Prior to the regulator approving an application for an excavation permit or an application for an amended excavation permit, a public hearing shall be held within 30 days on such application. A notice of said hearing shall be sent to all abutters and shall specify the grounds for the hearing as well as the date, time and place and at least 10 days’ notice of the time and place of such hearing shall be published in a paper of general circulation in the city, town or unincorporated place wherein the proposed excavation is to be located and a legal notice thereof shall also be posted in at least 3 public places in such city, town or unincorporated place; the 10 days shall not include the day of publications nor the day of the meeting, but shall include any Saturdays, Sundays and legal holidays within said period. Within 20 days of said hearing or any continuation thereof, the regulator shall render a decision approving or disapproving the application, giving reasons for disapproval.