Del. Code tit. 9, § 4617

At any time after the establishment of a district or extension thereof pursuant to this chapter, the maximum amount authorized to be expended for the original improvement in such district or extension thereof may be increased by a resolution of the county government, provided the county government shall, after a public hearing called and held in the manner provided in § 4604 of this title, determine that it is in the public interest to authorize an increase of such maximum amount. If zones of assessment have been established, such resolution of the county government shall further provide for the allocation of such increase as between such zones of assessment and the notice of such public hearing shall state such allocation.