PERMFILE52862

• Permit No: M1997054
• IBM Index Class Name: Permit File
• Section_Exhibit Name: EXHIBIT D MINING PLAN
• Media Type: D
• Archive: No

Eshibit D CMLRB 112 Permit Application
Agile Slone Systems. Inc.
• GEOTECHNICAL STABILITY EXHIBIT 6.5 (Requested J. Dillie 7/31/97)
Granite Rock Description
The granite rock matches the description of Algonkian Age (Precambrian) Pike's Peak
crystalline rock. The granite is considered part of a large batholith complex found in
South-Central Colorado, intruding into and considered younger than the Idaho Springs
granite gneiss complex found in the azea. The granite rock is macro-crystalline, red ,
course grained , porphyritic granite. The principal minerals present in the ground mass
include quartz, oligoclase, and biotite. In this matrix are set well formed phenocrysts of
red microcline (K-feldspar) which range in length from %" to 2", with an average of
about 1". Accessory minerals reported present in the rock include alianite, sphene,
apatite, and magnetite, although this mineralogy is not evident via hand tense. The
granite is a highly competent, massive crystalline rock portraying spherical type
weathering at the surface with no apparent foliation, jointing or cleavage within the
weathered or unweathered exposed rock surfaces. The granite body has been intruded
successively by sills, dikes, and small stocks of felsic minerals and fine grained granites,
pegmatites, dikes of diabase, and xenoliths of biotite gneiss. Evidence of faults crossing
the proposed mining area are limited to the occurrence of intrusions within the larger
mass of course crystalline rock. A major fault zone along the northwest boundary of the
affected land, trending northeast from the N-S drainage along the western affected land
boundary in Phase I area displays a vertical fault escarpment, slickensides, and an
occurrence of minerals not common in the bulk of the granite rock body, clays, chlorites,
and schists considered undesirable for mining. For this reason, mining will not occur in
• this area.
Two locations, one at the northwest end and one at tfie centraUsoutheastem end of the
proposed quarry area, were selected to sample unweathered granite. After drilling and
blasting, large (9" x 9" x 9") unfractured sample blocks were taken for confined and
unconfined compression testing. Sample preparation and testing was performed by The
Earth Mechanics Institute, Department of Mining Engineering Colorado School of Mines,
Golden, CO. Test results are included in the attached table.
Bieneawski Rock Mass Ratings were estimated for the rock based on the test results.
Cohesion values in the range of 475 kPa and Internal Angle of Friction was calculated at
52.5 degrees. These values reflect a highly competent rock unit capable of sustaining a
near vertical face in a stable configuration for an indefinite period of time. The rock
mass ratings and tri-axial compression test results are considered conservative (Azurite,
Inc. 10/97), since the samples were taken from blasted areas, a known way to obtain
weaker samples since the blasting most likely induced planes of weakness in the samples.
Samples aze normally taken from core drilling which would yield stronger test results.
The final highwall configuration planned for granite operations will include 50' vertical
bench heights at 0.25:1 slopes with 25' mine benches graded 1-2% to the toe of the
highwall face. About five 50' benches may be constructed in this manner at the extreme
northern and northeastern boundaries of the affected land. The mine benches will be
. graded to drain to either ends of the highwall contacts, drainage directed into rubble-ized
l6