2005-P09263 - land alteration - Laserfiche WebLink

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, , NIr. Ray Newkiak Wayzata,Minnesota Project No.9'S286 GEOTECHrRCAL ENGII�TEERING IIY CO1�lJUNCTION RiITH SIAPE MOVEMENT BEHIND NEWI�RK RESIDENCE II�I WAYZATA,MINN�SOTA I�iT�O,DU�ON A retatively steep slope exists behind the Newkirk residence at I489 Shoreline Drive in Wayzata, Minnesota. The slope le�ds down to an east-f�cing lakeshore on Lake Minnetvnka- Mr• Nev�+kirk reported ta as that in late August slo� movement occurred. Upon acceptance of aur August 30, 2005 pmposal, we met Mr. Newkirk an^site on August 31 and again on September 8, 2005 in order to observe the conditions. '�his report presents e discussion of our observatians, includes an evaluation of the slope movement and pre.se�nts potential repair options. We weTe provided a copy of thc constructioa 8radin8 Pfan. �L'�OBSERVATIONS �,' e V's' 1 Oaa Aug,ust 31, 2005, Mr. B. T'heroux, P.E. met with Mr. R. Nevwkirk, th� owner of the property. Mr. Newltirk reporbed to ns that following a weekend rainstorm event on A��gust 27, sod placed just behind the top of the siope behind the Newkirk �+esidenc;e leading dovm to the laice exhibited movement and c�racks appeared along the slape crat at the edge vf the sod and behind the tbp of tt�e stairs leading down ta the lake. Mr. Newkirk reported that the sod was installed in June,2005. A shallow excavation through the s�od by Mr.Newkirk revealed the underiyiag subgrade to be a silty clay. T!�slope is approxunately 2Q ft in height above th�e lake. T'here is an approxima�be 50 R level area behin,d the Newkuk residence. Based on a Grading Plan by Ste�er � Koppeiman dated January 20,2U04 provided to us,the overall slope angle is esdmated 4a be abotrt 1 %H: 1 V. 'The slope facs is covtred with shnibs at� wood c6ips aad � staircase leads down to the Iakeshore. A modular black retaining wa11 up t+m approximately 4 ft in height follows atong the (nvrth} upslope side of the sta�rcase. A small slide scarp ex�sted 3 to 4 ft b�ehuid the crest of the slope and ext�nded appraximately 35 �t from the b$ck of the top of the staircase aiorthward to s catchbasin. 'The catchbasin was cona+oCted to a 4-inch pipe which drainea davm underneaxh the slope to the lakeshore. A feve► of the sl.aircase concrete pavers hsd b�ckled up due tm iatcraP ffiovement of ihe slope, At the t�me of�aur August 3l visit, the small scarp �-covea�d with sod at the top of the sl�pe and Concept Laadscaping was in the process of ptacir�g boulder riprap along the toe of the slope. Mr. Ne�vkirk aepoa�ted t.hat svaioff from the house a�oof a�d par� of the garage ros�f is directed to daai,n rav�rland ae�s�s th� backyar� toward the slope and into the lakea Fi� Gale-Tec�ngiaeering, Inc.� 3EP E�t,2005 2