Section 50A. Notwithstanding the provisions of section fifty, every owner or operator of an oil terminal or wharf shall employ a trained crew and have a boom, on terminal property or readily available under a plan with other persons complying with the law or rules and regulations of the division and of a design approved by the division, which is capable of encircling any ship or vessel depositing oil into tanks or other receptacles at such terminal or wharf, and which is designed to prevent seepage, overflow or excess oil from polluting or contaminating any lake, river, harbor, tidal water or flats. If the director finds that because of the negligence of such owner, operator or one of his agents or servants repeated seepage, overflow or excess oil has contaminated any lake, river, harbor, tidal water or flats, he shall require every such owner or operator to encircle every ship or vessel depositing oil at his wharf or terminal with such a boom. The authority granted to the director under the preceding sentence shall not be construed to diminish his powers to regulate and control oil spillage, including his power to require the use of booms, granted by section fifty. The owner or operator of any such wharf or terminal shall remove any oil held within such boom prior to a ship or vessel leaving the same. A license issued under section fifty to operate a terminal may be revoked for violation of any of the provisions of this section.