A golf course with a lawn sprinkler system installed prior to the effective date of this amendatory Act of the 91st General Assembly may extend, relocate, or modify up to 200 linear yards of an existing lawn sprinkler system without being subject to the requirements of Section 2.5 of this Act. However, if the extension, relocation, or modification of an existing lawn sprinkler system involves a connection of the system to a backflow prevention device, a licensed plumber shall make the physical connection between the lawn sprinkler system and the backflow prevention device.