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~GEO TEST111G <br />Geotechnical Engineering and Materials Testing <br />LABORATORIES,111C. <br />July 9, 1981 <br />Dorchester Coal Co. <br />2795 Skyline Ct. <br />Grand Junction, CO 81501 <br />Re: Canon City Mine Sediment Pond #4 <br />Gentlemen: <br />C%f-! Lt/-C~ <br />% -~~-G~ <br />e`a~,; <br />The sediment pond observed is located directly north and lower <br />in elevation than a potable water treatment pond and east of the <br />coal refuse pile. A dike running north and south was placed <br />across a draw draining to the east to form a triangular shaped <br />pond. Two corrugated metal outlet pipes were located in the dike. <br />One through the center of the dike with a decant on the upstream <br />end, and one near the south end of the dike. <br />One compaction test was made on the top of the dike. The soil <br />measured 92.8% of standard Proctor density. The moisture content <br />of the soil tested was 10.1°,b. Optimum moisture content is 14.490. <br />The vegetation on the slopes of the dike was sparse and some <br />small erosion, on the order of 2 to 3 inch side ruts, was <br />observed. <br />The water level in the pond was 18" below the bottom of the <br />center outlet pipe. There was no'visible seepage on the outside <br />slope of the dike, or in the ditch below the dike. <br />We would recommend minimal wetting and compactive effort to <br />increase the densit3~ to the recommended 95~ of standard Proctor <br />density. The embankment, in our opinion, appears to be per- <br />forming satisfactorily to date. <br />Very truly yours, <br />GEO TESTING LABORATORIES, INC. <br />D~,O~~ <br />Pat Dressen <br />Engineering Technologist <br />PD/kr <br />Reviewed By: <br />Andrew A. Porter, P.E. <br />President <br />Cc: ~ <br />L'~` <br />P.O. Box 3142 • 3224 Highway 6 & 24, No. 3 • Grand Junction, Colorado 81502 • 303 - 434-9873 <br />