Ohio Rev. Code § 153.35: Plans shall be kept on file in county auditor's office.

The plans and specifications upon which the contracts are awarded, shall be kept on file in the office of the board of county commissioners and made a part of the contract with the successful bidder. When it is necessary to alter, repair, or make an addition to a bridge, the board of county commissioners in making contracts therefor, shall conform to sections 153.01 to 153.60, inclusive, of the Revised Code, in relation to the erection of bridges as nearly as the nature of the case will permit.