Philadelphia's ambitious plan to keep sewage out of drinking water relies on trees, not tunnels
Philadelphia: Green City, Clean Waters
The plan reimagines the city as an oasis of rain gardens, green roofs, permeable pavements, thousands of additional trees, and more. Announced in September 2009, and 12 years in the making, the new plan would 'peel back' the city’s concrete and asphalt and replace them with plants.