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drainage blanket and toe drain be conswcted. The plans call for a 6-inch diameter pipe be <br />phtced in the tce drain. We recorrtmend [hat the pipe consist of perforated PVC pipe meeting <br />the requtremen[s [or Schedule 3034 in accordance with ASTM. The free draining gravels to <br />be used in the toe drain should meet the spermcations outlined on page L3-3-11 of the <br />specifications for the toe drain materials. We would also recommend that [he same Free <br />draining materials be used for the drainage blanket. It is our understanding that Connell <br />Resources, in Milner, Colorado, is presently producing a washed aggregate material which <br />would meet this specification. The plans call for the drainage blanket to be a minimum of 1 <br />(oo[ thick; however, we would recommend that the drainage blanket be a minimum of 2 feet in <br />thickness. In addition, we recommend that [he toe drain and drainage blanket be wrapped, <br />top and bottom, with Mirafi 140N or an equivalent product. The base of the embankment, <br />below the drainage system should be underlain with Mvati 140N and not the 500X. <br />4; A stability analysis of the emban-kr~ent structure has not bee= completed for this project. <br />Therefore, based on our conversation with you, our Cum will complete a stability analysis for <br />this swc[ure using SB-Slope and the slope configurations shown on the project plans. It is <br />our understanding [ha[ [he Gll materials to be placed in the embankment will come from the <br />cut slopes being conswc[ed for Haul Roads Y-B and Y-A. We will use the triaxial shear <br />strength information obtained earlier on these materials [or the embankment fdl materials. <br />The results of the stabiliry analysis will be forwarded to your office as soon as they are <br />completed. <br />If you have any questi ns regazding [his letter, our observations or recommendations or if we maybe of <br />further service, ple contact [his office. <br />Sincerely, <br />INC., <br />Brian D. <br />Job No. 95-2384 Northwest Colorado Consultants, Inc. Page ? <br />