2012-02-01_REPORT - M1983194 (2)

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1 4.4 Geotechnical Program NSI monitors two (2) time - domain - reflectometry monitor wells, the 4A -5M and 3M -TDR. There has been no indication of subsidence near the 4A -5M well since installation. The 3M -TDR well was drilled late in 2003. Two of the four TDR cables in 3M -TDR subsidence well appear to have water infiltration damage. In 2011, readings were again taken and data was gathered from cables two and three. In addition to the monthly NSI readings, the installation contractor also collects data quarterly; no significant ground movement has been detected near the 3M -TDR well since the cables were installed. 4.4.1 Subsurface Subsidence Geophysical Logging On March 9, 2011, Rocky Mountain Wireline Services (RMWS) ran gamma ray and casing collar locator logs (GR/CCL) in the DS -3 and DS -4 monitoring wells to measure for any potential subsurface subsidence near the 7H and 10H mining intervals. The GR /CCL logs from the two wells were compared to baseline logs of these wells. The comparison of the logs from the DS -3 and the DS -4 showed no evidence of subsurface subsidence in the 7H and 10H mining intervals. The casing collar locations were identical and the gamma ray signatures showed minor inconsistencies probably due to tool and logging procedural differences between the original logger and RMWS. 4.4.2 Surface Subsidence Monitoring NSI utilized a new surveying company in 2011. NSI employs eleven surface monuments throughout the well field to monitor for any potential surface subsidence. The CP 9 monument was not found during the 2011 survey. The 2011 surface subsidence monument survey noted no corrected elevation change greater than ±0.1 foot. 4.5 Water Well Pumpage In 2011, approximately 33.3 million gallons of water was pumped from water supply wells 90 -1 and WSW -2 with an average of 63.4 gpm. The total pumpage from WSW -2 was 31.4 million gallons, and the total pumpage from 90 -1 was 1.9 million gallons. 5.0 Environmental Monitoring and Protection 5.1 Hydrology Monitoring 5.1.1 Introduction NSI's hydrology monitoring program concentrates on ground water, as there are no perennial streams or springs located on or near the sodium leases. The USGS stream gauging station - monitoring program is conducted, with NSI support, to provide regional surface stream flow data on Yellow and Piceance Creeks. The hydrology- monitoring plan is designed to determine impacts of NSI's solution mining operations on underground sources of drinking water, as designated by the US EPA. Daub & Associates, Inc. 15 NSI Annual Report 2010