Beautiful waterways for the Big Apple

©REUTERS/Andrew Kelly

New York is investing in a greener, cleaner future.

New York’s earliest visitors found a vibrant natural ecosystem, with wooded hills surrounded by pristine waterways. That landscape began to change after colonisation, as the population of New York City grew rapidly over two centuries, from approximately 5,000 in 1700 to more than two million by 1900. As New York City grew into an international hub of commerce and manufacturing, its residents and industry discharged human waste, industrial pollutants and residential garbage into the waterways. By the late 1800s, more than 600 million gallons of raw sewage were directly discharged into the harbour every day from sewers that ended at the water’s edge.

Over the past 100 years, New York City undertook a significant campaign to capture sewage and rainwater by connecting those street end sewers with 146 miles of large interceptor sewers that run along (not into) the water, directing that flow from interceptors to one of 14 wastewater treatment plants, and by creating a network of 7,000 miles of underground sewers and 144,000 catch basins to accept wastewater and stormwater. But like most older urban centres in the northeastern and the midwestern United States that first addressed the public health threat of raw sewage discharges, New York City has a combined sewer system; in a majority of the city, the same pipes carry household and commercial wastewater (also known as dry weather flows) and stormwater runoff to treatment plants that handle 1.3 billion gallons of wastewater on an average dry day. In these areas, the capacity of our treatment plants is often exceeded when it rains, and to relieve pressure on the system during these high-flow periods, our interceptor sewers are equipped with regulators and overflow devices that divert stormwater and wastewater into the city’s surrounding waterways at 423 locations. This is known as a combined sewer overflow, or CSO.

With the construction of the last two of our 14 treatment plants in the mid-1980s, dry weather discharges of sewage into New York Harbour ended, and water quality has improved dramatically. But CSOs are our  greatest remaining hurdle to even better water quality. The 423 CSO outfalls cannot simply be “plugged up,” because the captive water flow would simply wash out and disable our treatment plants, cause sewer backups, and dramatically degrade water quality. One solution is to build completely separate sanitary and stormwater sewer systems, but that would cost more than $60 billion in New York City, would take decades to complete, and would severely disrupt the quality of life in areas where the construction would take place.

Over the past 20 years the Department of Environmental Protection (DEP) has upgraded its plants and sewers to handle more wet weather flow and has built tanks to store combined flow that can be pumped to plants for treatment when the rain subsides. This programme has resulted in greater overall capture and treatment of total volumes of combined wastewater and stormwater flows, from approximately 30% of all flows in the city during the 1980s to more than 72% today.

But these traditional solutions have limitations. As the most densely developed city in the US, New York City generates a tremendous volume of stormwater runoff from rooftops, streets and other impervious surfaces. If runoff continues from these impermeable surfaces, the city will have to build additional tanks and tunnels–also known as “grey” infrastructure because of their reliance on steel and concrete-to manage stormwater flows. These facilities are difficult to site, are expensive to build and operate, and displace competing uses of scarce land. With greater amounts of precipitation and more intense storms expected due to climate change, we may well find that today’s solutions are obsolete in mere decades.

The need to rethink the traditional approach to managing stormwater led New York City’s mayor, Michael Bloomberg, to unveil the NYC Green Infrastructure Plan in September 2010. A bold and innovative vision to improve water quality, the plan proposed to invest $2.4 billion in “green infrastructure” over 20 years. These types of controls include green roofs, bioswales, tree pits; and other adaptive structural additions to public works that address the root cause of CSOs by absorbing and retaining stormwater before it can enter the sewer system and trigger a combined sewer overflow. For New York City, Mayor Bloomberg set an ambitious goal to capture the first inch of stormwater from 10% of impervious surfaces in combined sewer areas by 2030–which would eliminate 1.5 billion gallons of CSOs per year.

The plan targets the city’s two most prominent impervious surfaces: rooftops and roadways. Impervious streets and sidewalks make up more than 26% of the land in combined sewer areas. By developing standard designs for enhanced tree pits, streetside bioswales, and stormwater-capturing Greenstreets, we expect to achieve significant penetration for a comparatively small marginal cost above what the city would have had to spend on roads and public spaces anyway. Similarly, impervious rooftops cover more than 46% of the city. Specially planted “green roofs” can reduce energy costs and provide a beautiful, verdant ecosystem, and inexpensive “blue roofs” use simple mechanical devices to moderate peak flows by gradually releasing stormwater.

The good news is that the plan is gaining momentum. This month, thanks to the leadership of New York State Commissioner for Environmental Conservation Joe Martens and his team, New York City and State released a modified consent order for public comment that embodies the key milestones and initiatives in Mayor Bloomberg’s Green Infrastructure Plan–and puts the city on the path to spend $1.5 billion on green infrastructure over the next 20 years. In exchange, New York State has agreed to eliminate $1.4 billion and defer $2 billion that would have had to be spent on traditional grey infrastructure like storage tanks and tunnels.

The potential benefits of the plan are tremendous. Combined with existing investments in more traditional infrastructure, it will cut CSOs by more than 12 billion gallons annually by 2030–a 40% reduction-which is almost 2 billion gallons more per year than the previously required all-grey plan, and will be achieved for $2.4 billion less in public spending. This is smart government. And we estimate that green infrastructure will create up to $400 million a year in additional benefits from increased property values, increased shading and lower energy use. The plan will also green and beautify the city at a time when many cities are cutting capital investments, and public services are contracting as needs increase.

