S.D. Codified Laws § 5-18B-14
The purchasing agency may appoint a competent superintendent who may be the architect or engineer furnishing the plans and specifications for the public improvement. The superintendent shall report to the purchasing agency or board every thirty days as to the progress and character of the work done by the contractor. Upon the reports of the superintendent, the purchasing agency shall make payments promptly to the contractor during the process of construction to the extent provided by the contract based on the value of the work done and materials furnished. The payments shall be divided into such installments as the board and the contractor may agree upon at the time of entering into the contract, and which shall be included in and be a part of the terms of the contract. No payment, however, constitutes an acceptance, in whole or in part, by the purchasing agency prior to making of the final payment and acceptance in full completion of the contract. Final payment of any sums due to the contractor shall be made within thirty days after the completion and acceptance of the public improvement by the purchasing agency.
SDCL 5-18B-14