2008-05-12_REVISION - C1980005 (4)

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Seneca Coal Company May2008 Phase 11 Bond Release Request 90 percent of the area-weighted reference area mean species density is calculated as follows: 0.9[(0.83 X 23.3) + (0.17 x 26.6)] = 21.5 species/100m2 The t test for BRB-2 is: t~ _ (21.5 - 17.8)/4.7/20 = 3.52 Critical t (table value) (alpha = 0.1, d.f. = 19) = 1.328 Alternative test B is not passed for BRB-2. Although Alternative Test B was not passed for BRB-2, an average of 17.8 species/100m' is not unreasonable based on the methods, procedures, and approved seed mixes applied to these early SMCRA reclaimed parcels. Three species applied in these early mixes benefited from too high of a seeding rate and rapid establishment and aggressive competitive abilities: alfalfa, smooth brome, and intermediate wheat grass. Together they accounted for nearly 80 percent of the vegetative cover in BRB-2 in 2006 sampling. While these species are very beneficial in meeting post-mining land use needs for livestock grazing and wildlife habitat (e.g., big game foraging and sharp tail grouse leks and nesting), they have tended to suppress species diversity for the successional short term. Note that revised mixes were incorporated to counter these issues and the results are reflected in BRB-3 and BRB-4. The BRB-3 parcel Alternative Test B results are as follows: The weighted average reference area species density is 21.5/100m2. BRB-3 species density is 22.1 / 100m2. The t test for BRB-3 is: t~ _ (21.5 - 22.1)/(6.9/20) _ - 0.39 Critical t (table t value) (alpha = 0.1, d.f. = 19) = 1.328 Since ~ is less than critical t, Alternative Test B is passed for BRB-3. The BRB-4 parcel Alternate Test B results are as follows: The weighted average reference area species density is 21.5/100m2. BRB-4 species density is 28.3/100m2. The 28.3/100mz species density in BRB-4 is much greater than the reference area standard and thus Alternative Test B for BRB-4 was met. 10