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

1
' Fora more complete discussion see Section D.B, Water Balance,
and Appendix G, Water Balance Calculations.
The ponds and solution conveyance ditches will be double
lined with a lower liner of 40-mil HDPE and an upper liner of
60-mil HDPE. The ponds will be equipped with painted depth
' markers on one side. The thicker upper liner has been selected
to improve abrasion resistance in anticipation of some ice
development in the ponds during the winter.
No significant sediment accumulation is anticipated based
on the sandy characteristics of the San Luis cre. BMR will
lower the ponds annually for a visual examination of sediment
levels. If sediment levels are in excess of 2.'~ ft, thereby
eliminating one ft of the provided two ft of freeboard, BMR
will remove the pond sediment and dispose of the sediment on
inactive areas of the leach pad.
' D.7.4.3 Secondary Recovery/Leak Detection
A secondary recovery system will be constructed between
the liners in the leach pad and a leak detection system will
i he constructed between the liners in the solution ponds. The
leach pad system will drain to the downgradient edge of the
1 pad along the perimeter berm at the center axis, and to a
gravel collection sump in the lower corners of the ponds where
it will be monitored. Riser pipes of sufficient size to allow
t pumping for sampling and removal of any solutions that occur
in the systems, will be installed. Geonets will bE, used on the
' pond side slopes with a one-ft thick gravel layer used over
the leach pad and in the pond bottoms. Details of the secondary
recovery and leak detection systems are shown on ~igure C-10.
BMR will monitor the secondary recovery/leak detection
i systems once each day during the initial month of start up for
each phase. After the initial month, the secondary

D-51 (Revised 4J20/89)