11.4. A dam is to be constructed for flood control. Project costs and benefits vary with the reservoir volume as shown below. Assume a 50-year project life (plan- ning horizon = 50 years) and 4% interest. Reservoir Volume (acre-feet) 50,000 100,000 150,000 Initial Construction Costs ($) 4,500,000 5,000,000 8,000,000 Annual O&M Costs ($/year) 32,000 79,000 127,000 Annual Benefits ($/year) 317,000 761.000 1,078,000 a. Which dam size will maximize the net present value benefits? b. What is the annualized net benefit of the 150,000 acre-feet project