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I- I I I I I I I I I I I I I I I II II I Similarly, each point represents a combination of depth and velocity which produces a hydraulic force exactly equal to the opposing force of balance produced by the design monolith (Table 2). Using the same line of reasoning as in the analysis of slippage hazard, the area above the curve represents a high hazard under the base conditions, while the area below the curve represents less hazardous conditions. Hazard Envelope Superimposing these two curves reveals that the slippage hazard controls for low depths and high velocities, while the toppling hazard controls for greater depths (Figure 8). For example, at 2 feet of depth, slippage becomes hazardous at a velocity of 3.15 fps as discussed previously. Toppling however, occurs at a velocity of 2.22 fps. While slippage is not affected at the lower velocity, toppling is affected and therefore controls (Table 3). This results in a "hazard envelope" in which depths greater than those at a given velocity or velocities greater than those at a given depth will result in hazardous conditions. Hazard Envelope Hazard Envelope Deoth Velocitv 10 0.4 9.61 0.6 7.62 0.8 6.39 V 1.0 5.52 e 1.2 4.44 1 1.4 3.66 0 1.6 3.07 5 1.8 2.60 c 2.0 2.22 1 2.2 1.91 t 2.4 1.64 II 2.6 1.41 2.8 1.20 0 3.0 1.00 3.2 0.82 0 2 3 4 3.4 0.64 Depth 3.6 0.45 Figure 8 Table 3 -9-