Requiring the seller of residential real property located within 1 mile of a National Priorities List (NPL) Superfund site to provide the buyer with an addendum to the contract for the sale of the property that contains the identification of the Superfund site, the definition of an NPL Superfund site, web addresses for certain websites, and a notice that the buyer may void the contract of sale within 5 days after signing and dating the contract of sale.