2018-01-16_REPORT - M1977004

• Permit No: M1977004
• IBM Index Class Name: REPORT
• Doc Date: 1/16/2018
• Doc Name Note: Reclamation Report
• From: Homestake Pitch Project
• To: DRMS
• Email Name: DMC
• Media Type: D
• Archive: No

MOM11 STAKE
January 1
Colorado Department of Natural Resources J ary 5, 2017
Division of Reclamation, Mining and Safety
Attention: Mineral Division
1313 Sherman Street, Room 215
Denver, CO 80203 ECEIVED
' JAN 6 2018
8
RE: HOMESTAKE PITCH RECLAMATION PROJECT �f� F�q �MATiON
2017 ANNUAL GEOTECHNICAL REPORT (M-1977-004HR) ANDSAFj:TY
Dear Division:
Attached is the 2017 Annual Geotechnical Report for the waste rock management areas at the
Homestake Mining Company Pitch Reclamation Project(Figure 1). The purpose of this report is
to provide the results of ongoing geotechnical monitoring of the Indian and Tie Camp rock
dumps at the Pitch Reclamation Project(Figure 2). The history of the rock dumps has been
provided in previous annual geotechnical reports and is not repeated here. In 2017, the rock
dumps were inspected monthly in accordance with the recommended monitoring program. The
inspections indicate stable conditions for the Indian and Tie Camp rock dumps.
The Indian and Tie Camp rock dump piezometer water level readings are presented in this
report. The 2017 monthly water level measurements are provided in Table 1 and shown on
Figure 3. Water level data collected since 1996 are shown on Figure 4. As reflected on Figure 3
' and Figure 4, the water levels in the rock dump piezometers show little fluctuation in the fall and
winter months, with a temporary rise in response to the spring snow melt or summer rain
events. The extent that water levels rise each year depends on the fluctuation in snow pack and
summer precipitation, and the location of the piezometers within the rock dumps. The onsite
precipitation gage recorded 21 inches of precipitation during the 2017 monitoring period
(November 2016 through October 2017), compared with 20 and 23 inches during the 2016 and
2015 periods, respectively, and 31 inches in 2014 consistent with the heavy snow pack
observed that year.
In 2017, four new piezometers (RD-06, RD-07, RD-08, RD-09)were installed at the 10300 level
' of the Indian Rock Dump and one shallow piezometer(RD-05)was installed near the toe of the
Indian Rock Dump (Figure 2). These piezometers were approved by the Division in April 2017
under Technical Revision #8 (Division 2017a). These piezometers were used in combination
' with Piezometer 10300R, and four shallow piezometers (RD-01, RD-02, RD-03, RD-04)
approved by the Division under Technical Revision#7, to facilitate large-scale in situ source
zone treatment of uranium, with extraction from the piezometers at the toe of the Indian Rock
Dump and injection into the piezometers at the 10300 level (Division 2016). Water level
' measurements collected in 2017 from the piezometers near the toe of the Indian Rock Dump
and the 10300 level are shown on Figure 5 and Figure 6, respectively. Observed fluctuations in
both the new piezometers and 1030OR reflect the water level changes associated with the in-
situ source zone treatment. After cessation of injection activities, piezometers returned to long-
term water level trends (Figure 5 and Figure 6).
Pitch Reclamation Project Page 1
2017 Annual Geotechnical Report
M-1977-004HR