Del. Code tit. 29, § 7522

All bills for the expenses of the board of education of any school district for carrying out the school construction program of such school district under this chapter must be marked “approved,” and such approval must be signed by the president or vice-president of such board of education and attested by the secretary or acting secretary of such board of education. If such approval is countersigned by the superintendent of the school district or the superintendent’s authorized designee, any other signature on the approval may be a facsimile.