2013-03-08_REVISION - C1981008 - Laserfiche WebLink

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Page 6 of 9 for the Irrigated Pasture Reference area and Area 6, utilizing the information presented, the Division was able to review and verify the results of sampling using Microsoft Excel®. Total plant cover measured in the Reference Area was reported to be 61.47 %; this included all the plant life forms such as perennial grass and grasslikes, perennial forbs, annual and biennials, and noxious weed species. The applicant also reported what they believed to be the "allowable cover" percent used to determine the revegetation success criteria for Irrigated Pasture Reclaimed Areas. They included the cover attributed from perennial grasses and grasslikes and perennial forbs, but they excluded annual and biennial species and noxious weeds in the measure of "allowable cover ". The "allowable cover" percentage was reported to be 58.67 %, making the success standard for cover to be 52.80% (90% of 58.67 %). The dominant species found in the Irrigated Pasture Reference Area were Meadow Fescue (Festuca pratensis), Quackgrass (Agropyron repens), Tall Fescue (Festuca arundinacea), Small- winged Sedge (Carex micropteral), Kentucky Bluegrass (Poa pratensis), Baltic Rush (Juncus balticus) and Fowl Bluegrass (Poa palustris); contributing 24.4, 10.83, 10.09, 9.11, 8.03 and 6.83 percent of the relative cover at the site respectively. The Division does not consider state listed noxious weeds as contributing to the successful establishment of the post mine land use and in accordance with our "Guidelines Regarding Selected Coal Mine Bond Release Issues, " dated April 18, 1995, the Division requires all noxious weed contributions to cover and production be deleted from both reference and reclaimed area data prior to success comparison of those parameters. Based on the Division's review of the data, the applicant included two species in the "allowable cover percentage" that are currently on the State noxious weeds list, Quackgrass and Field Bindweed (Convolvulus arvensis). The applicant argues these species are not currently on the Montrose County noxious weed list and thus were included in the "allowable cover" measurement. The Division re- categorized these species as noxious weeds and found the "allowable cover" percentage to be 51.60 %, thus making the success standard for cover to be 46.44 % (90% of 51.6 %). For Area 6 (IP -4 area), the applicant found the total plant cover and the "allowable cover" to be 81 %. The dominant species encountered included Alfalfa (Medicago sativa), Orchardgrass (Dactylis glomerata) and Meadow Brome (Bromus biebersteinii) contributing 50.86, 22.63 and 16.54 percent relative cover respectively. Similar to the Reference Area, the applicant included Quackgrass and Field Bindweed in the "allowable cover" measurement. The Division re- categorized these species as noxious weeds and found the "allowable cover" to be 79.07 %. These species were not as prevalent in the Reclaimed Area as opposed to the Reference Area. This is likely due to the fact the Reference Area is dominated by perennial grasses and grasslike species where the Reclaimed Area is dominated primarily by Alfalfa, a perennial forb. Based on the Division findings, the success standard for allowable plant cover for 2010 based on the reference area is 46.44 %; the allowable cover found on the Area 6 (IP -4) was 79.07 %. Sample adequacy was demonstrated for both the sample efforts on the reclaimed and the reference area. Given this, in accordance with Rule 4.15.8(3)(a) the vegetative cover found on Area 6 exceeds the success standard derived from the Irrigated Pasture Reference Area. As indicated above, revegetation will be deemed successful if the herbaceous production of the reclaimed irrigated pasture is greater than 90% of the herbaceous production of the Irrigated Pasture Reference Area after the weighted average soil adjustment has been applied. According to the 2010 revegetation monitoring report, weighted average soil adjustment factor for reclaimed area IP -4 (Area 6 in SL14), was found in the 2009 revegetation monitoring report. This parcel of land was not evaluated in the 2009 revegetation monitoring report submitted to the Division for SL14. The applicant will need to provide a demonstration of how the weighted average soil adjustment factor was calculated for Area 6. This issue is further discussed below. In the 2010 revegetation monitoring report they used .728 as the weighted average soil adjustment factor. The Division used this number to evaluate and review the production data.