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Table 4 Transient Boundary Conditions for Upstream Face of Dam <br /> <br />Date Reservoir Water <br />Elevation feet <br />7/18/06 7329.2 <br />7/21 /O6 7329.2 <br />7/25/06 7329.2 <br />7/28/06 7329.0 <br />8/2/06 7328.5 <br />8/4/06 7327.5 <br />8/11 /06 7322.0 <br />8/15/06 7316.2 <br />8/28/06 7280.7 <br />9/11 /06 7280.7 <br />9/28/06 7286.2 <br />It should be noted that the boundary node is set to a flux of zero if the function head is less <br />than the elevation of the node. This is the same as imposing a potential seepage face review <br />node when the water level drops below a given point on the face. <br />• There is no infiltration on the ground surface (other than from the water in the reservoir) or <br />leakage from the 12" cast iron pipe. <br />8.1.3.2 Calibration Using Field Performance (Existing Conditions) <br />The model was calibrated by adjusting permeability values to match as closely as possible the <br />computed with the measured pore-water pressures, assuming that the measured porewater pressures <br />had reached steady state. The results of the seepage analysis under existing conditions are interpreted <br />in terms of total heads at the piezometer tip locations at Cross-Sections B and C, and are discussed <br />subsequently. <br />The measured values used in the calibration were read on July 21, 2006. These values were used <br />because the piezometer readings appear to have reached steady state by this date and the reservoir <br />had been at or near the spillway level (Elevation 7,330.2) for at least one month. <br />Table 5 summarizes the results of the steady-state seepage analysis in terms of the computed total <br />head at the piezometer tip locations. Table 5 also includes a comparison between the computed and <br />measured total heads at the piezometer tip locations at Cross-Sections B and C. The comparison is <br />made by monitoring the closest node in the model to the actual piezometer tip location. It can be seen <br />from Table 5 that the computed and measured total heads are in close agreement, generally within <br />about 1.2 feet at Cross-Section B and 6.2 feet at Cross-Section C. <br />P:\Mpls\06 CO\26\0626067\WorkFi]es\DesignReport\FINAL\DesignReportFINAL.doc 22 <br />