NYC Put Millions Into Green Infrastructure by the Bronx River. Did it Work? (Part 2)

This is the second article in a three-part series on green infrastructure policy in NYC. Read the first article here.

Back in 2012, New York City Department of Environmental Protection (DEP) had a big decision to make.

The city promised to use more green infrastructure to control combined-sewer overflows, sewage dumps into the New York harbor. The question now was how?

In the first article in this series, we learned that DEP experimented with several different types of green infrastructure: blue roofs, perforated pipe systems, rain gardens, and more. After DEP compared the cost, complexity to build, and co-benefits of each type of green infrastructure, rain gardens emerged as winners. DEP decided to paint the city with rain gardens, at least for the next several years.

Fast-forward to today, and the success of DEP’s rain garden strategy is mixed. A spokesperson for DEP highlighted the improved water quality, and scale of construction:

NY Harbor is healthier today than it has been since the Civil War.

We’ve constructed or are in construction on over 7,400 distributed green stormwater infrastructure assets which manage over 900 greened acres. These 7,400 assets, coupled with the remainder we are building this year, will lead to a Combined Sewer Overflow (CSO) reduction of more than 500 million gallons per year.

Indeed, if you stroll through the neighborhoods of Bushwick, Sunnyside, Brownsville, or Rego Park, you will seem rain gardens everywhere. But in the densely-populated South Bronx where thousands live near heavy industrial facilities and polluting infrastructures, rain gardens are hard to find.

A small fraction, less than 5% of the 7,000 plus green infrastructure assets built under the NYC Green Infrastructure Program are in the South Bronx.

In part two of this series, we will examine the execution of DEP’s right-of-way rain garden strategy in the South Bronx. Publicly available information and interviews with DEP, former staff from other city agencies, and local residents, tell a story of overcoming obstacles and unintended consequences.

Wanted: Space for Rain Gardens

DEP needed an aggressive implementation strategy to meet the stormwater management targets in the NYC Green Infrastructure Plan. The agency needed to capture stormwater from 1.5% of impervious surfaces in combined-sewer areas. By 2020, that percentage would be up to 5%.

DEP bet that with enough right-of-way rain gardens, it could hit its target. “Right-of-way” specified that the rain gardens be constructed on sidewalks and traffic medians—land that the city owned. The work would kick off in neighborhoods near highly polluted water, like the Bronx River. The site selection process would test DEP’s organizational capacity, and the logic of its rain garden strategy.

Streetscape in South Bronx
Image courtesy of Michael Minn

Site Selection is No Walk in the Park

DEP kicked off a hunt across the South Bronx for suitable locations to install rain gardens. You could liken the site selection process to the nightmare of searching for an apartment in the city.

To start, it could be difficult to organize a time to conduct a site walk through. DEP needed to coordinate schedules with the Department of Parks & Recreation and the Department of Transportation to ensure every agency had a representative present. In a 2013 report, DEP wrote schedule misalignment was common and often delayed project start dates.

Next, DEP needed to ensure the site met its long wish list. The agency had developed careful guidelines for where it could build green infrastructure. The aforementioned report stated, “conservative evaluation is prudent at this early stage in the Green Infrastructure Program to ensure that all sites function as designed and do not cause a public concern.”

To address this, the team would distribute brochures about the green infrastructure program to residents and business owners. They would also observe traffic and pedestrians in the area, and note the location of bus stops and mature street trees. The rain garden needed to integrate well into the existing streetscape.

Finally, of course, there was the fierce competition for the same slim piece of real estate. After DEP’s team surveyed the areas above ground, it was time to evaluate what was hidden below ground. If DEP found utility lines, clay soils, shallow groundwater, or other disqualifying features, the site would be ruled out.

Dr. Nandan Shetty, a former Parks Department employee who worked in the South Bronx, recalled that the initial results of the site walkthroughs in the South Bronx were worrying. DEP wanted right-of-way rain gardens in the South Bronx to improve water quality, but could it build enough of them to make a difference?

The Search Results

According to a DEP spokesperson, the department has evaluated over 5,300 locations in the South Bronx to date. The spokesperson also provided this statement when asked about the most common siting challenges:

bedrock in the Bronx

The most common siting challenges we’ve encountered in the Bronx are bedrock and high groundwater, both of which limit or prevent the ability of green infrastructure to infiltrate stormwater. Narrow sidewalks and conflicts with other infrastructure have also limited our ability to site green infrastructure on sidewalks in the Bronx.

While DEP declined to answer what percentage of sites in the South Bronx were unsuitable. However, reports on other neighborhoods offer clues. For example, in one section of Bushwick, approximately 50% of evaluated sites (835 in total) were infeasible.

We do know that DEP only approved a few dozen sites for construction in 2013. With the locations selected, DEP’s next challenge was to actually build the rain gardens.

A Plan in Motion

The decentralized and diverse nature of green infrastructure demands non-standard approaches to capital planning and streamlined processes to meet aggressive targets. -NYC DEP

DEP assigned the Parks Department to solicit contracts to build rain gardens and Greenstreets in the Bronx River watershed. Instead of creating separate bids for each $26,000 rain garden, the Parks Department created bids for clusters of rain gardens in a close geographical area. At a DEP-hosted event for the green infrastructure construction industry this March, DEP and Parks Department officials agreed that the bundling strategy made the bids more attractive to potential contractors.

design standard for a type 1 rain garden

At DEP’s green infrastructure construction industry event, a DEP employee recalled the hectic nature of rain garden construction during the early years. DEP frequently updated the standard designs and guidelines for green infrastructure. By the time a city agency awarded a bid to a construction firm, the design specs in the bid might not match the new standard.

