Capping is currently underway at the East Mound, where soil is being compacted atop an impermeable plastic membrane. This gives visitors a peek at the process, which is designed to prevent leakage of toxic gases and leachate, a sludge byproduct of decomposing trash and water, into the new environment.
Atop compressed garbage of an indeterminate depth, a soil barrier layer and gas vent (gravel) layer are laid out. These layers allow for the gradual transmission of gas to a vacuum system of gas wells, composed of perforated intake pipes, valves, and transmission lines. Methane gas is extracted from other vapors created by the decomposing trash at on-site purification facilities, and sold by the local utility to power and heat over 20,000 Staten Island homes. When repairs must be made to the system, gas is routed to a flare station, and burned in a controlled manner. In the future, minimal amounts of gas will not be useful, so a system of goose neck pipes will passively release the gas to prevent dangerous buildup underground.
Above the impermeable membrane, a drainage layer directs stormwater to reduce runoff and prevents breaks in the plastic. On top of that, a barrier protection material 2 feet in thickness provides additional protection for the membrane, and atop that minimum of 6 inches of planting soil, used to shape the mounds and provide an organic base for vegetation. A natural plastic clay layer, originally seen as a benefit for landfill use, prevents leachate leaks into groundwater, and walls of manufactured impermeable material complete the seal. Because of high toxicity of present materials, Sanitation will continue to monitor each mound for 30 years after each cap, and then reexamine risk factors.
Freshkills Park designers and organizers plan on utilizing every bit of infrastructure left to them by the Department of Sanitation, including buildings, treatment facilities, and even landfill vehicles. Massive excavators present one of the most innovative uses of these obsolete machines. One of these imposing contraptions will be positioned by a highway cutting through the site, supporting a billboard advertising the opening of the park. Others may be positioned as urban furniture along a promenade. Landfill barges used to transport trash into Staten Island will be transformed into floating gardens docked at the main creek in the Confluence zone.
The reconstruction of nature in a place so ravaged by the byproducts of modern society takes decades of effort and numerous contamination risks. Freshkills Park is and will be an inspiring testament to man’s power to remediate his effects on the environment. But unless we begin to monitor our consumption, specifically disposable goods and packaging, there will be the need for more Freshkills, and more reconstructed, instead of preserved, environments.
All images © Leonel Lima Ponce for Inhabitat