August 2020
In August 2015, during the tunnel boring works at the Mai Po section of the XRL project just below Tam Kon Chau Road, the pressurization process caused the slurry to seep through an previously used bore hole and flooded parts of the fishponds and the Wetland Conservation Area aboveground. Although the MTR Corporation Limited (MTRCL) immediately took remedial actions and sealed the hole with concrete, subsidence of the concrete together with part of the fishpond bund occurred after two days. So why are we bringing up this issue again five years later? What does it tell us?
1. Is Environmental Impact Assessment (EIA) effective?
The XRL EIA published in 2009 concluded, like in other EIAs, that tunnel boring works at the Mai Po section would have no adverse impacts on the environment, and monitoring and emergency plans would be made according to the Environmental Monitoring and Audit Manual [1]. Ironically, when MTRCL reported the XRL project progress to the Legislative Council in 2014, the corresponding discussion paper mentioned that there was compressed air leakage from the tunnel causing bubbles to appear in a fishpond in the Ramsar Conservation Area [2], but it seems MTRCL made no evaluation of its potential impacts on the Mai Po wetlands and the structure stability of fishponds. Finally, the tunnel boring incident and land subsidence occurred at the fishpond in 2015. The leaked slurry overflowed into the wetlands and streams in the Ramsar site causing environmental pollution. So is this purely just an accident, or an indication of the inadequacies of the current EIA system? All these suggest that the EIA system in reality cannot effectively monitor and prevent the environmental damages caused by the proposed development.
2. Underground works do not affect aboveground environment?
We generally agree that tunnel boring works can better protect the aboveground environment and ecology than flyover works, as illustrated in the case of Lok Ma Chau spur line. However, with the above XRL project incident, should’t we question the impacts of tunnel boring on the structural stability of the ground and thus its corresponding ecological impacts on the wetlands? Yet, this incident is just a tip of the iceberg. Since the commencement of the XRL project in 2009, quite a number of environmental problems appeared along the XRL alignment. For instance, some Ngau Tam Mei residents claimed the underground works affected the water table and caused the wells and fishponds to dry up, while several old buildings in the urban area experienced vibrations from the works and cracks even appeared on the walls [3]. Aren’t these examples warning us about the environmental impacts of underground works?
In May this year, MTRCL submitted the Project Profile of the Tung Chung Line Extension for the application of the environmental permits. The Environmental Protection Department issued the EIA study brief in June and MTRCL was required to prepare and submit the EIA report accordingly. The preliminary alignment of the project would pass through Ma Wan Chung village. Since Ma Wan Chung has the same type of geology as Mai Po, we are concerned similar incident as that in Mai Po would occur again during the tunnel boring works for the Tung Chung Line Extension. This would potentially pollute the Tung Chung Bay and nearby coastlines and cause adverse ecological impacts, and may even affect the ground stability at Ma Wan Chung village and the structural safety of the stilt houses above it.
【HKBWS’s comments on the Project Profile for the Tung Chung Line Extension】
https://bit.ly/3kygxdb
【Tung Chung Line Extension Project Profile (public consultation closed)】
https://www.epd.gov.hk/eia/register/study/latest/esb-329.pdf
[1] EIA report of the Hong Kong Section of Guangzhou - Shenzhen - Hong Kong Express Rail Link
http://www.epd.gov.hk/eia/register/report/eiareport/eia_1692009/index.html
[2] LegCo Paper of MTRCL reporting the XRL project progress (p.109)
https://www.legco.gov.hk/yr13-14/english/panels/tp/tp_rdp/papers/tp_rdp0505cb1-1354-1-e.pdf
[3] Apply Daily: Speed limit, environmental destruction; many defects in XRL (Chinese version only)
https://hk.appledaily.com/local/20140507/RCZMMNPM4ZVG5ECNXO4AFQOU7E/
