After going through the recently-released Environment Impact Assessment on soil investigations at the Central Catchment Nature Reserve (CCNR) at MacRitchie, plant expert Lahiru Wijedasa is concerned.
"The disturbance that might be caused by soil investigation is significant and if damage is caused, it will be irreparable," the former senior arborist at the Singapore Botanic Gardens told The New Paper.
"The most damage from the soil investigations will be on the rare plants and old trees in MacRitchie, from the weight of the machines that will go into the area."
Studying the various tables and schedules in the assessment, Mr Wijedasa explained that a boring machine weighing 2.5 tonnes will be moved into CCNR.
And with each borehole requiring 1,000 litres of water, an ancillary machine weighing 2.4 tonnes will have to transport the water to the various sites. (See graphics at right.)
He stressed the immense damage the tree roots and other plants will suffer even if the 16 boreholes within the CCNR are on existing footpaths.
From 2007 to 2014, Mr Wijedasa oversaw, among other projects, the development of the 5-hectare healing garden and boardwalk in the Botanic Gardens rainforest.
"In those projects at the Botanic Gardens, we put in place mitigating factors like a boardwalk or even temporary boardwalks to prevent putting weight on tree roots," he said.
"This is crucial because the clay soil in Singapore makes most trees grow their roots wide, not deep. If heavy weights are placed on them, they will die and not grow back.
"And it is almost certain that there are tree roots growing under the footpaths in MacRitchie."
Mr Wijedasa studied the map of boreholes in the assessment.
The map revealed that in addition to the 16 boreholes, there are 21 others in the forested area on the fringes of the CCNR, which will have an impact on the area.
"These additional boreholes, while not within the gazetted boundary, are still close enough to have an effect on the gazetted CCNR. "You can't look at things in isolation," he said, pointing to hydrology - the circulation of water below the earth's surface - as another major cause of concern.
Mr Wijedasa presented his findings at a Green Drinks event at the Sing Jazz Club on Feb 25.
Mr Tony O'Dempsey from Nature Society Singapore, who was at the event, expressed concern.
"The impact of the soil survey shouldn't be played down or ignored," he said.
"The public can give their feedback on the assessment and I strongly recommend that Mr Wijedasa writes in to present his findings. This is an issue of grave concern."
Singapore Arboriculture Society president Rick Thomas, who was not at the event, concurred with Mr Wijedasa about root damage.
He said: "When it comes to works on the surface (during the soil investigation), you don't need heavy machinery to do damage.
"Any machinery going over the top will see damage sustained by the trees."
Member of Parliament for Nee Soon GRC Louis Ng believes it is not too late for robust discussions on the matter before damage is done.
Mr Ng, who was at the event, said: "The second phase (including soil investigations) is a gamble and if we fail with mitigation factors, the impact could be irreversible. It is a primary forest.
"I don't think the final chapter (on the soil investigation) is written yet. There is avenue for discussion, so let's start the debate."
The Cross Island Line (CRL) will undergo a four-stage process before its projected completion in 2030:
Stage 1: Feasibility studies before a decision is made on CRL's final route (24 to 30 months)
Stage 2: Detailed engineering design (24 to 30 months)
Stage 3: Construction (72 to 78 months)
Stage 4: Testing and commissioning (30 to 36 months)
The process is still at Stage 1 because an Environmental Impact Assessment had to be done on soil testing, which is required to study the viability of tunnelling since the line will run through the Central Catchment Nature Reserve at MacRitchie.
The 1,000-page assessment showed that soil testing would have a "moderate" impact on the environment.
This article was first published on March 7, 2016.
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