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~: ;.:~ " - _ _ . __-_ ,, energy fuels m~ining=~eofnpany one tabor center • suite 2500 t 200 sevenleenih sheet • tlenver, coloratlo 80202 April 5, 1995 Ms. Janet H. Binns Division of Minerals and Geology 1313 Sherman Street, Room 215 Denver, Colorado 80203 ~II ~I~II~~I~~~~~ ~I~ i sss 13031623-6317 ~wz 910-931-2561 RECE'~IVED~'~ APR ~ p 19951 %~ion of Minerals & Gedlogy i i RE: Highwall Backfill Compaction Data and Construction Certification Raton Creek Mine, Permit No. C-82-055 Dear Janet: Accompanying this transmittal letter, per your verbal request, Energy Fuels Mining Company (EFMC) is providing copies of compaction test data and certified construction inspection reports. This information verifies that the highwall segments backfilled with coal) refuse material were constructed in accordance with the permit and meet or exceed the required factor of safety for highwall backfill. The average constructed compaction of the refuse in the highwall backfill was 95.8 percent of dry density based on a total of twenty-two nuclear density tests. This average density, as well as every individual density test, exceeds the 90 percent compaction required by the permit. Copies of the density tests, numbered 1 through 19, and 22 through 24, are attached hereto for your records. In addition, three Standard Proctor tests of the refuse were performed to calibrate the nuclear density test information. Copies of these test reports dare similarly attached. All refuse placed during highwall backfill construction was done in accordance with procedures used for construction of primary refuse pile. Refuse was placed in lifts no greater than 2 feet in thickness and compacted to achieve a minimum of 90 percent of dry density. The resultant factor of safety of the highwall backfill should be 2.5, or greater. Stability analysis of the refuse pile and highwall backfill are discussed in Section 2.05.3(8) and Section 2.05.4 (2)(c) of the permit application. EFMC constructed the highwall backfill with refuse during April, May, and early June of 1994. In accordance with the permit, compaction tests of the fill material were done approximately once every two weeks. Compaction test results are summarized below. In addition, a registered engineer inspected the highwall backfilling on three occasions during construction; copies of the inspection reports are attached hereto for your,records. - ~~,.J~v~y"~#.~-wya~.y~+'4gT Rm +amr+a'QS~ - -- - - - - - - ` ~- ~ _ _ - - " _ _ -- .aax r ~~ ~ ~ _~-