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• EXECUTIVE SUMMARY <br />In 2002, Savage and Savage prepared an analysis of the current revegetation success <br />criteria for the Coors Energy Company Keenesburg Mine. From this analysis it was <br />concluded that the approved method of utilizing a reference azea (in this case, the Osgood <br />Sand Reference Area) was less than representative of the struchue and composition of the <br />reclaimed vegetation community likely to be achieved. A method of employing a regime <br />of data collected at the mine to derive predictive mathematical equations for total <br />vegetation cover and total herbaceous production was proposed to supplant the use of the <br />reference azea. Comparison of the equations derived from empirical data from the <br />reference azea, older reclaimed areas, and younger reclaimed azeas revealed that equations <br />derived from the older reclaimed areas yielded predictive equations that correlated well <br />with the empirical data as well as verifying expected theoretical plant ecological <br />relationships. An additional evaluation of the species composition of the reference azea <br />from sampling data collected from 1994-2001 revealed that the then current species <br />composition revegetation success criterion for the mine did not reflect the reality of <br />species composition at the reference azea or reclaimed areas. A revised species <br />composition revegetation success criterion was proposed. <br />This addendum to the 2002 investigation presents the results and conclusions of a review <br />of the original investigation in light of additions to the original data set since the issuance <br />of the 2002 report. This addendum provides a review and interpretation of the continued <br />• annual sampling of the Osgood Sand Reference Area and the 1995, 1997, and 1998 <br />Reclamation Areas. Of particular interest is the fact that this time frame corresponds to <br />drought conditions in the state that aze reflected in responses by both native and reclaimed <br />vegetative communities. <br />Based on the additional data and subsequent review, the original assertion that predictive <br />mathematical equations could provide an effective, efficient, and fair means of developing <br />revegetation success criteria for total vegetation cover and total herbaceous production <br />was resubstantiated. A further review of additional species composition data verified that <br />the original species composition success criterion approved for the mine was overly <br />ambitious and not representative of either the native vegetation community or well- <br />developed stable reclaimed vegetation communities at the mine. <br />Given the discussed effects of drought conditions and stand age, the predictive equations <br />originally proposed in the 2002 investigation remain the most reliable predictive tools in <br />establishing alternative revegetation success criteria for total vegetation cover and total <br />herbaceous production. <br />The limitations of the current species composition success criterion were reverified with <br />the addition of the 2002-2004 relative cover data from the Osgood Sand Reference Area. <br />The revised species composition revegetation success criterion from the 2002 <br />investigation has been reaffirmed by this investigation. <br />Loons Energy Company Keeneaburg Mine Page 1 <br />2005 Addendum to Reviebn of RevegetaUon 5uccese Criteria <br />