Del. Code tit. 19, § 3122

General and special rules may be adopted, amended or rescinded by the Department only after public hearing or opportunity to be heard thereon, of which proper notice has been given. General rules shall become effective 10 days after filing with the Secretary of State and publication in 1 or more newspapers of general circulation in this State. Special rules shall become effective 10 days after notification to or mailing to the last known address of the individuals or concerns affected thereby. Regulations may be adopted, amended or rescinded by the Department and shall become effective in the manner and at the time prescribed by the Department.