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APPENDIX <br /> STATISTICAL METHODS TO DETERMINE CONCENTRATION LIMITS <br /> Tolerance Limit Methodologies <br /> The purpose of a tolerance interval approach is to define a concentration range from background <br /> well data, within which 8 large proportion of the rDoOitO[iDQ observations should fall with @ high <br /> probability. The proportion Ofthe population included iSreferred tO@Sthe coverage. The <br /> probability with which the tolerance interval includes the proportion of the population is referred to <br /> aathe tolerance coefficient. <br /> Consistent with U@EPAand state recommendations, Sanitaa (computer program utilized) uses e <br /> S5percent coverage and S5percent tolerance coefficient. The upper S5percent tolerance limit <br /> will contain at least 95 percent of the distribution of observations from background well data. The <br /> tolerance interval method is described iOthe following documents: <br /> — <br /> Introduction to Statistical Quality Control, D.C. Montgomery. John Wiley Publishing, <br /> New York. 1SO5. <br /> — 8tGUSUC8| Analysis of Groundwater Monitoring Data at RCFA Facilities, Interim Final <br /> Guidance Document, USEPA. USEP/V530-GVV-88-028. February 1989. <br /> — <br /> Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities, Addendum to <br /> Interim Final Guidance, U8EPA. USEPA/530-Fl-93-003. July 1992. <br /> Sanitas is used to calculate tolerance limits for the Harney Lane Sanitary Landfill. Sanitosiea <br /> statistical software program developed by Intelligent Decision Technologies, Ltd. (IDT). It is <br /> specifically designed to evaluate water quality monitoring data for landfills. Ganitaaperforms all <br /> pre- and post-analysis tests required mothat the data do not violate size and distribution <br /> moaurnotiono of the relevant statistical analysis. <br /> Within Senbae. the UGEPAStandards are used toevaluate all data. <br /> Parametric Tolerance Limit <br /> When conducting the tolerance interval nlethod. Smnitae automatically evaluates the distribution <br /> ofthe data. 8anitaaselects the Coefficient ofVariation test for normality tobe applied. Ganitmo <br /> applies the parametric tolerance limit test when the background data set is found to have less <br /> than 50 percent non-detects and the background data have a normal or transformed normal <br /> distribution. If greater than 15 percent but less than 50 percent of the background data set <br /> consist of non-detect values, the mean and standard deviation of the data set is adjusted using <br /> the/\itchiaoO'S Method. Calculation Ofthe tolerance limit follows by using the adjusted values. <br /> Harney Lane Sanitary Landfill D'1 Department ofPublic Works/Solid Waste <br /> 1"Semester uo1aGroundwater Monitoring Report County ofSan Joaquin-July 1s.zn1a <br />