2015-03-16_REPORT - M1977342

• Permit No: M1977342
• IBM Index Class Name: REPORT
• Doc Date: 3/16/2015
• Doc Name: Annual Report Fee Map
• From: Climax Molybdenum Company
• To: DRMS
• Email Name: PSH
• Media Type: D
• Archive: No

W. W. WHEELER
& ASSOCIATES, INC.
Water Resources Engineers
February 17, 2015
Mr. Miguel Hamarat
Climax Molybdenum Company, Henderson Mine
1746 County Road 202
Empire, CO 80438
Re: #1333.0 - Henderson Mill
Tailing Pond Flood Storage
Dear Miguel:
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WWW.WWWHEELER.COM
MAR 0 6 i.0 17
Division of ROCINMA00n,
Hurling & SAWY
As requested, we have evaluated the availability of flood storage capacity in the Henderson
tailing impoundment using information from the spring and fall 2014 pond surveys. The
spring survey of the beach and pool area was performed in May and the fall survey was
performed in October. Figure 1 is the pond contour map that was generated by Wheeler
from the fall survey point data. A similar map was prepared for the spring survey. The
survey shows that the average dam crest elevation of 1 Dam at the end of the spigot
deposition season is about 8872.8 feet, which is a 4.7 -foot increase from last year. The
minimum elevation surveyed along the dam crest was 8869.3 feet. This information, as well
as other characteristics of the pond, is summarized in the table in the upper right -hand
corner of the pond map drawing. Table 1 and Figure 2 is the elevation- capacity data for the
impoundment that was generated from the fall 2014 contour map. Note that this data is
representative of the pond at the time of the pool survey and changes continuously as
additional tailing is deposited.
One of the primary uses of the survey data is to evaluate the flood storage capacity
conditions in the water system. As summarized on Figure 1, at the approximate time of the
fall survey there was a total system surcharge storage capacity of about 9,192 acre -feet in
the system. This capacity includes both the TSF and East Branch Reservoir and is based
on 0.5 feet of residual freeboard below the minimum dam crest elevation of 8,869.3' and a
water level of 8,856.4'. The current flood storage requirement for the system is 3,582
feet. This requirement is based on hydrologic modeling of the probable ma)
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