Some of our West Creek residents

Sites 5 and 6

The concept for Sites 5 and 6 has been combined to better address the opportunities and constraints that exist at both sites. Sites 5 and 6 are confined between the Landfill and the Independence Concrete Recycling facility on the north bank, and I-480 to the south. The total reach length to be restored is approximately 2,350 feet. The failing concrete flume within Site 6 is a major fish migration barrier that provides virtually no instream or riparian habitat. The adjacent/downstream Site 5 is recovering from past relocation, straightening and channelization from the construction of I-480. Review of as-built construction documents for the highway and flume revealed that at least the upstream portion of Site 5 was originally constructed with a much larger cross section and at a lower elevation to dissipate energy from water exiting the flume. The oversized cross section slowed velocities to such a degree, that bedload material could not be transported and settled in the upstream reach of Site 5. Subsequent aggradation has raised the channel invert in this area as much as seven feet above the original design. Currently, this portion of the reach is in the process of creating meanders within the deposited material and causing erosion along the outside meander bends. Approximately 1200 feet downstream from the flume (near the southeast corner of the landfill), the channel within Site 5 has been more recently reshaped and armored with riprap. Although the north bank has benches, significant vegetative growth (unfortunately dominated by invasive Common reed, Phragmites australis), and shows signs of recovering; the south bank exists as a steep riprap slope that covers approximately one third of the elevation to I-480. The channel in this section is generally a long glide habitat, with only a few riffles and shallow pools. The chosen restoration concept focuses on removing the fish barrier, and restoring some of the meanders and habitat variability within the channel.

The preferred concept for both sites involves removing the concrete within Site 6 and raising the channel invert through the upstream portion of Site 5 to better tie-in with the elevation at the downstream end of Site 6. Concrete removal must consider the Ohio Department of Transportation embankment, which is thought to be failing due to visible soil slumping. Therefore, any proposed work within the creek must follow the ongoing investigation and recommendations of the geotechnical analysis. Assuming concrete removal is feasible, the outside bank of West Creek will be stabilized with a combination of boulder bank protection, step/pools and live branch layering. Steeply sloped outer banks may require advanced methods of preventing failure. Within Site 6 groundwater seeps occur on the south bank between I-480 and the stream channel. The wet hydrology provides an opportunity for wetland enhancement and creation above the flood elevations of the creek. The wetland creation is also contingent on the geotechnical analysis. Step/pools will be constructed between Sites 5 and 6 to gradually span the elevation change between these sites and provide a path for fish migration.

Much of Site 5 is beginning to re-form meanders with small riffles and pools. Ideally, a meandering riffle/pool, “C” channel could be created within the much of Site 5, however, the adjacent highway, landfill, and private property preclude creating the correct meander pattern. Instead a stabilized “Bc” channel will be created. Where bank erosion exists through this reach, it will be stabilized with boulder toe protection, boulder bank protection, and bioengineering. Rock j-vanes and rock cross vanes will be placed to maintain pools and provide habitat variability. After the banks have been graded, they can be stabilized with boulder toe protection and bioengineering such as live branch layering, or live stakes. The invasive Common reed on the upper banks should be removed and replaced with native riparian vegetation. These sites receive ample sunlight making them ideal for riparian enhancement. In addition the growing trees of a forested buffer will eventually begin to shade the stream from the sunlight which warms the channel within these sites. Wherever feasible, riprap armoring should be removed, graded to a stable slope, and replaced with native plantings and/or bioengineering. Riprap removed from stream banks can potentially be reused assuming material meets final specifications.

Benefits

• Remove the fish barrier between Sites 5 and 6
• Enhanced riparian habitat and bank stability with bioengineering and native plants
• Added vegetation also will help shade the channel
• Step/pools help dissipate energy and offer a habitat for fish
• Step/pool sequences also help transport sediment downstream
• Stable bank angles can be graded with little or no impact to adjacent properties
• Remove invasive species

Risks and Constraints

• Potential slope instability along I-480
• Leachate from the landfill
• Litter may collect in the rootwads and newly established vegetation

Maintenance

• Remove debris jams
• Replace the dead or inadequately established vegetation within the first year
• Invasive species management

Project Plans, Maps & Photos

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West Creek Site Overview Project 5

West Creek site 5 concept plan

West Creek Site Overview Project 6

West Creek site 6 concept plan

West Creek Site 5 photos

West Creek Site 6 photos

West Creek Site 5-6 FINAL Engineering Plans