EXH1303052455

PCHBPollution Control Hearings Board of the State of Washington

Seattle Tacoma International AirportMasmr Plan Updsre improvements directly affect sueams and wetlands, and the Natural Resource Mitigation Plan Master Plan Update Improvements Seattle Tacoma lmernational A/rport (NRMP) has beenpmpm_ to mitigate these impacts. This reportdescribes additional wetland mitigation (restorationand enhancement), upland buffer restoration, stream enhancement, and stream buffer restoration as additional supplemental mitigation. The additionalmitigation (5.79 acres) has been planned at the request of the US Army Corps of Engineers (ACOE) to fu_er assure the no net loss of wetland functions result from the MasterPlan Updateprojects. Appemtix N N-3 November 2001 Natural Resource Mitigatw_l P/an 356-2912-001 (03) Seattle-Tacoma lnte_ Airport Matter Plml Update AR 052458 2. DES MOINES WAY NURSERY MITIGATION PROJECT This section describes on-site mitigationactivitiesat Des Moines Way Nursery. The mitigation is designedto restoreand enhancephysical and biological functions in Miller Creek riparianwetlands andassociated buffers areas. This mitigationsupplementsotheron-site mitigation describedin the NRMP that are designed to compensate for unavoidable project impacts to wetland, stream, and hydrologicfunctions. In developing this plan, the Port of Seattle (Port) used agency guidance to identify in-basinmitigationactivities thatwill compensateforproject impacts to wetland andstream functions. Elements of themitigation planarespecifically targetedto restore in-basin functions that will be impacted by the project,and includesediment and nutrientretention (water quality), organic carbon production and export, and aquatic habitat functions (e.g., instream aquatic habitat and riparianhabitat for fish and amphibians). The mitigation plan will result in increased functional performance of the wetlands, streams, and buffers at mitigation site relative to their degraded existing conditions. For example, wetlands currentlydominated by non-native ornamental vegetation…
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