New York City’s largest solar array will be constructed in the borough of Staten Island atop a brownfield and former landfill at Fresh Kills, which is being transformed into public park space. New York City Mayors Office
Before the end of his final term as mayor of New York City, Michael R. Bloomberg announced that the city’s largest solar array would be installed at Fresh Kills Park, on Staten Island.
January 14, 2014—For just over 50 years, the former wetlands at Fresh Kills in the New York City borough of Staten Island was used as a landfill, accepting household waste from the city. Since the 2,200-acre site’s full closure in 2001, however, the final two of the four landfill mounds have been capped and the site is currently in the process of being regenerated as parkland for visitors to enjoy. (See “NYC Project Transforms Landfill into a Sprawling Recreational Oasis,” Civil Engineering, February 2011, pages 20, 22, and 24.) As part of the site’s redevelopment, a 47-acre solar array—the city’s largest—will soon be built, according to an announcement made by Michael R. Bloomberg before the end of his final term as mayor of New York City.
The New York City parks commissioner, Veronica M. White, sanitation commissioner, John Doherty, and the director of the mayor’s Office of Long-Term Planning and Sustainability, Sergej Mahnovski, joined Bloomberg in making the announcement at the end of November.
The 47 acres will be leased to the Belmont, California-based solar company SunEdison, which will develop the new array by securing its necessary financing, shepherding the project through all of the necessary permitting processes, and building and operating the system, according to Steve Raeder, SunEdison’s east coast director of sales, who has led the firm’s negotiations with New York City.
The array will be constructed in two locations and will generate five times more energy than any current solar energy system in the city, according to Bloomberg’s press release. The combined sites are expected to generate 10 megawatts of power, according to the mayor’s office—enough to power approximately 2,000 homes—and will increase the city’s current solar power capacity by 50 percent.
The first site will be located along the river and is known as the Arthur Kills site. The second site, which is slightly larger and located less than a mile from the first, will be located atop capped landfill ground and is currently known as the East site, Raeder says. The former is a brownfields site, so while it is still a remediated site it does not have the settling issues that the capped landfill site will have, Raeder points out.
Placing photovoltaic arrays atop an unused former landfill or brownfield site is an ideal use for the space, according to Adam Wingard, LEED AP BD+C, a commercial operations engineering manager at SunEdison. Wingard heads the company’s East Coast sales engineering team and is responsible for system sizing, conceptual design generation, system energy output estimates, and project cost estimations.
“It can be a nice way to reutilize the space, provide some green energy, and also receive some monetary funds in the form of lease payments,” Wingard says. “It’s really a good use of space for these types of projects.”
When the Fresh Kills landfill was decommissioned, the final two of its four landfill mounds were capped and a landfill gas control and collection system was installed so that any gas produced by the breakdown of landfill waste could be collected and either burned off or processed for domestic energy use at an on-site plant, according to the Department of City Planning for the City of New York’s Fresh Kill’s website.
The caps placed atop the landfill mounds comprise five layers. The first is a primary soil barrier that is used to contour the landfill mound to ensure that the maximum grade of the slopes fall within the 4 percent to 33 percent parameters required by the New York State Department of Environmental Conservation. These slope limits help to maintain drainage flows, but decrease the chance of slope instability. Atop this layer, an impermeable plastic liner is placed as a hydraulic barrier to prevent water from entering the landfill waste from above the layer and gas from escaping from the waste below the layer. A network of wells connected by pipes below this layer will collect any landfill gas that is produced by the breakdown of waste and convey it through a vacuum so that it can be treated or burned off at specific locations.
The third layer of the cap, placed atop the plastic lining, is a drainage layer that prevents oversaturation of top layers, according to the department of planning’s website. This is topped with a soil layer that is a minimum of 24 in. deep that protects the underlying layers from extremes weather conditions. The cap is finished with a minimum 6 in. top layer of fertile soil—in this case sandy loam—that provides an opportunity for vegetation to grow.
Because of the capping system that has been put in place, it is crucial that the solar arrays rest atop of the capped landfill without penetrating the subsurface, Raeder says. Although the brownfield site does not have the same limitations as the capped landfill, the subsurface is still an unknown, so the best choice here is also an array that rest atop the ground’s surface, Wingard notes.
For this reason the arrays on both the Arthur Kills site and the East site will likely be ballasted, fixed-tilt, racking structures that extend 8 to 9 ft in height, according to Wingard. With the ballasted systems, a string of photovoltaic modules are connected to one another, much as a string of lights would be, and held in place at either end by solid concrete ballasts measuring 14 by 70 in. Depending on the final equipment selection, 18 to 20 modules will be connected in a string, according to Wingard.
The string of modules will “sit on top of the existing grade, so there is no real subsurface type work that we would have to physically do,” Wingard says. “The modules themselves are typically placed at a twenty degree fixed tilt, [and although] we could look at potentially going in ten different scenarios...we’ve typically found that two modules in portrait style is the best approach.”
Because the Fresh Kills site is an elevated site, wind loading will be the controlling design force for the solar array there, rather than any floodplain issues, according to Wingard.
While the photovoltaic panels will generate direct current electricity, the current will be passed through 1000V DC design UL-rated inverters to become alternating current before being sent to the utility company, Wingard says. The postinverter interconnection process with the utility is the biggest unknown when it comes to the design of the arrays, Wingard says, because each site is unique.
Currently, SunEdison is undertaking a nondestructive and noninvasive site investigation, according to Raeder. Once this work is complete, the various zoning and other approvals necessary to ultimately obtain a building permit will be completed, including the city environmental quality review, the uniform land use review procedure, and the public design commission approval. In addition, SunEdison will need to obtain a state pollutant discharge elimination systems permit for the capped East site, which is also subject to an air quality permit, according to Raeder.
SunEdison will also go through the New York City Department of Parks and Recreation site approvals process to demonstrate that the planned solar arrays can safely be installed atop the capped landfill at the East site without damaging the environmental protection systems that are already installed there, Raeder says.
It is SunEdison’s hope that the first array, on the Arthur Kills site, will begin installation and come online in 2015. Because the permitting process for the East site is slightly more involved, SunEdison anticipates that that array will be online later, perhaps by the second quarter of 2016.