(UPDATE) According to Kanagawa Shinbun (8/26/2011), the radiation measurement of the sludge was: 1.70 microsievert/hour at 5 centimeters off the sludge, 0.42 microsievert/hour at 50 centimeters, and 0.21 microsievert/hour at 100 centimeters.)
16,500 becquerels/kg of radioactive cesium, and the park officials and the Kawasaki City government are at a loss what to do. They don't know where it came from, they don't know what to do with it.
On August 18, the sludge by the swimming pool in Hirama Park in Kawasaki City was also found with 12,400 becquerels/kg of radioactive cesium (see my post here). The air radiation level near the compost was 0.90 microsievert/hour.
From Tokyo Shinbun Kanagawa Local version (8/26/2011):
Following Hirama Park in Nakahara-ku, Inada Park in Tama-ku in Kawasaki City has also shut down the swimming pool because of the high air radiation level. Residents are surprised at the radiation contamination in their neighborhood, and the city officials are at a loss what to do.
The national safety limit for radioactive sludge is 8,000 becquerels/kg for disposal. But 16,500 becquerels/kg of radioactive cesium, more than twice the national limit, was detected in the sludge near the swimming pool entrance. The swimming pool is used by about 200 children per day during the summer break.
Some cloth and paper were found mixed in the sludge, and the Tama-ku center for roads and parks says it doesn't know where the sludge came from. Cleaning contractor who cleans the parks and the pool staff say they don't know either. It is unlikely that the sludge was from the swimming pool, according to the officials.
A citizens' group called "Peace and Smile Project Kawasaki" has been measuring the air radiation levels in Inada Park. One member says he was surprised. "My child comes to this park and use the swimming pool, so I measured several locations and found very high radiation far exceeding the normal level." He also says, "Kawasaki City is also measuring radiation, but the city is focused on locations with fallen leaves, and Inada Park was not included. I hope they measure more locations from now on."
One of the city officials who were measuring the air radiation at the site was totally at a loss. "We thought [the high radiation] was caused by fallen leaves. But it wasn't the fallen leaves. How much more should we investigate? We're confused because this is so beyond our expectation. If we expand the survey to many more locations, our regular daily work will be affected. To be honest, we would like the national government to do the survey".
The radioactive sludge at both parks were found by this volunteer group "Peace and Smile Project Kawasaki". Looking at their tweets on the Hirama Park sludge, the group has had such a struggle with the bureaucracy at the city offices and the Board of Education in Kawasaki City, who would rather not know about anything like highly radioactive sludge in the park. At one point, it seems the city was just going to have the sludge removed by a contractor and have it disposed as regular waste.
The word of the year in Japan for 2011 must be "想定外(soh-tei-gai)" - beyond expectation, unforeseen. From Kawasaki City officials to TEPCO officials to the national government ministers, it has been one big "beyond expectation" ever since March 11. (At least so they say.)