The Ullr Tightline project is the largest of four Great Lake Commission grant projects intended to reduce sediment into the Poplar River at Lutsen Mountains. Engineers estimate that the project will reduce sediment by 90 tons per year and will be able to handle a 100- year rain storm. Above: This giant pipe is part of the project and it is designed to help slow down the energy of the water flowing down the hill. Left: Riprap has been installed along the channel that discharges into the Poplar River. Riprap works by absorbing and deflecting the energy of the water flow before it reaches the streambed.
This last construction season saw the completion of two more significant sediment reduction projects by the Poplar River Management Board (PRMB) in collaboration with the Cook County Soil and Water Conservation District (SWCD).
“With the completion of these projects, we continue to make significant and measurable progress in reducing sediment in the Lower Poplar River,” said Tom Rider, president of the Poplar River Management Board.
The Ullr Tightline project is the largest of four Great Lakes Commission grant projects intended to reduce sediment into the Poplar River. Not long after the Poplar River was placed on the Minnesota Pollution Control Agency (MPCA) Impaired Rivers List because of its turbidity, this historical gully was identified as a major contributor of sediment in the river.
The selected solution for the Ullr Mountain gully was an engineered tightline system. The system consists of a drainage collection pool at the top, a drainage tightline down the hill, an energy dissipater at the bottom of the tightline system, an energy dissipater outlet pipe, and a riprap-armored channel that discharges to the Poplar River.
The tightline will accept all water flowing from the adjacent County Road 5 and ski runs and send them to the river without degrading the steep slope below the county road. The tightline was placed inside the gully and measures were taken to ensure that water landing on top of the tightline (the old gully) would be transported to the bottom without causing further erosion. This project is estimated to reduce sediment by 90 tons per year and handle a 100-year rain storm.
“It is exciting to complete this major sediment reduction project,” said Kerrie Fabius, district manager for the Cook County SWCD. “This project has been in the works for several years and represents a collaborative effort on the part of the Soil and Water Conservation District, PRMB and Lutsen Mountains.”
The Ullr Tightline was funded 25 percent by landowners and 75 percent by a $687,000 grant from the Great Lakes Commission.
When awarded in 2010, the grant was one of only nine awarded in the entire Great Lakes Basin, was the second-largest of all nine, and was the only one awarded in Minnesota. “It was an incredibly competitive process, but the strong history of collaboration with the SWCD, a track record of completed and successful projects, and strong landowner commitment allowed us to be successful. It was a big victory for the community. We were very excited,” added Rider.
The other projects completed this past season were improvements made along County Road 5. “After years of planning with state and local officials, this project is the last piece of a comprehensive system of stormwater infrastructure that spans the entire length of the ski resort on the side of the river most susceptible to erosion,” said Rider.
The country road stormwater improvements include an engineered storm sewer system that will intercept the storm water flows and direct them to either the Brule Tightline or the newly constructed Ullr Tightline. “All of these flows will be transported to the river without delivering additional sediment to the river,” said Fabius.
To date the Poplar River Management Board and Cook County SWCD have implemented more than 10 conservation projects in the watershed. Including funded projects planned through 2013, these projects will eliminate an estimated 835 tons or 42 percent of the median sediment load.
The Poplar River Management Board was organized in response to the Poplar River becoming listed on the Impaired Rivers List as developed by the Minnesota Pollution Control Agency (MPCA) in 2004. In partnership with the Cook County Soil and Water District and other organizations, $1.7 million has been invested in sediment reduction projects with nearly one-third of the investment made by landowners in the watershed. PRMB’s goal is to be removed from the impaired list as soon as possible.
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