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

Gcotcchnical Enginccring Evaluauun L.ettcr Masman Basement Everett, Was6ington CONCLUSIONS AND RECOMMENDATIONS Genesal NGA File Na. 886013 December17,2013 Page 5 It is our opinion that the previously perfortncd alterations may be viable from � gcrotechnical standpoint, providecl that the recommendations found in this letter along witl� t6e results of any structural engineering rcview are utilized in the design review and construction of this projcct. We recommend that a swctural and a civil engineer be retained to review the consWction of t6e basement foundations and utilize our recommendatior.s presented in ttlis letter to verify the design of structural elements associated with the basement construction. It appears that thc newly poured fonndations for lhe basement area were cast direcdy onto competent native soils approximately SA to 8.0 feet below the existing ground surfacc along thc exterior of the residence. We also anticipate itizt the new slab-on-grade �vas alsu supponed on thesc competent native soils. However, we were unable co confirm the slab subp�ade conditions as a part of this cvaluation based on your rcquest not to dis:urh �Se slab. �1%e did not ob;.rve any significant indications of settlement or distress within the ❑ew foundation efements or slab-on-grade. Furthcr recommcndations regarding the residence foundation design arc included in the Foundation subscction of this lcttcr. We also did not obscrve thc presence of a foundation footing drain within our explorations perfonned along the exterior of the r:sidence. Wc recommend that a new foundation footing drain be placcd along thc cn�i-e extent of the residence ihat is tighlined to a suitable discharge tocation. We also recommend that extensivc waterprootmg measures be applied along the eniire extcnt of the basement retaining walls along with frce-draining material used for backfilling the walls once thesc improvements arc carried out. This is Curthcr discussed in the Site Drainage subsection of this letter. T'hc ❑pper surficial soils encountered on this site are considered moisture-sensitive and may disturb easily when wet. "fo lessen the potential impacts of conslruction on the scnsitivc soils and to reduce cosl overtuns and dclays, we recommend that constructio❑ take pface dunng the drier summer monihs if possible. If construction takes place dunng thc rainy months, addilional expcnscs and dclays should be expected. NELSON GEOTEGHNICAL ASSOCIA TES, INC.