456 VIEW RIDGE DR 2016-01-01 MF Import

G E O T E C� �3256�oi;l�cnst ZUIh Succt,5uilc �G Bcllcvuc.\1'ashiugluu 9ti00S CONSULTANTS, INC (azs)'ra�-sr,is I'.\X(4?5)747-6561 �< <� �U �� May20, 2011 JN 11186 Rose Erickson 456 View Ridge Drive , Everetl,Washinglon 98203 SubjecL• Slope Stability Assessmont ' Proposed New Deck Erickson Residence 456 View Ridge Drive E�e�ett, Washin�lon Dear Ms. Erickson: This letter presents our c�eotechnical observations and conclusions related to slope stablliry for tne proposed new deck on your property. We were provided wiih plans for the proposed deck, and have discussed the project with your designer, U Build-I:. We understand that a multi-level deck wili be constructed on the easlern portion of the property, and will essentially fll In ihe northern open yard space bounded by the two "legs" of your existing house. This deck will be localed in existina grass la�vn area and will not extend closer lo the westem �,�ep slope than the existing concrete aalio does. Based on our field measurements, the deck will be over 75 feet from the steep slope. On May 20, 2011, the undersigned principal engineer visited your property to observe the existing ' conditions. The area in which lhe deck evili be constructed is a ilat yard located to the north of the existing residenr,e. West of this, the ground slopes downward for a short distance Qess lhan 8 feetj to a lower yard area that is also level. There is a garden area �vest of the yard. Al the �vestern 'i edge of this garden is a tall, very steep slope that extends downevard into a large north-trending revine. There were no indications of recent large-scale instability on the sid2slopes of this ravine in proximity to your property. As with any steep, tall s!ope such as this, it is relatively commor, t� be periodically affected by shallow "skin" slides in the topsoil or heavily-�veathered soils imm�:diately below the slope's surface. This typo of slope movement is typically caused primarily by extended heavy rainfall and does not a(fect the stability of the underiying c,lacieliy-compressed soil. To our la�owledge, there is no history of deep-seated slope movement in the immediate vicinity. Based on our observations, ihe proposed deck is sufficiently set back from the steep slope that the stobiliry of the slope wlll not bo affected by lhe deck's construction. Nor will the deck be widermined by any futuie shallow soil movzment on U�e steep slope's face. We expect that the slope, and the existing gar fen area beri,�een it 2nd the grass yard, wili not be disturbed by the planned construction. No soil from the decti oxcavation should be placed closer than 25 foet to lhe top of the slope. We also recommend that d�bris such as sod, branches and other organics nol be ; placed on lhe slope, bul be hauled away fc �roper disposal. This type of material has a very lo�v + strenglh, and its�veight can cause slope ;r ement. All (ootinns on tha dec�c should be placed on native soils beneath any fill and/or topsoil. Footings such �s this can support an allowaLle bearing capacity oi up to 2,000 pourds per square fool(psi). ��