3606 W MUKILTEO BLVD 2016-01-01 MF Import

Geotechnical Enginccring 8valuation Mukilteo Boulevard Devclopment Evcrett, Washington Marcli 31, 2003 NGA Filc No. 3GG503 Pngc 13 should bc overescavated and replaced with structural fill. We should bc retained to observe the prooGoll test and provide subgradc repair recommendations, as needed. Site Drainagc Surface Drainage: The finished ground surface should bc graded such that storm water is directed to an appropriatc stonn water collection system. Water should not be allowed to stand in any area where footings, slabs, or pavcmcnts are to be constructed. Pinal site grades should allo�v for drainage away from buildings. Wc suggcst that the finished ground be sloped at a minimum gradient of 3 perccnt for a distance of at Icast 10 fect away from buildings. Surfacc watcr sliould be collected by permanent catch basins and dmin lincs, and bc discharged into an appropriate discharge system. Subsurfacc Drainagc: Shallow perchcd watcr may bc encountcrcd in building, utility, and vault c�cavations. If ground �vatcr is encountered, thc bottum of the c�ca��ation should be sloped to dtain to a low arca wherc a sump and pmnp system should be installcd and watcr pumped out of the excavation. �r sevcre scepage is cncoimtercd, cutoff or curtain drains may nccd to be installcd on the uphill side of thc cxcavations to capturc ground wnter and route it around the escavation. 7'he neccssity, extent, and depth of any cutoft'drains should bc dctcmiined at tlic timc of construction, based on prevalcnt conditions. Wc rccommend the use af footing drains around structures and behind all retaining walls. Footing drains should bc installcd at Icast I foot bclo�v planncd finishcd tloor slab. Thc drains should consist rf minimum 4-inch-diamctcr, rigid, slottcd or perforated, PVC pipc surrounded by Gec-draining material ��rapped in a filtcr fabric. Wc rccommcnd that thc frcc-draining mntcrial consist of an 18-inch-widc zonc of cican (Icss than 3 perccnt tincs), gnnular matcrial placed along tlic back of tl�c wall. Pca gravcl is an acceptable drnim m�terial or drainage compositc may also be used instcad. The frce-draining material should c�tcnd up tlic wall to I foot bclow thc finishcd surface. Thc top foot of soil should consist of impermcablc soil placed over plastic shecting or building paper to minimizc surface water or fines migration into thc footing drain. I�ooting drains should dischargc into tightlines leading to an appropriate collcction and discl�argc point with convenicnt cleanouts to prolong the useful life of the drains. Roof drains should not bc conncctcd to �vall or footing drains. NELSON GEOTECHNICAL ASSOCIATES, INC.