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� . Aug. 18 , 2006 11 �47AM No �0015 P � 2 C <br /> ___---- <br /> Clvil Solutions �'�Y`�G <br /> Croup,LLC� <br /> . �_ <br /> lr� ['•��K�I\�Ul�'1 <br /> DATE: A,ugust 17, 2006 <br /> TO: Steve Sundby—Uwncr . <br /> FR.OM: Mich�l R. Jc7hnspn, P_E.—Civil S�lulions C'rroup, LLC <br /> RE: Sundby Resid.ence Reta.i.nino Walls (06-380) <br /> Orono, MN. <br /> Steve� <br /> Attached are ihe design calculations ��r the eritical seclions c�i`both the npper and lower retaining <br /> walls at you.r projec� I will address each of the items requested in the memorandum prepared by <br /> Matt Jensen, P.E_ of B�netitrc�o Rosene Anderlik and Assc�ciaies, the re�vievving engineer for the <br /> city. <br /> 1� Y have made an assumption on the stren.gth of the foundation mat,erial based on the <br /> report prepared by Rarr�ngineering and my experience in dealing with lhe s�ils in <br /> the'1'wi.n Citics area. 7:hc matcrial that exists at the retainin�walls varies from silty <br /> lean clay tv sand with si.lt. CSG a.ssumed the worse �a�e maleria] exist,�on site (silty <br /> lean clay) and assumed a strcngth of�=26°and Cohesion of 200 psf(which would be <br /> a reasanable conside�ing tbe r�aterial unde.r the ba,tie of the wa11 ha,5 been cc�mpressed <br /> si.ncc thc construction of thc original timber walls) in our desi�n.calculations. 'W'e <br /> reco�ez�d that CSG be h'tred ta perform a f�uncia.tion inspeclion to �nsure adequa�e <br /> bearing eavacity and strcngth of matcrial at the ti.mc of the wall construction in lieu of <br /> any additianal testi.r.tg at th.�s tam.e. T)�is recammendalion is based an ihe facl Lhal ihe <br /> cxisting walls have experienecd settlement. lf the sub soil is unable to support the <br /> proposed loadix�conditions we wi)1 direct the cc�ntractor ic�m2.l:e ihe n�ceSsary <br /> corrcetion to the sub base matcrial to achieve the requued bearin� capacity to support <br /> ihe propased ret�ining walls. Slope stability is nvt an issue for ypur reia.ining walls _ <br /> due to the flat surface that exists at the base of the lower wall. <br /> 2, The c:alculaticros pr�vided show thei the walls will function safely as designed. CSG <br /> has required an import of select graaular behind the retaining walls to ensure adequate <br /> drainage exist,t and reduce preSSure t� lhe houlder walls. Water•uplill.is not <br /> applicable to the design because the water ta.ble is not located immediately beneath <br /> the reia.ining walls_ <br /> 3. The construction plans provided by CSG addressed these requirements„ <br /> ,�.,�.r.M1�u.t�Nlnneaeeue,�.oM • 8200 NYIi10o1Qt AvenYe 3oYSl1.SYlte 100.Bloomin900�.Mlntwr.otR 55431 • Tolvphono�952�?�1A7ES Faz(962)286.4696 <br />