60 STAT.] 79TH CONG., 2D SESS.-CH. 251-MAY 13, 1946 To insure compliance with this section, the Administrator shall pre- scribe such project sponsorship requirements, consistent with the terms of this Act, as he may deem necessary. Among other steps to insure such compliance the Administrator is authorized to enter into contracts with public agencies, on behalf of the United States. GRANT AGREEMENTS SEO. 12. Upon approving a project the Administrator, on behalf of the United States, shall transmit to the sponsor or sponsors of the project an offer to pay the United States share -f the allowable project costs of such project. Any such offer shall be made upon such terms, and subject to such conditions, as the Administrator may deem necessary to meet the requirements of this Act and the regula- tions prescribed thereunder. Each such offer shall state a definite amount as the maximum obligation of the United States payable from funds appropriated under authority of this Act, and shall stipulate the obligations to be assumed by the sponsor or sponsors of the project. If and when any such offer is accepted in writing by the sponsor or sponsors to which it is made, such offer and acceptance shall comprise a grant agreement constituting an obligation of the United States and of the sponsor or sponsors so accepting, and there- after the amount stated in the accepted offer as the maximum obliga- tion of the United States under such grant agreement shall not be increased. Unless and until such a grant agreement has been executed with respect to a project, the United States shall not pay, nor be obli- gated to pay, any portion of the project costs which have been or may be incurred in carrying out that project. ALLOWABLE PROJECT COSTS SEC. 13. Except as provided in section 14, the United States shall not pay, or be obligated to pay, from amounts appropriated to carry out the provisions of this Act, any portion of a project cost incurred in carrying out a project unless the Administrator has first deter- mined that such cost is allowable. A project cost shall be allowable if- (1) it was a necessary cost incurred in accomplishing airport development in conformity with approved plans and specifica- tions for an approved project and with the terms and conditions of the grant agreement entered into in connection with such project; (2) it was incurred subsequent to the execution of the grant agreement with respect to the project, and in connection with airport development accomplished under such project after the execution of such grant agreement: Provided,however, That the allowable costs of a project may include any necessary costs of formulating the project (including those of field surveys and the preparation of plans and specifications, including costs of acquir- ing land or interests therein or easements through or other inter- ests in air space, and including any necessary administrative or other incidental costs incurred by the sponsor specifically in con- nection with the accomplishment of the project, which would not have been incurred otherwise) which were incurred subsequent to the enactment of this Act; and (3) it is reasonable in amount, in the opinion of the Admin- istrator: Provided,That if the Administrator determines that a project cost is unreasonable in amount, he shall allow, as an allow- able project cost under this section, only such amount of such 80634-47-PT . --- 12 Offer to pay U. S. share. Conformity with approved plans. Incurrence after ex- ecution of grant anree- ment. Reasonable amount. 177 Prescribed require- ments.