9 Del. C. § 507

(a) Upon the submission by the Director of the Division of Highways of the Department of Transportation to the county government of complete plans, specifications and estimates covering the improvements, the county government shall fix a date for an election, at which all citizens and real property owners of the community may vote, on the question whether the county government should proceed to issue bonds in the manner hereinafter provided, in an amount sufficient to finance the cost of the improvements contemplated and shall include costs estimated by the Division of Highways for preliminary engineering, which shall not be reimbursable in excess of 10 percent of the estimated project cost, and for construction inspection at the rate of 10 percent of the amount of the contract bid.

(b) The election shall be held not less than 20 days nor more than 60 days after the submission of the plans, specifications and estimates to the county government.