2010-08-23_INSPECTION - C1981019

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August 18, 2010 C-1981-019/Colowyo Coal Mine S accordance with the approved plan with regard to the channel width, side slopes, depth, and channel lining. - The inspection proceeded to the lower portion of the East Pit Ditch in an area also reclaimed during 2009. This portion of permanent ditch is constructed in the approved location as shown on approved Map 41. However, oversized riprap and poor ditch shape precluded meaningful flow within the ditch itself. Side cutting of the ditch was noted in numerous locations in the lower 500 feet of this ditch. The approved ditch designs for this ditch are found in Exh. 7-14D of the approved permit application and require a 10 foot bottom width with 3H:1 V side slopes and 15-21 inch average riprap. Field inspection found most of the ditch to be a long "mound" of very large rock, some approaching 10 feet in length, 3 feet in width and three feet in thickness. Given the poor shape and construction of this section of ditch, flow within the boundaries of the ditch cannot be anticipated in the future with any certainty, especially when additional upstream areas are reclaimed in the future. The operator has failed to construct the 2009 portion of the East Pit Ditch in accordance with the approved plan with regard the channel width, side slopes, depth, and channel lining. This ditch segment is included in NOV CV-2010-004. (***See Pictures 4 and 5***) -The Section 28 Pond was compared to the as-built construction plate dated 27 November 2007. The pond was found dry and access to the primary riser was good. The riser was measured for diameter, elevation of weep holes, presence of a trash rack and anti-vortex device, dewatering gate (found closed), emergency spillway depth, width, and riprap lining, presence and level of measuring flume, and embankment conditions. The pond was found in excellent condition and all measurements were confirmed as depicted on the as-built. - The Prospect Pond below the East Pit was also visited during the inspection. The pond held some water but the level was below the lowest weep hole on the primary riser. Some seepage was entering the pond and the conductivity was measured at 2,700 umhos/cm with a hand held pen meter. This is indicative of spoil spring flow, probably from a small spoil aquifer in the east end of the East Pit. Highway 13 is immediately below this pond embankment. Flow from the primary spillway passes under the pond through a 24-inch corrugated metal culvert. Potential flow through the emergency spillway would pass through a 30-inch culvert. Some sediment was noted in the 24-inch culvert and the operator should consider cleanout of this culvert in the near future to restore full function. - West Taylor Pond was also inspected and compared to the as-built construction plate dated 20 October 2007. Water was discharging from the pond but the water level was approximately four feet below the weep holes. There should be no water discharging from the pond when the water is below the weep holes so, obviously, there is a problem with the riser or culvert through the embankment (or both) that will need to be fixed. Colowyo will need to either drain the water from the pond through the gated pipe or pump the water out of the pond. All applicable NPDES standards and Colowyo CDPS discharge permit requirements must be met when performing the pond draining. Based on the inflow to the West Taylor Pond (from the A-A' and B-B' underdrains of the West Taylor Fill), Colowyo may also need to temporarily block the West Taylor Pond as the maintenance is performed. The pond discharge was clear and the EC was measured by the operator at 832 umhos/cm and by the DRMS at 900 umhos/cm (accurate to within 100 umhos). The pond was leaking and is in violation of Rule 4.05.6(2), requiring the pond be "designed, constructed and maintained in compliance with 4.05.6 and 4.05.9. The West Taylor Pond is included in NOV CV-2010-004. - The Taylor Tributary Ditch is located on the west side of the mined in the 2009 West Pit reclamation block above the East Taylor Pond. The operator is actively reclaiming in this area and was replacing topsoil side slopes in the 2010 reclamation block at the time of the inspection. A notable change in construction technique was observed at approximately station 15+00 to approximately 25+00 (stations shown on approved Map 41). In this Number of Partial Inspection this Fiscal Year: 2 Number of Complete Inspections this Fiscal Year: 0 Page 4 of 14