Large Woody Debris Design and Installation

Large woody debris assessment procedure

TriMedia’s staff was selected to perform a Large Woody Debris (LWD) assessment procedure, which included inventorying natural, in-situ LWD.

To start, the crew classified LWD in the field by size, position, orientation, and habitat value, documenting their findings with tablets. 

Using that information, TriMedia designed new LWD structures to mimic the observed natural effects and habitat values. The team also prepared bid documents and helped create the LWD work plan, which presented challenging obstacles including:

• Landowner access
• Geomorphic feature protection (riffles)
• Avoiding invasive species

Construction management and safety oversight

TriMedia also provided construction management and safety oversight services for LWD structure installation.

The team’s extensive experience dealing with large equipment working in challenging riverine environments was critical for this project’s success. 

To help keep operations running smoothly, TriMedia:

• Coordinated multiple daily tailgate meetings
• Inspected the quality and compliance of all activities
• Obtained pre/post photos of each LWD location

In total, over 250 LWD structures were installed. The structures ranged in complexity from single log habitats and vane structures to complex wing deflectors with multiple large rootwads, logs, and slash. Additionally, approximately 150 feet of log toe was installed to stabilize a historic erodible bank. Toe was also used where the contractor repurposed in-stream boulders.

Mussel surveys

TriMedia also assisted and managed mussel surveys, where riffles were surveyed for presence of mussels. Where sensitive mussels were observed, TriMedia worked with the general contractor to prepare mitigation routes that help heavy equipment avoid traversing through riffles.