2010/03/31 Council Agenda Packet

r, i An expanded riverfront trail system will encompass a hierarchy of trails that will tie together the large Riverfront Development site and integrate its widely varied site uses. New trails and trail connections, with boardwalk segments in the wetland areas, will include accessible connections to public amenities and public-use features within the private developments. Significant public amenities will be provided by the private developer. The master plan proposes multiple connections to these gathering places, with stepped paths and accessible ramps that connect to the trail system below. i. alt - I mgr.— r !K•atiR..RF m. Y Existing and proposed trails integrate diverse site uses. The Public Amenities Master Plan proposes and promotes the conservation, enhancement, and restoration of natural areas. These proposals are predicated on an understanding of the site's existing water regime: historic and contemporary stream flows, well-documented wetland and wetland buffer boundaries, the seasonally-varying flows of the Snohomish River, and the tidal fluctuation of the Snohomish River estuary all contribute to this understanding. Special emphasis has been given to the opportunities to enhance the site's existing natural hydrologic processes and to restore the site's degraded habitat. These improvements will enrich the public experience of the site and exemplify the processes addressed by interpretive elements. The Public Amenities Master Plan proposes to redirect one of the site's most ecologically significant streams, Bigelow Creek, to an alignment consistent with its historic passage. The plan for redirecting the stream contributes to the overall enhancement of various wetlands, and supports a broader plan for accommodating environmental restoration or mitigation efforts for both the private and public developments. The benefits of this stream realignment project extend to incorporating water quality improvement facilities that will address pre-existing conditions in the upland watershed. in addition, surface flows currently channeled in railroad ditches will be routed into the site's most expansive central wetland as the new "Walton Creek". Walton Creek will provide water to the wetland and will be tidally influenced at its low-bank outflows on the Snohomish River. Most of the Snohomish River edge will be retained much as it is today, with some portions stabilized to protect soft bank soils from erosion by the river. Stream outfalls on the river will be returned to natural, low-bank profiles, and improved with large woody debris installations designed to foster a robust and complex fish habitat. The riverfront currently has extensive installations of timber industry-era wood pilings, some of which will be removed as the public amenity improvements progress. Along some portions of the shoreline, the pilings will be left largely intact, with the understanding that their removal is likely to be more environmentally disruptive than leaving them in place would be. Riverfront Development Public Amenities Master Plan 3 40