Long Island Lemonade

When the Town of Hempstead on Long Island, N.Y., was told to cap the closed Merrick Landfill in 1994, Sanitation Commissioner Richard T. Ronan knew he had a problem. Changing the landfill's steep sides to conform to New York's slope requirements would have extended the site into tidal wetlands and other environmentally sensitive areas.

Ronan decided that because he had been handed a mess of lemons, he would make lemonade. Ronan and the consulting engineering firm Lockwood Kessler and Bartlett Inc. (LKB), Syosset, Long Island, N.Y., came up with a design to cap the top of the landfill and trap rainwater in two lined ponds on the plateau. This would keep rainwater from seeping into the buried garbage and limit runoff on the slopes.

By minimizing the amount of excavation, Ronan and LKB were able to preserve and enhance the growth that nature had accomplished in the decade since the landfill closed. Taking advantage of the site's spectacular location, they created not just a park, but a unique community asset.

The result is the Norman J. Levy Park and Preserve, which was formally dedicated in October 2000. The park puts “green” principles into practice by including:

  • three miles of hiking trails (many of which are handicapped-accessible),

  • exercise stations,

  • two rainwater ponds aerated by a windmill,

  • plantings of indigenous species,

  • a restored tidal wetland,

  • a kayak-launching ramp,

  • informational signs explaining the site ecology,

  • recycled materials used for paving and construction, and

  • composting toilets.

Future plans include a fishing pier and The Children's Environmental and Recycling Learning Center museum of solid waste and recycling. The project cost the town $17 million but saved taxpayers more than $40 million.

A Natural Advantage

The process was not simple. Some of the slopes were on a 1-to-1 ratio, and the state required 1-to-3. “When the landfill was built in the 1950s, it was state-of-the-art. Using concrete slabs taken from the demolished Mitchell Field airfield, they buttressed the sides and filled them. That is why the slopes are so steep,” says Paul Lappano, director of environmental engineering for LKB.

But reducing the slopes would have extended the landfill deep into the tidal wetlands and Meadow Brook along the western boundary of the site, and over the golf course on the site's eastern boundary. It would have also extended out into Merrick Bay to the south.

Merrick Bay is part of Long Island's system of south shore embayments and is an important shell-fishing and recreational resource. Furthermore, the project would have cost the town $60 million.

Ronan had an important natural advantage, however. The site is underlain by meadowmat, a dense, silt-laden, clayey material that acts as a natural filter. This was confirmed by three rounds of groundwater well sampling. Additionally, because of the volume and type of buried waste, gas generation was minimal. Ronan therefore undertook what he calls a “holistic approach,” combining three key elements — “the consultant, the community and state regulatory agencies.”

LKB was hired to help the town develop the design and to shepherd it through the complex permitting and approval process, Ronan says. The firm had the in-house resources for the project: engineering, hydrogeology, ecology, surveying, landscape architecture and construction administration.

Ronan already had a base of community support. Opened in 1950, the Merrick Landfill received household garbage, rubbish and demolition debris, street sweepings and landscape waste. When the landfill was closed in 1984, it contained an estimated 4 million cubic yards of waste. Rising 115 feet from the shores of Merrick Bay and Meadow Brook, the 50-acre site was untouched for the next 10 years.

As trees (some now as tall as 20 feet), sedges, grasses and other plants began colonizing the slopes, local residents began using the landfill for bird watching and for its spectacular views of Great South Bay to the south and New York City to the west. A citizens group had approached the town with a nature preserve proposal. And residents wanted the site preserved.

In addition, Ronan had been offering residents tours of the landfill and the adjacent solid waste handling facility. He also would meet with local groups to discuss the future of the landfill. Thus, the community was solidly on board and backed the plans before the regulatory agencies.

Even with strong community support, the permitting and approval process took a year. According to Lappano, the project needed permits and consent order approvals from the New York State Department of Environmental Conservation (DEC), Stony Brook, N.Y., and permits from the U.S. Army Corps of Engineers, New York, N.Y. This included detailed engineering plans and specifications, an ecological study plan, an operations and maintenance manual, and wetlands permits.

The project also had to satisfy 44 policy initiatives to get coastal zone certification from the New York Department of State, Albany, N.Y. “The permitting and approval file alone on this job is about a foot thick,” says Matthew Lang, the LKB ecologist who was in charge of the permitting process.

An Eye on Ecology

Under the plan, the slopes were not altered. LKB capped 8.4 acres at the top and collected rainwater in two ponds, which are aerated by a mechanical windmill. Electrical generation was investigated but not considered feasible because of low wind speeds.

In accordance with New York State solid waste regulations, the storage and drainage system was designed for a 25-year, 24-hour storm. However, the DEC wanted to ensure that as the landfill settled, the ponds would not leak into the waste mass. Consequently, the half-acre ponds were double-lined, a leak detection system was installed between the liners, and a 60-mil, white, high-density polyethylene (HDPE) cap liner was placed over the entire system. This provides three liners over the landfill at the ponds. Additionally, having two ponds interconnected with a valving chamber ensures that if one is taken out of service for repair, the other pond will still operate.

