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;.. <br />.. <br />r1 ~~~~I <br />I~~ <br />CTL/THOMPSON, INC. <br />CONSULTING GEOTECHNICAL AND MATERIALS ENGINEERS <br />August 7, 1980 <br />Energy Fuels Corporation <br />P.O. Box G <br />Steamboat Springs, Colorado 80477 <br />Attention: Mr. Jay James <br />Subject: Construction Observation <br />Eckman Park Excess Spoil Area 2A <br />Jab No. 6210 <br />Gentlemen: <br />A representative from our office was present during the construction of <br />portions of the Excess Spoil 2A. The purpose of this letter is to sum- <br />marize the construction and our observations. <br />Our firm prepared a geotechnical investigation (Job No. 56646) for the <br />excess spoil area in September of 1979.which provided construction recom- <br />mendations for tfie overall spoil area. Due to the anticipated mining <br />sequence, Energy Fuels Corporation desired to construct the upper one- <br />half of the spoil area first (between elevations 7355 and 7450). In a <br />letter dated Marsh 31, 1980 (our Job No. 6210) we expressed our opinion <br />that, from a long-term stability point of view, the spoil area could be <br />constructed as desired with no reduction in the overall stability of the <br />structure, provided the construction recommendations presented in our ori- <br />ginal report were followed. We further suggested constructing a buttress <br />fill at the base of the initial fill area to minimize any risk of insta- <br />bility during construction when men and equipment would be working below <br />the fill. <br />Excavation for the construction of the keyed buttress fill for the upper <br />area began in March, 1980. The excavation extended between 5 and 12 feet <br />below natural grades and was generally bottomed in hard claystone bedrock. <br />The excavation was backfilled using over-burden removed from the initial <br />box cut from area 30. The spoil was dumped by over-burden trucks near <br />the excavation and pushed into place using bulldozers. Lift thicknesses <br />were generally on the order of 2 feet. After the fill was leveled, com- <br />paction was obtained by directing loaded and unloaded 50 and 100 ton over- <br />hurden trucks across the fill surface. Photographs taken during the exca- <br />vation of the buttress are included with this letter in Appendix A. <br />During excavation and backfilling of the buttress trench, topsoil was re- <br />moved from the upper area above elevation 7355. Excavation for a rock <br />drain was accomplished at the location of the natural drainage which <br />1701 SOUTH FEDERAL BLVD. SUITE D DENVER. COLORADO 80219 - (303) 934-5x73 <br />