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New Horizon Mine TR-58 <br />Adequacy Review <br />07 April 2009 <br />Page 4 of 4 <br />in late May/Early June immediately prior to 1St cut harvest of the reclaimed <br />fields and prior to any growing season livestock grazing in the reference <br />area. <br />8. On page (e)-19, as a part of the proposed "quality standard", the narrative <br />indicates that "no more than 3% relative production will be comprised of county <br />listed noxious species". The Division's policy is that noxious species are not <br />allowed to contribute to achievement of cover or production success standards. <br />Please amend the wording to clarify that county listed noxious species will <br />not be counted toward the success standard for cover or production. <br />9. On Map 2.05.4(2)(e)-1, the soil type mapping does not extend far enough north to <br />include the entirety of the mine disturbance. A small area immediately to the <br />north and northwest of the pit location in the map photo is located outside of the <br />soil mapping boundary. Please revise Map 2.05.4(2)(e)-1 to include all areas of <br />mine disturbance within the soil mapping boundary. <br />10. Based on review of the 2007 reference area sampling data, the Division notes that <br />the production sample fell substantially short of the number of observations <br />required for statistical adequacy. For success demonstration purposes, failure to <br />meet statistical adequacy would necessitate use of the more stringent "reverse <br />null" demonstration approach, and the relatively wide confidence interval <br />associated with a high sample variance could be problematic. The high variance <br />within the reference area is likely attributable to variable production zones within <br />the reference site, reflecting differing soil types and non-uniform irrigation water <br />distribution. Sample stratification, in which the area is divided into two or more <br />zones or strata based on visual production assessment prior to sampling, may be <br />have merit in this situation. If such an approach is utilized, sample adequacy <br />would need to be demonstrated within individual strata, and use of area weighted <br />sample statistics would be necessary to calculate sample mean and sample <br />standard deviation for the entire reference area. <br />Please do not hesitate to contact me with any questions that may arise as you prepare <br />your response to this review. <br />Sincerely, <br />G?tiua.?° <br />Marcia L. Talvitie, P.E. <br />Environmental Protection Specialist <br />xc: Greg and Lewicki & Associates <br />DRMS Files <br />4