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<br />I <br />I' <br />I <br />I <br />I <br />I <br />J <br />I <br />I <br />I' <br />I <br />I <br />I <br />I' <br />I <br />I <br />I' <br />. <br />.' <br /> <br />4. The left abutment of the dam was constructed on a baked, clinker-like <br />stratum believed to be the result of burning of an underlying coal bed <br />which resulted in loss of volume and disturbance to overlying bedrock <br />layers. Permeability of this stratum was not measurable, but is believed <br />to be very high, in the range of 1 cm/sec to 1 x 10.2 cm/sec. The <br />measured permeability of the rock underlying the baked, clinker-like <br />stratum ranges from 2 x 10-4 cm/sec to 5 x 10.3 cm/sec. <br /> <br />5. In the right abutment, a zone of crushed or sheared shale was observed at <br />a depth of approximately 24 to 32 feet in test hole WCC-2. Measured <br />permeabilities in the right abutment range from 4 x 10.3 cm/sec to 4 x 10'. <br />cm/sec with typical values between 4 x 10.3 cm/sec and 2 x 10-4 cm/sec. <br /> <br />6. The embankment soil is class'ified as a clayey sand. The material shows <br />no signs of dispersive tendencies and,~ppears to have been generally well <br />compacted during pl<lcement._. <br />""- ----.., <br /> <br />7. The results of the geophysical survey are inconclusive with respect to <br />seepage, as a [,esult of the reservoir having been drawn down at the time <br />of our survey,-However, three areas were identified as potential seepage <br />areas. .These areas are .!1~ar coordinates 50N, 140E, along the east and <br />west ends of 200N, 'and along the east end of ON, 50N, and 200N. <br /> <br />", <br /> <br />8. PFiorto. completion of the 1992 temporary repairs extensive seepage was <br />j" . t, <br />/ nofe,(fdownstream of the dam from the left and right abutments (Norfleet, <br />1992). Left abutment seepage nearest the dam is located along the groin <br />,at elevation 8060 feet beneath the rockfill and is generally heard rather <br />,.,thim ,seen. Seepage is typically heard at this location when the reservoir <br />is'at or above elevation 8071 to 8072 feet (gage height 51 to 54 feet). <br />Right abutment seepage nearest the dam is located along the groin at <br />elevation 8022 feet. Seepage at this location decreased significantly when <br />the reservoir was drawn down below the 1992 right abutment sinkholes <br />shown on Figure 1-4. <br /> <br />23067/Rl.6 09-03-93(3:21pm)/RPT <br /> <br />6-3 <br />