To supersede the requirements of Sentence 4.8.7.1.(1) in order to permit bulk transfer operations on general purpose piers and wharves if certain measures are taken [guards or fences are installed around valves or pumping equipment to prevent entry of unauthorized personnel].
This is to limit the probability that unauthorized persons will gain access to the valves and pumping equipment, which could lead to the unwanted escape of liquid, which could lead to harm to the public.