Still, by the end of 2014, there were 35 new green infrastructure assets in the Bronx River watershed. Citywide, there were 282 new green infrastructure assets.

DEP put out a press release in November 2014 proclaiming “City Announces Major Expansion of Nationally Recognized Green Infrastructure Program to Further Improve the Health of Local Waterways.” The city planned to create over 2,000 rain gardens or other green infrastructure assets in 2015, alone.

The South Bronx Wants More

Throughout this whole process, and continuing into today, community members in South Bronx have consistently advocated for more green infrastructure.

In 2015, DEP had to submit a plan to control combined-sewer overflows (CSOs) in Bronx River to the New York State Department of Environmental Conservation. The Long Term Control Plan specifies how DEP will meet the state’s water quality standards in the future. DEP specified that it would spend $185M on grey infrastructure, but did not promise a dollar amount for green infrastructure.

During public meetings to discuss the Long Term Control Plan, green infrastructure experts like Dr. Shetty and prominent community activists, like Carolyn McLaughlin asked DEP to allocate more funding for green infrastructure.

bar chart projecting 43% CSO reduction in the Bronx River from long term control plan implementation
Projected Benefits of the Long Term Control Plan. Image courtesy of DEP.

Dr. Shetty, who worked for the Parks Department at the time, included this in his letter:

“The Bronx River CSO LTCP has a tremendous amount of money considered for GREY infrastructure. All of the alternatives (p33 on the most recent DEP presentation) number in the tens and hundreds of millions of dollars. It is safe to say that all of the green infrastructure built and planned in the Bronx River sewershed is at best a tiny fraction.”

When I interviewed Dr. Shetty this year, he said he wanted DEP to explore alternatives to infiltration-based technologies like rain gardens. For example, detention-based green infrastructure technologies, like green roofs, negate the challenge of shallow bedrock.

The final version of the long term control plan was approved in 2017. There were no changes to the amount of green infrastructure DEP promised to build.

The NYC Green Infrastucture Map does show a significantly larger number of rain gardens are under construction today than there were in 2015. DEP asserts community feedback influences the design and construction on green infrastructure projects in multiple ways.

DEP’s Response to Community Feedback

DEP uses several channels to collect community feedback on the NYC Green Infrastructure Program. Before DEP builds a new rain garden, Community Construction Liaisons reach out to local residents and businesses. The department also holds public meetings, sometimes in partnership with community boards or local community-based organizations.

I asked DEP how the feedback it collects influences the design and construction of green infrastructure assets. A DEP spokesperson responded that community feedback, real-time data, field experience, and local land use data, all helped broaden the types of green infrastructure DEP builds.

These include infiltration basins with concrete or grass tops to match existing sidewalk conditions, cloudburst swales to capture larger storm events, and porous pavements to allow for siting in constrained areas.

The DEP spokesperson also said community reports of flooding are integrated into project planning, design, and implementation. DEP conducts hydrologic analyses to model how stormwater flows when it rains. However, nothing compares to your lived experience leaping to avoid puddles on your way home.

In my research, I found that the support for building green infrastructure in the South Bronx is overwhelming. Residents are glad to see the city make investments that help clean up the Bronx River and create more green space. However, accompanying the praise for the successes of the green infrastructure policy is wariness about potentially detrimental consequences.

The Decade Ahead

According to the most recently available numbers from 2018, DEP has still yet to meet the 2015 milestone.

However, the missed deadline is not the most important headline. What is important is the unintended consequence the pursuit of this milestone had on the South Bronx.

From 2013-2018, most rain garden construction happened outside the South Bronx (see table below). A spokesperson for DEP said that this was partially because the agency staggers construction projects, and partially because of contractor issues. The 52 green infrastructure assets DEP built in the South Bronx manage 21.1M gallons of stormwater each year. In comparison, the 1,327 green infrastructure assets in Newtown Creek manage 152.8M gallons of stormwater each year.

table of number of green infrastructure assets and equivalent greened acres by watershed
Table in NYC Green Infrastructure Annual Report 2018. Courtsey of NYC DEP.

The NYC Green Infrastructure Plan only dictates that the city manage a certain percentage of stormwater with green infrastructure on a citywide basis. However, Dr. Shetty confirmed that DEP prioritized neighborhoods where it was easier to build rain gardens. The South Bronx landscape makes it difficult to build rain gardens, and therefore the neighborhood received less funding over the last decade.

The Social Impact of Going Green

The good news is that we are only halfway through the 20-year horizon for the NYC Green Infrastructure Plan. There is still time for the city to invest more into green infrastructure in the South Bronx.

The slow pace of construction in the South Bronx may also be slowing another potential consequence of green infrastructure investment: gentrification. Numerous community activists I spoke to expressed concern that these and other infrastructure investments would make the South Bronx a more attractive target for luxury developers.

Real-time monitoring systems and computer modelling calculate the impact of green infrastructure on stormwater management. However, it is much harder to calculate the impact of green infrastructure on the quality of life.

In the final installment of this series, we will explore the social impact of the NYC Green Infrastructure Plan. If green infrastructure yields meaningful social benefits, how can it be equitably incorporated into all public and private development?

To learn more about how to measure the impact of your green infrastructure program and foster community engagement, check Temboo’s tutorials or email us at