The ponds are a maximum of six feet deep at the center and were stocked with goldfish to eat mosquito larvae and enhance the wildlife habitat. Ronan also plans to use mosquito fish, Gambusia affinis, to control mosquitoes. Pond overflow is piped into a two-acre restored tidal wetland at the base of the landfill and into existing wetlands on the southern base. This prevents overflow rainwater from going through the garbage. Furthermore, any stormwater from the capped side slopes is collected in a gravel trench and also directed to the wetlands.

When the two-acre tidal wetland at the base of the landfill was restored, an overlook was constructed for park visitors. “Everyone on Long Island knows the value of wetlands,” Ronan says, “but it's surprising how few people have actually seen one.”

The kayak launch ramp, deck and railings of the wetlands overlook are constructed from lumber made from recycled wood and plastic. Wastebaskets also are made from recycled materials. An outdoor orientation center is used by school groups and nature study organizations.

To integrate plans for the landfill capping with plans for the nature preserve, the engineers added documents into the contract that included layout, drainage, the public entrance, the outdoor orientation center, the composting toilets and the pathways. It also saw that the facilities met the Americans with Disabilities Act requirements. “The major challenge was creating the environment — transforming it into something else while it is still a landfill,” says LKB's Steve Fuhrman. “I wanted to take this waste site and turn it into something that a person [would recognize] as a wildlife refuge with paths. Most people don't even know it is a landfill, and making this transition was the most difficult part. I tried to change the experience of being in that place.”

A large part of the experience involves the site vegetation. As much as possible, the engineers tried not to disturb the existing vegetation and used plants indigenous or widely distributed on Long Island to improve the wildlife habitat, provide slope stabilization and improve overall site aesthetics.

The plantings had to survive a wide range of harsh conditions such as drought, high winds and poor soils. To accomplish this, the engineers worked with local nurseries to acquire as many Long Island-grown trees and shrubs as possible, while working with a specialized supplier in Wisconsin to obtain the seed mixtures.

The planting program uses six different seed mixtures, including one that duplicates the Hempstead Plains, a Long Island prairie environment that now is largely destroyed. Because it will take three years to establish the plantings, each mixture includes a nurse crop of fast-growing rye grass to control erosion and stabilize slopes and soils. And visitors say the results are dramatic.

Looking across the Great South Bay to the barrier beach beyond, or down to the wetland from the top of the landfill, it is difficult to believe the site is in one of the most densely populated counties in the nation. Some 30 miles to the west, the twin towers of the World Trade Center in New York City are visible on the horizon. Ronan says on the clearest days, visitors can see as far as the Palisades across the Hudson River in New Jersey.

Additionally, a dozen bird species have been recorded onsite, including great blue heron, great egret, northern harrier, belted kingfisher, green heron, American coot, seaside sparrow, brant, bufflehead, spotted sandpiper, mallards and seagulls. Visitors look forward to seeing fledgling osprey in nesting platforms constructed on the site, Ronan says.

A rustic, arched wooden bridge crosses between the ponds to provide visitors glimpses of the goldfish. And water bubbles across a jumble of rocks from the windmill to the ponds.

To provide further enthusiasm for the park, exercise stations are set up with suggestions for both vigorous and gentle exercises. Signs and illustrations explaining the site ecology are placed at the wetlands overlook and along the hiking trails.

The parking lot and many of the paths are paved with recycled clamshells obtained from a local clam canning company. The mix of 60 percent to 70 percent shells with 30 percent sand gets well-ground-up during use, and calcium leaching from the shells bonds the mixture together. Beneath the path mix, a filter fabric and gravel have been underlain to aid in drainage and prevent the soil-clambshell mix from migrating into the subsoil. This layering also provides a stable, flexible surface that can be easily maintained and will not crack during settling, LKB says.

The composting toilets are similar to those used by the National Park Service, Washington, D.C., and the state DEC. Air is drawn through a mixture of wood chips and waste, which also is misted. The air discharge is well-above head height to prevent odors. The engineers estimate it will take two to three years to produce the final compost mix, which then could be added to the onsite plantings.

Looking Ahead

To ensure the Merrick Landfill does not harm the environment, the site will be monitored for the next 30 years, Ronan says. Leak detectors have been placed between the pond liners. And, methane and air quality monitors dot the site.

The state also is requiring ecological monitoring. The restored wetland, which was densely planted with the marsh grass, Spartina alterniflora, must have 85 percent aerial coverage within five years. LKB has done baseline studies of flora and fauna as well, and these will be compared on an annual basis.

Ronan is confident that the project protects, preserves and enhances the environment. He considers it a major educational resource that teaches the public about solid waste in the community, as well as about Long Island's natural resources. And with hundreds of visitors per day and public requests for additional activities, such as snowshoeing and cross-country skiing, the preserve is an unqualified community success.

Judy Fischer is a free-lance writer based in Port Jefferson, N.Y.