The U.S. Department of Interior is planning to build a dam and construct a hydroelectric power plant. In addition to producing electric? power, this project will provide flood? control, irrigation, and recreational benefits. The estimated benefits and costs expected to be derived from the three alternatives under consideration are listed as follows in the table below. The interest rate is? 5%, and the life of each project is estimated to be 40 years.

Initial investment Annual recurring benefits Annual recurring costs Salvage value $100 M $20 M $8 M Design Alternatives $160 M $220 M $40 M $60 M $18 M $25 M