well. |
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The job is now complete. Seed has been spread and mulch blanket placed. The final bill for the job totaled $218,214.00. However, the actual cash outlay from the County only amounted to $7,954.00. Credit was received for seeding, silt fencing, and $21,821.00 from the Wisconsin Department of Natural Resources. |
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The repair to the Jersey Valley Dam took place in 2000. |
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