WASHINGTON ? Thirty-four military bases shut down since 1988 are on the Environmental Protection Agency’s Superfund list of worst toxic waste sites ? most of them for at least 15 years ? and not one is completely cleaned up.

As the latest base-closing commission begins its work, an examination by The Associated Press shows the EPA is troubled by incomplete pollution cleanups at more than 100 Defense Department facilities. Other military-related cleanups are being led solely by states.

Of the $23.3 billion in costs from four previous rounds of base closures and realignments, the Pentagon has spent $8.3 billion so far on pollution cleanups and other compliance with environmental laws, congressional investigators say. EPA officials say it will be at least a decade before many are completed ? at a cost the government estimates will reach an additional $3.6 billion.

They anticipate more military facilities will be added to the Superfund list after the newest round of base closings is completed. The Pentagon plans to give a list of recommendations to the Base Realignment and Closure Commission on Friday, the first major step in the process.

“A large majority of these [Superfund] sites will have all the remedies in place by 2015,” said Jim Woolford, head of the EPA’s Federal Facilities Restoration & Reuse Office. “It may take longer to remove them from the list because of groundwater contamination or unexploded ordnance.”

Maine has had 14 Superfund sites identified over the years, including the former Loring Air Force Base in Limestone, which was decommissioned in the early 1990s. Brunswick Naval Air Station and Portsmouth Naval Shipyard in Kittery are among the U.S. bases that could appear on the latest closure list. “Unlike the typical Superfund private-party sites, these sites are much larger and will generally have more contamination, and consequently take longer to clean up,” Woolford said.

However, it is the cleanups still under way that pose the most frequent obstacles to the Pentagon’s ability to cut costs by converting an installation to other uses.

Hard-to-remove contaminants include trichloroethylene, a cleaning solvent linked to cancer, as well as asbestos-tainted soil, radioactive materials and leaded paint.

“The environmental issues, including what type of cleanup needs to be done, have been the main holdup on all of these places,” Pentagon spokesman Glenn Flood said. “We’ll get it done, but it’s going to take time in some cases as we work with the communities.”

For the Air Force, 98 percent of the delays in transferring 24,000 acres from military hands are due to environmental issues. For the Army, it’s 82 percent of 101,000 acres. For the Navy, it’s 65 percent of almost 13,000 acres, says the General Accountability Office.

The GAO, Congress’ investigative arm, found the Defense Department has saved $29 billion, and can expect to save $7 billion more, from the closures.

About 72 percent of the property has been unloaded, but 28 percent remains in federal hands “due primarily to the need for environmental cleanup,” the GAO said in a report this month.

The Pentagon insists progress is being made but that it takes time to involve communities. “You don’t know what you have until you do a thorough examination, and it can result in some delays,” Flood said. “It’s never going to be fast enough for some communities.”

Flood said the base closures actually speed decontamination. “We have to clean them up whether they close them or not. With BRAC, they just move to the head of the line,” he said.

Since the Superfund program began in 1980 to clean up the nation’s most hazardous waste sites, base closure commissions in 1988, 1991, 1993 and 1995 made recommendations that led Congress to shut down 97 bases.

Twenty-eight of the 34 closed bases put onto the Superfund list were added at least 15 years ago, including 11 that went on a year before the first round of base closings.

Woolford attributed the delays in finishing those cleanups to the sites’ complexity.

EPA lists 10 sites where “groundwater migration” of contaminants is not considered to be fully under control yet. Five are in California; the others are in Arizona, Florida, Tennessee, Oregon and Utah. Two of those, California’s Fort Ord near Monterey and Tennessee’s Memphis Defense Depot, also note “human exposure” to possible health risks.

Woolford said some of those problems are nearly fixed, but the toughest and costliest remain at California’s McClellan Air Force Base, in Sacramento, and Fort Ord, in Marina.

Top 10 dirty base sites

The 10 closed military bases listed by the Environmental Protection Agency in its Superfund program with “groundwater migration” of contaminants or other pollution problems affecting “human exposure” not yet under control:

The Marine Corps Air Station, El Toro, Calif., groundwater migration.

Fort Ord, Monterey County, Calif., groundwater migration and human exposure.

Mather Air Force Base, Sacramento County, Calif., groundwater migration.

McClellan Air Force Base, Sacramento County, Calif., groundwater migration.

Memphis Defense Depot, Memphis, Tenn., groundwater migration and human exposure.

Moffett Naval Air Station, Santa Clara County, Calif., groundwater migration.

Tooele Army Depot, Tooele, Utah, groundwater migration.

Umatilla Army Depot, Hermiston, Ore., groundwater migration.

Jacksonville Naval Air Station, Jacksonville, Fla., groundwater migration.

Williams Air Force Base, Chandler, Ariz., groundwater migration.

Source: EPA