There are several programs a contaminated site may be registered in and each has it’s own conditions for remediation and responsibility of ownership.
Read the following from the FDEP.
The Petroleum Restoration Program encompasses the technical oversight, management, and administrative activities necessary to prioritize, assess, and cleanup sites contaminated by discharges of petroleum and petroleum products from stationary petroleum storage systems. These sites include those determined eligible for state funded cleanup using qualified contractors selected through competitive procurement or selected by the property owner or responsible party and state lead contractors under direct contract with the Department, as well as non-program or voluntary cleanup sites that are funded by responsible parties.
Some helpful information can be found here;