Roux Associates designed a NYSDEC approved alternative landfill cover (2nd approved alternative landfill cover in NYS) for a nine-acre industrial landfill at an 80-acre former chemical manufacturing facility adjacent to the Hudson River in Rensselaer, New York.
The alternative landfill cover design consists of a 30-inch soil cap to eliminate direct exposure of human and ecological receptors to underlying landfill waste. Rhizodegradation (i.e., degradation of organic compounds in the plant root zone) mechanisms provide for the insitu treatment of the landfill COCs, while phytostabilization (i.e., sequestration within the plant root zone) mechanisms provide for enhanced containment of metal COCs.
In order to obtain regulatory approval for the alternative landfill cover and preclude the need for a 10-7cm/sec low permeability liner, the design had to demonstrate equivalency with the state landfill closure regulations (6 NYCCR Part 360). Accordingly, the vegetation planting density for the landfill cover was designed to balance the water needs of the various plants with the evapotranspiration requirements to minimize infiltration.
In addition, the landfill cover was designed to minimize leachate generation even during plant dormancy periods, with residual water stored in the surface soil material. Through the completion of a detailed water-balance analysis and discussions with the state, Roux Associates demonstrated the water infiltration equivalency requirements of the state regulation were achieved, and the alternative cover design was therefore approved.
The cap vegetation includes numerous native species to promote ecological diversity and create a valuable wildlife habitat. The project was officially certified by the Wildlife Habitat Council in 2008 as part of the Wildlife at Work and Corporate Lands for Learning programs.
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