San Francisco, Chicago, and Portland, Oregon, along with other major cities, all suffer from this same infrastructure problem. This is a very damaging environmental problem, causing issues like eutrophication and algal blooms. However, it is also a potentially expensive problem to fix, as it involves replacing all of the underground pipes in large concrete laden metropolitan areas. To help reduce the quantity and improve the quality of stormwater in New York City, Mayor Michael Bloomberg revealed a Green and Blue Roof plan for the city.
What are Blue Roofs and Green Roofs?
Green roofs, on the other hand, are vegetative layers growing on rooftops. The vegetation removes heat from the air through evapotransporation. Green roofs can reduce and slow stormwater runoff in the urban environment; they also filter pollutants from rainfall.
New York's Stormwater Plan
A large component of the stormwater management plan is the installation of blue and green roofs, which use mechanical devices or vegetation to slow roof water from draining too quickly. This will capture the first inch of rainfall on 10% of the impervious areas in combined sewer areas of the city. The cost for the city to invest in grey infrastructure and green infrastructure will total $5.3 billion, rather than the $6.8 billion it would cost to improve the traditional sewer infrastructure.
This stormwater improvement plan will not only improve water quality, but is also producing “green-collar” jobs. The Osborne Association, a Bronx nonprofit that works with the formerly incarcerated, was given a large grant to implement a blue and green roof on their headquarters. Their social enterprise participants were able to gain experience in the installation of blue and green roofs. They also plan to use the new rooftop environment to start a new honeybee business to support their catering company. The “blue” detention trays use gravel to slow the flow of stormwater into the sewer system and the “green” trays use soil and vegetation to absorb rainwater and improve air quality.
With the growing need for wastewater and stormwater management in many aging cities, new blue and green roof systems could be the cheaper more effective method for improving the issue. New York has stepped forward as a living laboratory for blue and green roof stormwater management systems. Other cities struggling with similar combined sewer overflows should learn from the innovations taking place in New York and implement them as needed.