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1 <br />1 <br />2. Mois ,r Cnnt nt: The moisture content of selected soil samples was established in accordance <br />' with the ASTM D 2216 test method. Individual values are summarized on Table C-1. <br />3. Sieve Analvsgs: Grain size distribution tests were performed on representative samples of the <br />' natural soils to assist in their classification. Sieve analysis was performed on that portion of the <br />sample retained on the No. 200 sieve in accordance with the ASTM D 422 test method. The <br />percent passing the No. 200 sieve for the random fill(RF-I) material was 17 percent. The percent <br />' passing the No. 200 sieve for the tailing ranged between 7 and 33 percent. Results for all <br />samples subjected to sieve analysis are summarized on Table C-2 and are presented in greater <br />detail on the accompanying grain size distribution plots,vhich can be found in Appendix D. <br />' 4. Hvdrometer AnalYcis: Hydrometer analyses were conducted on several samples of the tailing <br />that were subjected to sieve analysis. This test quantifies the percentages of silt and clay that <br />pass through the No. 200 mesh sieve. Results are shown on the detailed grain size distribution <br />t test reports for the samples that were tested. <br />5. In Situ Dencity: Laboratory measurements were made on hand drive and Shelby samples to <br />' determine the in situ density and moisture content. Test results are presented on Table C-2. <br />6, tvtoict~ ,r -Density Relationship: A laboratory compaction test was completed to establish the <br />' maximum dry density versus moisture content for potential construction materials. Material used <br />for the compaction test was composed of the sample obtained from sample location S-4 located <br />within the proposed tailing pond expansion area. The compaction tests were performed in <br />' accordance ,vith ASTM D 698-91 test method D (Standard Proctor). The results of these tests <br />are summarized in Table C-2. <br />' 7. Time Consolidation Testing: Time consolidation tests ,were performed on select undisturbed <br />specimens representative of the existing tailing. This laboratory procedure involves applying a <br />step-wise increasing load to a soil specimen inundated with water and observing the resultant <br />change in specimen thicimess with time. Analysis of the recorded data provides the engineering <br />parameters necessary to assess the time-dependent consolidation behavior of soils in response <br />to changes m their effective stress state. Such parameters include, among others, maximum past <br />pressure or preconsolidation pressure (PP), compression index (C~, and recompression index (C,). <br />Typically, soils will compress or consolidate under increased load and then rebound once the <br />load is removed. However, this rebound usually only recovers a fraction of the initial <br />compression. If the soil is then reloaded, it exhibits a much stiffer response until the previous <br />' maximum load is exceeded. That previous maximum effective stress is defined as the <br />preconsolidation pressure. Sotls ,which exist in the field under stresses less than their <br />preconsolidation pressure are considered to be overconsolidated, and those whose current <br /> effective overburden stress equals their preconsolidation pressure are considered normally <br />' consolidated. The behavior of an overconsolidated soil in response to an increase in effective <br /> stress to a stress level that does not exceed the maximum past pressure is represented by the <br /> recompression index, and it results in a relatively smaller amount of compression. The behavior <br />' of a normally consolidated soil in response to an increase in effective stress (or the behavior of <br /> an overconsolidated soil in response to a stress in excess of its preconsolidation pressure) is <br /> represented by the compression index of the soil, and it results in a relatively larger compression. <br />1 I <br /> ndividual test data sheets (Appendix D) depict the consolidation behavior of the material. The <br /> decrease in void ratio ,with increasing effective stress illustrates compression of the soils. The <br />' flatter portions of the curves show recompression of the soils within the overconsolidated range, <br />and the steeper portions show the relatively larger amounts of compression associated with <br /> <br />