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1 2-9 During the grouting program, coring was done in holes adjacent to previously grouted holes. In Boring C-8, a core was removed from near Elevation 8860 which showed relatively coarse gravel encased in a matrix of grout. Sampling of the gravel without grout would have been diffi- cult. This observation indicated that such soils exist beneath the downstream toe of the dam. The difficulty in sampling because of coarse particles in the alluvial soils further supports the contention that highly permeable, coarse materials exist beneath the downstream portion of the dam. The flow paths developed from the piezometer readings and discussed in Chapter 4 also support this contention. I Soil Samples Thin-walled tube samples were obtained from the grout borings for pur- poses of laboratory soil testing to provide input to the stability analysis. The borings were drilled with a roller -bit using water. Casing was advanced with the boring. The sampling tubes were pushed ahead of the casing. Sampling efforts were concentrated at the depths corresponding to the bottom of the dam fill and within the alluvial soils below the dam fill. Table 1 lists the samples which were taken and attempted in this effort As indicated in the table, many of the attempts to take samples were unsuccessful. In some cases, no sample recovery was obtained. In other. -cases, the sampling tube bent when it ........_ ... .. }p�M wvw .Yk.:� ♦ _. 5...:. .esFy �...,pa y, ..r ,: �,.. - was pushed, generally due to gravel and cobble size rock fragments in the soil. From the samples which were obtained, laboratory test samples were selected as discussed in Section 2.3. The difficulty in sampling because of coarse particles in the alluvial soils further supports the contention that highly permeable, coarse materials exist beneath the downstream portion of the dam. The flow paths developed from the piezometer readings and discussed in Chapter 4 also support this contention. I