Kill2 (kil) n. A creek, stream, or channel: an element in many U.S. Geographical names. - Funk & Wagnalls comprehensive edition 1987

Creation of Coastal Scrubforest on a Landfill

By William Young, RLA

With the proliferation of landfills and other highly disturbed sites in space-starved urban areas, interest has grown in trying to restore these areas using an ecological approach. Landfills have strict post-closure requirements, steep slopes and limited building options. The landfill also tends to have a large acreage and is virtually saved open space. Therefore, restoration to a native habitat is one of the few options available. In fact, we hypothesize that landfills can act as "Greenways" or wildlife corridors to adjacent protected natural areas, uniting disparate ecological units.

Yet state regulations do not allow woody vegetation to be planted on standard final cover, which unfortunately severely limits the restoration potential. The solid waste regulators are worried about tree roots impacting the clay cap, which is the only barrier that seals the landfill from infiltration. In response to that concern, a hydroseed mixture of non-native grasses is what usually gets specified. The standard final cap and cover can cost up to $250,000 dollars an acre and then each acre has to be certified to the state Department of Environmental Conservation.

In 1989, the New York City Department of Sanitation performed demonstration plantings on a six acre section of the Fresh Kills Landfill. This was notable for being our first attempt to install entire plant communities on capped portions of the landfill. Our previous plantings, over 10,000 trees and shrubs, were for perimeter screening on non-landfill areas. This demonstration landfill planting was to gather information to form the basis of our restoration program at Fresh Kills.

The Fresh Kills Project

What we set out to demonstrate was the following:

• Performance of various soil mixtures,

• Performance of native plants installed in rough approximations of their natural habitat

• A real, live plantation to illustrate to the Department and the regulators we were capable of restoration

• Restoration costs

• Qualifications of contractors

Native plants were installed in three distinct communities: Oak scrubforest, Pine-oak forest and Ericaceous (acid-loving) shrubland. The Rutgers University Graduate Ecology Program for survival and recruitment monitored it over a one year period. A meadow reminiscent of the eastern prairie as it exists on Staten Island was added, and since grasslands are allowed on the cap, this could end up being the dominant ecosystem designed for the landfill final cover. The ericaceous plants also had obvious merits for over the clay cap, which was known to produce acid soils.

Instead of the standard cap and cover, an undulating dune-like slope was designed over 40 cm. of compacted till soil to simulate coastal sites. As part of an overall ecological approach, topsoil was manufactured out of dredge spoils, sand, and compost of various experimental ratios and depths (30 to 90 cm). Discarded Christmas trees were chipped to provide mulch to supplement contractor-supplied wood chip mulch.

The plantings took two full seasons to install. The oak forest consisted of 14 species, with single species clustered in groups of 6-10. The pine-shrub mix of 14 species, and an ericaceous shrubland of six species clustered over 1 1/2 acres.

Because many of the eighteen native species were hard to find, we used techniques like contract growing and plant rescue. "Plant rescue" is a program with the NYC Parks Department to rescue plants from sites slated for development on Staten Island.

Approximately 3000 shrubs were planted in small clusters (6-12 plants of one species per cluster) among the three sites, and 500 trees were distributed among the pine and oak dunes. In addition to woody species, the site was overseeded with native perennial grasses and wildflowers as found in the original eastern prairie on Staten Island.

Since irrigation systems are impractical on remote sites like Fresh Kills, watering was sparse. The only care the plants received was during the one year "Guarantee" period. In spite of this virtual neglect, the plants did very well. Ironically, the landfill soils and slopes are not much different from the natural habitats of these plant communities. Our challenge was to model these as closely as possible, knowing that the best reproduction was still very much a synthetic ecology.

Bill Young is a Project Manager for the Department of Sanitation. He has spoken extensively on the end-uses of landfills and is a staunch advocate of restoring landfills to native habitat. He has been featured on ABC News, CBS News, and CON Network Earth. For further information contact him at: NYC Department of Sanitation, 4 Beaver Street, 9th Floor, New York City, NY 10004.LASN