In order to prevent or minimize thermal pollution from the operation of a nuclear power plant, cooling lakes are commonly used to allow the heat from the plant to dissipate through a natural process. At one location, the dikes for the lake were constructed on a relatively pervious ground where water seepage is possible. Such seepage can cause a loss of water as well as become a nuisance to the surrounding area. As a remedy, pumps may be installed on the downstream slope to pump back the water to the cooling lake as shown in Fig. 1. Based on a theoretical seepage model and soil data from the site, the flow of water is estimated for simplicity, Q = 100 gal/min or Q2 = 120 gal/min., with relative likelihoods of 8 to 1. There are two pump system capacities that the engineer may order, namely, pump system A with 100 gal/min or pump system B with 120 gal/min which cost 19 and 24 units (1 unit $100) respectively. If pump system A is insufficient, an additional small pump system C with 26 gal/min will be ordered and the overall additional expense, including inconvenience and temporary disruption of performance is estimated t be 9 units. Over the expected service period, the total operational (OMR) cost, = including maintenance and repair costs, discounted to present values are, 23, 26 and 6 units for pump systems,B A and C respectively. Two units of the OMR cost of pump B could be discounted if the flow of Q is actually 100 gal/min. Another feasible alternative is to install a barrier of bentonite seal beneath the upstream end of the embankment. The total material and installation cost of the seal will be 39 units and there are negligible maintenance costs over the years. Draw the decision tree for this practical problem showing clearly the costs associated with the costs associated with each path of the decision tree. Indicate which pump should be chosen for minimum loss. Cooling Lake Embankment Pump System Bentonite Seal Figure Cross-section of embankment 1