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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 Case No. 1 Factor of Safet 1. 929 These factors of safety generally meet the nummum safety requirements of 1.5 for static conditions and 1.2 for unusual or extreme conditions, as outlined in the Code of Colorado Regulations, lICR9,9-88 and by the Bureau of Reclamation, Design Standards, Embankment Dams, No 13, Chapter 4. B. Seepage Evaluation Method of Analyses The seepage analysis was performed using the computer program ELF developed at Harza. The program solves the hydraulic head distribution within a seepage domain and the flow problem for the same conditions. ELF program is a modified version of FRESURF written by Neuman and Witherspoon (1970). This program is a finite element procedure that uses a two-step iterative cycle to determine the location of the free surface and adjusts the size of the elements to the new location of the free surface at the end of each cycle. In the first step, the head is equal to the elevation on the free surface and the seepage surface sections. In the second step, the finite element equations are solved by imposing the rate of flow, dq = 0 across the free surface sections and by setting the rate of flow across the seepage surfaces equal to the amount calculated in the first step. At the conclusion of the first step, the location of the free surface is adjusted to satisfy the zero pressure condition. Each step calculates the head distribution within the seepage domain for a different free surface boundary condition. This procedure was modified to take advantage of the fact that the head and the stream function are solutions to similar differential equations by solving the flow problem in the first step and the head problem in the second step of the iterative cycle. Continental Dam Page 14