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Site Characterization and So,..[emediatiaa Plat: 7500 1'Vest Eleventh Street, Tract, -.A. Page 24 <br /> out will be significantly greater than the estimated number of soil samples <br /> required to perform a statistically meaningful analysis of the mean and <br /> standard deviation of the contaminant content of the treated soil at the desired <br /> level of confidence Based on the preliminary estimate of I 1 samples derived <br /> above, for planning purposes, a minimum of 30 sub-areas is recommended. <br /> However, the actual number of sub-areas into which the spread soil is to be <br /> divided may be adjusted to comply with field conditions or with any revised <br /> estimate or calculation of the number of sampling points required that may be <br /> developed as the work progresses. <br /> The specific sub-areas to be sampled during any round of sampling and <br /> ' analysis of the treated soil will be determined randomly using a random <br /> number generator to select from the range of identifying numbers assigned to <br /> the sub-areas. Within the selected sub-areas, discrete sampling points will be <br /> arbitrarily selected by the field technician with no consideration for the <br /> appearance, olfactory properties or any other characteristic of the soil therein. <br /> >: The precise number of samples required to make the statistical determination at <br /> the specified degree of confidence will depend upon the data obtained from <br /> analysis of the samples that are obtained in the field. To check that the <br /> estimated number of samples is sufficient, I 1 samples will be taken during the <br /> first round of sampling from the spread of treated soil. The results obtained <br /> from that round of sampling will be used in a manner similar to that employed <br /> =' above but using actual values of mean contaminant concentration and their <br /> standard deviation to check that I 1 samples is sufficient to comply with the <br /> stated statistical requirements. If it is not, a new estimate of the number of <br /> samples required will be made and additional samples gathered (from <br /> randomly selected sub-areas of the soil spread not previously sampled) until <br /> sufficient number have been analyzed- Conversely, if the field data shows that <br /> the number of samples may be decreased while maintaining the statistical <br /> Lj confidence of the evaluation as to the cleanliness of the treated soil, the number <br /> F.-, of samples gathered in any subsequent sampling rounds will be adjusted <br /> i downward, as appropriate- <br /> F- When the samples of the treated soil have been analyzed, the results will be <br /> 4. � reviewed to determine whether or not they show that the cleanup criteria have <br /> 1 been met with sufficient statistical confidence. If they have not, the spread soil <br /> will be subjected to further treatment and will then be re-sampled. <br /> Sampling Procedure <br /> iThe procedure for recovery of specimens of the treated soil from the randomly <br /> selected sampling Iocations will be as described below. <br /> At each sampling point a small pit will be excavated so that its bottom is at <br /> least 3 in. below the surface of the spread soil. A clean, 2-in_ diameter by 6-in. <br /> sic <br />