PERMFILE128342

• Permit No: M1988112
• IBM Index Class Name: Permit File
• Doc Date: 11/8/1988
• Section_Exhibit Name: EXHIBIT D MINE PLAN
• Media Type: D
• Archive: No

i 1
what slope the ultimate pit walls would be stable, assuming
that ongoing dewatering would keep water levels in the pit area
' below the mining activities. The pit designs shown on Figures
C-3 and C-4 represent a stable pit mining configuration based
on the results of the study.
' D.2.6 Pit Inflows
The South wall of the West Pit will experience some
seepage toward and into the pit from the Rito Seco through the
surface alluvium, if exposed during mining operations, and to
' a lesser extent the Santa Fe Conglomerate. The extent of the
surface alluvium along the south wall cannot be determined
t until mining exposes this area. During mining operations the
seepage into the pit through the surface alluvium and the Santa
' Fe Conglomerate will be actively collected or inTercepted and
manage, if necessary, to prevent slope deterioration. Following
cessation of mining operations, the seepage management
' operations are expected to cease and additional measures may
be necessary to ensure long-term stability of the south wall
' of the West Pit. The Santa Fe Conglomerate exhibited a low
hydraulic conductivity (10-s x 10-~ cm/sec) in several boreholes
' tested in the south pit wall of the West Pit. The result of
these tests are presented in Appendix E The hole locations
' are shown on Figure C.I in Appendix C. Tie conglomerate will
be dewatered through a series of horizontal drains, the spacing
of which will be determined once the Santa Fe Conglomerate is
exposed. Pit inflows will be monitored and a quarterly report
documenting the quantity of inflow of water will be submitted
t to the Division.
' Pit wall stability will be maintained through
construction of a rock buttress composed of interburden waste
' rock materials. The preliminary buttress design ~~s discussed
in Section E.3.1 and shown on Figure E.3.1-2.

D-8 (Revised 4120/89)