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RN-03 Revegetation Success <br />Page 2 <br />primary types, in the denominator (consistent with the weighted average formula for herbaceous <br />production). <br />Response: The steep mountain brush type should have been included in the weighting for both the <br />cover and production success evaluations. Note that the steep mountain brush, while not a large <br />acreage, is an important component of the premine vegetation that was disturbed by mining and <br />should be included in the weighting. Pages 34 through 40 have been revised to cover this specific <br />comment and to make the language consistent. <br />2. The narrative applicable to the acreage weighted extended reference area cover and production <br />comparisons does not make it clear that each of the primary vegetation types that would comprise <br />the area weighted standard would be sampled with sufficient intensity to meet statistical adequacy <br />and minimum sample size requirements of Rule 4.15.11. Please amend the narrative as <br />appropriate to confirm that each of the reference area community types would be sampled to <br />statistical adequacy and minimum sample size of 15 (for success demonstration using the <br />"standard null" approach or the one-sample "reverse null" approach), or a minimum sample <br />size of 30, (to allow for use of the two-sample "reverse-null" approach, if sample adequacy is not <br />achieved in one or more reference types). <br />Response: The text on page 35 has been revised to include reference to minimum sample sizes of 15 <br />and 30 for the various approaches as specified in rule 4.15.11. <br />3. For the species diversity "Alternative Test B- Total Species Density Test ". it is our understanding <br />that the "mean reference area species density " and "standard deviation "parameters employed <br />would need to be defined as "area weighted mean reference area species density " and "area <br />weighted reference area species density standard deviation ", when employed in situations where a <br />reclaimed block is being compared to a weighted average standard derived from multiple <br />reference area community types (as would be the case for reclaimed shrub grassland and mesic <br />drainage bond release blocks). If this is the case, please revise the wording to confirm. If our <br />understanding is not what was intended, please provide additional explanation to clarify and <br />justify. <br />Response: The text on pages 40-45 covering species diversity success evaluations has been modified <br />to clarify approaches in alternative tests B and D. Area weighted mean reference area species <br />density and area weighted reference area species density standard deviation language is included. <br />Also, reference is made to the appropriate reference areas for reclaimed shrub grassland and mesic <br />drainage. <br />4. Similar to Item 3, our understanding of "Alternative D - Assessment of the Presence of Native <br />Species ", is that the cumulative number of native species in the data set for a reclaimed area bond <br />release block would be compared to the area weighted reference area species density (in the case <br />of reclaimed shrub grassland or mesic drainage bond release blocks). In other words, the total <br />number of native species in a statistically adequate sample of the bond release block would need to <br />equal or exceed the weighted average number of native species per 100 sq. meters in the extended <br />reference area, based on a statistically adequate sample of each component vegetation type within <br />Seneca Coal Company • P.O. Box 670 • Hayden, Colorado 81639 <br />Telephone (970) 276-5217 • FAX (970) 276-5222