Turning landfills into wildlife habitats.

It is a theme heard over and over again from environmentalists and concerned citizens – open space and wildlife are disappearing.

As housing developments, shopping malls, industrial complexes, landfills and roads gradually compete for the last remnants of our urban and suburban open space and the wildlife that lives in it, innovative solutions are emerging. One of the best solutions is the result of an unlikely collaboration between industry, environmental groups and local citizens.

Although it may seem like landfills and industrial facilities are unlikely candidates for wildlife habitat, recent efforts show that some of them can de rehabilitated or restored as high-quality wildlife habitats.

There are millions of acres of landfills and industrial facilities across the country, and many are within urban or suburban areas where open space is limited. Determining what should be done with these facilities is a formidable task, although transformation of many of them to wildlife habitat is an ideal solution.

The idea for converting landfills and industrial facilities into wildlife habitat has emerged over many decades, in part, by accident. As such sites were closed or renovated, people noticed that wildlife started to return or became more abundant. Slowly, environmental groups and those companies that owned the land began to realize its value to wildlife. This realization took shape as concerted efforts were made to transform “brownfield” sites to viable habitat.

Near Boston, the town of Saugus, Mass., is capping a 40-year-old landfill with the intention of returning it to the marshland it originally was.

Locally based Wheelabrator RESCO, a subsidiary of Wheelabrator Technologies, has used the Saugus landfill since 1975 as a repository for ash that is generated by its municipal trash-to-energy facility, which is adjacent to the landfill.

Facing closure of the landfill, the company decided to convert the site into a wildlife sanctuary complete with trails. The conversion of the Saugus landfill to wildlife habitat is more critical than it would seem because the adjacent 1,500-acre Rumney Marsh was recently classified as an Area of Critical Environmental Concern by the state.

To restore wildlife habitat to the Saugus landfill, the company contracted with Great Meadow Farm, a salt hay farm/habitat rehabilitation company, and the Massachusetts Audubon Society, the largest non-profit environmental organization in New England. Great Meadow Farm is doing the actual restoration and collaborating with Massachusetts Audubon on habitat and sanctuary design.

Surrounding the landfill is a pristine salt marsh, tidal creeks, mudflats and thousands of migrating, wintering and breeding birds. Snowy owls visit these marshes, as do waterfowl, sandpipers and endangered peregrine falcons. The design of the wildlife area balances two factors: the physical constraints straints of a capped landfill and the needs of wildlife.

Grassland was chosen as the primary habitat because the shallow roots of grasses, unlike many trees, will not damage the plastic landfill cap. Coincidentally, grasslands are the most endangered of all habitats.

If properly created and managed, the created grasslands may attract nesting upland sandpipers, grasshopper sparrows and other endangered or threatened birds. Massachusetts Audubon hopes that declining species of native plants and butterflies will be reintroduced. In addition, a 40-acre freshwater wetland and some small forested areas are planned.

The latter habitats will provide for greater biodiversity as well as making the site more aesthetically pleasing.

When the Saugus landfill-to-wildlife habitat conversion is finished in 1998, it will permit safe, public access to the Rumney Marshes.

More than a mile of trails with interpretive signs (some in Braille) will be built. Designated trails will be handicapped accessible.

Blinds for observing and photographing marsh and water birds will maximize viewing opportunities while minimizing wildlife disturbance. For those less intent on watching wildlife, the trails will afford panoramic views of the Boston skyline and harbor as well as the surrounding marshes.

Improved technology for landfill closure and strong regulatory requirements now ensure that sites such as this will not be environmental liabilities, clearing the way for wildlife habitat restorations.

For example, Wheelabrator used recent innovations in Saugus to prevent landfill run-off from polluting ground-water and nearby wetlands. The most important feature is a plastic liner that “caps” the landfill and is covered with at least two feet of earthen materials.

Rainwater that percolates through this soil hits the cap and runs off without contacting landfill contents.

Equally important is the construction of a bentonite slurry wall that encircles the landfill. The underground bentonite wall is impermeable to liquids, yet flexible so it will not crack.

In the case of the Saugus landfill, the bentonite slurry wall is at least three-feet thick, and in some places descends more thanfeet.

The depth of the slurry wall depends on the depth of impervious clay, which prevents water from percolating from the landfill downward into groundwater.