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I <br />I <br />V <br />11 <br />To <br />4-4 <br />Some cement grout was intercepted in core runs immediately above and within <br />the rock in holes G-6 and G-8. This would indicate that, in some instances, <br />the injected grout can travel up to 30 feet through the rock fractures and <br />through the coarse material which lies above the rock at some locations. The <br />very large grout takes in some of the borings also suggest that the grout must <br />be traveling relatively long distances in some cases. <br />The zones of higher grout take were, in the alluvium, generally located <br />Immediately downstream from the dam cutoff, as indicated in Figure 7 for grout <br />boring G-5. Although sampling during drilling in these zones was generally <br />unsuccessful, the first core run in boring G-8 recovered gravel and fragments <br />of cobbles from approximately 105 feet which were surrounded by grout. It is <br />believed that zones of very high grout take consisted of relatively clean <br />coarse gravels and cobbles of high porosity. Such zones were observed during <br />the construction of the dam cutoff in 1974 as, indicated in the daily reports <br />from dam construction. Difficulty in obtaining alluvium samples adds further <br />evidence of such conditions. <br />Zones of grout take occurred at unexpectedly high.elevations; in - the dam,.. up <br />within the dam fill, as shows in Figure 6. One particularly notable instance <br />of this was hole G-7, where grout was placed within 62 to .66 feet of the`dam <br />crest. At this location, a total of 38 bags were placed over a 4 foot <br />interval. Since this interval lies within the dam core, which should consist <br />of relatively impervious fill, this take volume was unexpectedly high. This <br />zone was also injected with red dye (Rhodamine) prior to grouting, and a show <br />of dye occurred in the tailings pond upstream immediately from the grout hole <br />after injection of 350 gallons of dye. The hole was then grouted. Other <br />intervals of significant grout take within the dam core are indicated in <br />Figure 6. Figure 6 also shows intervals in several grout borings where a loss <br />of circulation was observed during drilling through the dam core. <br />O N" <br />