2016-03-24_REPORT - M1977424 - Laserfiche WebLink

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Logan Wash Mine Annual Report Permit No. M-1977-424 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 2015 showed a total precipitation of 20.9 and 11 inches, for the Lower Bench and Evaporation Pond, respectively(see Figure 7). The Lower Bench gauge recorded from February 6 to November 13, 2015 and the Evaporation Pond gauge recorded from May 22 to November 11, 2015. 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 2015 during the spring and summer quarters, access permitting. Surveys in 2015 were conducted on March 27,June 25,August 21, and November 23. 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 6 extension stakes have shown minor(0.07 ft.)amounts of movement. Throughout 2015 minor movement was detected in 1 of 6 extension stakes. This movement is localized as no movement has been detected in the other extension stakes or survey monuments. Further measurements in 2016 will evaluate if there is a trend in this movement. Physical observations of the Daylight Bench do not indicate ongoing slope failure. 4.0 Reclamation Activities in 2015 Monitoring activities described in Section 3 are considered activities that impact successful overall mine reclamation. Other reclamation activities conducted at the Logan Wash Mine in 2015 are discussed in the following sections. 4.1 Revegetation Maintenance During the reporting period,the irrigation system installed for planted saplings on the Upper and Lower Mine Dumps was not deployed. Areas seeded during past revegetation work are self- sustaining; it is anticipated that the irrigation system will not be used in the future.No other revegetation work(weed removal or mowing)was conducted. Transplanting of the endangered plant species P. debilis is discussed in Section 8. 4.2 Well Abandonment No monitoring wells were abandoned during the reporting period. 5.0 Maintenance Activities Maintenance activities included periodic inspections of mine roads, benches, portals,mine water drainage systems associated with the retorts and general mine workings, as well as the inspection of Evaporation Pond facilities including the pond's liner, security fencing, operation, and leak detection system. Maintenance activities conducted at the mine and Evaporation Pond are summarized in the following sections. Western Water & Land, Inc. 8