(UPDATED) High Radiation Level Near an Elementary School in Yokohama Caused by Adjacent Business Washing Air Filters?

NHK News reports that 6.85 microsieverts/hour radiation detected at one centimeter off the ground at what used to be a sewer right next to the school yard in an elementary school in Yokohama City last month may have been caused by the waste water from a facilities management company on the other side of the drain.

The soil in the sewer was found to contain 62,900 becquerels/kg of radioactive cesium (according to Sankei Shinbun, 2/3/2012 in Japanese).

The company has been washing the air filters from air conditioning systems in buildings and factories in Kanagawa Prefecture, and apparently dumping the waste water into the drain.

NHK News (3/1/2012; if NHK link disappears, here's an alternative):

横浜市瀬谷区の小学校に隣接する水路の跡地で、通常より高い放射線量が計測された問題で、横浜市は１日、原発事故の影響で放射性物質が付着した空調システムのフィルターを洗浄した排水が流れ込んだのが原因ではないかと発表しました。

Regarding the high radiation levels detected at what used to be a sewer next to an elementary school in Seya District of Yokohama City, the Yokohama City government announced on March 1 that the high radiation may have been caused by the waste water from washing the air filters for air conditioning systems which had trapped radioactive materials from the Fukushima I Nuclear Plant accident.

先月３日、横浜市瀬谷区の市立二つ橋小学校の校庭に隣接する水路の跡地で、１時間当たり最大で６．８５マイクロシーベルトが計測されました。

On February 3, maximum 6.85 microsieverts/hour radiation was measured at where the sewer used to be, adjacent to the school yard of Futatsubashi Elementary School in Seya District Yokohama City.

横浜市などが調査したところ、隣接する設備管理会社が敷地内で神奈川県内のビルや工場などの空調システムの外気を取り入れるフィルターを水で洗浄していたことが分かりました。

The city's investigation revealed that a facilities management company located next to the sewer had been washing the air filters of the air conditioning systems at buildings and factories in Kanagawa Prefecture.

横浜市では、福島第１原発の事故で飛散してきた放射性物質がフィルターに付着していて、洗浄水と共に流れ込んだのではないかとみています。

Yokohama City suspects radioactive materials from the Fukushima I Nuclear Plant accident were caught in the air filters, and they flowed into the sewer as the filters were washed with water.

これを受けて横浜市は、この会社に排水設備が整った場所で洗浄を行うよう注意するとともに、現場の土壌はコンクリートの入れ物に入れ遮蔽する措置を取ることにしています。

The city has cautioned the company to wash the air filters at a location with a drainage facility, and is going to put the contaminated soil in a concrete container to shield radiation.

これについて、この設備管理会社は、「福島県から離れた場所のフィルターを洗い、このような事態が起きたのは遺憾です。去年１１月からは敷地内では洗浄しておらず、フィルターを線量計で測るなど取り扱いを徹底させています」と話しています。

The facilities management company says, "It is regrettable that washing the filters from locations far away from Fukushima Prefecture has caused such a problem. We haven't washed the filters since November, and we measure the radiation levels of the filters by a survey meter to make sure we handle them properly."

"Regrettable". Amazing.

Screenshots from NHK News video shows a drain from the facilities company that leads to the side of the school yard. The contaminated soil is under the blue tarp:

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