2013-04-19_REVISION - M1990057

• Permit No: M1990057
• IBM Index Class Name: REVISION
• Doc Date: 4/19/2013
• Doc Name: 110‎(d)‎ PERMIT APPLICATION
• Media Type: D
• Archive: No

The Leadville Mill
4.3.3 TSF STABILITY & TSF DESIGN
M 1990 -057
EXHIBIT C — MILL PLAN
Page 4 -12
• Install TexDrain® TD 300 leak detection drainage net system, or equivalent,
between the top of the geosynthetic clay liner and the bottom of the 45mi1
reinforced polypropylene capable of intercepting liquid within the leak
detection zone and conveying the liquid to a collection sump for storage.
• Install leak collection sump and piping in pond corner and connect leak
detection drainage net system to the sump.
• Lining contractor to install geosynthetic clay liner, leak detection drainage net
system and 45mi1 reinforced polypropylene.
• Liner materials will be tested at intervals specified by manufacturer and
contractor but not less than two tests will be performed.
• Materials or construction not meeting standards and design specifications will
be removed and repaired.
The existing tailings facility will be removed and the new TSF embankment will be
reconstructed as shown in Figure 4 -6. The compacted fill embankment has a 2.5:1
(horizontal to vertical) outside face, and a 2:1 interior face. Fill material will have top
size of 6in and contain approximately 50% silt and clay. Fill will be placed in 10 -12in
level lifts and compacted by a self - propelled sheep foot roller. Fill will be placed and
compacted to 95% of Standard Proctor dry density (ASTM D 698). Fill will be scarified
between lifts. Fill will be moisture conditioned to within 2% of optimum.
Construction engineer will be on site to provide testing during fill placement and
verify compaction of floor of pond by number of tests recommended by CTL
Thompson. CTL Thompson, Inc. has conducted slope stability analysis on the TSF
embankment as shown in Figure 4 -6 and 4 -7. Samples were collected from drilling
two (2) additional holes to verify and confirm the 1990 permeability testhole data
and additionally confirm the embankment materials and underlying soils.
Additionally, a sample of tailings materials generated from laboratory .testing was
analyzed. The embankment materials, native soils and tailings materials were tested
for strength and classification, using direct shear tests for use in analyzing slope
stability of the embankment. The results are presented in the July 8, 2011 Report
(see Appendix 15 -5). Subsequently, CTL Thompson issued an update to the July 8,
2011 Report (see Appendix 15 -6).
Version 1.0 April 2013