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. SENT BY~ B- 4-93 ;12~43PM ~ CANONIE FNGL.E1900D-~ <br />• <br />5.0 . IQENTIFY STATISTICALLY SIbNIFlCANT IMPACTS <br />Water quality dots upgradient of the Henderson MITI site (HW-1) were statistically <br />compared to downgradient water quallry data (HW-4) for regulated analytc~s. The <br />comparison Identlfled no statistical difference between the two groups of samples. <br />Therefore, there Is no significant Impact of the Henderson Mill site for cadmium, <br />copper, iron, lead, manganese or zlno. Comparisons were not made for mercury, <br />sulfate or cyanide because upgradient analytical data were not available. <br />U.S. Environmental Protection Agency IEPA)~ecommended methods (EPA, 1989) <br />were used for ffie statistical comparisons. For cadmium, copper, lead, manganese and <br />zinc, more then 50 percent of reported analytical values were nondetects; therefore, <br />the test of proportions was used to identify statistical significance. For iron, loss than <br />15 percent of reported analytical values were nondetects; therefore, analysis of <br />variance (ANOVA) was used to identify statistical signfficence. The statistical ;~nalysls <br />for iron included natural logarithm transformation of the data and two-way ,4NOVA <br />to account for nonparamatric data end seasonal variation in the data, reaptiotively. <br />Details of the atatlsttaal analysis are included in Appendix B. <br />;f10/19 <br />5 <br />r~nw,.o-,HVa+~kurr uw... uu~ <br />