WASHINGTON — Thirty-four military bases fully or partially 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.

Utah's Tooele Army Depot is listed among 10 sites with problems — groundwater contamination in Tooele's case — not yet fully under control.

As the latest base-closing commission begins its work, an examination by The Associated Press shows EPA concerned with 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 EPA's Federal Facilities Restoration & Reuse Office. "It may take longer to remove them from the list because of groundwater contamination or unexploded ordnance."

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.