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0 STANDARD PROVISIONS AND REPORTING REQUIREMENTS September 1993 FOR WASTE DISCHARGE REQUIREMENTS FOR DISCHARGES REGULATED BY CHAPTER 15 AND/OR PART 258 -11- taking more than four samples per Monitoring Point, based upon past monitoring results. The ANOVA shall be carried out at the 95% confidence level. Following the ANOVA, the data from each downgradient Monitoring Point shall be tested at a 99% confidence level against the pooled background data. If these multiple comparisons cause the Null Hypothesis (i.e., that there is no release) to be rejected at any Monitoring Point, the Discharger shall conclude that a release is tentatively indicated for that parameter or constituent. C. The Method of Proportions shall be used if the "combined data set"—the data from a given Monitoring Point in combination with the data from the Background Monitoring Points—has between 50% and 90% of the data below the MDL for the constituent or parameter in question. This method requires— i. at least nine downgradient data points per Monitoring Point per Reporting Period, ii. at least thirty data points in the combined data set, and iii. that n * P > 5 [where n is the number of data points in the combined data set and P is the proportion of the combined set that equals or exceeds the MDL]. Therefore, the Discharger shall anticipate the number of samples required,based upon past monitoring results. The test shall be carried out at the 99% confidence level. If the analysis results in rejection of the Null Hypothesis [i.e., that there is no release], the Discharger shall conclude that a release is tentatively indicated for that constituent or parameter. 2. The Discharger shall use the following non-statistical method for the VOCwaterand V0CSp9 Monitoring Parameters and for all Constituents of Concern which are not amenable to the statistical tests above (i.e., less than 10% of the data from background samples equal or exceed their respective MDL). Each qualifying constituent at a Monitoring Point shall be determined based on either— (1) the data from a single sample for that constituent, taken during that Reporting Period from that Monitoring Point, or (2) (where several independent samples have been analyzed for that constituent at a given Monitoring Point) the data from the sample which contains the largest number of qualifying constituents. Background shall be represented by the data from all samples taken from Background Monitoring Points during that Reporting Period (at least one sample from each Background Monitoring Point). The method shall be implemented as follows: