2009-01-02_REVISION - C1980005 - Laserfiche WebLink

Home Browse Search

c) An argument might be made that data from the 18 transects that were located within SL-3--BRB-4 parcels, could be used to demonstrate vegetation cover success for those portions of the ESCO Map 4-BRB-4 sample universe located outside of the East Wadge exclusion area. The Division has considered this, but based on our assessment of the data, it appears that the sample size of 18 would be insufficient to allow for a statistically valid demonstration of success. We performed a detailed review of the SL-3 vegetation cover data, and generated DRMS Tables 1 through 4 (enclosed), from the individual transect data presented in SL-3 Attachment E. DRMS Table 1 pertains to the Mountain Brush Reference Area, DBMS Table 2 pertains to the Sagebrush Reference Area, DRMS Table 3 pertains to the BRB-4 cover data for the twenty-four (24), transects included in the SL-3 application, and DRMS Table 4 presents cover data and statistics for the eighteen (18), BRB-4 transects located outside of the East Wadge Exclusion Area. While t-test comparisons indicate that the reclaimed area allowable herbaceous cover mean (adjusted sample mean = 28.6%) is not less than 90% of the weighted reference area herbaceous sample mean (standard = 31.9%), the test is not statistically valid pursuant to Rule 4 15 11(2 W because the minimum sample size requirement was not met. Application of the required sample adequacy formula to total vegetation cover data for the 18 transects resulted in a minimum required sample size of 23, while application of the formula to herbaceous cover data for the 18 transects resulted in a minimum required sample size of 22. In summary, our concerns regarding BRB-4 cover success demonstration are that (a), data from six transects located outside of the bond release request area were improperly included in the demonstration; (b), a major portion of the BRB-4 release request area was not included in the vegetation sample universe; and (c), sample adequacy was not achieved, when evaluated based solely on data from the 18 transects located inside the bond release request area. Please give consideration to these identified deficiencies, review the information and conclusions presented in the enclosure tables, and provide response, explanation, and proposed course of action as appropriate. Based on the information we have reviewed, it would appear that either SCC will need to revise the application to remove BRB-4 from the release request area, or the Division will issue a partial approval, with BRB-4 excluded from the approval. 2 The Division noted that in the revegetation success demonstration sections of the application, statistical sample adequacy for vegetation cover was demonstrated only for total vegetation cover, and not for herbaceous vegetation cover. This is consistent with the methods specified in Appendix 13-13 of the approved permit. However, because herbaceous vegetation cover is the basis for the cover success