2014-12-15_PERMIT FILE - M2014043 ‎(2)‎

• Permit No: M2014043
• IBM Index Class Name: Permit File
• Doc Date: 12/15/2014
• Doc Name: Preliminary Adequacy Review Response #2.
• From: Environment, Inc.
• To: DRMS
• Email Name: TOD
• Media Type: D
• Archive: No

MINING PLAN EXHIBIT D(CONT)
In stage 1 the mining setback will be 10 feet inside the slurry
wall on east and north sides . Along the west side it will be a
minimum of 200 feet from the Thornton slurry wall/dam structure
and on the south side it will be 42 feet from the permit line or
10 feet inside the slurry wall . In Stage 2 along the north and
south the setback will be a minimum of 25 feet and on the East
side it will be 50 feet from the permit lines . On the west side
it will be 10 feet inside the slurry wall . The plan for mining
along the perimeter by leaving an adequate setback adjacent to
any structures so if needed a graded 3h to lv slope could be
built if needed that eliminates any chance that these structures
will be affected by mining. This means leaving some gravel but
will insure the integrity of the banks until filling is complete.
MAP EXHIBIT C AND EXHIBITS contain information on all structures within
200 feet of the mined area.
Site preparation will begin in Stage 1 on the southwestern part
of the permit area. Once the area has been cleaned of trees,
buildings and other rubbish, a slurry wall will be constructed
around the area to be mined. This will serve to block ground
water from entering the mining area to reduce the exposure of
ground water and allow the area to be mined and backfilled as a
dry site. The estimated length of the Stage 1 slurry wall will be
2270 feet and when keyed into bedrock will average 28 feet deep.
The mining face will be worked at a near vertical slope (%: 1) as
mining progresses thru the area. No mining will take place
within 200 feet of the Thornton Reservoir complex slurry wall/da-
m. This setback is shown on Map Exhibits; C-1, F, and Figures E-
1, E-2 and E-3 . Please see the attached Geotechnical data
prepared by Deere and Ault Consultants for the analysis of the
mining setbacks around the mine. Along the south side of Stage 1
the mining setback will be 42 feet . This allows for a safety
factor of 1 . 3 to protect structure along the mine perimeter.
A Plant Site/Stockpile area will be graded on the east side of
the existing lake and the access roads will be improved to
facilitate hauling from the site. Once these areas are completed
mining will begin on the west side of Stage 1 and all material
will be hauled to the Plant Site or stockpiled on the west end of
Stage 2 above the Plant Site until it can be processed. This
8(Revised 12/15/2014)