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AET//20-02044 - Page 17 <br /> <br /> Split-Spoon Samples (SS) <br /> <br />Standard penetration (split-spoon) samples were collected in general accordance with <br />ASTM:D1586. This method consists of driving a 2" O.D. split-barrel sampler into the in sim soil <br />with a 140-pound hammer dropped from a height of 30". The sampler is driven a total of 18, into <br />the soil. After an initial set of 6", the number of hammer blows to drive the sampler the fmal 12" <br />is known as the standard penetration resistance or N-value. <br /> <br /> Sampling Limitations <br /> <br />Unless actually observed in a sample, contacts between soil layers are estimated based on the <br />spacing of samples and the action of drilling tools. Cobbles, boulders, and other large objects <br />generally cannot be recovered from test borings, and they may be present in the ground even if <br />they are not noted on the boring logs. <br /> <br />Classification Methods <br /> <br />Soil classifications shown on the boring logs are based on the Unified Soil classification (USC) <br />system. The USC system is described in ASTM:D2487 and D2488. Where laboratory <br />classification tests (sieve analysis and Atterberg Limits) have been performed, classifications per <br />ASTM:D2487 are possible. Otherwise, soil classifications shown on the boring logs are visual- <br />manual judgments. We have attached charts (Appendix A) illustrating the USC system, the <br />descriptive terminology, and the symbols used on the boring logs. <br /> <br />The boring logs include judgments of the geological depositional origin. This judgment is <br />primarily based on observation of the soil samples, which can be limited. Observations of the <br />surrounding topography, vegetation, and development can sometimes aid this judgment. <br /> <br /> <br />