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Ground Subsidence and Chromium Contamination Raise Environmental Concerns Near Japan's Linear Shinkansen Construction

In the city of Mizunami, Japan, near a Linear Chuo Shinkansen construction site, ongoing ground subsidence has been observed. JR Tokai reported that in some areas, the ground has sunk by more than 1 cm since August, with one location showing a total drop of 3.7 cm as of September 23. They believe that this subsidence could be related to underground water drainage caused by the construction. To investigate potential impacts, JR Tokai is conducting on-site inspections of around 60 nearby households and public facilities. Some residents have already reported issues such as doors becoming harder to open and cracks in concrete.

Additionally, JR Tokai revealed the results of an investigation into a chromium contamination issue near a tunnel construction site in Ena City. In April, tests showed that levels of hexavalent chromium in groundwater exceeded national safety standards. The company concluded that rainwater had likely washed hexavalent chromium from cement-based materials used at the site, after protective coverings were displaced by wind. JR Tokai has vowed to prevent such incidents from happening again. A subsequent government inspection of wells within a 500-meter radius of the site showed no further contamination.

These issues have raised concerns about the environmental impact of the Linear Chuo Shinkansen construction on local communities.

Info based on NHK report https://www3.nhk.or.jp/lnews/gifu/20240 ... 14346.html Accessed 2024-09-26

岐阜のリニア工事現場付近で地盤沈下、1カ月に約1cm進行

Land subsidence near the linear construction site in Gifu, progressing at a rate of about 1 cm per month


Land subsidence is continuing near the tunnel construction site for the Chūō Shinkansen in Gifu Prefecture. It is progressing at a rate of up to about 1 cm per month, and the amount of subsidence has reached a maximum of 4.9 cm. JR Tokai revealed this on October 29, 2024, at a Gifu Prefecture expert committee meeting to assess the impact on the environment.
. Measurement results of the ground surface (Source: JR Tokai)
Source: https://cdn-xtech.nikkei.com/atcl/nxt/c ... 072/01.jpg Accessed 2024-11-01.

The construction of the Hiyoshi Tunnel in Okute-cho, Mizunami City, Gifu Prefecture, has caused a continuous drop in the groundwater level in the surrounding area. According to the results of an analysis of the amount of ground surface displacement using satellite data, the maximum displacement from December 2003 to June 2006, before construction began, was about 0.8 cm, so it is thought that the ground subsidence is also due to the tunnel construction.
JR Tokai has continued to measure the ground surface at 30 locations around the site, and has confirmed subsidence at 17 of these locations. At the point where subsidence has progressed the most, the amount of subsidence recorded from the end of May 2012, when measurements began, was 3.7cm as of September 23rd, and 4.9cm as of October 21st.
During construction of the Hiyoshi Tunnel, water began to flow into the tunnel in February 2012, causing the water table in the surrounding area to drop. Since then, the amount of water flowing out has decreased, but the drop in the underground water level continues.
, Trends in the amount of water flowing out and the underground water level (Source: JR Tokai)
Source: https://cdn-xtech.nikkei.com/atcl/nxt/c ... 072/02.jpg Accessed 2024-11-01.

Reviewing construction methods for countermeasures against water flowing out of the linear, referring to the tunnel in Kagoshima where there was an incident of sand and earth flowing in
Following the incident of sediment inflow that occurred in the “Hokusat Tunnel” on the Hokusat Transversal Road in Kagoshima Prefecture in late July 2024, JR Tokai is re-examining the content of the construction work to prevent spring water inflow in the “Hiyoshi Tunnel” on the Chuo Shinkansen Linear maglev Line.

Source: Translated Japanese Media news. https://xtech.nikkei.com/atcl/nxt/colum ... 142/02072/ Masayuki Aono. Accessed 2024-11-01.