2011-03-03_REVISION - C1981028 (3)

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2.2 FIELD SAMPLING 2.2.1 Timing Field investigation was undertaken during the period August 6-15, 2009. 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. Cumulative precipitation for the September-December 2008 period was 2.49 inches, 27.3 percent below the average for those months (3.01 inches). Overall total precipitation for 2009 from January through July was 11.22 inches, reflecting an amount 41.6 percent above average precipitation for that time period. April, June, and July 2009 precipitation amounts were significantly above the averages recorded for the mine site, resulting in above average moisture conditions during the 2009 growing season. 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 2008- July 2009 was 13.71 inches, the fifth highest value since 1993. Compared to the corresponding averages, this represents a 23.5 percent above the average September-July precipitation amount. 2.2.2 Vegetation Cover . Vegetation cover was estimated by the use of the point-intercept method. An ocular point frame (ESCO Associates) was used to minimize instrument error and maximize precision and observer accuracy. Cover transects were 25 meters in length, with two sample data points collected at 1.0 meter intervals along the transect on opposite sides of the transect centerline, 1.5m apart. Transect direction was established randomly through the use of computer generated random directions (0-360°). In no event were transects allowed to extend within ten feet of reference or revegetated area boundaries to minimize impacts from "edge effect." For statistical purposes, each cover transect (comprising 50 data points) served as a sample unit. Data points recorded the first vertical "hit" on vegetation (above or below the instrument), soil (bare ground), rock, litter, or cryptogamic crust. Subsequent "hits" on vegetation were also recorded. Cover data were recorded and reported by individual plant species. The first interception was used to calculate total vegetation cover values. Additional interceptions were used to calculate relative cover of individual plant species and lifeforms. The quantitative cover data also provided the basis for calculation of species composition and relative importance. Coors Energy Company KeeneSburg Mine Page 6 Areas 2, 5, 6, 7, 9, 10, 15, 16, and 19 Vegetation Study (2009)