Oral Answer by Ministry of National Development on Cross Island MRT Line

Feb 29, 2016

Mr Leon Perera: To ask the Minister for National Development (a) what are the impediments to releasing the Cross Island MRT Line (CIL) Environmental Impact Assessment (EIA) Phase 1 report online; (b) what are the main environmental impact the EIA has identified about the site investigations preceding construction of the CIL through the Central Catchment Nature Reserve Area and how the Ministry intends to mitigate them; and (c) how is the 'moderate' impact from the CIL (assuming successful mitigation measures) determined and what is the reasoning for why this is acceptable.

Answer:

The Environmental Impact Assessment (“EIA”) for the two possible underground alignments of the Cross Island Line (“CRL”) consists of 2 phases.

Phase 1 of the EIA focuses on the impact of site investigation on the two alignment options. The data and findings from the site investigation are needed for Phase 2 of the EIA, which will provide a detailed assessment of the environmental impact of the construction and operations of the CRL based on the two possible alignments.

When LTA first announced the possible alignment of the CRL in 2013, nature groups raised concerns about the potential serious environmental impact that this may have on the Central Catchment Nature Reserve (CCNR). Because of this, LTA formed a working group to define the scope of the EIA study of the Cross Island Line. This working group included representatives of nature groups. NParks also participated in the working group to provide views and inputs. Separately, a group made up of residents staying around the CCNR expressed concern about how the possible alignments may affect their homes, and LTA has been engaging them as well.

Over the course of more than two years, LTA consulted the nature groups extensively in preparing for Phase 1 of the EIA. For example, in studying the impact of the proposed site investigation works on the water quality, ecology and biodiversity within the CCNR, LTA’s EIA Consultant took into consideration a very useful baseline study on various aspects of the CCNR which was put together by the nature groups.

As indicated in the Phase 1 EIA report, the impact assessment framework adopted by LTA’s EIA consultant has two criteria: one, the sensitivity of the receptor, which is the CCNR in this case; and two, the magnitude of the environmental impact. Members may refer to the handout, which shows the impact assessment framework as reproduced from the EIA report.

LTA’s EIA consultant has rated the sensitivity of the CCNR as “high”, as it comprises primary rainforest with ecologically sensitive habitats. While this is so, the consultant has assessed the magnitude of impact due to the site investigation to be mainly “small”. This is because of the adoption of stringent mitigating measures that had been proposed. These mitigation measures were arrived at in close consultation with several representatives of the nature groups and NParks. 

Let me briefly describe what the site investigation entails and what mitigation measures have been proposed.

The site investigation adopts two methods to determine the geological properties of the site. The first method is borehole drilling, by which boreholes, about 10cm in diameter, are drilled to extract vertical columns of soil samples. To minimise these disturbance and damage to the forest environment, the number of boreholes to be drilled will be reduced from an earlier estimate of 72 to 16. More importantly, these boreholes will be confined to existing trails so as not to affect any vegetation. And the drilling machine will be modified to reduce the noise level and prevent spillage of slurry and fuel.

To make up for the drastic reduction in the number of boreholes, and because boreholes will be restricted only to the trails, a second method of site investigation will be carried out. This involves non-intrusive geophysical survey. To carry this out, surveyors will venture off-trail into the forest to collect data using hand-held equipment. This will be of significantly lower impact than borehole drilling in the forest. One of the concerns is that the surveyors may inadvertently trample on plants on the forest floor as they move through dense vegetation. So the geophysical survey is limited to a 100m-wide corridor and will not be carried out in sensitive locations such as streams, swamps and dense vegetation. NParks officers will supervise the surveyors full-time to ensure that they adhere to the strict rules for movements in off-trail forested areas and to reduce damage from trampling on plants. All site investigation activities will be restricted to daylight hours, so as not to affect nocturnal animals.

These stringent measures have been incorporated into the Phase 1 EIA report, which will reduce the impact of the site investigation to a level that is as low as reasonably practicable. A great amount of efforts has been put in by all parties – representatives of the nature groups, NParks and LTA – to arrive at this set of mitigation measures. The ongoing public consultation for the EIA report, which has been put online, allows the public an opportunity to provide further suggestions to LTA on what more can be done to further reduce the impact of the site investigation. 

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Impact Assessment Framework adopted by LTA's EIA consultant in the Phase 1 EIA report