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A Mr. Thomas M. Robertson 6 June 17, 1981 from the north or pond side of the east -west trending ravine and both sides of the north -south trending ravine. There is also seepage on the flatter ground surface immediately upstream from the ravines. There is a small "pipe" located on the north side of one ravine (sample point no. 12) which is flowing at a rate of approximately 4 gpm, indicating rela- tively high seepage pressures in this area. (' The piezometric map in Figure 4 is based on piezometric readings from IL both the rock and the soil (see table in figure for location of screened interval in piezometers and wells.) The piezometers downstream of the dam (sampling point 15S and 15N) indicate a higher pressure in the top of rock as compared to the overlying soil. This indicates that water is seeping upward through the rock and into the soil, and there are signi- ficant uplift pressures within the east abutment. A similar flow condi- tion is found at the toe of the dam, where pressures in the rock are higher than those in the soil (see sample point No. 3 and No. 16). These two conditions indicate that the rock is providing a significant path for seepage in the downstream toe area. It is also noted that the piezometric head of the piezometers at the toe of the dam is the same as that measured in Wells 6 and 7, which are further downstream and to the east. The fact that there is no pressure gradient between these wells may indicate that the major flow path is not along the stream channel, but rather that the major flow paths are through the abutments, primarily the east abutment. Along the crest of the dam, there is only one piezometer, which is sealed in the rock. Thus, there is no information about pressures in the natural soil and in the dam fill along the dam crest. Since the pressures within the natural soil and the dam fill may be different than those in the rock, piezometric information along the crest is very limited, and the piezometric contours which are drawn on Figure 4 in the area may not be representative of the general flow conditions under the dam. The flow paths as shown in Figure 4 can be delineated only in a general sense from the piezometric surface contours and observed exit flow conditions. The piezometric pressures indicate that flow is occurring beneath the entire length of the dam, although the relative quantities of flow at different locations are not known. Exit conditions and the trend toward higher pressures to the east at the toe of the dam indicate the potential of greater flows beneath the east abutment. 2.4 WATER QUALITY ANALYSIS Water quality can often be used as an effective tracer in assessing the source of seepage as well as help delineate the paths of seepage. Water was sampled in the tailings pond and at 12 points downstream of the Lower Tailings Dam during the period of March 9, 1981 to May 11, 1981. The parameters measured were temperature, pH, total copper, total zinc and free cyanide. Figure 5 shows the average pH and free cyanide concentrations monitored over the two month period. These two parameters are the best indicators for identifying seepage from the pond.