Prepping for what Delaware's reef program manager Jeff Tinsman calls "luxury condominiums for fish," did take some time. While the small amount of asbestos in the subway cars was considered safe underwater, pollutants like oil had to be removed. In addition, the cars were also stripped of the seats, straps, and wheels that are either recycled or sold. Only after the structures met the strict guidelines of the US. Environmental Protection Agency were they allowed to be dumped into the ocean.
The artificial reefs are still constantly monitored and studied to ensure they don't pose any threat to the underwater sea life. Thus far, numerous sea creatures have successfully converted the carbon steel subway cars into their new homes. In many instances, the metal surfaces are covered in algae, making them almost unrecognizable.