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REP41945
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Entry Properties
Last modified
8/25/2016 12:43:45 AM
Creation date
11/27/2007 9:09:43 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1996083
IBM Index Class Name
Report
Doc Date
10/1/1998
Doc Name
BOWIE 2 MINE GOB PILE ISSUES PERMIT C-96-083
From
J E STOVER & ASSOCIATES
To
DMG
Permit Index Doc Type
STABILITY REPORT
Media Type
D
Archive
No
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.~ <br />J. E. STOVER & ASSOCIATES <br />2768 COMPASS DRIVE, SUITE 101 <br />GRAND JUNCTION, COLORADO 81506 <br />PHONE: (9T0) 245-4101, FAX 242-7908 <br />MINE ENGINEERING <br />MINE RECLAMATION <br />September 28, 1998 <br />J. J. Dudash <br />Division of Minerals & Geology <br />1313 Sherman St., Room 215 <br />Denver, GO 80203 <br />Re: Bowie No. 2 Mine <br />Gob Pile Issues <br />Pernit C-96-083 <br />Dear Mr. Dudash: <br />~~I IIII~~'I~II~~'II <br />999 <br />CIVIL ENGINEERING <br />GON57. MANAGEMENT <br />RECEIVED <br />DIV. OF MINERALS <br />8 GEOLOGY <br />The DMG's letter dated September 3, 1998 transmitted its numerous concerns regarding the <br />gob pile at the Bowie No. 2 Mine. Following are BRL's responses to the DMG's concerns: <br />The moisture in question was apparent during the initial stages of construction of the <br />gob pile during the first quarter of 1998. The source of the moisture in the gob material . <br />was primarily from precipitation_that infiltrated the gob pile which was stockpiled on the <br />portal bench. <br />2. As of the end of the second quarter, BRL had run two separate proctor tests. One of <br />the tests was on the gob material and the second was on a gob, clay sandy mix. The <br />gob material has a maximum dry density of 69.5 pounds per cubic foot (pct) and the <br />gob clay mixture has a maximum dry density of 99 pcf, The compaction tests <br />performed during March and April were on the mixture so compaction results were <br />compared to the 99 pcf reference value. The tests performed during June were on <br />straight gob so the 69.5 pcf reference value was utilized. Additional proctor tests will <br />be routinely run on the coal waste to confirm its material properties have not changed. <br />I discussed the issue of relative densities which exceed 100% with BRL's geotechhical <br />consultant, Norman Johnston, P.E., (Lambert and Associates). He is not surprised-by <br />results which exceed 100% relative density. The laboratory tests which are used to <br />determine the maximum dry density exert a defined amount of compactive effort. If <br />more compactive effort is exerted, the maximum dry density will increase. This is true <br />in the laboratory and in the field. Generally contractors who are constructing roads or <br />building sites will exert minimum compactive effort to achieve specified compaction. On <br />large projects, compaction tests are performed to determine the number of passes a <br />compactor must make to achieve compaction. Therefore, a contractor can be assured <br />compaction is achieved at the lowest possible cost. This is not the case at BRL's coal <br />gob pile. A relative large compactor is running over a relatively small site. No effort is <br />made to assure the compactor does not make to many passes over the material. The <br />key factor is compactive effort. BRL is not concerned with compaction tests which <br />
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