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APPENDIX D <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 a large proportion of the monitoring observations should fall with a high <br /> probability. The proportion ofthe population included isreferred to8s the coverage. The <br /> probability with which the tolerance interval includes the proportion of the population is referred to <br /> oethe tolerance coefficient. <br /> Consistent with USEPA and state recommendations, Sanitas (computer program utilized) uses a <br /> S5percent coverage and 95percent tolerance coefficient. The upper 95percent tolerance limit <br /> will contain at least 95 percent of the distribution of observations from background well data. The <br /> tU|8[8OCe interval D1S1hDd is described iOthe following dOCUOO8OtS: <br /> — <br /> Introduction t0Statistical Quality Control, D.C. Montgomery. John Wiley Publishing, <br /> New York. 1S85. <br /> — <br /> Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities, Interim Final <br /> Guidance Document, USEPA. USEPA/530-GVV-09-028. February 1989. <br /> — <br /> Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities, Addendum to <br /> Interim Final Guidance, UGEPA. USEP/V530-R-93-003. July 1992. <br /> 8anitaSimused tmcalculate tolerance limits for the Harney Lane Sanitary Landfill. Ganitaeiaa <br /> statistical software program developed byIntelligent Decision Technologies, Ltd. U[}T\. It is <br /> specifically designed to evaluate water quality monitoring data for landfills. @anitonperforms all <br /> pre- and post-analysis tests required eothat the data do not violate size and distribution <br /> assumptions ofthe relevant statistical analysis. <br /> Within SanitGS. the USEPAStandards are used toevaluate all data. <br /> Parametric Tolerance Limit <br /> When conducting the tolerance interval method. 8anitae automatically evaluates the distribution <br /> of the data. 8anit@s 88|eCtS the {}Oe0ioieOt of Variation test for OO[rna|ity to be applied. S8nitaS <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 /\iƒuhison'o Method. Calculation of the tolerance limit fo||ovva by using the adjusted values. <br /> Harney Lane Sanitary Landfill [)'1 Department mPublic Works/Solid Waste <br /> e"^Semester and Annual uo1zGroundwater Monitoring Report County mSan Joaquin-January oo.001u <br />