Megaproject: Building Singapore's Deep Tunnel Sewerage System | Tomorrow City | Part 1/3

singapore is running out of space space to develop and prosper [Music] there are more developments now it's harder to find land now the little red dot is being re-engineered for the 21st century nobody has done it before this is the only job that allows you to work on a smart city project in singapore we are going from about 350 megawatts of solar to two gigawatts of solar and that's a huge jump new mega projects using state-of-the-art technologies will harness the power of the sun it's a kind of new for singapore to have solar panels on water automated sports i can't imagine we will be developing a 60 plus both and dig deep i did not believe the space saving part until i saw it with my own eyes this is what engineering is to find more space and allow singapore to flourish this is a journey into singapore's tomorrow city it's a critical moment for one of singapore's new mega projects one of the biggest machines on earth is being delivered to a site in the heart of singapore a tunnel boring machine or tbm today we are lifting all the main bodies for the just unloading at the site we do this at night because the oversized cargo is only allowed to transport after 9 30 pm the tbm is so big that all six parts have to be delivered one at a time in singapore space is a luxury both on the surface and at its only landfill at palau samacal which is reaching full capacity to create more space one project is going underground to revolutionize waste disposal and water management the deep tunnel sewerage system or dtss is one of singapore's biggest underground projects at about 7 billion us dollars this is the second phase where 19 tbms will carve out hundreds of kilometers of tunnels underground that will take waste water across the island to different reclamation plants to maximize space the dtss system will be dug deeper than any existing road and rail network at depths between 35 to 55 meters this is one of 50 shafts the entry into the underworld a gaping 10 meter wide hole known as shaft m it's nearly 50 meters deep the work site at shaft m is crammed with construction equipment and lifting supervisor johnson and his team must now find space for these six massive parts okay stop things stop stop wire down the space constraint is the biggest challenge for us today [Music] 2 20 am now it's going to shift the front body lower 2 meters inwards then we're going to prep the cutter head unloading area with the timbers with the heavy ss and it's the most delicate as well once all the sections of the tbm are delivered and unloaded they must be lowered one by one into shaft m and then reassembled underground the most important section of the entire tbm is the cutter head the cutter head has a diameter of 7.5 meters and comprises of dozens of heavy-duty cutting disks that chew away at rock at a rate of approximately 3 meters every hour behind the cutter head comes the power source the tbm is multi-purpose as the cutter head bites away this section erects the walls of the tunnel which are made from these concrete rings the cutter head generates huge quantities of waste or slurry and this section of the tbm is its waste disposal system to drive the tbm forward thrust cylinders push against the newly built tunnel rings with a force great enough to shift an elephant the cutter head arrives [Music] the engineers take special care unloading this spaceship-like equipment okay swing stop stop warm up warm up the cutter blades are precision engineered the team positions wooden blocks underneath to prevent any damage to the blades slowly swing to your left by the time the engineers complete the unloading dawn is breaking job well thanks guys good job good job [Music] it will take another six weeks of preparation before the tbm sections are ready to be assembled in the tunnel below shaft m the deep tunnel sewerage system is not scheduled for completion until 2025 it is being built to last for at least a century and so engineers will inspect every detail of work during construction to make sure nothing is overlooked one of the engineers on the inspection team is wu lai lin so what are they doing in the shop now today access i've been doing dtss since dtss one which was completed in 2008 so yes we have been talking about the deep tunnel switch system or dtss for many many years by the time the dtss is completed it will free up 300 hectares of land above ground more than half of which is currently being taken up by pumping stations and reclamation plants the 19 giant tbms still have 100 kilometers of tunnels to construct dtss 2 follows the heavily used aya raja expressway to get all the tbms working away below ground 50 vertical shafts must be sunk along the route of the expressway without disrupting traffic so the first thing we do is sight the long shafts sink the launch shafts and then we would launch the tvms from these shafts then the tvms will tunnel along happily hopefully until they reach the retrieval shaft which is where we take out the machines sighting shafts along the ayah raja expressway is a challenge space is definitely one of the challenges can we find space on the surface to site our shafts or more importantly to side the shelf big enough where we can actually launch our tunnel boring machines there are more developments now it's harder to find land for your shafts and things like that at lower delta road a new piece of machinery is changing the way shafts are being constructed and saving space at the same time it's called the vertical shaft sinking machine or vsm i did not believe the space saving part until i saw it with my own eyes it enables the construction of a shaft without the need for men to be inside the shaft excavating away you can actually use it in very tight places very close to to existing buildings site engineer guo hao is here to check the progress one shaft has already been constructed and another is underway so this shaft is approximately 10 meters wide diameter and is approximately 50 meters thick how's the side program uh everything goes well today they're going to finish the tie bridge on the website so after that we'll fill