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2011-08-31_REVISION - M1977215
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2011-08-31_REVISION - M1977215
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Last modified
8/24/2016 4:42:48 PM
Creation date
9/7/2011 7:58:44 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M1977215
IBM Index Class Name
REVISION
Doc Date
8/31/2011
Doc Name
Technical Revision TR-18
From
Rio Grande Silver, Inc.
To
DRMS
Type & Sequence
TR18
Email Name
RCO
SSS
DMC
Media Type
D
Archive
No
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2.0 EXISTING CONDITIONS <br />As was typical for underground mining operations in the 1960s, Homestake had constructed an <br />incline at an upward grade of approximately 1% to allow gravity water drainage from the mine. <br />By constructing a new decline, RGS will be able to control water, which will flow toward the <br />underground working face rather than out of the portal. This means that upon closure, a seal will <br />not have to consider hydrologic head pressures as did that of Homestake's 9360 portal seal. <br />Safety and logistics are other items that RGS must consider when planning to enter the old <br />Bulldog Mine workings. The initial 1,300 to 1,400 feet of the proposed new decline will be <br />through the Creede Formation, which is a fractured conglomerate rock formation that may <br />require enhanced ground control support measures. Because Homestake used track (rail) <br />haulage, the existing incline is much smaller (6 feet wide by 8 feet high) than required with <br />today's technology where declines are 12 to 13 feet wide and 15 feet high. To use the existing <br />incline, RGS would have to undertake a rigorous rehabilitation program, one that could expose <br />workers and equipment to unnecessary risk. After considering these aspects, RGS decided that it <br />will be safer and more cost effective to construct a new decline, where modern development <br />techniques and state -of- the -art ground support can be installed. <br />By using the previously- disturbed Homestake portal area and mill pad, RGS will limit new <br />disturbance. RGS will mostly be able to utilize previously - disturbed areas for the required <br />surface infrastructure that will support the proposed underground exploration work, although <br />RGS will provide access to the "new" 9400 level portal area, which will be approximately 40 <br />feet higher in elevation than the 9360 level where Homestake gained access to the Bulldog <br />operation. Eventually, the 9400 level will become the portal working area for the new RGS <br />decline. The majority of the area needed for surface facilities will be located on private surface. <br />See Table 1, Estimated Project Disturbance. <br />RGS proposes to initiate work in the late summer and early autumn of 2011. This will include <br />refurbishing the old Homestake office and installing necessary surface support facilities, such as <br />the water holding ponds and maintenance facilities. The office, maintenance facility and water <br />holding ponds are located on private property. This work will be followed by initiating the <br />portal face -up work on Forest Service administered ground. The goal is to be underground as <br />soon as possible, preferably before winter. <br />RGS estimates about 12 months will be necessary to complete the decline, with another 18 to 24 <br />months of underground exploration work once the company reaches the historic Bulldog Mine <br />workings. To provide for added safety, both in terms of ventilation and a secondary escapeway <br />from the Bulldog Mine workings, RGS proposes to re -open and rehabilitate the existing <br />Homestake escape /ventilation raise in 2012; this raise is located off Forest Road 505 in the upper <br />reaches of the Windy Gulch watershed. <br />Page 15 <br />
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