Evaluation of the adequacy of the number of landfill excavated samples by the central limit theorem

The adequacy of the number of samples extracted using the central limit theorem (CLT) was evaluated for 11 excavation waste items at the S landfill site in the Seoul metropolitan area of Korea. The relative error range, which is the error-capable range for the estimated average value for each analyzed item, was the largest at 22.2% hemicellulose, 19.9% sulfur, and 14.7% cellulose, and the smallest at 3.4% combustibility. At the 95% reliability level and 10% relative error range, the number of samples of N, S, hemicellulose, and cellulose was insufficient, and at the 5% relative error range, the number of samples was insufficient for all items, except for moisture and combustibility. It was determined that it would be practically impossible to secure excavated samples below 3% error range. The results of this study show that CLT is useful for evaluating the reliability of the results of landfill collection sample analysis and determining the appropriate number of samples.