(a) The boards of commissioners mentioned in this chapter shall have control of the construction of the improvements in their districts.
(b)
(1) A board may advertise in local papers or papers published in other states for proposals for doing any work by contract.
(2) No work exceeding twenty thousand dollars ($20,000) shall be let without public advertisement.
(3) A board may accept or reject any proposals.
(c) A board may:
(1) Appoint all necessary agents for carrying on the work and fix their pay;
(2) Buy all necessary material and implements;
(3) Sell material or implements on hand which may not be necessary for the completion of the improvement; and
(4) Make all such contracts in the prosecution of the work as may best subserve the public interest.
(d) It shall be the duty of a board to have the amount of work done by any contractor estimated, from time to time as may be desirable, by the engineer selected by the board. The board shall draw its warrants in favor of the contractor for not more than ninety percent (90%) of the amount of work so reported, reserving the remainder until it has been ascertained that the work has been completed according to contract and is free from liens.