3313 SMITH AVE 2018-01-01 MF Import

March 30,2009 • I1WA Project No.2009-030-21 with pipe beddins material. In wet conditions, 1'/.-inch-minus granulaz fill mecting the gradntion requirements for Civshed Surfacing,us described in Section 9-03.9(3) of thc WSDOT Standard Speci,Jlcarinns, mny be used to backfill thc ovcr-excavated portion of ihc trcnch. • I'ipc bcdding should provide a firn�,uniforni cradlc for thc pipc. Wc recommend tliat a niinimum 4-inch thickness of 6edding material benenth the � pipe be provided. I,argerthicknesscs may be neccssaryto preventloosening and • soficning of thc naturnl soils during pipe placement. • Prior to die instullation of thc pipe,the pipe bedding sliould be shaped to fit Qic lower part of the pipe exterioc wiQi rcasonnble clo§eness to provide continuous support afong Aie pipe. ' • I'ipe bcdding mnterial und/or bnckfill nround the pipejsltould be placed in luyers nnd tamped to obtuin complctc contact with the jfipe:'In nrens where a Vench box is used,the bedding material should bc placcd bcforc thc trcnch box is advenccd. � ,,\�,., ;> We recommcnd thut trcnch backfill consist of Dank Run GravZl for Trencli I3ackfill, as described in Section 9-03.19 of tlre WSDO"1'.Standard Spec fcaBrnas. During placement of thc initiEil lifts,thc trcnch bnckfill mnterial should not bc bulldozcd into ilic trcnch or dropped directly on thc;pipc. I�urthennore,heavy equipment should not Ue permitted to operote direcdy over lhepipe until a minimum of 2 fcct of backfill has been placed. Trench backfill should be placed iii 8 to 12 inch, loose IiRs und compactcd using mech�nical equipment to al Icast 90 perccnt of its maximum dry density, �s detemiined by tcsting in general nccordance,witlt ASTM D 1557. 1'hc upper 2 fcet of bnckfill should bc co�iipactcd to nt Icnst 9Sperccnt,of it's maximum dry dcnsity. As nn flltcmntivc to compncfed gr�nular bnckfill;controllcd dcnsiry till(CUF)per WSDOT Sta�idard Specificatiott 2=093(1)L' nia�be used. I ? 3.7 CONTINUINGGtiOTEC1INICALSEflVIC65 Geotechnicat obseivntion nnJ testing by the geotechnicnl c�ns�itant is recommended during il�e constn�ction phlscs to verify that thc rccommendntions presentcd hcrein are incorporatcd into thc constructed work. Of particulnr importuuce Arc gcotcchnica! monitoring, observation vid/or testing of the following project elements: • L.00se fill identification and over-cxcuvntion within structure nreus; • Ynvcment subgrnde prepnrntion; 2009•030•:1 Urull mn �3 1IWA G�ASCm'r7CrS Ir7C / �