water okay starting situation [Music] bsn that we're currently using is the only vsm machine in asia as is relatively new concept compared to a traditional excavation method the system works like this first a narrow shaft is excavated to a depth of about 10 meters then it's lined with pre-fabricated concrete rings now the shaft is ready for the vsm which has a telescopic arm with a road head that can swivel around to dig deep the engineers must carefully calibrate the robot arm before they set it to work done so how vsm works is that there's a cutter drum so this tattered drum will move towards the shaft in and out in and out as if the arms will turn is it okay [Music] the vsm is doing vertically what the tbm or tunnel boring machine is doing horizontally underground as soon as the cutter drum excavates a complete circle of 100 millimeters both shaft and cutter drum will move downwards it takes at least 10 hours to dig one meter as the ground sinks engineers will insert concrete rings that form the shaft wall okay stop checking okay please measure the lens okay down ready that's all thank you very much okay okay okay this is the last time engineers can enter the shaft once the telescopic arm is calibrated the opening will be filled with water for the machine to begin the excavation work [Music] this is what engineering is all about so where we come up with solutions to reduce the risk of workers and to actually improve the efficiency of excavation the vsm system lets the tunnelers do their job in cramped urban sites like the one at lower delta road on the expressway but underground the engineers will soon confront the biggest challenge of all singapore's subterranean geology [Music] singapore's planners are spending billions of dollars to build a new waste disposal system the dtss huge tunnel boring machines are at work deep beneath our city down here the biggest problem for the engineers is the geology the hidden world beneath our feet so between where i'm standing now and perhaps just behind the camera the ground conditions can differ greatly so it's difficult for a tunnel boring machine to be catering to different types of ground conditions that are changing so rapidly [Music] adam switzer is a geologist at earth observatory of singapore he has spent many years studying the geology of singapore and understands its challenges for tunnelers tanjong rimao is one of the few places locally where the hidden world beneath is exposed these rocks were laid down millions of years ago and over time have been twisted and folded by the movements of the earth's crust much of the geology of western singapore is like this lots of different rock types very closely placed together and very complicated in terms of folding and small faulting which means that engineering that adds a lot of complexity so if you look here the rocks change a lot over a very short distance and you've got your engineering system running in a way that drill through sandstone and all of a sudden you come into a muddy shale like this the unit here or you run into a bed that's full of big boulders which we have in singapore as well then your engineering is going to run into problems and that's what's happening in shaft x1 located by the benoit flyover along the aya raja expressway irregular readings from the instruments on the tunnel boring machine or tbm have put a stop to tunneling works well before we start our works of course there's a whole series of site investigations done boreholes are sunk and all that but you can only sing that many ball holes that close apart so you have some idea of the ground conditions we are encountering so between two ball holes you could draw a line that shows you where the rock head is but in reality you could go this this way the exploratory boreholes were sunk here before the tunneling started despite that ground conditions still proved tough for the cutter head to tunnel through can you switch to the normal screen yes we are at 2.9 bar yes for engineer christian schilling one of the most important tasks is maintaining the cutter head [Music] as the tbm inches forward the cutter blades are constantly worn out and the huge machine must be stopped periodically for maintenance and in subterranean singapore it's a tricky operation so this is a example of a mixed fish right yes mix of rock and soil and these are the rock yeah and we teach the soil ah it's very bright i can feel that this is like like soy it's much softer and then the one you actually have here is actually quite hot to understand the ground conditions engineers examine samples of the rocks excavated by the tbm and confirm that the rock face they've been tunneling through is made up of a mix of hard and soft materials [Music] at the moment we have stopped the tbm for a cutter head intervention to carry out a cutter head intervention or chi a team of engineers enters the space at the front of the tbm but chilling has to choose the right moment when the ground ahead is stable and less likely to collapse on the workers the geology let's call it interesting up to now on this over 500 meters we had mainly soft rock now we are since about 200 meters in a soft geology it's mainly clay it's never a good time because of course we want to continue channeling but we have to that time we need to check what's the level of the road and what's the level of the soil and based on that we prepared this place for our face map really okay the tbm is tunneling 50 meters below sea level and the air pressure down here is much higher than at the surface for the team it will be like diving under water and like divers they will need to acclimatize to the pressure this particular one we have finished changing our disk cutters that was 10 pieces this time and now we still have some scrapers to change the soft ground tools and then tomorrow we should be on the way again the tbm engineers can only plan ahead if they have a good idea of the kinds of rock and soil that the tbm must cut through as they push forward underground geologist adam switzer and his colleagues continue to map out singapore's subterranean world today they've come to the north to investigate the mysterious sembawang springs