N.D. Cent. Code § 61-35-13
If the cost of construction or maintenance of a project does not exceed the amount provided for construction of a public improvement under section 48-01.2-02, the work may be done on a day work basis or a contract may be let without being advertised. If the cost of the construction or maintenance exceeds the amount provided for construction of a public improvement under section 48-01.2-02, the lowest and best bid must be accepted. The board must comply with the requirements of sections 61-35-88 through 61-35-103 when bidding a project.
The competitive bid requirement of this section may be waived if the board determines that an emergency exists requiring the prompt repair of a project and a contract may be made for the prompt repair of the project without seeking bids.
N.D.C.C. § 61-35-13