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Stream Restoration and Soil Restoration cont.

This reach of stream had not been channelized and maintained a somewhat meandering alignment, but was unstable and experiencing severe erosion problems caused by urban runoff. Although there was development upstream and downstream of the project site, the entire project reach was virtually undeveloped. Moving the pump station and service road was not an option, so MSD opted to relocate the stream using natural stream channel design techniques. Principles of fluvial geomorphology were applied to design the cross-section, alignment, and profile of the stream relocation.

This project incorporated the same rock toe protection and live branch layering techniques used on the Lakeview project. In addition, root wads from felled trees were used to construct a natural revetment on outside bends. Vortex rock weirs were installed in the streambed to direct flows to the center of the stream, away from its banks. Riffle and pool zones were incorporated into the design to help propagate stream life and to aerate the stream by inducing turbulence.

The Winding Falls site is well established four months into its first growing season.

Project Construction

Using live plant materials dictates that cuttings are harvested and installed in the reconstructed streambank during the dormant season. In Louisville, the dormant season typically falls between November and April, a wet time of the year. This made it difficult to divert stream flows around the Lakeview work site and to obtain soil moisture conditions that are suitable for compaction at both sites. Limited site access at the Lakeview project made it impossible for the contractor to work from the stream banks; thus, the contractor was forced to work in the stream. On the Winding Falls project, much of the excavation work could be completed in the new stream alignment before stream flow was routed through it. Longview Creek is also much smaller in cross-section and has much smaller baseflows than the South Fork of Beargrass Creek.

It has been MSD's experience that construction of stream restoration projects should be scheduled such that earth-moving operations, especially those in the stream, can be accomplished during dry months and soil bioengineering installations can be made in the dormant season. This could be accomplished by bidding projects in two distinct packages (i.e., earthwork and vegetation work). In this case, temporary erosion control measures such as temporary seeding and installing temporary erosion control fabrics would be needed to protect the stream between construction phases.

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Last Updated: July 06, 2012

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