SDCL § 31-14-8: Bid and certified check or bond deposited with county auditor before opening of bids.

Each bid shall be made in accordance with the plans and specifications on file. Each bid in excess of fifty thousand dollars shall be accompanied by a certified check, certified by a state or national bank domiciled within this state, in the sum of five percent of the total amount of the bid, or a ten percent bid bond issued by a surety authorized to do business in the state. To be effectual for any purpose the bid and certified check or bond shall be securely enclosed in a sealed envelope and deposited with the county auditor before the hour of opening the sealed bids.