Big Lick Hollow Stream Mitigation Project: Using a Combination of Hand Placed Wood Structures and Filling with a Wood, Stone, And Soil Matrix to Restore Headwater Channels
Davis Huston, PE
Stantec Consulting Services, Inc.
Louisville, KY
Authors: Davis Huston, PE
The Big Lick Hollow Stream Mitigation Project is located on a primarily forested site in rural Nelson County, Kentucky. The project includes the restoration of approximately 25,000 feet of streams varying from first-order headwater channels to a fourth-order channel at the project’s downstream end. All streams on site are generally considered headwater streams due to the suite of functions they provide and the organisms that occupy their habitats. The headwater streams on site are typically ephemeral streams with steep gradients and confined valleys. Energy dissipation naturally occurs from roughness elements and where grade is lost over drops comprising of localized threshold colluvial material or, more prevalent, woody debris jams.
Two treatments were developed to restore these smaller headwater channels (>0.1 sq. mi.), a hand placed ‘Large Woody Debris Drop’ structure, and a ‘Headwater Channel’ structure. Large Woody Debris Drop structures were utilized in the uppermost confined colluvial reaches in the watershed that are very difficult to access with construction equipment. This treatment technique uses logs, brush, and hand tools to install structures that provide vertical grade control, promote aggradation, and add bedform diversity and habitat while minimizing disturbance to the area. The Headwater Channel structures were utilized in the moderately confined colluvial reaches that exhibited significant lateral and vertical erosion and habitat degradation. The intent of this treatment technique is to reconnect the channel with its floodplain and re-establish a stable morphological dimension, pattern, and profile. The Headwater Channel structure consists of combining brush, cobble, gravel, and soil to form the bed and banks of the channel. The material is installed between channel spanning logs that are placed on regular intervals. This provides grade control, bank protection, and habitat within the stream channel.
This presentation will discuss the design, implementation, and performance of the hand placed Woody Debris Drop structures and the Headwater Channel structures used to restore the headwater reaches on the Big Lick Hollow Stream Restoration Project.
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