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ATTACHMENT D SAMPLING METHODOLOGY AND CALCULATIONS <br />SEg = standard error for waste component g <br />The overall waste composition estimates were calculated by performing a weighted average <br />across the relevant sampling groups. For the transfer station substream, the estimates were <br />calculated by performing a weighted average based on the tonnage disposed by each <br />transfer station. For the commercial substream, the estimates were calculated by performing <br />a weighted average based on the tonnage hauled by each vehicle type. For the self -haul <br />substream, the estimates were calculated by multiplying total self -haul mixed loads by the <br />waste component percentages from mixed loads from the 2001 sampling study. To that was <br />added the tonnages disposed by 18 pure loads. Component percentages were then <br />calculated based on the tons of mixed material and pure loads for each component. <br />The weighting percentages that were used to perform the composition calculations are listed <br />in Exhibit D -2. This information was obtained from scale records at the West Hawai i <br />Landfill for FY 2008. The composition estimates for both the overall waste stream and each <br />substream were applied to the relevant tonnages to estimate the amount of waste disposed <br />for each component category. <br />The weighted average for an overall composition estimate is performed as follows: <br />where: <br />Oi= (Pi *rjl) +(p, *r,,) +(p3 *r;s)+ <br />Oj = overall composition estimate for component j <br />p = the production of tonnage contributed by the noted sample group <br />r = ratio of component weight to total waste weight in the noted sample group <br />for j =Itom <br />where m = number of components <br />APPX B WASTE COMPOSITION REPORT 121709.DOC D -5 <br />