REFUSELINKS@CAUSEWAY

Tja Kim Huat

There is something very wrong with our causeway today. It is missing something important and we have all forgotten about it because we cannot see it anymore since they are under the sea now. What happened to the 10 refuse tunnels of the causeway? They were there when the causeway opened in 1924 and they were big, as in 5 feet diameter each, at somewhere between 200 to 300 meters from the middle span towards Johore.

First, let us understand why the British engineers put these tunnels under the causeway. It was to do with time and speed mathematically. The persons that designed this causeway understood the needs of these 10 refuse tunnels in their construction because of the location of the causeway – it is in the middle of the Straits of Johor. The distance from Kranji to Tuas which is more than 110,000 feet is just too far apart for the causeway to work effectively. These 2 points are
too far for the tide to bring out any floating refuse towards the western route at the Straits of Malacca.

With the strait surface only flowing at 200 feet per minute, it is calculated to take up to 9 hours to reach the other end. With the tides coming in at every 6 hours interval, this will only result in the out-going low tide’s floating refuse hitting the in-coming high tide from the Straits of Malacca resulting a push back action.

The purpose of the 10 refuse tunnels are to a shorten that route to bring out refuse from Kranji Sea toward the South China Sea.

To really understand how these refuse tunnels work is for MPA to study the Straits of Sentosa. It is identical in current movements as the Straits of Johor when during low tide it flows eastward and at high tide the flow reverses westward. They too recorded the same 800 feet per minute at its bottom today as the same speed the refuse tunnels recorded in 1925 by the British. That 800 feet per minute is what is missing today at our causeway.

It is calculated to take only 2 hours and 30 minutes with that speed for the refuse to reach the end of the Straits of Johor from the causeway. The refuse tunnels are actually a booster pump to flush out refuse before the next tide come in.

There is no actual written reports about what happened to these refuse tunnels but I can ensure you they are not working anymore or we will still be catching fish in the kelongs at Kranji like in the 1970s and not having fish farms there now. We do know the British blew a 25 meter gap in the causeway during the war but how nobody can say. There is a 1960 photo by Mr Lee Kip Lin that shows only 4 refuse tunnels remaining and your guess is as good as mine to what the British did to the other 6 tunnels in 1942 at their desperate hours of the war in defending Singapore. They only blasted off one tunnel but the nearest remaining tunnels were damaged too because they were constructed by engineering brickwork plastering only.

The real problem came after the causeway expanded in 1980 when the fish and crabs started to go missing too. What happened in 1980 to our causeway’s remaining 4 refuse tunnels?

It is a known story how Dr Mahathir in his first year as Prime Minister of Malaysia toured his nation states. On his visit to Johor state, he walked on the causeway towards the remaining tunnels. It was in front page news how he scolded MBJB when he saw large floating debris where the tunnels were supposed to be – bad luck for MBJB since only 2 refuse tunnels were barely working then.

So for the next 30 years, MBJB has done what they can in cleaning these floating rubbish accumulated at the causeway into bags and that volume itself would have built us another floating causeway if they are laid coast to coast today. In fact they cleaned it so well that everyone soon forgot about the refuse tunnels until the National Library webpage in 2014 highlighted the causeway.

The crooked bridge is not really about shipping, it is more about the 10 missing refuse tunnels and the floating refuse at our causeway. If Singapore keeps half of the sea wall then it could be Singapore’s turn to collect endless rubbish bags for the next 30 years when time and speed are applied again at the insufficient curve below the crooked bridge. Some of the reclamation works has reached just 90 meters from the middle of the strait nowadays and will result in a more crooked strait than the crooked bridge in terms of flow.

My brother-in-law told me that if the late Mr Lee Kuan Yee had walked on the causeway then, he would have solved the problem of these refuse tunnels long ago. We might even have expanded the causeway too, for another 20 meters – just right for an additional train track for the MRT line today if the 4 last refuse tunnels were saved in 1980.

From 10 refuse tunnels to 4 refuse tunnels and lastly from 2 refuse tunnels to zero refuse tunnels was too much to ask from mother nature. The whole ecosystem started to fail and the stagnant sea began to rise a meter submerging the tunnels completely at the Kranji side from our view today.

In 2017, Johor Bahru will remove the tide gate of Sungai Segget once they complete building the sewerage treatment plant of their new city. If you think harder, you will understand what these tide gates are actually being used for. That means there will be 2 sewerage treatment plants, one at Mandai River and another at Sungai Segget discharging their treated bathroom water into the choked Straits of Johor just opposite each other. I hope things will not get any worse than now or the mudskippers will start to go missing too.

This is something we can officially count in surveys since the mudskippers are still visible at the Sungai Buruh Reserve yearly under Nparks care. We do have more than 50 fish farms on the Kranji side of the strait under AVA care too. More debris netting are needed at our shores since the refuse links at the causeway failed as in the Tuas desalination plant and
even the swamp reserve too, claimed NEA.

To save the causeway is to rebuild the last 4 refuse tunnels again but will Singapore do it ? PUB told me in 2013 they will not do it because the tunnels are over Malaysia’s side of the causeway so they are not in their maintenance list. In 2024, we might be required to celebrate the causeway’s 100 years birthday for its service to the island. There is no such thing as a half sea wall celebration just because LTA only collected half the toll of the causeway. It will also not be helpful for Singapore to protest against environment effects at the strait to Malaysia if PUB does not see the importance of saving
these refuse tunnels ….

Thanks you.

Yours sincerely,
Tja Kim Huat

Ref about the refuse pipes from National Library webpages,
The Straits Times :
1923 oct 1 page 10
“the ten circular culvert each 5 ft in diameter at the Johore end of the causeway will prevent accumulation of floating refuse near the lock”
1924 June 27 page 9
1925 May 28 page 21
1946 Feb 24 page 4