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4 <br /> � <br /> IPrcliminary Gcotcchniril Lcttcr � <br /> Landslidc Evaluation and Rcpair � <br /> � d703 Glcnhavcn Drivc � <br /> Evcrett,Washington j <br /> I�ebruary l, 2007 <br /> I NGA Pilc No. 75570G <br /> Pagc 12 <br /> USE OF THIS LETTER <br /> IIt is our opinion, from a �cotcchnical standpoint, performing surficial improvements on the slope below <br /> the residence shoulJ help rcduce thc r.uc of recession, sliding, and erosion on th� slope. This measurc, <br /> Ihowever, should not be considercd a pennanent slopc stabilization approach. Slope erosion and <br /> sloughing :�rc chronic conJilions in this area duc to thc naturc of the surficial so�ls, climatc, anJ thc <br /> stcepness of thc slope. Wc havc provided recommcndalions for removing the soft soil from lhc surfacc <br /> of the upper portion of the slope und construction of a rock fili slope lo stabilize the upper portion of the <br /> slopc a�dj:+cent to thc residencc and alung a portion of the driveway, as requcsted. Even with lhesc <br /> tneasures, tho stecp slope arcas adjaccnt ro and below ihe repairs should be expected to continue to crode, <br /> ' especially during cxlrcme wcathcr conditions, and the entire slopc m:ry evcntually nced additional <br /> � <br /> rcpairs. <br /> Duc to the �cnsitivc naturc of this sitc, wc rccomn�cnd Uiat thc slopc bc monitored on an on-€oing basis � <br /> I after thc recommended improvemaus have been installed to assess the future pert'ormnnce of these areas, 'I <br /> and to assess lhe potcntial nced for additional repairs. It should be understooJ th•a the recommcnded <br /> improvcmcnts aJdresscd in this preliminary Icttcr arc intcndcd to rcducc thc ratc and potcntial for futurc <br /> Islopc movcnunts, but arc not intcndcd to entirely climinatc this potential. <br /> I NGA has prcparcd this prcliminary rcport for Mc Hadi Aghaghafnr, and his agents, for use in thc <br /> p�annina and design of the proposed slope repairs. Thc scope of our work does not include scrvices <br /> I rclatcd ro conslniction safety prccautions and our reconmundations are nut intended to direct Ihc <br /> contractors' methods, techniques, sequences, or procedures, cxcept as specifically described in our Ietter <br /> I for consider:uion in design. Thcre :ve possiblc varialions in subsurfacc conditions between thc <br /> explorations and also with time. Our preliminary Ielter, conclusions. and interpretations should not hc <br /> I constnicd as a warranty of subsurfacc conditions. r\ contingcncy for unanticipated conditions should bc <br /> induded in the budget cmd schedule. <br /> INc recommaid th:�t NGA bc retained to provide monitoring and consultation services during <br /> construction to confinn that the conditions encourtered are consistent with diose indicated by the <br /> e�plorations, to pro��idc recommendalions for design chauges should the conditions revealed during the <br /> � NELSON GEOTECHNICAL ASSOCIATES, INC. <br /> i <br /> /3 <br /> � <br />