Together with the public and our partners in federal, state and local government, we are using all of the resources at our disposal to drive toward a greener, greater New York City. With green infrastructure, we are making innovative investments in a sustainable future–and making our waterways cleaner than they’ve been in over a century.

Global Forum on Environment: Making Water Reform Happen Paris, 25-26 October 2011

Visit www.nyc.gov/mayor and www.nyc.gov/dep

See also www.oecd.org/water and www.oecdobserver.org/water

©OECD Observer No 286 Q3 2011




Economic data

GDP : +0.50%, Q4 2014
Employment rate: 65.7%, Q3 2014
Annual inflation : 0.51% Jan 2015
Trade : -3.0% exp, -3.7 imp, Q4 2014
Unemployment : 7.045% Q4 2014
Recovery ahead? Composite leading indicators
Updated: 24 Mar 2015

E-Newsletter

Stay up-to-date with the latest news from the OECD by signing up for our e-newsletter :

Twitter feed

Don't miss

  • Events at the OECD: Click on the image to get the full calendar.
  • Asia to maintain a strong 6.3% growth rate in 2015 and 2016, according to the Asian Development Bank
  • Greece should tackle not only domestic corruption but also foreign bribery warns the OECD Working Group on Bribery.
  • After three decades of extraordinary economic development, China is shifting to a slower and more sustainable growth path, according to the OECD's latest Economic Survey of China.
  • In pursuit of the American Dream
  • The OECD turned green to mark Saint Patrick's Day, the first international organisation to do so. Click photo for more global iconic landmarks.
  • Iceland's strong recovery stems from the good use of its natural resources, the energy sector and tourism according to Peter Dohlman, IMF Mission Chief for Iceland.
  • cyclone
  • Government representatives and experts from around the world are gathering in Japan this week to develop a post-2015 framework for global disaster risk reduction. The World Bank and the Global Facility for Disaster Reduction and Recovery (GFDRR) will share expertise at the conference.
  • Switzerland’s recent moves towards greater tax transparency were welcomed by the Global Forum on Transparency and Exchange of Information for Tax Purposes, based at the OECD, as a boost to international efforts to end tax evasion. Work will continue with Switzerland, notably on implementation, in 2015.
  • Help bridge the gap between business integrity policies & practices:participate in this new OECD survey by clicking on the image.
  • The Power of Social and Emotional Skills (The Huffington Post)
  • pisa
  • Secretary General Angel Gurría describes the Programme for International Student Assessment (PISA) as a useful tool to enhance educational systems but states that improving a country's ranking should not be a goal per se. Article in Spanish by El País.
  • [VIDEO] In spite of economic improvements, the OECD recommends that austerity measures remain unchanged in the UK.
  • [VIDEO] Although many countries have made great progress in narrowing gender gaps in education, new challenges are looming.
  • 5 things you might not know about the state of Amazonas. The World Bank identifies the main colossal challenges Brazil's biggest state is facing.
  • Gender mainstreaming: young French lady working in an engine assembly plant. Women and men in the same boat when it comes to job insecurity. © Raphaël Helle / Signatures / La France VUE D'ICI
  • The Asian Development Bank together with the International Labour Organization challenge the concept of women's work in Asia and the Pacific.
  • Gender wage gap
  • Visit the OECD Gender Data Portal. Selected indicators shedding light on gender inequalities in education, employment and entrepreneurship.
  • World Water Day: 22 March 2015 For World Water Day, UN-Water identifies upcoming challenges and sets the theme for the years to come. In 2015, the theme for World Water Day is Water and Sustainable Development.
  • 2015, a year full of dangers? Laurent Bossard, director of the Sahel and West Africa Club, acknowledges that the situation in the region is complex and unstable but refuses to give in to fatalism.
  • The 5th Anti-corruption conference for G20 governments and business in Istanbul on 6 March will address how all businesses can play their part in contributing to growth and investment, and can operate with clean hands in a safe environment.
  • Success story. Discover the story of this young Ethiopian woman who launched a successful business in the footwear industry and became a UN Goodwill Ambassador for Entrepreneurship.
  • Transports in Asia. The Asian Development Bank advocates sustainable transport in a continent where vehicle ownership is perceived as a sign of social success.
  • Vote for your favourite photograph! This World Bank #EachDayISee photo contest aims to display visual stories from all over the world through which people express what they would like to see changed and improved.
  • Why is investment so low in the euro area? This short IMF blog post gives you an insight into the causes of the euro-zone's drastic decline in investment.
  • Have your say! The UN wants to know what matters most to you: pick six global issues in the list and send it to the United Nations.
  • Tim Harcourt Video
  • G20 and Australia: Bestselling economist Tim Harcourt speaks to the BBC about how Australia has gone from "Down Under to Down Wonder".
  • Clear air and healthy lungs: how to better tackle air pollution. From New Delhi to Accra, millions of people breathe polluted air. A new report examines the World Bank’s experience working to improve air quality.
  • The boring secret of great cities. Plenty of things make a city great but what really makes a difference originates in the structure of municipal government according to the OECD's report "The Metropolitan Century".
  • Guinea gets $37.7 million in extra IMF financing to help combat Ebola

Most Popular Articles

Subscribe Now

<b>Subscribe now!</b>

To receive your exclusive print editions delivered to you directly


Online edition
Previous editions

Poll

What issue are you most concerned about in 2015?

Euro crisis
Unemployment
Global warming
International conflict
Other

OECD Insights Blog

NOTE: All signed articles in the OECD Observer express the opinions of the authors
and do not necessarily represent the official views of OECD member countries.

All rights reserved. OECD 2015