2017-04-11_REPORT - M1977424 (2)

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Logan Wash Mine Annual Report Permit No. M-1977-424 3.4 Research Mine Manometer Monitoring The manometer installed in the Research Mine Vault is monitored and recorded on a monthly basis and on a more frequent basis in the spring months of April and May, or until the peak level begins to subside. If manometer measurements were to indicate a very high (> 36 inches) reading for more than a week's time, the water in the mine can be released and allowed to infiltrate at the Lower Bench. The manometer level rose in late May, peaked at 13.5" June 21 and began slowly receding. The last measurement of the reporting period was 11.5" on October 11 `". All manometer measurements made during the reporting period are shown in Table 4. 3.5 Evaporation Pond Leak Detection System Monitoring of the Evaporation Pond Leak Detection Vault is conducted by continuous measurement of water pressure (depth) in the vault sump using an installed pressure transducer. On-site monitoring is conducted monthly as access conditions allow. Figure 7 shows the pressure received water beginning in mid-February, 2016 and reached the automated pumping depth of approximately 1.0 feet in late July. Intermittent pumping then occurred but the sump pump system was malfunctioning so the vault was not automatically pumped out. The automated sump pump system was repaired in late November and the vault was pumped out. Over a three day period in mid-January, the water level rose to a depth of approximately 3.5 feet. The automated pump system was not triggered due to float switch failure. The sump was manually pumped out on January 25`" and the float switch was replaced on February I". Flooding of the sump since that event has not exceeded a 2 -foot depth. Periodic inspections of the liner did not reveal any new open holes, cuts or cracks near the water line. 3.6 Precipitation Precipitation was monitored on the Lower Bench and at the Evaporation Pond through the use of Novalynx Corporation Model 260-2101 SK -P rain gauge instruments. The Lower Bench gauge is typically operational from April through December, depending on access to the bench. The Evaporation Pond gauge was installed for the first time in May, 2015. Each gauge measures precipitation with an automated logger that is downloaded periodically. Precipitation data collected in 2016 showed a total precipitation of 7.60 and 4.63 inches, for the Lower Bench and Evaporation Pond, respectively (see Figure 8). Both rain gauges recorded from May 12`h, 2016 to November 29`x'. The NWS Cooperative Network Altenburn, CO station (Coop # 050214, elevation 5,690 feet AMSL) recorded total precipitation of 8.86 inches for May through November 2016. The Evaporation Pond gauge is not equipped with a wind screen. 3.7 Daylight Bench Slope Stability Monitoring The Daylight Bench was constructed to support sealing of the Daylight Portal in 2004. Tension cracks and minor subsidence was first observed in 2009 on the small bench. The contractor Geo - Smith Engineering has continued to survey the Daylight Bench for slope movement since May, 2011 and continued through 2016 during the spring and summer, access permitting. Surveys in 2016 were conducted on May 27`x', and October 12. Prior to the October, 2013 survey, no significant movement of the survey monuments was observed. The October 2013 survey noted that 2 of 6 extension stakes have shown minor to small (0.42 ft.) amounts of movement. The June 2014 survey also noted that 2 of 5 extension stakes Western Water & Land, Inc. 8