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February 1998 Hayden Culch Mine • Phase 2 fi 3 Bond Release Application ~ PaAe 8 methods for either the 1996 or 1997 studies. However, reverse hypotheses test methods • performed in accordance with DMG directions confirm that the sample sizes were indeed adequate. Species diversity data presented in the 1996 and 1997 Reclamation Study indicates that species diversity in the reclaimed azeaz is similar to that observed in the reference areas. The revised 1996 data indicates that all the reference areas had slightly greater diversity than the primary reclaimed area. The 1997 data indicates that the chokecherry and sagebrush reference areas had slightly higher diversity than the primary reclaimed area while the aspen and oak brush reference azeaz had slightly less diversity. Perennial grasses and fortis were the dominant life- forms on all of the study azeaz. In comparing pre-mine data with reclaimed area data, the revised 1996 data indicates that all of the pre-mine reference areaz had greater diversity than the reclaimed area. The 1997 data indicates that the primary reclaimed area had higher species diversity than all of the pre-mine reference azeaz. The bond release vegetation data indicates that a good diversity of plant species have been established on the reclaimed azea. Both the revised 1996 and 1997 data, az presented in the 1996 and 1997 Reclamation Study, indicates that none of the perennial grass species exceeded 40 percent relative cover and the top three dominant species combined for less than 75 percent of the total relative cover. In addition, both studies indicate that ac least five species accounted for greater than five (5) percent of the relative cover. Data for both years, therefore, meets species diversity requiremenu. • Table 8, Compazison of Revised 1996 Data for Reference Area Means Versus Primary Reclaimed Area Means, and Table 9, Comparison of 1997 Data for Reference Area Means Versus Primary Reclaimed Area Means, indicate that the reclaimed area has cover and production values greater than that of the weighted averages for the reference areas. The 1996 and 1997 vegetation sampling indicates that the reclaimed area meets the required statistical revegetation sztccess criteria for all cover, production and shrub density parameters. Species diversity also meets the required standazds and is similaz to pre-mine conditions and adjacent reference areas. Consequently, the reclaimed area at the Hayden Gulch Mine meets the vegetation bond releaze criteria pursuant to Rule 4.15.8. 4) Documentation Ofl'roductivity From Reclaimed Alluvial [/alley Floors And Croplands: The Hayden Gulch Mine site did not disturb any alluvial valley floors or croplands. 5) Documentation O{~Topsoil Replacement: Due to the abundance of deep, high quality A horizon loamy soils within most of the disturbed areaz, only the A horizon was stripped from disturbed areaz. Topsoil stripping volumes were calculated using an average topsoil depth for each soil series. For example, the Routt soil series, which covered about 55% of the total disturbed area, ranged in depth from 20 inches to 34 inches, az Montgomery Watson A mencas (dba TenaMatrizJ * PO. Bos 774018 Steamboat Springs, Colorado 80477 • (970J 8796160 m:vmp.,,:aseaw ndd.npp~~r w~..acs m,Jndu.nppium, U:U-I J.