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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. General Comments This was a partial inspection of the mine site, conducted by Dan Mathews of the DMG Grand Junction Field Office. The inspection was conducted July 26`h and 27`", concluding on the morning of July 28. Tonya Hammond, SCC owner representative, was present during the inspection on the morning of July 26. There was no operator contact present during the remainder of the inspection. Weather was clear and very warm (up to 100 degrees during the afternoons). Ground conditions were variable (moist to dry) across the site, depending on location. Operator Documentation of Intense Storm Event of July 20. 2006 Tonya Hammond notified me by phone message on the morning of Monday, July 24, that there had been a major, cloudburst type rain/hail storm at the mine on the evening of Thursday, July 20. 1 was out of the office on the 24th, and received her message on Tuesday, July 25. Based on Ms. Hammond's initial phone message, subsequent conversations with her, and written reports from Ms. Hammond and Jim Stover, consulting engineer, a summary of the circumstances and consequences of the storm is as follows: • On July 20'" there was an intense rain/hail precipitation event on portions of the mine site, with heaviest precipitation apparently falling on the South Portal vicinity, North Portal vicinity, and along lower Coal Canyon in the CRDA refuse area vicinity. Operator's on-site rain gauges did not function during the event, due to prior damage. • From discussion with numerous nearby residents, operator determined that heavy rain and hail began at approximately 5:30 p.m. and lasted for 1 to 1.5 hours. One resident, whose house is located approximately'/. mile from the RSRDA Soil Borrow Area, did have a functional rain gauge, and indicated that he recorded 1.75 inches of precipitation in approximately 1.5 hours. • On July 20`h, the National Weather Service issued a warning at 5:55 p.m., stating that Doppler radar indicated a strong thunderstorm developing just north of Cameo, with the potential to produce heavy rain, frequent lightning, and pea sized hail. • Operator filed written reports of the storm event and consequent sediment control system breaches to the Water Quality Control Division (July 28, 2006) and DMG (August 1, 2006). The reports noted that runoff resulting from the intense storm event had caused damage over a wide area of the mine site, including a breach of the RSRDA upper diversion (steep south Segment BB), that allowed disturbed area drainage to bypass Sediment Pond 9, and discharge without passing through a sediment pond or treatment facility. Damages specifically cited in the written reports included damage to the upper diversion ditches of the Roadside and CRDA-2 refuse disposal areas. • Operator's report of August 1, 2006, to DMG, noted that site damage assessment was conducted on July 24, and that repair work began on the morning of July 26 (beginning with remedial repair of the RSRDA upper diversion Segment BB, necessary to direct disturbed flow into Sediment Pond 9). • Based on information compiled regarding the storm magnitude and duration, operator submitted SEDCAD modeling documentation within the August 1 report to DMG. Based on the modeling, operator concluded that the peak flow caused by the storm exceeded the 100 year, 24 hour design flow in the RSRDA perimeter ditch segment that failed, by a relatively wide margin. The Division has not yet completed a review of the modeling conducted by the operator. Determination regarding whether enforcement will be pursued is pending completion of that review. DMG inspection observations concerning effects of the storm event are discussed separately try mine area in the subsequent section of the report. 3