2016-03-08_REPORT - M1977342

• Permit No: M1977342
• IBM Index Class Name: Report
• Doc Date: 3/8/2016
• Doc Name: Annual Fee, Report & Map
• From: Henderson Mine
• To: DRMS
• Annual Report Year: 2016
• Email Name: PSH
• Media Type: D
• Archive: No

Annual Report—2015
Henderson Mine and Mill Reclamation Activities
Permit No. M-1977-342
2.3.2— Water Quality Data
Water quality data will be provided in the Annual Water Quality Report,per the approved Groundwater
Management Plan(TR-16).
2.3.3—Flood Storage Capacity
Analysis of flood storage capacity in the Mill tailings impoundment was carried out by W.W. Wheeler,
per DRMS requirements stipulated for Technical Revision (TR) 14. This analysis is included as
Attachment B.
2.3.4—3-Dam Seepwater Line Leak-Down Test
The annual 3-Dam seepwater line leak-down test for 2015, per DRMS requirements stipulated in TR-09,
was completed on May 19th. The seepwater lines held static pressures over a 24-hour period, as
designed. See test report in Attachment C.
2.3.S—Hydrogeologic Investigations
Henderson completed Phase II of the Ute Park Extraction Wellfield downgradient of 1-Dam, including
the installation of two extraction wells (MLEX-2 and MLEX-3) and two monitoring wells, per Technical
Revision 25. As-built drawings and engineer certifications have been submitted and accepted by the
DRMS. Phase III is planned for 2017,with the installation of up to three additional extraction wells.
Henderson also completed the Sand Seam Project in 2015 (Technical Revision 26). This project included
the excavation of a defined lens of permeable sand-based material, followed by backfilling with low-
permeability material, and capping with a PVC membrane. This installation is expected to mitigate any
future process-impacted waters from entering the native groundwater system to the north of the Number I
Tailing Dam. A monitoring well was also installed as part of this effort for integrity assurance measures.
2.3.6—Gravel Pit Operations
Crushing and screening activities resumed at Henderson Mill's gravel pit in 2015. 74,950 tons of
material was produced during 31 days of production. At present, no gravel production is scheduled for
2016.
2.3.7 Tailing Delivery Line
Henderson Mill completed the refurbishment project in 2015, whereby all pre-existing structural steel on
the Tailing Delivery Line was replaced by a system of more robust I-beam and concrete footer
construction. All pertinent TR-related documentation associated with this activity have been submitted to
the DRMS. HDPE pipeline that was temporarily repaired in late 2014 and 2015 was removed and
replaced with new HDPE piping.
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