2012-02-28_REVISION - M1980244 ‎(71)‎

• Permit No: M1980244
• IBM Index Class Name: REVISION
• Doc Date: 2/28/2012
• Doc Name: VOL 5, Appendix D: Assessment of Underground Workings within Limits of Valley Leasch Facility
• From: CC&V
• To: DRMS
• Type & Sequence: AM10
• Email Name: TC1
• Media Type: D
• Archive: No

Type of Feature
Total Number
Mapped
Number Mapped
Within Proposed
VLF Footprint
Number Indicated
in Historical
Mining Records
Test Pit or Conical Surface Working
> 430
> 430
--
Trench
26
25
--
Depression
17
17
--
Collapsed Shaft
48
45
--
Shallow Shaft or Surface Working
20
16
--
Deep or Timbered Shaft
68
59
58
Slot Mine or Open/Collapsed Stope
20
18
--
Open or Collapsed Adit
40
36
17
February 7, 2007
-5- 063 -2140
While the field program focused on features within the limits of the proposed Squaw Gulch VLF,
some shafts and other important features are present just outside the VLF limits These workings
may, depending on their size, adversely affect the VLF or a future perimeter access road. Therefore,
these features were included in the mapping effort.
Table 2, below, provides a summary of the number of features of each type mapped. Also included is
a comparison between the number of features mapped and the number predicted by the historical
mining records. Note that there are many more mapped features than indicated in the historical
records. In the case of shafts, some of this is likely caused by conservatively classifying some
features as collapsed shafts when, in fact, they may be large test pits or surface workings. Also, there
are probably some smaller shafts that were never recorded in the historical records. In the case of
adits, some were probably counted more than once in the field. This was done because most of the
adits were at least partially collapsed. When an adit collapses, it can appear that there is a second
opening at the location of the collapse. If a single adit is collapsed in several locations, it can appear
that there are several smaller adits as opposed to one larger one. This reasoning is supported by the
fact that many of the mapped adits are clustered together along the alignment of adits recorded in the
historical records. These classification uncertainties will be resolved by the results of the proposed
Phase II field investigation activities.
TABLE 2
NUMBER OF MAPPED HISTORICAL MINE WORKINGS
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