bioengineered bank stabilizationgrants pass, oregon  The City of Grants Pass Water Treatment Facility is located directly above a riverbank that was undercutting. Inter-Fluve was initially retained to develop and evaluate riverbank stabilization alternatives analysis for plans to protect the city’s only water supply. Subsequently the city contracted Inter-Fluve to provide designs and construction oversight. Riverbank stabilization alternatives focused on protecting the existing water treatment plant and preventing future erosion. Additionally, consideration was given to preventing erosion upstream and/or downstream of the site, as well as avoiding deposition that could restrict flows to the plant's intake structure. The alternatives proposed were: 1) No action, 2) Retaining wall structure, 3) Bin wall structure, and 4) Bioengineered structure. Evaluation criteria for the alternatives included constructability, cost, habitat enhancement potential, probability of success (stability), aesthetics, likelihood to be permitted, and maintenance requirements. A bioengineered structure in the form of a stacked geocell wall was selected as the preferred alternative. Because a highway bridge and sharp river bend located immediately upstream of the site creates complex site hydraulics, a two-dimensional hydraulic modeling analysis was then performed for the chosen alternative. The second phase of the project included the preparation of detailed plans and specifications, assisting with obtaining funding, permitting, and producing contract documents for construction. The US Army Corps of Engineers administered the construction contract utilizing Inter-Fluve's final design and Section 14 emergency funding.
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