it's an area famous for its 70 degrees celsius water source and this we place the eggs here and we leave it about one hour maybe the thing will be poured our eggs we're a bit runny we put them 20 minutes under the hot tub but they were good it was a good day yeah and it was fun to be able to cook them outside and in the in the water the sembawang hot springs do more than cook runny eggs they provide vital clues to singapore's subterranean geology singapore isn't known for earthquakes and volcanoes so the puzzle is where is all this heat coming from it's quite rare for a hot spring to occur in a setting like this you need hot rock sauce it needs to be shallow enough that it still gets to the surface with some heat capacity and the water is coming out here at about 70 degrees it's it's enough to cook eggs and so you know that that means that that heat surface must be reasonably proximal [Music] at the earth observatory of singapore geophysicists are using state-of-the-art technology to solve the mystery of the springs and to look deep under the surface of the island the hot springs are evidence of an active fault line located somewhere deep below a fault is a fracture in the earth's crust and here it heats groundwater that is conveyed to the surface atsembawang to steam up those springs faults can also become active and cause earthquakes but where exactly is this fault and could it pose a danger for the dtss tunnelers so this kind of instrument is actually our ears and the earthquakes or any other kind of seismic source are like our hands patting on the watermelon so when these energy penetrating through the earth it carries the information about the underground structure the team positions seismometers at locations all over singapore to record the data [Music] i'd adjust the position a bit yeah it's really yeah it's working now yeah you can just take it off and then that's it over a period of five weeks the seismometers record vibrations from road traffic construction and far off seismic events the result is a digital portrait of underground singapore which they hope will pinpoint the location of any dangerous fault line this is actually in the very high frequency so this kind of map tells us uh what kind of frog that is under the ground so these numbers are representing the speed of the shareway that is traveling within the earth we can work out where this fault line is which is separating the granites in the middle and the jurong formation sediments in the west and that's really important when there's construction work underground the team will need more time to install additional sensors to figure out possible problems lying in weight for the tunnelers with expanding built up areas and new mega projects like the dtss the information will provide insights and help avert disasters like the nickel highway incident in 2004 on april 20th 2004 steel supports over the circle line mrt tunnel below the six-lane wide nickel highway collapsed the disaster triggers a blackout and plunges traffic into chaos construction work for the circle line had to be stopped and the highway closed for seven months for repairs the lives of four men lost this catastrophe still serves as a haunting reminder today huge mega projects like the dtss are built to last into the next century the tunnel is 22nd century technology but the project depends on one of the oldest of all building materials concrete and one of the most critical ingredients in that is running out [Music] there is no limit to singapore's ambition to build the city of tomorrow and to free up space for the future to achieve this the new dtss or the deep tunnel sewerage system is burrowing deep beneath singapore to create a network of tunnels that will revolutionize waste disposal and water management all kinds of waste will be treated reducing the amount of throwaway rubbish and generating energy in the process the dtss will redefine recycling for the future and take the pressure off singapore's only landfill site at palau samacal which is reaching full capacity but solving the problem of waste on such a scale creates another construction projects like the dtss are hungry for concrete and this demand is escalating the need for a key ingredient sand and sand is in short supply at the nanyang environment and water research institute researcher den hui thinks he has found a solution basically a concrete is made of a cement and then our fine aggregates such as sand and then also cost aggregates such as pebble or bigger rocks it's the binding between cement and aggregates like sand that makes it strong enough to take high compressive loads making concrete the perfect raw material for mega projects like the dtss the sand is uh mostly in using construction at the river sand the world uses like almost like 50 billion tons of sand every year we don't have enough sand ten hue believes he has the answer to the sand shortage waste he is convinced that waste can be the new sand and a solution to better quality concrete our aim is to improve the quality of a concrete we have this um project with nea we have this waste to energy research facility we use a very high temperature gasification to convert waste into very stable um classification select a new scent [Applause] the key to the process is heat high temperatures of 1600 degrees celsius to be exact this produces gas that can be used for power generation and the rather unattractively named slag or new sand in this process very little is wasted [Music] this new sand is made from pure waste we are trying to use it to replace our sand at higher ratio this leg is a very new material and we do not know a lot of the properties about this and then currently ours are still doing the characterization and then to understand fully this material the big question is how does new sand compare with river sand we can see that the riverside is consists of a lot of very fine particles with occasional large particles all the sand particles are more of like a rounded because of the natural erosion along the rivers the consistent and rounded size of river sand particles help them to bind easily with cement so for our new sand the select experience that we can see very