New York City is hiding a healthy little secret: its dirt. Beneath a layer of toxic topsoil, New Yorkers are finding clean sediments and using them in ways apparently unmatched by any city, the New York Times reports. A non-profit "soil exchange" run by the mayor's office is finding uncontaminated dirt in construction sites and sending it to projects in the five boroughs—like cleaning a Superfund site in Sunset Park and building new wetlands in Brooklyn and Queens to limit the damage of future storms. "We're essentially matchmakers," says Dan Walsh, who runs a city environmental office. "We don't stockpile the soil, so both a donor and a recipient have to be ready at the same time. Our job is to coordinate the transfer."
Before now, the word on Gotham soil wasn't good. A 2015 study found scary levels of lead and arsenic in backyards and community gardens, putting children and gardeners at potential risk. "The lead levels found in Brooklyn backyards are often similar to areas where there has been past lead smelting activity," study author Joshua Cheng told Reuters last year. But the discovery of cleaner dirt below means New Yorkers could grow clean food, reduce pollutants, and improve storm drainage. And builders won't be paying to send as much excavated dirt to upstate landfills. Los Angeles and New Orleans are among the cities watching. People must "make better use" of soil, a New York official says: "If we keep on beating soil up, we won't be able to sustain our cities of the future."