SEOUL — Hundreds of South Korean soldiers have begun environmental cleanup at seven former U.S. bases in South Korea, Defense Ministry officials said.

Cleaning began on former U.S. camps Kyle, Garry Owen, Edwards, Essayons, Sears, Grey and Page on Sept. 7, a ministry spokesman said. The news wasn’t announced until late last week.

They also examined another 16 sites and bases turned over by the U.S. since 2006 before turning their attention to South Korean military bases.

The 512 troops — split into two units — are the first in South Korea’s military ever to be dedicated to environmental issues, a ministry spokesman said.

“Currently, the environmental units are taking measures to curb the spread of pollution in the 23 returned bases and checking related facilities including the sewage systems,” the ministry said in a statement.

The cleanup units began work after 100 days of study and field training, the statement said.

The South Korean government has budgeted 10 billion won, or about $10.9 million, for the cleanup efforts.

A ministry spokesman declined to provide details on the extent of the pollution.

The status of forces agreement allowed U.S. Forces Korea to return the sites without environmental treatment of pollutants beyond those posing “known, imminent, and substantial endangerments to human health.”

In return, South Korea received the sites and infrastructure, which U.S. Forces Korea estimates as worth billions of dollars, at no cost.

However, Camp Page in Chuncheon showed elevated levels of petroleum byproducts and other chemicals in its drinking water, according to a report earlier this year from the South Korean National Assembly’s Environment and Labor Committee.

Benzene and other chemicals also were found in underground water at levels exceeding South Korean health standards, a committee aid who spoke on condition of anonymity said Friday.

Benzene is listed by both the U.S. Environmental Protection Agency and its South Korean counterpart as a carcinogen.

Total petroleum hydrocarbon levels registered at 50,552 milligrams per kilogram of soil at Camp Page, according to the committee report.

The same figure had been leaked to South Korean media in February 2006. South Korean standards call for “anti-contamination” measures at 1,200 milligrams per kilogram of soil.

Levels of BTEX, a group of four chemicals that make up a large percentage of petroleum products, registered at 1,152 milligrams per kilogram of soil at Camp Page. South Korean standards call for a cleanup at 200 milligrams per kilogram of soil.

The United States began transferring the military sites in July 2006.

They were supposed to be returned to South Korea in 2005 as part of an earlier agreement. However, environmental groups and some lawmakers protested that the agreement should be renegotiated to have the United States pay for cleanups.

South Korea agreed again to pay for cleanup costs in April.

USFK expects to return 59 camps totaling 33,000 acres valued at more than $1 billion to South Korea’s government within four years.

The base handovers are part of the plan to move nearly all U.S. servicemembers from Seoul and the Demilitarized Zone.

Camp Humphreys, located about two hours south of Seoul in Pyeongtaek, will triple in size to accommodate the transition. The move originally was to begin in 2008, but protests and planning delays have pushed the date to 2012.

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