distinct um rod like structure which are known as some glass fiber and also very angular particles is carrying out a test to compare new sand with river sand samples so we're doing a 50 replacement ratio so the design mix will be 4 kg of cement and then we do um 2 kg of sand and 2 kg of slag [Music] so we'll be putting in the cement and the fine aggregate into the mixer and then we'll start the mixing process his sample will now undergo a compressive test to see how much load or weight they can withstand before cracking he starts with the typical concrete cube so in the lab setting we test the amount of load it can take through the compression machine we keep applying higher and higher compressive strength onto the concrete and then see the maximum load it can take before it cracks or before it fails we can see that as the strength increases the deformation increase very rapidly next ten hue tests the new sand concrete the higher the number the more load or weight the concrete cube can take the number to beat is 82.4 [Music] but in our new sand concrete you can see that as the strength increases in the initial stage there is very little deformation and the winner is nussan the superior strength of new sand is all to do with these rod-like structures which bond with the cement with the theory proven this new sand concrete will soon be ready to be tested in reality at ports down road engineers have reached a critical stage in the dtss project preparations at shaft m have been completed and it's time to lower the six different parts of one of the largest tbms also known as tunnel boring machines into the completed shaft it's a very tight squeeze the entire process will take at least two weeks okay so means we lower down the erector after 1 pm all right so one of the milestone is to complete the assembly of the tbm so that we can proceed the next step which is the mining work below ground engineers begin connecting the different sections of the tvm the completed parts are pushed into a pre-excavated opening to make space for the next piece then comes the second stage these gantries will house the control cabin electrical supplies and rail tracks to transport tunnel segments as soon as the tbm has chewed its way about 100 meters into the rock the remaining gantries will be lowered into the shaft when completed the machine will be 130 meters long the length of 10 buses this is one of the biggest tbms so far in singapore that's why it needed to be segmented in a bottom part in the top part so to make sure the alignment is correct it is all properly sealed during the assembly we need to pay attention that all these seals are staying in place senior project manager uli is another tunneling veteran today he has come to the portstown road site to make sure the assembly is proceeding according to plan it doesn't take long for eagle eyed oolie to discover that there's something wrong i've been down to the shaft and have inspected the tightening of the bolts in the status and i've reported to the main contractor the boats are not tightened we cannot confront it with a cutting wheel installation the tbm is applying support pressure at all time to the tunnel phase from stopping it from collapsing so if the bolts are not tightened properly there will be a leak through the machine segment the only solution is to work through the night to tighten the bolts all 280 of them the next morning uli returns to the site to find out if the problem has been resolved apparently what situation yeah we are ready so now we are pulling up all the wire into the drum yeah we are making sure all the wires will be quite nicely in the front okay then we'll be ready to hook up [Music] when the cutting wheel is just one meter above the crater we'll slide the front body forward so this is to prevent damage to the rotary coupling this is the cutting wheel the biggest and heaviest section of the tbm its size and weight explain why uli is so cautious we shifted the tvm backwards so that there is a big enough gap to fix the cutting wheel in front of the dbm nevertheless it's getting very very tight now the tricky process of lowering the cutting wheel 50 meters down to the shaft bottom can begin and it's a very tight fit 500 yeah it's very tight we have to make sure that it's not swinging and functioning if any part of the million dollar tbm is damaged the consequences in terms of repair costs and delays would be catastrophic as the operation begins it's all hands on deck there's just a five centimeter gap between the cutting wheel and the shaft wall [Music] the rotary coupling was actually colliding with a shield on top [Music] but we managed to make up enough space to fit the cutting wheel down after two hours the tbm section reaches the bottom of the shaft safely one day late the engineers are relieved the hardest part is over and the cutting wheel can now be attached to the front body going underground is an important solution to singapore's diminishing land space a new urban scheme at punggol in northeast singapore is going to show that putting transport links underground is a way to return city streets to the people that use them [Music] space is a luxury in singapore to create more room on the surface projects are going underground but city planners have come up with another way to tackle the problem and it's simple plan cities in advance to maximize space that's the concept behind the smart city and the first in singapore is pongol where a new district has been planned from scratch led by gilbert chur the team has designed a digital district which is targeted for completion in 2024 it comprises a business park and a university campus an environment where business professionals academics students and their families can call home so pongo drill district together with a few other districts around singapore are one of the ideas of decentralization to maximize space for people the planners made a crucial decision all transport links are being built underground from the new mrt connector to huge car parks leaving the ground level free for pedestrians and cyclists i can tell you as my favorite angle of the model when you look at this model it's actually right down