PERMFILE137359

• Permit No: C1981022
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Doc Name: Coal Refuse Pile and Haul Road Design ‎(Lincoln DeVore 1997)‎
• Section_Exhibit Name: Exhibit 2.05-E4 Part 1
• Media Type: D
• Archive: No

Lincoln DeVore,lnc.
Geotechnical Consultants
1441 Motor St.
Grand Junction, CO 81505
June 18,1997
Balaz & Associates
203 Sunset Cv.
Palisade. CO 81526
Re: 1Jevv Coal Waste Pilc and Haul Road Project
Sanborn Creek Mine, Somerset, CO
TEL: [phone]
FAX: [phone]
We arc N roccipt of a facsimile transmission oCa portion oC the Initial Adequary Review Letter from the Division
of Minerals and Geology regarding the Sanborn Creek Minc Project. At your request we arc addressing the
second paragraph of Ilcm 17 and all of Items 18 8t 24. Following are our findings and rccommrndations.
Item 17. Cut and Fill Slone Stability The drawings provided by Balaz .$ Assoc., West
Valley Haul Road. OXWVF-OS to OXWVF-IS have undergone scvcral revisions based upon preliminary cut
• and fill sections provided by Linwln DeVore. The recommended sections from Lincoln DeVorc were based
upon the bottom bench and toe of the major earth fills to be founded upon the more compctrnt rocks oC the
Bowie Member of the Mesa Verde Formation. The original road wnswction/cut Cill sation provided by
Lincoln DcVorc N our 2-20-97 report oCthc Haul Road Slope Stability assumed the existing bedrock might not
be ulilizcd for fill support and the toe area would be Coundcd on the wlluvial soils on the slopes. During the
analysis for the 2-20-97 report, the maximum ill slope height vvas computed to be 20 fat, with the strength oC
the foundation colluvium governing the slope configuration.
Careful anaysis vvas made of the higher earth fills proposed for this site, with adjustments in the road alignments
made to play the base of the earth fill on the rclalivcly more compctrnt rocks oC the Bovvib Member. With these
adjustmrnts in Otc road alignment. the Cill slopes rnuld be stceprncd to as much as I : t (horizontal:vertical) and
the computed slope stability could be governed by the design and conswction techniques of the earthrn fll
itself. rather than the foundation soils. Thc construction techniques would include, fill soil selection, appropriate
slope benching. proper fill placemrnl and compaction and use of a mechanical soil stabilization with
Gcotechnical Fabric or Gcogrid as required. In general, the same slope materials utilized Cor the 2-20-97
Lincoln DcVorc report are utilized Cor this study.
Thc appendices of this report contain the printouts of the Slope Stability Sludy. Thc computtt program
GEOSLOPE. Version 4.10. suppliod by GEOCOMP Corp., vvas used The GEOSLOPE program is based upon
the program STABL3. developed at Purdue Univcrsih~. External loads, 2-16,000 Ibs for a single axle, were
applied in tltc 'outside lane' of the haul road to model truck traffic.
For wmpulational purposes the section along the haul road at station 8+00 vvas determined to probably be the
worse case on the south facing slopes and vvas studied Cor global stability, stability oC the fill portion and stability
• of the cut section, assuming the Bovvie shale is present in the majorih~ of the cut, with scvcral significant
sandstone beds which arc evident in surface exposures.