If for any reason the Department of Transportation is unable to secure any such property or rights required by the United States government for the construction and maintenance of the intracoastal waterway from the Savannah River to Cumberland Sound by voluntary agreement with the owner or owners thereof on terms and conditions satisfactory to it, the department is vested with the power to condemn the same and in so doing to employ the way, means, method, and procedure of Chapter 2 of Title 22 and Article 6 of Chapter 3 of Title 22, relating to the acquisition of property by condemnation on the part of the State of Georgia and of the United States; and in all instances any general and specific benefits to the owner or owners of such property or lands shall be offset against any damages to such property or lands. When the easement or property is thus acquired, a deed shall be executed conveying it to the United States. All easements granted under the authority of this Code section shall be approved by the State Transportation Board and shall be executed by the commissioner of transportation.