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Nonparametric Tolerance Limit <br /> When the background data set contains greater than 50 percent but less than 100 percent <br /> nondetect values and/or its distribution is not normal (or transformed normal), Sanitas applies the <br /> nonparametric tolerance limit method. However, this method requires a large number of samples <br /> to achieve a false positive rate of 1 percent or less, which is required by CCR Title 23, Chapter <br /> 15, Article 5 guidelines. Thus, when the alpha level was higher than 1 percent, the concentration <br /> limit was not established and data was compared to established limits in the Waste Discharge <br /> Requirements. <br /> Nonstatistical Approach <br /> ! When the background data set contains 100 percent nondetect values, Sanitas applies the <br /> nonstatistical approach. This approach takes into consideration that if historically a constituent <br /> has not been detected, any detection of that constituent would be considered an exceedence. <br /> Thus, in these situations (100 percent nondetected values), the tolerance limit is set at"detect", <br /> meaning that if a value is detected above its method detection limit,this value is an exceedence <br /> of the concentration limit. <br /> North County RCSLD_2 Public Works/Solid Waste <br /> 2nd Semester and Annual 2005 Groundwater Monitoring County of San Joaquin—January 24,2006 <br />