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2 Environmetatal Analy�zs <br /> Most of the proposed constxuctian activity would occur adjacent to Redwood Creei�,in areas of <br /> disturbed rudexal vegetarion and compacted soils. The area beneath the US 101 bxidge is barren with <br /> no riparian vegetat�on. Construction would avoid wetland vegetation along Redwood Creek except <br /> for approximately 0.01 acres of fragmented tidal salt marsh vegetation at either end of the US 101 <br /> undercxossing. Construct�on would also require dewatering a 175-foot b�� 15-foot area belovv the <br /> MHHW level undex the bridge. The contractar would install a temparary cofferdam surrounding the <br /> dewatered area in Redwood Creek,which would prevent constxucrion activity from affecring the <br /> nearbp ridal maxsh, a sensitive nat�al community. The Citp would also implement Best Management <br /> Practices {BMP's} to reduce erosion and sedimentarion impacts to Redwood Cteek and the ridal <br /> marshes (see the Ciry's NPDES Compliance Checklist Append�I). 'I`he BMPs listed above in <br /> Mirigatian Measure BIO 7 include site management pracrices,restricbions on refueling and use <br /> hazardous materials,and erosion controi measures,which would also reduce t�e potential for project <br /> impacts to t�.dal salt maxsh to less than significant levels. (Less than Significant Impact with <br /> Mitigation Incorporation) <br /> c)Have a substantial adverse e�`'ect on federally protected wetlands as deftned hy Sectioa 404 <br /> ofthe Clean WaterAct(rncludirig, I�utuatlrmited to, marsh, vernalpool, coastal, etc.) <br /> throrxgb ditect removal, ftlli�g,hydrological interruption, or other means? <br /> The project would have temporary and permanent impacts to a small atea subject to USACE <br /> jurisdictional as waters of the U.�.The joint-use path and retaining wall would be Iocated on the <br /> creek bank above the ordinary high water ma�k, and the only permanent facilities within jurisdictional <br /> watexs would be one 24-inch pipe for discharge stormwater, either polyvinyl chloride (PVC} or high- <br /> densiry pol�ethylene (HDPE) pipe, from the joint-use path and rock slope protection (RSP) below <br /> this pipe. Construction of the project, howevex,would require access to the bank slope below the <br /> orc�inary higl�water line. The temporary cofferdam would confine the impacts to a small area and <br /> prevent them from affecung the surxounding waters. The location and extent of the temporary and <br /> potential impacts of the project to jurisdicrional waters are as follows: <br /> �}•]�e �}� Square <br /> Va�urne Linear <br /> Activity Excavated/ Location Feet ��) {� <br /> Fill Material Feet <br /> �gq ft) <br /> Temporary Fill/ gravel Creek bank below US 1d1 87� 260 175 <br /> co fferdam bags overcros sing <br /> One permanent Excavarion Creek bank below L)S 10� 47 10 14 <br /> stormwater and fill/bank overcrossing <br /> discharge pipe soils <br /> �ne permanent FiII/ PVC or Creek bank below US 101 �' ' 13 <br /> starmwater HDPE pipe overcrossing <br /> discharge pipe <br /> ?-��' US 109 Pedestrian Uradercrossirrg and Bair <br /> Island Koad Storm Drafn Pump Station Project <br />