2010-09-10_GENERAL DOCUMENTS - C1981028

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determined on adjacent non -mined areas." The approved reclamation plan is found in Section 2.05.4 of the permit application. The required topsoil replacement thickness is two (2) feet. The approved post - mining land use is rangeland. The Dugout Pond, perimeter ditches, and Pond 2 have been approved to remain as permanent structures. III. OBSERVATIONS AND FINDINGS Revegetation The Keenesburg Mine permit previously utilized comparison of an approved reference area, known as the Osgood reference area, for revegetation success of the reclaimed areas. Comparison to the Osgood reference area was not ideal due to a successional change of the species composition in the . reference area to a community heavily dominated by sand sagebrush and a reduction of forage grasses and forb species over the years. Also, a change in surface ownership of the property upon which the reference area was located caused concerns regarding management of the reference area. CEC proposed revegetation success standards for vegetative cover and herbaceous productivity based on a formula derived from historic data collected on the Osgood reference area and a correlation to precipitation records (TR37, approved June 15, 2006). Permit page 2.05.4 -116b defines the required cover standard for the Keenesburg Strip Mine. The permit states, "Reclaimed areas will be considered successfully reclaimed if the total vegetative cover on the reclaimed area is not less than 90 percent of the predicted calculated cover value with 90 percent statistical confidence using the equation: y= 0.0173x3 — 0.8592x2 + 14.562x — 47.015, where x is the cumulative value of precipitation from September to July of the following year, and y is the resultant vegetation cover." This cover standard is in agreement with Rule 4.15.8. The calculated cover standard for 2009 is 35.7 percent live vegetative cover, based on 13.71 inches of measured precipitation for the preceding September to July. CEC reported in the 2009 vegetation sampling report that the overall vegetative cover for reclaimed areas seeded in 1998, 1999, and 2000 (reclamation areas 2, 5, 6, 7, 9, 10, 15, 16 and 19) was 60.96% live vegetative cover. However, per Rule 4.15.1(2) and the Division's 1995 Bond Release Guidelines, noxious species cannot contribute to reclamation success. Table 2 in CEC's revegetation report shows that Bromus tectorum (cheatgrass) contributed 8.3% to the live vegetative cover (LVC) on this Bond Release Block (BRB), and this amount must be removed from the value of 60.96% for a sub -total of 52.66% LVC. Furthermore, in measuring reclamation success the allowable cover contribution of annual and biennial species should not exceed 10 percent (based on Division policy and the Division's 1995 guidelines). Of the 36 plant species sampled on the 1998/1999/2000 BRB, 14 species were determined to be annual or biennial. The 14 annual and biennial species contributed 13.19% of the total cover and 28.67% of the relative cover (from Table 2). To limit the relative cover of annual and biennial species to exactly 10 percent, a portion of these species were removed from a revised Table 2, and the resulting LVC is 44.07 %. C1981 -028, SL -05 5 9/10/2010