There are authorized to be appropriated, such sums as may be necessary, but not to exceed $600,000,000, to carry out the provisions of this subchapter and, effective October 1, 1986, not to exceed an additional $600,000,000: Provided, That the Secretary shall advise the Congress promptly on the receipt of each proposal referred to in section 422c of this title, and no contract shall become effective until appropriated funds are available to initiate the specific proposal covered by each contract. All such appropriations shall remain available until expended and shall, insofar as they are used to finance loans made under this subchapter, be reimbursable in the manner hereinabove provided. Not more than 20 percent of the total amount of additional funds authorized to be appropriated effective October 1, 1986, for loans and grants pursuant to this subchapter shall be for projects in any single State: Provided, That beginning five years after October 27, 1986, the Secretary is authorized to waive the 20 percent limitation for loans and grants which meet the purposes set forth in section 422a of this title: Provided further, That the decision of the Secretary to waive the limitation shall be submitted to the Congress together with the project proposal pursuant to section 422d(c) of this title and shall become effective only if the Congress has not, within 60 legislative days, passed a joint resolution of disapproval for such a waiver.