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West Elk Mine <br />• In order to obtain a representative record of the variability of the microclimate of the area, and <br />therefore the effect on vegetation growth, it was determined that the three yeazs comprising the <br />historic record should represent the variability of precipitation to be encountered at the site. For the <br />purposes of the historic record; one low, one average, and one high precipitation year would be <br />represented, based on precipitation records from a weather recording station in the azea. <br />Determination of the year type (low, average, high) would be made based on the precipitation sum <br />preceding the growing season (i.e., the sum of precipitation from October of the previous yeaz to <br />May of the current yeaz). L.ow and high precipitation yeazs were defined as yeazs where the <br />precipitation sum differed by 10 percent or more from the average precipitation sum for the <br />October-May time period. <br />This vegetation community is to be quantitatively sampled for three yeazs for total vegetation cover, <br />total herbaceous production, species composition and woody plant density. Initial collection of data <br />began in 1996. After collecting three growing seasons data, the mean values from each pazameter <br />for each of the three yeazs are averaged to obtain a historic record revegetation success standard for <br />each parameter. The revegetation success criteria developed from the historic record data will be <br />applied to all revegetated azeas at the West Elk Mine. <br />A summary report will be completed after each yeaz that vegetation sampling has occurred in the <br />Historic Record Study Area. The summary report will be submitted to CDMG for review. Upon <br />completion of the fmal vegetation sampling (third year), a revision application will be submitted <br />which includes a final report that details the results of all historic record vegetation sampling and <br />• estblishes revegetation success standazds based on the values of the historic record. <br />Revegetation success criteria for reclaimed and revegetated lands at the West Elk Mine aze <br />presented in Table 41. When monitored or sampled for bond or liability release, vegetation <br />sampling will employ quantitative methods previously accepted by CDMG. Timing of all sampling <br />will be consistent with plant anthesis and/or maximum biomass development. Vegetation sampling <br />will be undertaken to sample adequacy for bond release vegetation sampling. A Student's test <br />comparison will be undertaken for each applicable pazameter. Revegetation will be judged <br />successful when the mean value from the revegetated area is equal or greater to 90 percent of the <br />historic record standazd with 90 percent statistical confidence for the pazameters of total vegetation <br />cover and total herbaceous production. Species composition will be judged successful if the <br />revegetated azea meets the standazd. Woody plant density will be judged successful if the woody <br />plant density within the wildlife shrub clusters is equal or greater to 90 percent of the numerical <br />standazd with 90 percent statistical confidence. <br />The Historic Records Study Area has been fenced to restrict access to domestic livestock and will <br />remain fenced until revegetation success standazds have been established. Weeds will be managed <br />in accordance with the approved Weed Control Plan. The Historic Records Study Area site was <br />chosen in an azea which is partially permitted for an Upper Refuse Disposal Pile. MCC will <br />maintain the Historic Record Study Area in its current state for the time period required to acquire <br />the necessary historic record vegetation information. The location of the Historic Record Study <br />area is shown on Map 53. <br />• <br />Revised Nw. 1996 PR07; Revised Feb. 2000 TR90: Rev. Apri11006 PR70 <br />1.05-69 <br />