All contracts and agreements which the state may enter into shall be approved as to form by the Attorney General. The commissioner is authorized to furnish, at the request and expense of such local authority authorized to contract under section 25-94, such technical advice consisting of plans, specifications, surveys, cost estimates, engineering and inspection services as such local authority deems advisable. If such local authority enters into a contract with the commissioner for the construction of a system, such expense shall be deemed part of the cost of construction.