1530 51ST PL SW 2016-01-01 MF Import

Geotechnical Engineering Evalu�_.n Lett, r NGA File No. 886013 Mosman Buement December 17, 2013 Everett, Washington Page 10 Fill Placemeut: Following subgrade preparation, placement of structural fill may proceed. Al! fili placements should be accomplished in uniform lifts up to eight inches thick. Each lifi should be spread evenly and be thoroughly compacted prior to placement of subsequent lifts. All stnictural fill should be compacted to a minimum of 95 percent of its maximum dry density. Maximum dry densiry, in this report, refers to that density as detertnined by the ASTM D-1557 Compactioe Test procedure. The moisture content of the soils to be compacted should be within about two percent of optimum so tt�at a readily compaetable condition exists. II may be �ecessary to overv excavate and removc wct soils in cases where drying to a compactable condition is net feasible. All compaction should be accomplished by equipment of a typc and size sufficient to ateain the desired dcgree of compaction. Site Drainagc Surfnce Drainage: The finished ground surface should be graded such that runoff is directed away from the residence. Water should not be allowed to collect in any areas where footings, slabs, or pavcments are prescnt. We suggest that the finis6ed ground be sloped at a minimum gradicnt of three percenl, for a distancc of at least ] 0 fcct away from the structure. Subsurface Drninage: If groundwatcr i; encountered during consWction, we recommend [hat the contractor slope the bottom of the excavation and collect the water into ditches and small sump pits wl�cre the water can be pumped from the excavation and routed to a suitable discharge point. Wc recommend the usc of footing drains around the entire exlenl of thc residence. Footing drains should be installed at least onc-foot below the finished Floor clevation. Thc drains should consist of a minimum 4-incl�-di+imelcr, rigid, slotted or perfor.ited, PVC pipc surtounded by frcc-draining materiai wrapped in a filtcr faoric. Wc recommend that thc free-draining material consist of an 18-inch-widc zone of clean (Icss than !hree-percent fines), granular material placed along the back of walls. Washed rock is an acceptable drain material, or drainagc composite may bc used insicad. The Gee-draining matcrial or the drainage compositc should extend up [he wall to one foot below the finishcd surface. The top foot of backfill should consist of low permeability soil placed over plastic shceting or building paper to minimize thc migration of surface water or silt into the foo�ing drain. Footing drains should discharge inro tighUines Ieading to an appropriate collection and discharge point away from the residence, with NELSON GEOTECHNICAL ASSOCIATES, /NC.