Project

Big Hanaford Creek Floodplain Wetland Mitigation Project

Categorized Under: Environment

 

 

To obtain federal and state wetland/stream permits, ICF prepared a stream and 150-acre floodplain wetland habitat mitigation plan.

The habitat restoration plan presented the technical design information for realigning a 6,500-foot linear segment of channelized stream into a new stream channel following its historical channel planform alignment. ICF conducted a hydrologic analysis using MIKE11 to establish the hydrology and performed initial channel/floodplain hydraulic modeling that identified how the proposed project would improve connectivity of the channel to the floodplain and how the floodplain would become inundated during different peak flows. A HEC-RAS model was also used to evaluate specific channel parameters.

ICF conducted geomorphic assessments, fish habitat surveys, vegetation and wetland surveys, and stream/wetland functions and values assessment as part of the design process. The restoration design used hydrologic analysis and fish habitat guidelines to design the channel cross section and integrated channel design with instream woody structures, using bioengineering methods to stabilize channel slopes and prevent localized erosion at newly created features.

ICF also used ecosystem diagnosis and treatment (EDT) to confirm that this portion of Big Hanaford Creek was a priority restoration site within the watershed and that the design targeted limiting factors for salmonids within the watershed. Preliminary 35-percent and 60-percent engineering plans for the project were prepared for agency review. ICF then prepared 100-percent construction bid documents, including grading plans, habitat structure details, planting plans, and a project cost estimate.

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Insight Details

Client: TransAlta Centralia Mining, LLC
Location: WA
 
 

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