here looking towards the west you see the the main street which is really campus boulevard you can actually see how the business park the sit campers are really stitched together into one very cohesive hole so this is the whole concept of spacewalk where we are looking to have the deepest academia industry collaboration and that's not all room service at the beating heart of the smart district in pongol is a new software it's being developed by james tan and his team it's called the open digital platform it allows them to test out smart systems and real-world scenarios virtually zoom out can see the details of the construction progress yes this is what we call a digital twin why we do this is because we are able to have a good spatial view of what's happening in the real world especially when all this real-time sensor data comes in nobody has done it before this is the only job that allows you to work on a smart city project in singapore the idea behind the open digital platform is to integrate smart systems with everyday life at some point we will need to integrate with the pdd meeting room system if no one is using the room we should do a reality check that the meeting room is zero at this view i don't have one shot like where's the one that's overcrowding so what we hope to achieve is to derive better efficiency through energy savings and of course manpower distribution on the other hand we want to make people's life easier in fact we were cleaning about the idea of giving people 27 hours instead of 24 hours because we think they can save three hours out of every day through less waiting time faster moving into your office leaving the office and so on while the digital team works out the smart services two meters underground another team is spearheading the physical construction of the pongol digital district yeah any idea on the concourse level all the shopjimmy status in preparation for the tunneling works that will connect the digital district to the transport network are we reaching b1 already so this one we are target to complete one month after the mrt roof completed but this is a temporary slab so we are following closely with this construction sequence project engineer wing zu has worked on this from the start since 2017. we are working towards the tunnel virtual event which is a big milestone for gtc and lte collaboration we are doing okay but of course all the consuming projects is effective i call fit but we are catching up and she is in charge of preparing the basement works so now the machine is behind how far are we okay the giant tbm or tunnel boring machine that has eaten through over 700 meters of soil from the existing northeast mrt line is about to break through right here one of the key challenges is that we are going under a live lrt appear in a vaidar so obviously we tend to get a little bit more uh postures hey we're going very close make sure that we don't affect the lrt structure when a tbm tunnels close to critical areas underground it's high alert for the whole team across the project these critical points are known as influence zones the challenge is to actually monitor the instruments in the tbm carefully so that we can not over excavate to lead to sinkholes the results will be very disastrous at benoit flyover the team is on high alert two tunnel boring machines are tunneling in close proximity to the overpass the two massive tbms working together may destabilize the flyover so the engineers continuously monitor the structure for any signs of weaknesses so monitoring is extremely important all our monitoring data is gathered on this online platform so that you can access it at any time so let's say you're getting readings that give you maybe excessive settlement we will be alerted please take note that our tunnel is approaching the expressway any anomalies or significant changes please do highlight to your engineer we are here below the flyover where it's considered one of the critical structure for the project so along this area we have installed three sets of instruments for each of the tbms so this will be monitored during the mining works the risk is that as the tbms move forward underground the soil above the tunnels compacts causing a depression to form at the surface and in the worst case scenario develop into a sinkhole in densely packed singapore this would be catastrophic this is a bare area and in singapore most of our areas are quite congested so you are either underneath a road you know if not your other leaf some kind of services and everything these instruments are part of a vital early warning system if anything is amiss readings from the sensors are closely monitored with his decade of experience christian schilling keeps a close eye on the progress the tbm is moving constantly forward when we are tunneling everything okay here okay good stay on so far no warnings from the sensors above ground so basically we see from the survey system the the actual position of the tbm we have our navigation screen that shows us where we are currently how far we are of the alignment [Music] finally the tvms pass the critical risk zone and the next tunnel ring can be built back at pongo after tunneling past the vital lrt pillars the last few centimeters are about to give way signaling the end of the mrt tunnel and the machine's journey everyone gathers for this momentous event fantastic breakthrough very well coordinated and very well coordinated and planned all thanks to you such a good job it's a job well done for the team at pongol the moment you see the crack you know that it's coming next and within two minutes the whole world collapse but then you can hear all the cheering sound for everybody that's how we live from the entire team jtc and lta that finally we do it we have done it dtss 2 still has four years before it will be completed as singapore reaches for the sky building gleaming towers of glass and steel deep below 19 giant machines continue to excavate a network of tunnels stretching 100 kilometers this will transform how singapore manages water and waste propelling the state into the next century and building a new pillar of singapore's tomorrow city [Music] [Music] you

