2011-12-22_REVISION - C1981028 - Laserfiche WebLink

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The Keenesburg Mine is located in Weld County, Colorado, approximately seven (7) miles north of Keenesburg, Colorado and is accessed by Weld County Road 59. Coors Energy Company operated the Keenesburg Mine for coal extraction from 1980 to 1988. Reclaimed areas sampled in 2011 were backfilled, graded, topsoiled and revegetated in accordance with the approved mining and reclamation plan. The revegetation standards used to evaluate these areas are those currently in effect under the Colorado Surface Coal Mining Reclamation Act (CRS 34 -33 -101 et seq) and the Keenesburg Mining and Reclamation Permit (C- 1981 -028). 2.0 METHODS 2.1 SAMPLING DESIGN Discussions with revegetation specialists at CDRMS in February 2007, April 2009, and July 2010 formalized the sampling design for Phase III vegetation sampling at the Keenesburg Mine. Areas revegetated in 1998, 1999, and 2000 would be treated as one sampling unit as parcels within the revegetation areas and revegetation years were contiguous (or nearly so) and received the same seed mixes and reclamation management. Prior to initiation of fieldwork, the permit document and applicable maps were reviewed to evaluate topography, reclamation timing, seed mixes, revegetation methods, management, and applicable revegetation standards. A map of the mine site at 1:2400 scale (1 " =200') was used to delineate the revegetated areas (Coors Site Plan; Vegetation Sampling Locations). On a gridded overlay of the revegetation map, a Cartesian coordinate grid (50x50 feet) was established. Computer generated random numbers were used to establish a pool of x,y coordinates. The acreage of each revegetated area was established. Random sample locations were established for each revegetated area. Within each year's revegetation parcels, sufficient samples were established to represent each area by proportional acreage. Sample sites were located in the field through compass triangulation and pacing from known landmarks. 2.2 FIELD SAMPLING 2.2.1 Timing Field investigation was undertaken August 30, 2011. This time period coincided with anthesis and maximum development of the majority of plant species found in the reclaimed areas at the mine site to be evaluated. At the Keenesburg Mine, precipitation relevant to the growing season occurs from September to the following July. Total cumulative precipitation for the period from September 2010 - July 2011 was 13.37 inches. Compared to the corresponding averages, this represents 17.1 percent more precipitation than the average September -July precipitation amount. It should be noted that a singular precipitation event in May 2011 contributed 6.31 inches of precipitation that month, 280 percent above the average. Absent this event, the precipitation Coors Energy Company Keenesburg Mine Page 2 2011 Vegetation Sampling: Phase III Eligible Areas