Port Washington, N.Y. – A landfill in Port Washington, Nassau County, N.Y., has closed. The landfill opened in 1974 on the site of a former sand mine. The 2 million tons of garbage, known as L-5, will be capped and covered with topsoil. Residents and environmentalists hope the area will be reforested and used for recreational purposes when it becomes safe, a process that may take up to 30 years. The landfill has been a sore subject for residents who have complained of gas problems over the years. In 1983, the U.S. Environmental Protection Agency (EPA), Washington, D.C., called the effects of methane leakage in adjacent homes "potentially explosive."