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I I I I I I I I I I I I I I I I I I I The proposed proj ect could be scaled down to 1,200 acre-feet, but enlargement would be costly. If the 1,200 acre-foot reservoir were constructed, with future expansion in mind, the outlet works would initially be designed to accommodate the increased earth loads, as well as the increased length for the enlargement. The new spillway would be the most difficult to accommodate. With a lower dam height, the spillway could still be a combination grass-lined channel for the emergency spillway with a service spillway to handle lower flows. If the dam was then enlarged, a new emergency spillway concept would have to be investigated. One possibility would be the construction of a baffled~ apron drop spillway in the emergency channel to accommodate the additional 25-feet of head. The intake to the service spillway would also have to be raised to the elevation of the enlarged dam. The dam would be enlarged by adding additional fill to the downstream face of the dam. The addition of 25 feet of embankment to the smaller dam doubles the storage capacity. TABLE 5.1 - Reservoir Area Capacity Relationship ELEVATION (MSL) AREA (ACr'es) CAPACITY (AF) 7930 7940 7950 7960 7970 7980 7990 8000 8010 8020 8030 8040 8050 8060 .05 1.72 3.25 5.15 8.97 12.76 17.86 20.75 35.95 47.74 62.77 73.27 87.52 105.5 -0- 6.9 31. 73 73.75 144.37 253.03 406 . 13 621.68 927.68 1346.13 1896.18 2573.88 3377 .83 4343.00 After the first phase of the dam is constructed and the reservoir filled, the original borrow areas in the reservoir area may not be available for future use. This would require alternate borrow areas for the additional construction. Depending on the location, borrow sites may 5-8