Fort McCoy News February 27, 2015

Alderwood Dam removal, road rerouting begins

Public Affairs Staff

Work to remove a decades-old water impoundment and reroute a road that affected a surface danger zone (SDZ) at a nearby range began in January on Fort McCoy's North Post.

Michels Corporation, headquartered in Brownsville, Wis., is the contractor for this project, known as the Alderwood Dam Project.

Contract employees work on the Alderwood Dam Project on Fort McCoy's
North Post.

The project includes the removal of Alderwood Dam, obliteration of an existing asphalt road, removal of muck lake-bottom soil from what formerly was Alderwood Lake, and the installation of a new, precast bridge after 17th Road has been rerouted. The project was designed by Short Elliott Hendrickson Inc. of La Crosse, Wis.

Directorate of Public Works (DPW) General Engineer John Adams said the work will be done in several phases, and completion is expected in mid-September 2015.

"The first phase was installing erosion and sediment control," Adams said. "The second phase involved diverting stream flow and drawing down water levels (of Alderwood Lake), allowing the installation of sheet piling for sediment removal within the basin and proposed bridge structure."

Additional phases will include construction of a new wetland; installation of bridge footings and superstructure; new road construction; final grading; and removal of the old bridge and dam to promote a more natural stream flow of the La Crosse River.

"The overall goal of this project is to reroute 17th Road, also known as East Range Road, with a straighter alignment and to remove and replace the existing bridge," Adams said. "The new bridge will be a precast concrete arch structure, and the stream will be returned to a natural flow with a widened floodplain."

Currently, 17th Road borders the impact area, which directly affects the use of Range 32.

photo 2
Workers dig a trench that will be used to reroute water while work is completed in the area of the former Alderwood Lake.

"We have two firing points on Range 32 that we haven't been able to make available to customers due to the SDZ crossing the road to the current Alderwood Dam bridge site," said Range Officer Mike Todd of the Directorate of Plans, Training, Mobilization and Security. "After the Alderwood project is completed, we will keep the road as a range maintenance access road, and we'll have the ability to close it off with gates during training on Range 32 using all firing points."

Fisheries Biologist John Noble of the DPW Natural Resources Branch said Alderwood Lake was a prime fishing destination on Fort McCoy for many years. Though the lake is gone, he said fishing opportunities will remain, and more fish now may be able to move up into the north and south forks of the La Crosse River.

"We'll be removing a barrier for fish passage, so, in the end, we should improve water quality and water temperatures for the La Crosse River," Noble said. "There is already a substantial brook trout fishery there, so this will just improve the chance for more fish to move up and populate those tributaries."

The Alderwood Dam impoundment was constructed in the 1930s. The lake also was the primary site for water training on Fort McCoy until 2008 when a new site on Big Sandy Lake on South Post was opened as the primary site. Alderwood Lake served as a back-up location.

In 2010, the process to lower the water levels in Alderwood Lake began. Work then was completed to return the area to its natural state.

"There still is a lot of work to be done as construction has just begun, and it's taken us quite awhile to get to this point with all the planning, funding, permitting, and scheduling," Noble said. "When it's done, it will be a completely different looking area."

For more information about the project, call 608-388-3911.