Channel: CNA Insider

Views: 405,175

Rating: 4.8277206 out of 5

Keywords: CNA, CNA Insider, Channel NewsAsia, Asian perspectives, Tomorrow City, Singapore, documentary, engineering, infrastructure, building, construction, land scarcity, waste management, water management, waste disposal, technology, city, sewerage system, sewerage, TBM, PUB, engineer, sewage system, DTSS, deep tunnel sewerage system, building tunnels, tunnel, tunnelling, underground, concrete, newsand, slag, cement, mega project, urban development, outsourced, full documentary, narrated

Id: p_AgSrTc6P4

Length: 46min 15sec (2775 seconds)

Published: Fri Sep 03 2021

Reddit Comments

[u/zaitsev63]

Interesting how Singapore is the world’s most intensive user of TBMs yet we don’t really have skilled local tunnelling contractors.

Nor do we learn much about them especially considering Singapore’s varied geology posing interesting challenges

[u/DrCalFun]

I always thought that this series by CNA showcase Singaporeans who are innovating in many different fields. Yet, I also always find posts about Singapore being not innovative. I am trying to understand the disconnect. Are for example using garbage to replace sand, using caissons for reclamation, deep tunnel sewage system, converting pee into drinkable water on a national scale, having vertical fish, eggs and hydroponic vegetable farms, recycling lithium ion batteries with 99% purity, having earthworms for compost, having two of the most successful southeast asian start-up with Grab and Shopee, not a sign of innovation?

I guess it depends on what we mean by innovation and the extent of newness that one expect. Why do we keep thinking that we aren’t innovative?