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� <br /> � TERRA ASSOCIATES, �nL. <br /> Con�alunls in Geo�echnical Fngincering. Geology <br /> and <br /> � Environmen�al [arlh Sc_iences <br /> f�W v�1J_;.,i (, <br /> � ir � �� >>L r„e:rtl � �'f4rll�;,. <br /> o��obe�?�, 2on� <br /> � Project i�o. T->5(9 <br /> � Mr. Kcn Pn�ett <br /> Stcadf ast Companies <br /> 2041 i SN Birch Street, Suite 200 <br /> Newport Beach, Califomia 92660-1797 <br /> � SuUjec[: Lverett Mafl Gxpansion <br /> Pond Berm Evaluation <br /> � 100th Strect SG and R�est Mal' Drive <br /> Gvcrett, \Vashington <br /> Reference: Pmiiminar��Geotechnical Repon, F�crctt �tall Lxpansion,dated Augu;t 6, 2009, prepared b� <br /> � 1'erra Associates, Inc. <br /> � <br /> Dcar Mr. Pniett: <br /> As requested, we have conducted a geotechnic�l en�_inzecing e��aluation for the proposed south���cstem derention <br /> pond benn. This Ictter presents our findines and recammendatiuns pertaining to berm stability. <br /> i <br /> � Our cealuation specitically addres,cs ltcir 12 ofCity oCEveret[ SEPA re��ie��� comments for the project. Revic��� <br /> of[tem 12 indicates die City requires a geotechnical evaluation of the stability of the berm due to the presence of <br /> � a 16-inch �vater m.�in cuntained thereiii. In addition, the City requires that geoteclmical recommendations be <br /> ; pro��ided "to brinc tlie dam i��to compliance �cith current dam safety standards." Cu�rendy', "dam safety <br /> standards•" in �VasUington are set forth by the Department of Pcology Dam Safety Office (DSO), and apply to <br /> � projccts �vhere impoundment col:�mes are greater than ten acre-feet. Though the project's new detention pond <br /> �vill impound hvo to thrce acre-teet. �vc ha��e based our evaluation of the berm w be consistent ���ith the DSO <br /> requirements. <br /> � PROJGCT D�SCRIP'I'fON <br /> The proposed project consists of cor.structing a �to�m��ater detention pond at the soudiem marein of the E�crer. <br /> hfall �xpansion project adjacen� to 100th Street SE. Tlie approximate location of the site is shown on attached <br /> Picurc I. <br /> Ne�c pond construction includes an expansion of [lie esistine pond nonh��ard into thz area et existing IGOth <br /> Strect SG, �cliich will be re-aligned as part of lhe project. Ilie i�e�v pood will be constructed with 3:l <br /> (Horirontal:Vertical) interior side slopes, and will liace its bottom eraded to �::�v. 476.�. Pond grading uill <br /> requirc ma�imum cuts oC abuut nine fcet �t die pond's nonh�vestern corner. Pills approaching a maximum of <br /> about six feet will be required adjacent to the bemi. The benn top ele��ation �eill remain at its current L-le��. dS'_'.i. <br /> The design water surfacc�vill be at Ele��. -ii9A. Rcview of the pro��ided cross-section indicates die existing a�ater <br /> main has its imert at Clev. 476.27. <br /> 1 ';!_� ANill�,ws h��,id, Suite 101, Kirkland, Ah�ashing[on `)R03-# , ��(; <br /> PhoiSc (�:2�;) 7521-7-:7 • f,i� 1�1°�,I ;;�1--133-1 <br />