5. The earth dam shown in Figure 1 below is to be built on a gravelly sand with silt and cobbles. This dam will extend a distance of 850 ft perpendicular to the cross-section. To reduce the flow rate through these soils, a concrete cutoff wall will be built as shown in the figure. (a) Using the flow net provided in Figure 1, calculate total seepage loss, Q (in ft3/day) underneath the dam. [4 points] (b) Identify and mark the area in the flow net that has the greatest hydraulic gradient. [1 point] el. 701.5 ft el. 616.0 ft Reservoir 40 ft Earth dam (assume impervious) Gravelly sand with silt and cobbles 8ft x-52 ft concrete cutoff wall k=6x10cm/s el. 503.7 ft Stiff clay (assume impervious) Figure 1. A Flow Net for Problem 1 el. 620.0 ft