2011-02-28_REVISION - C1994082 (6)

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Yoast Mine SL-3 Phase li Bond Release Request February 2011 • Weighted mean reference area species density (no. of species per 100 sq.m.) - 1.15 s. The results of Test B are: Weighted reference area species density = 21.26 Phase II bond release block species density = 24.71 +/- 1.22 Since the Phase II bond release block value exceeds the standard, a determination of PASS is made. The Test C standard uses the Motyka similarity index to assess resemblance of the distribution of species density by lifeform for reclamation vegetation to that of the reference area. Because the average internal resemblance (i.e. between-sample similarity) of reference area species density data is often in the range of 75%, this is the Yoast mine species density similarity standard in Test C. The Motyka similarity index is: ISmo = 2c / (a + b) Where: c = the sum of the smaller of the paired species density values (for each life form) for reclaimed and Reference Areas* a = total of species density values for lifeforms of the reclaimed areas b = total of species density for the lifeforms of the Reference Areas* • *Weighted average lifeform species density using the Yoast Reference Areas (weighted as specified under Cover above). The results of Test C show the similarity of the species density by life form of the Phase II bond release block to that of the weighted reference area means was 0.71, exceeding 90 percent of the standard of 0.75 (.675) and indicating a PASS for this test. With regard to Test D, the reference area derived weighted average species density of native species is 26.4 per 100 sq.m. The cumulative number of native species in the 100 sq.m. samples for the Phase II bond release block is 60, well-exceeding 26.4 per 100 sq.m and indicating a PASS on this test. Based on all four tests of species diversity passing, species composition and diversity are demonstrated for the Phase II bond release block. References :Rohlf, F.J. and R.R. Sokal. 1969. Statistical Tables. W.H. Freeman and Company, San Francisco. .The results of the Phase II Evaluation Procedures are contained in Attachment E, Revegetation Supporting Documentation. • Water Quality - Total Suspended Solids (TSS) Monitoring Results • The Colorado Discharge Permit System (CDPS) permit has a TSS limit of 35 mg/l (monthly average) and a 70 mg/1 daily limit that can not be exceeded. Water quality statistics have 8