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-, <br />• CTLITHOMPSON, INC. ' <br />CONSULTING GEOTECHNICAL AND h",:aTERIALS ENGINEERS <br />January 12,1?87 <br />~~.Gj'-o~.C-~!% <br />Yampa Valley Coal Corporation ~ ~ - <br />2°°583 Routt County Road 1127 <br />Oak Creek, Colorado 80au7 /~.,`~A'/ <br />l I "~ i~ <br />AtTention: IAr. Richard D. Tifft, III ~~e.- ' <br />Mine Geologist <br />Subject: Laboratory Test Results <br />Riprap for Surface Drainage Ditches <br />Yampa Valley Coal Corp l~line <br />Oak Creek, Colorado <br />Job No. 13,887 <br />Your P.O. tJo. 0077 1-50 1 <br />Gentlemen: <br />• V!e Have completed our evaluation of a sandstone material proposed For use <br />as nprap cover for surface drainage ditches on reclaimed areas at the CYCC mine <br />near Oak Creek, Colorado. The sample was obtained by CYCC personnel from a <br />tense which occurs above tl~e Lennox cool wain a:id submitted to our laboratory. <br />The sandstone samples submitted were light gray with occasional dark grog <br />streaks. Samples were wetted with dilute hydrochloric acid with no reaction <br />observed, indicating cementation is not carbonate. '.:'e performed bulk specific <br />gravity determinations, sla!<e-durability and point load strength tests on selected <br />samples with tl~e follo•++ing results: <br />Specific Gravity (3 Tests) 2.23, 2.22, 2.22 <br />Two-Cycle Slal<e-Durability Index °2 percent <br />Apparent Strength From Point-Load Tests Avg. 0,100 psi <br />(o Tests) <br />Tlie sla!ce-durability test involves tumbling of rock samples in a wire cage <br />immersed in water, followed by oven-drying. The reported index is the percentage <br />weight retained after Iwo cycles of the test. 3ased upon the measured index, we <br />classified the sandstone as rocklike and durable. :.'e also measured the pH of the <br />water before and after the test and Jetc-clod no chance (p`~=o). This indicates tl:o <br />sandsron~, is nut acid-forming. <br />The point load test measures the indirect !ensile strength of small rorlc <br />samples by splitting the roc: bet:veun two conical points. This stn~ngth is ih,~n <br />used to estimete compressive strength using correlctions provided by the testing <br />. appnrr,fus manufacturer, Tcrrametrics, Inc. <br /> <br /> <br />