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Frequently Asked Questions About
Environmental Services

The following are answers to frequently asked questions regarding the District's involvement with landfills:

How did the District get involved in landfilling?

The District's first landfill, Mount Hoy, was constructed in the Blackwell Forest Preserve in Warrenville in 1965. The landfill was designed to replace the county's landfill that was located near the DuPage Airport and was getting ready to close.

Why did the District want to build a landfill on its property?

The District was involved in the expensive process of building Silver Lake at the Blackwell Forest Preserve in Warrenville. Building a landfill and charging a disposal fee was a way of offsetting the cost of the lake construction and providing a place to dispose of surplus soils from the lake construction. About half of the material in Mount Hoy is soil. Landfills constructed today are about 20 to 30 percent soil.

Can you give me some specifics about Mount Hoy at Blackwell?

The landfill was operated from 1965 to 1973. It was originally constructed to a height of 150 feet above land surface, but, due to settlement, is currently about 112 feet high. The landfill occupies about 40 acres and contains about 1.5 million yards of refuse and about the same amount of soils.

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 National Priorities List is a nationwide listing developed by the U.S. Environmental Protection Agency (EPA) that evaluates and ranks sites for potential cleanup. The Superfund is a federal fund that is utilized to clean up sites that are on the National Priorities List when none of the people or companies responsible for the problems can be located to pay for the cleanup. The fund is supported by a federal tax on certain chemicals. In the early to mid 1980s, the District detected contaminants leaking into the groundwater just south of Mount Hoy and reported the findings to U.S. 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 site was put on the list.

What would have happened if the District had not agreed to do the studies?

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

How is the cleanup being paid for?

The costs of cleanup at Mount Hoy are being paid out of revenues that the District received from the operation of the Greene Valley and Mallard Lake landfills. No tax dollars are being used.

How does the leakage at Mount Hoy impact drinking water?

When the site was originally scored, no impacts to drinking water supplies were detected that could be connected to the site. The site was listed because there were enough people in the site's general area, and a potential did exist for contamination of drinking water. Today, no contamination to groundwater can be detected beyond 200 feet from Mount Hoy, and none of the contamination exceeds any health-based standard for drinking water.

What are the green fiberglass box-like things on Mount Hoy?

These are 8-foot by 4-foot vaults that contain the tops of wells that go into the landfill to remove contaminated liquid (leachate) and landfill gas from inside the landfill. The leachate is conveyed by underground pipes to a collection tank. The leachate is then trucked to a processing facility for treatment and disposal. The gas is conveyed to a flare at the top of Mount Hoy.

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

On October 3, 1972, the DuPage County Board passed a resolution permitting landfills to be built at Mallard Lake, Greene Valley and East Branch Reservoir. The same resolution was passed by the Forest Preserve District of DuPage County's Board of Commissioners on October 19, 1972. The reasoning for the passage of the joint resolution was that the County needed disposal sites, the District had land that could not be incorporated into a village, the County had the authority (at the time) to regulate disposal, and the District wanted to construct recreational hills. A landfill at East Branch Reservoir was never constructed.

Can you provide some specifics about the Greene Valley landfill?

Disposal operations began on October 3, 1974, and the last load of waste was received on August 31, 1996. The disposal area occupies about 200 acres, and the permitted height of the hill is about 190 feet above land surface at the highest point, which is 980 feet above mean sea level. The airspace occupied by refuse in the landfill is more than 40,000,000 cubic yards.

The plant has three solar (Caterpillar) 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 (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 approximately 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 last load of waste was received on March 13, 1999. The disposal area occupies 230 acres, and 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 40,780,750 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 the land surface. We are currently searching for information on how Mallard Lake and Greene Valley rank by height above land surface.

What are the end uses planned for the Mallard Lake and Greene Valley landfills? Will they be used as ski hills?

The ski hill concept was abandoned in 1982. In spring 2000, construction of the landfill's end use was started at Greene Valley. This phase of construction consists of a parking lot near the bottom of the hill, a parking lot at the top hill, a road to the top of the hill, a perimeter road (about 2 miles), and native-vegetation-test-plot planting. The parking lot at the base of the landfill will also service the rest of the preserve via a trail connection.

Construction delays have changed the opening date of the landfill for recreational use to sometime in 2003. Greene Valley will serve as a template for the Mallard Lake landfill.

How will the costs of the recreational improvements at the landfills be paid for?

The construction costs will be paid for from the royalties the District received when the landfills were operational. No tax dollars will be used.

Why was the swim beach closed at Blackwell? Will the beach be reopened?

The District closed the beach in 1984 as a precautionary measure after the groundwater contamination was detected in a monitoring well located between the beach and Mount Hoy. At the request of the U.S. EPA, the beach area remained closed until the required studies and cleanup were completed. In 1999, the U.S. EPA issued a set of guidelines under which they would allow the swim beach area (now call Sand Pond) to reopen for recreational use. Although no contamination of Sand Pond from the landfill has been detected, the EPA is concerned that any use of water associated with the redevelopment of the Sand Pond area may interfere with the groundwater monitoring of the landfill. The current cost estimate to reopen Sand Pond as a swim beach that meets today's health codes is $5,000,000. The District is currently investigating other recreational uses of Sand Pond that will make maximum use of the existing topographic features.



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