In response to the “Huge Boulder that caused KLCC to shift from original location

In response to the “Huge Boulder that caused KLCC to shift from original location”

Posted by admin
Monday, 05 October 2009 17:02
By JBao
Yes Hakim Joe is darn right – we are all damned because our nation was built on poor foundation. Recently, my friend passed me a map of KL showing the charted KHF-LST contact zone. Not sure whether I should post the picture here as it might cause some panic now, especially with so many earthquakes in Indonesia and the tremors being felt here in KL. Let me know your views.
Dear junjun40 (Sorry I could not post the full reply in the comments feedback).
Your question:
“Talking about hugh boulders, I heard (unverified) that KLCC was under construction they discovered a big boulders, then a certain amount of diversion was done.
Then the SMART tunnel in Jln Tun Razak, they similarly discovered a boulder then diversion and delays in completion was the excuse.”
Jbao replies:
No, it is not a boulder but a karstic limestone mass jutting into the Kenny Hill formation.
After drilling purportedly “400 boreholes” (more than 100 deep) in that small area (<2 acres) they decided to move into the Kenny Hill Formation zone to avoid the huge (and I mean real huge) cost of stabilizing the deep pile foundation in highly karstic limestone. Even then no one is certain that the Twin Towers would not tilt to become World’s Tallest Leaning Twin Towers of Kuala Lumpur.
The whole matter is a classic case of “wasting millions and yet can still be a hero”. In the first place why built the world’s tallest building in the worst possible geological situation. Can’t built at a safer location, meh? Makes you wonder if anyone did a feasibility study first. Or is it built first think later, as all problems can be solved. Yes, but at what costs?
Why waste millions drilling into the limestone only to switch to shallow raft foundation after drilling 400 holes? After 5 holes, they should have enough information to make the decision already. So why continue drilling up to 400 holes? Isn’t this wastage? Rumour has it that they had already decided on the shallow foundation but why waste the budget already allocated for the drilling investigation? So they went on to “spend the money” and at the same time be a hero to save the Twin Towers from a potential disaster. 200 holes (or 50%) using recycled limestone cores (without drilling for the uninitiated) would be a very conservative estimate. Who will know the difference? The public certainly would not. Anyway, all the deep drilling data would be of no use if shallow foundation (cement float raft) is to be used.
Before the Twin Tower project, MSI bungalow lot (next the Chinese school, opposite the heritage museum) at Jalan Ampang was used to store all the limestone cores from over 20 years of drilling. It was an eyesore and many had innocently asked the question, why waste prime estate just to store all the old limestone cores? Apparently, the cores were more valuable for recycling (we were already green back then). Most of the projects in KL used some percentage of recycled limestone cores to make up the short fall. But the Twin Towers project apparently used a much higher percentage. Soon after the drilling investigation started at Twin Towers, the cores at MSI store (less than a km away) started to disappear until the whole compound was completely cleared. Amazing! You have to be there to believe it. One even joked that MSI had a clearance sale. After the Twin Tower project, the bungalow lot was converted to a parking lot since there were no more limestone cores to recycle.
When the Putra LRT planned the tunnel route from Kg Bahru to KLCC station, the seismic team detected the same limestone mass across the proposed tunnel route. However, the consulting engineers refused to believe there was limestone bedrock since the drilling team had only picked up the Kenny Hill Formation rock. There were arguments but the consulting engineers had the final say. All the limestone labels on the charts were ordered removed but the senior geologist had a smart idea. He put asterisks on the seismic velocities >3500 m/s for the bedrock with a note in the legend (* bedrock with velocities greater than 3500 m/s are likely to be limestone).
More than two years later (in 1997), Hyundai the second contractor hit limestone at the disputed section. Hyundai wanted to claim (millions) in a Variation Order for the month-long delay in encountering unexpected limestone bedrock. Putra, of course, asked the seismic company to explain and take responsibility. Hyundai lost their case when the senior geologist pointed to the little notes in the chart legend – confirming that limestone were to be expected – thus no variation order.
Amazingly, Hazamas had a tunnel collapse problem at the Jalan Ampang Junction (in front of Standard Chartered Bank/Bank Bumi, Masjid Janek station). Again, the seismic team predicted a (low velocity) major fault zone (in 1994) at precisely the collapse location and again the Consultant refused to believe it, arguing that the seismic results were unreliable since the drilling had cores to prove their results. The 1997 tunnel collapse just proved who was more unreliable – Honest Seismic Interpretation or “Silat Mata” drilling using recyled cores.
All these goes to show how misleading or useless our soil drilling investigations are. Just for show and to make money only.
Now, more than 12 years later, we have the SMART Tunnel along the same Kenny Hill – Limestone contact zone. Recently, we have Giant Sinkholes at Jln San Peng (July 25th 2009) and the reported appearance of severe cracks in a building at the junction between Jln Tun Razak - Pudu Smart Tunnel Junction (Star July 2009). Even while the SMART tunneling was in progress there were already reports of sinkholes, cracks in buildings and other problems. But this is another story…. Too long to elaborate here.
Guess what? The two locations (Hazamas collapse and Hyundai – near KLCC limestone) and the recently reported cracks/sinkholes all lie within the same Kenny Hill – Limestone contact zone. The soil – bedrock conditions at the Kenny Hill – Limestone contact zone are already precarious in their natural state. All the tunneling and construction only made them worse. Anyone remember the flooding at the KLCC basement just after its completion? Wait for more things to happen at the contact zone. All these due to poor planning, poor soil investigation (or shall I say corrupted and biased findings) and just “Satu Lagi Projek oleh BN”. All good and honest men (and women) professional in their work had been and still are being pushed aside. All those who bodek and “only say yes and never say die” rose to occupy all the top project posts just as what is happening to the Judiciary now.