PRPs fall into four categories: the current owner or operator of the site, anyone who owned or operated the site before, anyone who arranged for hazardous wastes to be dumped on or treated at the site, and anyone who dansported hazardous wastes to the site. Rarely is only one person or company responsible for a site's pollution. Usually there are dozens of PRPs involved. If only a few of the PRPs can be located, they are responsible for paying for the entire cleanup. Because Superfund sites cost anywhere from $15 million to $100 million to clean, identified PRPs will seek out the others involved, and the companies decide among themselves how much each party is responsible for. Superfund also holds polluters responsible after the site is cleaned up. If the government or an individual citizen spends money to clean up a hazardous-waste site, they can sue the person or company that was responsible for polluting the site. The money won in a lawsuit would be used to recover the crust of cleanun