Former Landfills

Landfill Frequently Asked Questions

At one time, landfills on Forest Preserve District property accepted residential and commercial refuse and served the solid-waste disposal needs of DuPage County. Revenues collected from operating these landfills are now part of an ongoing, nontax-supported revenue stream that benefits a variety of Forest Preserve District developments and operations.

The Forest Preserve District's Resource Management & Development department oversees the management of these former landfills. It also manages the cleanup of contaminated parcels the Forest Preserve District has acquired over the years. Revenue the District has collected from operating the landfills and not tax dollars fund these cleanup and remediation projects.


Why did the Forest Preserve District build landfills at Mallard Lake and Greene Valley?

On Oct. 3, 1972, the DuPage County board passed a resolution permitting landfills at Mallard Lake, Greene Valley and East Branch Reservoir forest preserves. The Forest Preserve District’s Board of Commissioners passed the same resolution on Oct. 19, 1972. The joint resolution succeeded because the county needed waste-disposal sites; the District had land that could not be incorporated into a municipality; the county had the authority, at the time, to regulate waste disposal; and the Forest Preserve District wanted to construct recreational hills. In the end, an East Branch Reservoir landfill was never constructed. 

Can you provide some specifics about the Greene Valley landfill?

Disposal operations began on Oct. 3, 1974, and the landfill received the last load on Aug. 31, 1996. The disposal area occupies about 200 acres. The permitted height of the hill is about 190 feet above land surface at the highest point, which is approximately 880 feet above mean sea level. The airspace occupied by refuse in the landfill is more than 40 million cubic yards.The plant has three Caterpillar solar gas turbines, each rated at 3,300 kWh for a total of 9,900 kWh or 9.9 megawatts. After removing the power necessary to run the plant, the parasitic load, the plant delivers about 9 megawatts to ComEd power lines located at Greene Road and 75th Street. This power is enough to serve the average needs of about 7,500 homes or the energy equivalent of 84,000 barrels of oil per year. The plant became operational in May 1996 and is expected to produce power for at least 20 years.

Can you provide some specifics about the Mallard Lake landfill?

Disposal operations began on March 4, 1975, and the landfill received the last load on March 13, 1999. The disposal area occupies 230 acres. The permitted height of the hill is about 190 feet above land surface at the highest point, which is 982 feet above mean sea level. The airspace occupied by refuse in the landfill is roughly 40.7 million cubic yards.

Is the Mallard Lake landfill the highest point in DuPage County? In Illinois?

The Mallard Lake landfill is the highest point in DuPage County. Charles Mound in Jo Daviess County in northwest Illinois, 15 miles northeast of Galena, is the highest point in Illinois, with an elevation of 1,235 feet above mean sea level. However, Charles Mound is only 75 feet above land surface. The District is currently searching for information on how Mallard Lake and Greene Valley rank by height above land surface.

Why did the Forest Preserve District build a landfill at Blackwell?

Mount Hoy, the District’s first landfill, was constructed at Blackwell Forest Preserve in Warrenville in 1965. It was designed to replace one near the DuPage Airport, which was about to close.At the time, the District was involved in the expensive process of constructing Silver Lake at Blackwell. Building a landfill and charging a disposal fee was a way to offset the cost of the project and provide a place to dispose of surplus construction soil. About 50 percent of the material in Mount Hoy is soil; landfills today are 20 to 30 percent soil.

What are some specifics about Mount Hoy at Blackwell?

The landfill was open from 1965 to 1973. It was originally 150 feet above land surface but, due to settlement, is currently at about 112 feet. It occupies roughly 40 acres and contains about 1.5 million yards of refuse and roughly the same amount of soil.

I’ve heard that Mount Hoy is on the EPA’s Superfund list. What does that mean?

The term “Superfund List” is a shortened reference to the National Priorities List and the Superfund Program. The U.S. Environmental Protection Agency developed the National Priorities List to evaluate and rank sites for potential cleanup. The government uses monies from the Superfund Program, which is supported by a federal tax on certain chemicals, to clean up a site on the National Priorities List when it cannot locate the individuals or companies responsible for the contamination to pay for the cleanup.In the early to mid 1980s, the District detected contaminants leaking into the groundwater just south of Mount Hoy and reported the findings to the EPA. In 1986, the EPA evaluated these contaminants and scored the site for inclusion on the National Priorities List. In 1989, the District agreed to conduct the necessary studies to determine the risks associated with the site; and in 1990, the EPA placed the site on the list.

How is the cleanup funded?

Revenues the Forest Preserve District received from the operation of landfills at Greene Valley and Mallard Lake are funding the cost of the cleanup at Mount Hoy. No tax dollars are being used.

What would have happened if the Forest Preserve District didn't agree to the studies?

Under the Superfund Program, if a responsible party refuses to conduct the required studies and cleanup, the EPA can step in, perform the necessary work and charge the responsible party three times the cost of the work.

What are the green fiberglass “boxes” on Mount Hoy?

The devices are 8-by-4-foot vaults, which contain the tops of wells, which remove contaminated liquid, called leachate, and landfill gas from inside the landfill. Underground pipes convey the leachate to a collection tank, which is then trucked to a processing facility for treatment and disposal. Separate pipes convey the gas to a vent stack at the top of Mount Hoy.

Why was the swim beach closed at Blackwell? Will it reopen?

The Forest Preserve District closed the beach in 1984 as a precautionary measure after monitoring wells detected the contaminated groundwater between the beach and Mount Hoy. At the request of the EPA, the beach area remained closed until the completion of the required studies and cleanup.In 1999 the EPA issued a set of guidelines under which it would allow the swim beach area, now call Sand Pond, to reopen. The EPA has not detected any contamination of Sand Pond from the landfill but is concerned that any use of water associated with the redevelopment of the Sand Pond area might interfere with groundwater monitoring. Additionally, to reopen Sand Pond as a swim beach under current health codes would cost about $5 million. Instead, the Forest Preserve District incorporated the pond into a recreational area featuring a trailhead, archery range, ADA-compliant fishing pier, picnic shelter and restrooms.

How are costs for recreational improvements funded?

Construction costs for the Blackwell recreation area were paid for from the Forest Preserve District's royalties received when the landfills were operational. No tax dollars were used.

How does the leakage at Mount Hoy affect drinking water?

When the EPA originally scored the site, it did not find any connection between the site and contaminated supplies of drinking water. It listed the site because of the number of people who lived in the general area and because a potential did exist for contaminated drinking water. Today, ongoing monitoring has detected contaminated groundwater only within 200 feet of Mount Hoy, and none of the contamination exceeds any health-based standards for drinking water.


What does the Forest Preserve District have planned for Mallard Lake and Greene Valley? Will they be used as ski hills?

At both locations, the ski hill concept was abandoned in 1982.

In spring 2000 at Greene Valley, crews started construction on the landfill’s end use. Today, the hill features parking lots at the top and bottom, a road that connects the two, a 2-mile road around the perimeter, and native-plant test plots. The parking lot at the bottom of the hill also serves the rest of the forest preserve via a trail connection.

Greene Valley is expected to serve as a template for the hill at Mallard Lake.