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Rinkcr Matcrals' <br /> July 23,2003 <br /> Pagc 3 <br /> loosc and disturbcd soils that had accumulatcd on thc pit floor. Accumulations oCsloughcd soils <br /> along Ihc highwalls and fill slopcs wcrc also removcd pr:or to eveluating thc pit tloors and prior <br /> to placing fill in Ihosc arcas. Native advance outwash sand dcposits werc cxposed on lhe pit <br /> iloors. Our representative cvaluatcd thc pit floor areas by probing with a %,-inch-diameter stcel <br /> probc rod and by obscrvied thc condition and performancc of the pit tloor undcr cquipmcnt loads. <br /> Based on our observations and cvatuations, it is our opinion that the pit floor areas evaluatcd <br /> during our si[e visits wcre prepared in general accordance with our recommendations and the <br /> project requirements. <br /> FLATTENING OF INTERIOR HIGHWALLS <br /> RcmnanLs oCpit highwalls intcrior to Lots tI though L wcrc Ilattened such that they wcrc no <br /> stccper than 3H:1V (horizontaL•verlicai). This was nccessary in ordcr fo achicve an ar,ceptablc <br /> transition in the sWctural fill thiclrncss placcd on I.ots H through L and to reduce thc risk of <br /> unacecptablc diffcrcntial building setUements in deep cxcavation arcas. Stecp cuts resulting from <br /> mining activitics around the haul road constcucted du-ing thc 2000 grading scason in the west <br /> portion of the site wcre also [lattencd to 3H:1V di�ring grading in 2001. IIased on our <br /> obscrvations, it is our opinion that thc rclativcly low hcight highwalls and haul road <br /> embankments wcrc Ilattened to an inclination no stecper than 3H:iV in generai accordance with <br /> our rccommendations and Qic proiect requiremcnts. <br /> 7'hc highwalls adjacent to the Merrilt Creek Parkway right-of-way to thc north and the <br /> Rcgional Dctention Pond to the norlheast wcre not 1laltencd as thc mincd pits were excavatcd too <br /> closc lo thcse property boundarics. Differential setQement should be a design criteria in these <br /> arcas. <br /> BENCHING <br /> Pill placed against native or previously compacted fill slopes steeper than SH:IV was <br /> benchcd or keyed into the slope facc. This allowed for f ll placement and compaction to occur on <br /> near Icvel working surCaccs. This was done by cutting a scries of horizontal benchcs into the <br /> existing slope face. Pill that was placed against the tlattened 3H:1V highwalls was bcnched into <br /> lhc native soils at lcast 1 to 2 fect. New fill was benchcd into previously compactcd fill (i.c.,fill <br /> placed during 1999 anb 2000) by excavating hori�.ortal benches that were at Icast G feet wide, <br /> thereby removing looscr soils along thc outr. slope of the previous fills. 17iis oc�urred primarily <br /> along thc PSA dctcntion pond slopc and �long intcrior shortcr highwalls Ihat cxistcd on LoLs II <br /> through L. Denching activities genernliy occurred during the fill placement proccss. Thc width <br /> of the bcncl�es was adjustcd such that thc outer looso soils along Ihc cxisting fill slopes werc <br /> complctcly removcd. Whcrc Qic highwatis could not bc flattencd to Icss than 31I:1 V Uecausc oC <br /> thc proximity of property bowidarics (Mcrrill Creck Par}.�vay and the Regional Detention Pond), <br /> thc fill was placcd and compactcd as closc as practical to the highwalls. IIascd on our <br /> obscrvations, it is our opinion th�t bcnching oUscrvcd during our sitc visits was perCormcd in <br /> gcncral accordancc wilh our rccommendations and the project rcquircments. <br /> G c o IS n g i n c e r s PiI<No. 6192-007L1 <br /> 3� 1 <br />