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I I I I I I I I I I I I I I I I I I I Geotechnical Engineering Investigation B. Monitoring Program We recommend that a groundwater and seepage monitoring program be implemented in 1995 when the spring runoff occurs. The monitoring program should consist of measuring water levels in all piezometers. In addition water flow from the interceptor drains should also be measured, if any is observed. A table for recording water levels is enclosed, in Appendix F, as a suggested form to tabulate the readings. We suggest that the piezometers and Parshall flumes be read on a daily basis for reservoir gage height above 64 feet. Below gage heights of 64 feet, we suggest readings on a twice a week basis. The daily readings above gage height 64 feet will allow continuous assessment of the embankment. The monitoring program should be implemented for one (1) reservoir filling and emptying cycle to correlate piezometer and flow responses to gage height elevations and the theoretical seepage analyses. Depending on the elevation of the phreatic surface and flow from the drains, future phases of mitigation measures might require implementing a trench drainage system near the areas of seepage along the downstream face, an abutment grouting program, or other fonn of cutoff. The stability of the embankment is decreased by high phreatic surface elevations within the dam. Our stability analyses have given us infonnation on the levels that begin to cause concern about the dam stability. In the table that follows we have listed the limiting values of the water levels in the piezometers. Readings of "depth-to-water" less than those outlined in the table implies that the phreatic surface is too high and the embankment's safety factors are below minimum recommended values. Limiting Depth Va1Il~ofthe~hreatkSurfac~ Below Piezometer.LOcatioo". . Piezometer No. CE-l CE-2 CA-l B-1 B-2 B-3 B-3A B-4 30 30 30 30 25 18 20 25 Continental Dam Page 19