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III. COMMENTS-COMPLIANCE Below are comments on the inspection. The comments include discussion of observations made during the inspection. Comments also describe any enforcement actions taken during the inspection and the facts or evidence supporting the enforcement action. This was a partial inspection of the North Thompson Creek Mine conducted by Tom Kaldenbach. No one else was present. Representatives of the mine operator, OSM, Pitkin County, and the Roaring Fork Conservancy had been notified of the inspection. The main objective of the inspection was to search for evidence of mine subsidence on the undermined areas. This search was conducted as a follow-up to the final bond release inspection conducted on April 17, 2007. The site has greened up considerably since that inspection. This inspection was conducted on June 6 and 8, 2007. Intermittent light rain fell during the inspection on June 6. The weather was dry on June 8. Photographs taken during the inspection aze provided at the end of this report. Hydroloeic Balance Mine 3 was discharging into the treatment pond system. There was no dischazge into the treatment pond system from the Mine I pvc pipe. The pond treatment system was dischazging an estimated 25 gpm of clear water at the former [ocation of outall 001. Field parameters of the discharge were Ec 994 µmhos/cm, pH 7.8, and temperature 61 °F. A sample of the dischazge was collected in an acidified bottle, and was stored on ice. The sample was delivered on June 11, 2007 to an analytical laboratory in Lakewood for analysis For total iron. Note on Sample of Mine 3 discharge collected 4/18/2007- The sample of Mine 3 water that was discharging outside the treatment pond system was analyzed for total iron. Laboratory analysis indicated total iron concentration of 6.3 mg/1. DRMS is awaiting a final determination from the Colorado Water Quality Control Division on compliance with the applicable standazd in 40 CFR Section 434. Subsidence Three transects were walked during the inspection. The transect routes aze shown on the map, below. Several geographic points on the mine workings had been entered into a GPS prior to the inspection, enabling tracking of the location relative to the mine workings during the inspection. The transects crossed areas where massive sandstone beds aze exposed on the land surface, over mine workings that are at depths of less than 500 ft. below the ground surface. The brittleness of the sandstone beds in these areas, in combination with the relatively shallow depth to mining, aze factors that may have created the highest probability for the formation of surface subsidence features in the permit azea. The traverses crossed the mazgins of mine workings where tension may be significant, further promoting the formation of surface cracks. Mine subsidence can create open cracks on the ground surface and cause spalling from sandstone outcrops. Close examination of outcrops along the transects found no evidence of subsidence. Sandstone outcrops were intact at most locations. Fractures in sandstone beds generally were inclined from 3