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1 ' San Luis Mine Phase II. Raise 2 Design Repon ' drilled adjacent to CPT probes at the three locations to provide tailings samples for positive identification and verification of material types. The continuous tailings samples were obtained through the use of a split spoon sampler and penetration test data was also collected for correlation ' to the CPT data. ' In order to collect a larger sample volume, a 3-inch O.D. split spoon sampler rather than the Standard Penetration Test (SPT) 2-inch sampler (ASTM D-1586) was utilized. Research on the mechanics of the SPT sampling process by Schmertmann (1979a and 1979b) indicated that the ' increase in SPT blow counts associated with the use of the larger diameter sampler would be offset by not using liner sleeves in the sampler and the blow count data obtained could be considered ' equivalent to the SPT N-value. The sampler was driven in 24 increments using an automatic trip hammer system. The sampling rods consisted of pin-connected hex rods. An integrated electronic energy calibration system was incorporated into the sampling program to calculate the actual energy delivered to the sampler. This data was used to convert the raw blow ' count data (N-value) to Nom-values (blow count obtained using 60 percent of theoretical energy). The calculated energies were quite low (typically 30 to 40 percent) for the hammer system employed when compared to published results (Seed, et. a1.,1984; Skempton, 1986; and Farrar, 1991). It is ' believed that the abnormally low energy delivered to the sampler was due to the use of the pin- connected rather than threaded rods. Comparison of the corrected auger boring blow count data with the equivalent (N,)~ values derived from the CPT data indicated that the (N,)~ values for the ' . auger borings were much lower. Due to the uncertainty associated with the use of the 3-inch sampler and pin-connected rods, no further corrections or correlations were attempted with this data. The drive samples provided continuous samples of the tailings for visual classification and laboratory ' testing. The samples revealed that the tailings investigated consist primarily of the tailings sand fractions or tailings sand with thin layers of slimes (typically 1/16 to 1/2 inch thick) and occasional discrete slimes layers up to 2 ft thick, thereby cortfirming the general distribution of material types ' identified in the CPT testing program. Due to sample disturbance it was not passible to accurately determine which samples represented saturated tailings. As was the case for twinned CPT probes, ' little direct correlation between the auger borings and adjacent CPT probes was possible due to the frequent large lateral variations in material types. ' The drill logs for the auger borings are contained in Appendix B.3. Details of the laboratory testing program are presented in Section 2.5. 1 u Y 2-6 rorect o. 1