2908 49TH ST SW 2016-01-01 MF Import

i ISeptember 7, 2010 Mc John Mustach 1 L&A Job No. ] 0-03G 1'age 5 Stability Analyses and Design "I'he computer probram, SRWaII version 3.22 computer program, was used in our stability analyses of the precast concrete block wall. The results of the block wall stability analyses are presentcd under APPENDIX attached to this report. Our design o£ the precast concrete block wall is shown with the typical section of the wall and the general notes presented on Plates 3 and 4. CONS7'RUCTION Site Preparatiun and General Crading Vegetation within construction limits of the block wall and wall backfill should be cleared and roots lhoroughly grubbed. lbpsoil and surficial wcak soils within thc block wall and wall backlill should Ue stripped down to dense undisturbed Lsperance Sand soil. Over-excavation down to dcnsc Gsperancc Sund soil should bc backfilled with structural fill. A silt tcnce should bc crcctcd along thc downhill sidc of the construction area, as required, to kecp scdimcnt from being washcd down to adjacent strceL The bottom of the tilter fabric should bc anchorcd in ai trcnch filled with onsite soiL A layer of cican quarry spalls shoidd be placed over arcas of Gequcnl construction traffic, as rcyuired, to protcct subgrade soil f'rom disturbancc by construction traftic. Kcy�raV 'I'rcnch �I�hc ke>'��ay trench fi�r the block wall should bc cut into nativc, undisturbed, dcnse rsperance Sand soil, capablc of rcndcring an allowable bearing pressure of at Icast 3,000 psf. The soil c�posed at bottom of thc keyway trench should be compacted to a non-yiclding state with a vibratory compactor. Overvexcavation of unsuitable soils should be backfilled with structural �ill. A minimum 4-inch layer ot� 7/8-icch-minus crushed rock leveling base, compacted to a non- yielding statc, should bc placcd over the subgradc soils supporting the block wall. The base- course hlocks are to be placed on this crushed rock base with an embedment at least 12 inches LIU & ASSOCIATES, INC.