Cities are full of impervious surfaces including streets, roofs, and parking lots.  These surfaces do not absorb water; therefore, they produce a great deal of stormwater runoff.  Stormwater, a type of wastewater that comes from rain and melting snow, is a leading cause of water pollution.  The water that runs off of impervious surfaces carries pollutants with it into sewers, sometimes causing sewer overflows and flooding.  These events can lead to stormwater and wastewater spilling into our natural waterways, which impacts water quality and recreation.

Impervious surfaces cover approximately 72% of New York City’s land area, of which 8% are parking lots.  In 2008, zoning rules for parking lots were updated to require all commercial and community facility parking lots to have periphery landscaping to absorb and retain storm water.  In 2011, the Department of Environmental Protection launched the Parking Lot Stormwater Pilot Program, taking storm water management for parking lots a step farther than the 2008 zoning change.

This initiative requires owners of parking lots that are unaffiliated with buildings to pay annual fees for stormwater runoff.  Normally, wastewater sewer charges are included in water bills, which these stand-alone parking lots previously did not receive.  Each day, 1.3 billion gallons of wastewater flow through New York City’s 14 wastewater treatment plants.  The money generated from these bills now goes towards the cost of transporting and treating wastewater and runoff in the city.

To encourage the development of green infrastructure throughout New York City, it is possible to be exempt from these annual charges.  Parking lots that demonstrate on-site green management of stormwater (such as permeable pavement and subsurface water detention systems) can apply for an exemption with the DEP.  Parking lot owners who fail to implement stormwater-capturing infrastructure are charged $0.05 per square foot annually.  The average annual bill for New York City parking lots is just under $700.

The Parking Lot Stormwater Pilot Program is just one part of a larger initiative called the Green Infrastructure Plan.  The plan, which was introduced under Mayor Bloomberg’s administration, is “a sustainable strategy for clean waterways.”  Since the plan’s official implementation in 2011, the DEP has installed rain gardens, retrofitted public property, conducted sewer flow monitoring, completed grant projects, and more.

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Allegra Miccio