NYC’s Green Infrastructure Plan

18 11 2010

Last week, the Economist in an articled titled “Trees grow in Brooklyn” reported on U.S. cities implementing green infrastructure strategies to address the pollution of their waterways from storm water runoff. The article focused primarily on New York City and Philadelphia.

According to the article nearly 27 billion gallons of untreated water overflows into the New York harbor each year. NYC’s recently released green infrastructure plan seeks to address run-off from 10% of the impervious surfaces in the City with green infrastructure storm water strategies that range from rain barrels to pervious pavements to green roofs.

The plan estimates that on average the cost per gallon of Combined Sewer Overflow (CSO) avoided ranges between $1 to $2 per gallon. In addition, the City calculates that over a twenty-year period, it will receive between $139 million and $418 million in additional triple-bottom line benefits (i.e. energy savings, increase in property values, health) from the green infrastructure.

While NYC’s strategy is also employing grey infrastructure, they see the combination of the two costing less than a grey only approach. The cost of the green-grey strategy is approximately $5.3 billion of which $2.4 billion makes up the cost of the green infrastructure. This is $1.5 billion less than the grey only solution.

Chris Strickland, a deputy commissioner with the New York’s Department of Environmental Protection sums it up in the article saying that this (green infrastructure plan) is a way of achieving more than one thing with tax dollars.

Link to NYC Green Infrastructure Plan

-Brian Phelps


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Categories : Plans and studies, Sustainable Site Strategies

BLUE is the New Green

16 04 2010

I think I may have heard the term “blue roof” before last Saturday, but I must not have paid attention.  I was fascinated as I read New York City’s NYC Stormwater Sustainability Report 2008. It included a full description of a blue roof as an LID measure.   I checked out  few other leads to find this LID technique also being explored in Washington state and a recent article in EDC Magazine discussing it as well.

Bottom line:  a blue roof detains water on the roof of a structure in order to reduce the stormwater impacts.  The detention is done through a  flow restriction device around the roof drain which slowly releases the water or, in the Washington modeling, all of the rainwater on the rooftop is collected and stored.  The roof-harvested water can used to fill a water cistern for irrigation, a site infiltration system like a bioswale or rain garden or discharged slowly to the storm system.

The blue roof is best suited to a large flat roof in more urban areas with limited availability of ground level detention.  There are also designs which provide wide “gutters” near the perimeter of the roof to concentrate the water roof load where it can be supported structurally.  If the primary goal is stormwater reduction, then a blue roof can achieve that goal at considerably less cost than a vegetated green roof.  The estimates I found ranged from $1/s.f. to $4/s.f. for a blue roof while estimates for an extensive green roof might be $18-25/s.f.   Blue roofs also don’t have the same maintenance costs of green roof either – they basically require the same maintenance as a conventional roof..

Of course, the blue roof doesn’t provide the multi-benefit that green roofs do (such as energy use reduction, habitat, aesthetic, life cycle roof cost), but 2008 modeling conducted by Douglas Beyerlein, PE, Clear Creek Solutions in Mill Creek Washington does show the blue roof slightly outperforming the green roof for stormwater reduction.

-Kim Hawkins


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Categories : Sustainable Site Strategies

Getting More: Multi-Functioning Facilities

13 01 2010

When it comes to adding more park space, communities are increasingly looking at getting more bang for their buck. Budgets are tight and cities are having to pool their resources from a variety of sources to get projects built. Two recent projects, one that is under construction in Los Angeles and another just announced in New York City, seek to create a park and nature area for their citizens while also constructing wetlands to address stormwater management issues within the immediate neighborhood and the community at-large.

The first is the South Los Angeles Wetland Park. The 9-acre park under construction five miles south of downtown Los Angeles on a former transit maintenance facility that is nearly 100% paved. The City recognized that more recreational open space was needed in the area while also needing to improve the quality of the stormwater runoff that ultimately was polluting the city’s beaches. The park transforms the site into a extensive wetland that comprises most of the park. It includes a series of trails, an observation area, and public gathering areas.

The park is estimated to cost $24 million. The funding was cobbled together from a variety of sources, including money generated from Proposition O. Proposition O passes in 2004, authorized the city to issue up to $500 million in bonds for cleaning up polluted storm water and bacteria in the City’s rivers, lakes, beaches and ocean. Stormwater Magazine has a thorough article about the genesis of the park and its design. Also, more detailed information can be found on Proposition O’s website.

South Los Angeles Wetland Park Site Prior to Construction
Source: Google Map

South Los Angeles Wetland Park Site Plan
Source: Proposition O Website

The second improvement is the Paerdegat Basin Restoration Project in New York City. The Department of Environmental Protection recently announced the $15 million project. It is anticipated to be completed by 2012. The park will restore 38 acres of wetlands and natural grassland areas adjacent to the $357 million Paerdegat Basin Combined Sewer Overflow (CSO) abatement project. Five acres will be dedicated as a Ecology Park that will be accessible by the public and offer educational opportunities. Funding for the project is provided by Clean Water State Revolving Funds. The combined projects are designed to store 50 million gallons of CSO during a storm event. (Press Release fro DEP)

Both of these projects serve as examples of how various communities’ goals can be combined and met by a single green infrastructure investment. As cities approach future planning and implementation efforts, they should look beyond the immediate objectives of the project and assess how the project might serve to address other needs that have been identified in the community.

-Brian Phelps


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Categories : Parks & Open Space, Sustainable Site Strategies

Liquid Assets: A Review

7 12 2009

Trailer for Liquid Assets (Click Here if you don’t see it above)

Last week I ordered a copy of Liquid Assets from the WPSU media store and had a chance to watch it over the weekend. The documentary debuted Fall 2008 on public television stations across the country. It provides an informative overview of the issues facing our Nation’s water infrastructure and the need to address it. Through a series of interviews and helpful computer animations, the video examines the infrastructure for our drinking water, wastewater, and stormwater, primarily concentrating on the public health and economic development issues. The documentary is a sobering look at the great need to maintain or replace our aging water systems. It was able to capture the magnitude of the problems while offering hope by showing how cities are addressing the problem. Boston, Philadelphia, Milwaukee, Washington D.C., New York City, Pittsburgh, Herminie,PA, Los Angeles, Las Vegas, and Atlanta are profiled.

The audience for the documentary is not design and engineering professionals who are steeped in these issues and have a firm grasp on them. The video is intended for a general audience that may not have a thorough understanding of water issues. My seven year old daughter sat with me to watch it and surprisingly she lasted over an hour before getting bored. She seemed to take a lot of way from the portions she did watch. Some of the basics the video teaches people is what watersheds are, how we get our water, and what a combined sewer overflow is. As an entertaining tool for bringing the general public up to speed with the issues, the documentary is excellent. A complementary community outreach toolkit is provided on-line. This toolkit provides information on how to conduct public workshops in your city and facilitate discussions about water issues. In addition, the documentary is broken into chapters that address specific topics, allowing for groups to tailor it to specific needs within their community. However, I would highly recommended watching the entire 86 minutes. In context of the whole, the chapters are much stronger.

My only major disappointment was that green infrastructure was not addressed to any great depth. The Pittsburgh segment touched on it. The work of the Nine Mile Run Watershed Association was highlighted and concentrated on the Nine Mile Run Restoration. During this segment, there was some mention about street planting and rain barrels. Liquid Assets does however illustrate the issues green infrastructure can address within these troubled systems. This includes combined sewer overflows, protection of water sources, and non-point source water pollution.

Overall the video is a high quality documentary that can spur great discussions about the past, present, and future of our water system.

-Brian Phelps


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Categories : water issues