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I�nd�ng: Implementation of Mitigation Me,�sure Geoiogy-1 wauld raduce unpacts from <br /> diff�r�ntia.l settl,ing to a less than significant level. <br /> Facts�n Support of F�nding: Im�l�me�tation of Mitigation Nleastue G�ology-]. would reduce <br /> �tnpa�cts from differendal settling caused by strong ground s�akir�g hy recluiriag <br /> implementation of the recommendations included in the geot�ht�ical feasibilxty <br /> doc�ments prepared for the project to ensure the�afe�y an�stabi�ity of the <br /> structures. Impact 3.5-1 an�proposed mi#igation are described on Draft EIR <br /> pages 3.5-i0 through 3.5-12, and Revised Final EIR pages 4-17 through 4-19, <br /> which are h�reby incorporated by reference. <br /> Impact 3.5-2 <br /> Impact: Excavataon and backfilling for various roadwa�, utility,a:►d drainage <br /> improvements along Laurel Way would have the potential ta res�xlt in sail creep <br /> and slope instability. <br /> Mitigatavn: Mitiga�ion Measuxe Geoingy-1:All renommendatio�s in the TRC Lowney <br /> (ZOQ7}, Comerstone Esrth(",roup (2008), and Treadwell 8c Rollo(2Q�8a.and <br /> 20Q8b) geatechnical feasibility dacu.ments,include�in Appendix E,shall be <br /> implemented. These measuz�es include the following: <br /> a} All undocumen�ecl fills beneath pavemen�, d�nivewaY,ar other hard- <br /> scape a�as shall be removed down ta native soil �nd replace�d with <br /> coanpactad eagine�rad fi11. <br /> b) All undocument�d fills beneath prapose�.structures shal�be removed down <br /> to native soil and replaced as compacted en�ineered fill,�nless the <br /> steuetures are supported on dri�led.pier foundations,which derive support <br /> from the uac�erlying nati�e soils anQ be�rock. <br /> c) All drilled pier faundations shall be d�signed for soil creep press►�res. <br /> d} Petmanent dx�ainage mea�shall be installed an all lots ta int�ro�pt <br /> swface water infiltration and migrating subsurface water and thus re�duce the <br /> lik�lihood of soils beconaing wet and unstable. <br /> e) Drilled pier foundations sha�i he used for ho�s�.s on sloping lots. <br /> fl De�siled foundation exploratians shall be perfnrrned for each 1ot during the <br /> c�esige-level geotechnieal investxxgation to collect site-specific data regarding <br /> slope cr�ep,�ansive soils,and serp�ntinite rook. <br /> g) Garage slabs on grade, drivevvays,vs+a�lcways,sidewa�ks,and pavers shall <br /> have sufficient reinforcement and be supporter�an a layer af non-expansive <br /> fill. <br /> h} All residencesf ret�ining walls,and bi�-re�entiva basins s�ta11 be��apported <br /> dm drilled,cast-in-place, straight-shaft friction piers or similaz cons�iction. <br /> C�nsideration s�all be given on a case-by-case basis to the ne.ed for�tra <br /> steel rein�farceme�t nf the piers and grac�e beams, voids beneath g�de beams <br /> to mitigate uplift distress to�e strucfixres,perimeter subdrains and moisture <br /> 22 <br />