2012-10-11_REPORT - C1981022 (2)

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XBOW MINING LLC ENGINEERING INSPECTION EAST YARD, WEST VALLEY FILL AND II WEST COAL MINE WASTE DISPOSAL PILES `'I I / ' I -9( • . _a_ Li. f\ l C rJt / Inspected by James A ° & 4 O Thomas C. Anderson Dale C olorado Licensed Professional Engineer No. 14726 3137 Hwy 1 33 • P.O. Box 5',5 • Sorner,ef, Colorado 81 434 USA TEL (970) 929 -5122 • FAX (970) 92951 7/ The approved Oxbow Mining, LLC (OMLLC) Mine permit includes a requirement for quarterly inspections of coal mine waste piles for stability. The inspection is to be performed by a registered engineer or other qualified professional specialist, who is experienced in the construction of earth and rockfill embankments. On September 20, 2012 visual inspections were performed of the East Yard, West Valley Fill and II West coal mine waste disposal areas. Four successful compaction tests were performed during the quarter on August 16, 2012. Copies are attached. EAST YARD - The East Yard disposal area has reached its design capacity, and no new waste material has been placed since June of 2001. The revegetated slope was inspected for signs of erosion or instability. No erosional features were noted on the slope. The covering of the waste pile is considered complete. Nothing was observed during the inspection that would indicate the pile has a potential for structural failure. WEST VALLEY FILL — During the second quarter, no waste was hauled to the West Valley Fill area. The refuse pile was surveyed at the approximate 6226.8' elevation. The active waste storage area will continue to be an interim storage area for refuse rehandled later to II West and a staging area for miscellaneous projects . The revegetated outslope located between the fill slope toe to the approximate 6200' elevation was inspected for signs of erosion and instability. No erosional features were noted on the slope. The area was checked for noxious weeds. The third bench (approximate 6200' elevation) setback remains established for the final lift of waste material and the ramp constructed on the waste pile to provide access to the II West Coal Refuse Facility light use road and haul road. These two roads continue to be utilized. No springs or seeps were noted. Surface drainage control features are performing according to the plan. Nothing was observed during the inspection that would indicate the West Valley Fill has a potential for structural failure. I I WEST — The II West disposal area received approximately 4,640 cy additional coal mine waste during the third quarter of 2012. II West waste is at the approximate 6128.8' elevation. The material continues to be worked to meet compaction requirements. The rock underdrain crest is at a point where it will need to be extended to accommodate additional waste. The regraded outslope seeded on December 2, 2011 remains stable. Older seeded areas are performing according to the plan. No springs or seeps were noted. The area was checked for noxious weeds and treated as appropriate. Surface drainage control features are performing according to the plan. A portion of the East Surface Rock Channel remains temporarily covered with fabric and road materials while being used as an access ramp to the pile. Nothing was observed during the inspection that would indicate the II West Fill has a potential for structural failure.