Whenever any person, company, or corporation, municipal or private, shall undertake to secure any land or easement therein needed in connection with a work of river and harbor improvement duly authorized by Congress, for the purpose of conveying the same to the United States free of cost, or for the purpose of constructing, maintaining, and operating locks, dry docks, or other works to be conveyed to the United States free of cost, and of constructing, maintaining and operating dams for use in connection therewith, and shall be unable for any reason to obtain the same by purchase and acquire a valid title thereto, the Secretary of the Army may, in his discretion, cause proceedings to be instituted in the name of the United States for the acquirement by condemnation of said land or easement, and it shall be the duty of the Attorney General of the United States to institute and conduct such proceedings upon the request of the Secretary of the Army: , That all expenses of said proceedings and any award that may be made thereunder shall be paid by the said person, company, or corporation, to secure which payment the Secretary of the Army may require the said person, company, or corporation to execute a proper bond in such amount as he may deem necessary before said proceedings are commenced.Provided