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2011-09-29_REVISION - M1977215
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2011-09-29_REVISION - M1977215
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Last modified
11/20/2020 2:21:21 PM
Creation date
10/3/2011 8:16:54 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M1977215
IBM Index Class Name
REVISION
Doc Date
9/29/2011
Doc Name
Response to the preliminary adequacy review (TR-18)
From
Rio Grande Silver, Inc.
To
DRMS
Type & Sequence
TR18
Email Name
RCO
Media Type
D
Archive
No
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9400 Portal Face -up <br />Attached are two maps showing how the soil -nail wall /portal face up will occur (Figure 1) and <br />the final reclamation slope at the portal bench (Figure 2). It is anticipated that the cut for the <br />soil nail wall will be 45 to 60 degrees, approximately 30 feet high and 40 feet wide. The cut into <br />the bank will be up to 40 feet deeper into the bank than the portal pad. Yeh and Associates is <br />currently doing the design for the soil nail wall /portal face -up. RGS will submit the final "as- <br />built" design to Colorado DRMS when completed. As shown on the sketches, once the arched <br />steel set canopy is set in place, the canopy will be covered with the fill excavated during face -up <br />construction. The soil nail design will consider the possibility of slope failure along the surface <br />of the soil nail wall. <br />The entrance to the portal will be filled with development rock and the entire portal entrance <br />will be covered at reclamation. The final slope of the face -up and along the toe of the portal <br />bench will range from 2.3H:1V to 2.5H:1V, which matches the existing slope. There will then be <br />a low gradient slope to the edge of the portal bench, then the final bench out -sloe will be <br />graded to final 2.3H:1V slope prior to final growth media placement and revegetation. <br />Portal Steel Sets <br />The portal bench will be excavated at 9400 feet elevation. If the undisturbed ground is stable, <br />the feet of the steel sets will be welded or bolted in steel channel set directly on the portal <br />bench. If it is determined the ground is not stable enough to support the steel sets anchored <br />on steel channel, a concrete footer will be poured to support the steel sets. <br />The portal entrance (steel set canopy) will be completely covered at reclamation and therefore, <br />not removed from the project site. <br />Ventilation Raise (Section 3.4) <br />New disturbance associated with the opening of the vent raise will be .12 acres and involve <br />stockpiling of the existing topsoil and cover material adjacent to and north of the raise. The <br />vent raise is currently capped with a concrete cover. The cap will be removed and if it is in good <br />condition, it will be set near the stockpiled cover material and used to re -cap the raise for <br />reclamation. If the cap is not salvageable, it will be fractured and buried on site or disposed of <br />in the Mineral County landfill. The site will be reclaimed back to existing conditions. See <br />Existing Vent Raise photo -pg.3, and Bulldog Ventilation Raise Layout page -pg 3. <br />TR -18 Re. >ponse to PAR Letter _1 &S.doc 9%26'201I <br />7 <br />
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