2013-07-17_REVISION - C2009087 - Laserfiche WebLink

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ESCO ESCO Associates, Inc. P.O. Box 18775 Boulder, CO 80308 5360 Manhattan Circle, Suite 200 Boulder, CO 80303 May 2013 Summary Report — 2012 Vegetation Sampling Results, Wolf Creek Pre -Law Area, PSCM Vegetation sampling was conducted by ESCO on various reclaimed units and references areas at the Peabody Sage Creek Mine in Routt Co. CO in August of 2012. As a part of this sampling effort, 12 cover transects were established within a pre -law revegetation area of the PSCM permit area associated with Permit 75 -54C (referred to as the Old Wolf Creek area). This parcel had been removed from previous pre -law area bond release assessments that were conducted while the area was part of the Seneca II Mine permit area in 2007. The 12 cover transects were 50 m in length and randomly located and oriented within the 68.8 acre pre -law area (Exhibit D). Along each transect, 100 points were assessed as part of point - intercept determination of plant cover using an ocular point bar. For full description of the cover sampling method, please refer to any of the bond release or interim monitoring documents that have been prepared and submitted to the Division over the past 20 plus years and most recently submitted in 2012 the annual vegetation report titled: 2012 TESTING FOR REVEGETATION SUCCESS for PHASE III BOND RELEASE, Year One of Two (Peabody Sage Creek Mine Routt County, Colorado). The reference area sampling results from this 2012 study provide the basis for revegetation success evaluations for the subject pre -law area. While there are no formal success standards or a process for formally testing for revegetation success on Pre -law lands, the cover success evaluation process used on post -law lands at PSCM provides a means for assessment. The weight averaged sagebrush and mountain brush vegetation first -hit herbaceous cover values, with woody and noxious weed cover removed, will be used as the standard. Similarly woody and noxious weed cover will be removed from the pre -law cover values to determine first -hit herbaceous cover and the reclaimed and reference areas compared. The Wolf Creek pre -law sampling results are shown in Table 1, attached. Total live vegetation cover averaged 26.8 percent. This value may be used to assess success of revegetation by comparing the adjustment made by subtracting woody plant cover (1.8 %) and noxious weed cover (0.16 %) from the pre -law cover value to the weight- averaged value of the 2012 reference area values similarly adjusted. The adjusted pre -law revegetation cover value of 24.8% compares to 90 percent of the reference area based standard of 24.6 %. This standard is based on the following derivation: Calculation of 90 percent of the cover performance standard appropriate for 2012 sampling and using the highest possible cover value for the mountain brush reference area component is demonstrated here: Mountain brush reference area allowable first -hit herbaceous cover *(10.7 %) X 2 = 21.4% Sagebrush reference area allowable first -hit herbaceous cover *(28.3 %) X 2 = 56.6%