Laserfiche WebLink
2 Environmesatal Analysis <br /> duxing the CE&G subsurface explorarion program consists of interbedded layers of loose poorly <br /> graded sand with silt and silty sand. The report includes measures to prevent settlement af the <br /> path including over-excavation, a woven geotextile ma.t, 12 inches of crushed rock,and <br /> micxopiles extending 10 feet inta the Old Bay Mud {CE&G,2013). Cl:&G identified the <br /> potential for liquefaction-induced distress including lateral spreading,subsidence,and gxound <br /> lurching at the site as moderate,but did not recommend specific measures fox�iquefaction along <br /> the trail,which it does not consider a lifeline facility. In the event of si�nificant ground shaking, <br /> the City would automarically close the access gates to the�oint-use parh,so that the risk to the <br /> public would be less than signi�icant. (Less than 5ignificant Impact) <br /> iv)Landslides? <br /> The project area is relatively flat with elevations tanging from 5-15 feet above sea level. The <br /> proposed retaining wall would be constructed on a slanted surface undex the US 10L The City <br /> would implement the design-level recommendations contained in the geotechnical repo�t by <br /> constructing the rieback retaining walls with the appropnate tieback design and lengths,using <br /> corrosive p�otection for the anchors,adding grouting of the tieback anchors for addirional <br /> support,and testing the ma�mum load of the anchors for the tieback retauiuig walls (CE&G, <br /> 2013). The implementation of these design measures would reduce the potential itnpacts <br /> associated slope-related issues, such as landslides,to a less than significant level. (Less than <br /> Sigrlifrcarlt Impact) <br /> b)Resultrn substarrtial soil erosion or the loss oftopsoil.a <br /> The composition of the one soil type within the project area (Urban-land Orthents,reclaimed <br /> complex,0-Z pe�cent slopes) consists of bay mud,gravel,broken cement and asphalt,and salid waste <br /> materials. Based on the soil structure and hydtaulic conductivity,the Urban-land Orthents,reclaimed <br /> complex soil type is considered to have a moderate erosion po�enrial (0.20) (WRECO,2013). The <br /> propased project includes BMPs for erosion control,including the biadeg�adable coir rolls, straw <br /> wat�les, or silt fences installed along the base of slopes during construcrion, ta captuxe sediment and <br /> revegetarion. See mitigaaon measures BIO 7, Site Construction Management Practices;BIO 8, <br /> Revegetate Distuxbed Areas;and HYD 1,Implement Best Management Pracrices (BMPs). (Less <br /> than Stgnrfrcat�tlmpact with Mitrgatioti Incorporation) <br /> c)Be located oa a geolagrc urut or soil that is r.uzstable, or that would becorue unstable as a <br /> result ofthe pmject, arrd potentially result iu ari- or off-site landslYde, latexal spreadt�g, <br /> substde�ce,liquefactiorz or collapse? <br /> The proposed project includes expansive soils and would be subject to uplifting. The CE&G <br /> geotechnical report recommends design criteria for adequate stabilization of the foundation for the <br /> }aint-use path for both conditions. Due to the highlp expansive and saturated nature of the soils in <br /> t1�e project area (Young Ba�Mud),the subgrade soils that would underlay the pavement of the joint- <br /> use path would need to be stabilized prior to the construction of the joint-use path. The City would <br /> ?-31 US 901 Pedestrian U�adercrossirag and Bair <br /> Island I�.oad StorJfiz Draira Purrrp Statio�r Project <br />