The result of Seoul City’s probe into soil and groundwater in areas near a US military base in central Seoul over alleged oil leaks came out Tuesday, showing below average levels of contamination in the samples from six of nine sites around the military base in Yongsan.

In August, the Seoul city government conducted its own survey on soil and water near the US base for possible contamination with toxic chemicals, amid growing calls for the disclosure of pollution levels in the area. 

According to the analysis of samples released Tuesday, all six areas had soil and water contamination below average levels, based on the Soil Environment Conservation Act here.

However, two spots, the main post and the transportation office, will be reinvestigated next month, the city said, as samples from there were close to the average level.

Officials said that levels of total petroleum hydrocarbon detected from these sites were close to exceeding the standard level of 500 milligrams per kilogram. The detected amount was 471 milligrams per kilogram. 

“Although there were no significant traces of contamination found from the probe this time, we are still concerned about areas where contamination levels were close to the standard, while the source of the pollutants near the US military base remains unknown,” said Kwon Ki-wook, chief of the city’s water circulation safety bureau. 

According to the city government’s internal inspection last year, the average benzene concentration near Yongsan Garrison recorded 8.811 milligrams per liter, approximately 587 times higher than the permissible level of 0.015 milligram per liter. 

Benzene, a group one carcinogen classified by the World Health Organization, was found at 10 spots around the camp. The city has reportedly spent over 7.8 billion won ($6.9 million) in cleanup efforts over a decade.

The city government said it would request the USFK jointly conduct a comprehensive investigation for an additional inspection. 

Since 2001, when an oil spill was first reported near Noksapyeong Station, the US military has rejected requests by the city government and civic groups to run a comprehensive investigation. 

The military said that the US is not required to reveal any information about such contamination, according to the Status of Forces Agreement. It also refused to disclose the details of its cleanup efforts. According to SOFA, the US military is only responsible for contamination within its camp.

Last year, the Ministry of Environment conducted three separate tests inside the base in joint efforts with the USFK and it released the first set of results after a Seoul court ruled in favor of a civic group that filed a suit demanding the public disclosure. 

Activists have voiced concerns over the health effects of exposure to the contamination. Following the relocation of key military bases in central Seoul to Pyeongtaek by 2018, the city plans to turn the area into a public park.

By Kim Da-sol (ddd@heraldcorp.com)