Use of Saturation Diving Technique for Tunnel Boring Machine Cutterhead Intervention in the Tuen Mun–Chek Lap Kok Link Sub-Sea Tunnel Project, Hong Kong

Use of saturation diving technique for tunnel boring machine cutterhead intervention in the Tuen Mun–Chek Lap Kok Link Sub-sea Tunnel Project, Hong Kong

A W Y Chan1, Charles H C Yeung2, A J Westmoreland2, S W Fok2, Conrad C W Ng2 and F Guedon3 1 Highways Department, the HKSAR Government, Hong Kong, People’s Republic of China 2 AECOM Asia Company Limited, Hong Kong, People’s Republic of China 3 Dragages-Bouygues JV, Dragages Hong Kong Limited, Hong Kong, People’s Republic of China

ABSTRACT

The entire Tuen Mun–Chek Lap Kok Link (TM-CLKL) was commissioned on 27 December 2020 and it comprises a 9km-long dual 2-lane carriageway between Tuen Mun and North Lantau, Hong Kong. Construction of the 5km-long sub- sea tunnels was carried out by two 14m diameter Tunnel Boring Machines (TBMs). The tunnel alignment for the TM- CLKL sub-sea tunnel section is in mixed ground condition with 1.the Introductionfirst 500 m in mixed geology of slightly to moderately decomposed granite and completely decomposed granite (CDG), followedThe entire by soft Tuen ground Mun condition–Chek Lap with Kok CDG, Link alluvial (TM -CLKL) was commissioned on 27 December 2020 sand, alluvial clay and marine deposit. This mixed ground geologyand requires it comprises regular TBMa 9 km cutterhead long dual interventions 2-lane carriageway to change between Tuen Mun and North Lantau, Hong Kong the worn-out cutting tools during the tunnelling operation. As the(Figure tunnel 1)alignment. The alignment is up to 55 commences m below the at sea the level Lung with Mun Road and Lung Fu Road Roundabout in Tuen the deepest seabed level at -21 mPD, in order to maintain the cuttingMun faceArea stability 46. It duringheads thesoutheast intervention, on anthe elevatedintervention structure over Lung Mun Road and lands on a new pressure could be up to 6 bars. This paper describes different techniquesreclamation used (referredfor TBM tointerventions as the Northern under theLandfall sea such (NLF)) as adjacent to the Tuen Mun River Trade Terminal trimix bounce mode and saturation mode that appears first time in Hong Kong under a high hyperbaric pressure to change (RTT). The alignment turns south and heads into a 5 km long sub-sea tunnel passing under a busy the worn-out cutting tools at the TBM cutterhead. navigation channel between Lantau Island and Tuen Mun – the Urmston Road. After crossing the Urmston Road, the alignment daylights at the eastern edge of the reclaimed Hong Kong–Zhuhai–Macao KEYWORDS Civil Engineering; Geotechnical Engineering; Tunnelling;Bridge, Saturation Hong Diving; Kong TBM PortIntervention (HZMB HK Port) near Hong Kong International Airport at Chek Lap Kok CONTACT Charles H C Yeung [email protected] (referred to as the Southern Landfall (SLF)) and then head eastwards on a marine viaduct to connect the Received 21 October 2019 North Lantau Highway at Tai Ho Wan of Lantau.

1. Introduction

The entire Tuen Mun–Chek Lap Kok Link (TM- CLKL) was commissioned on 27 December 2020 and it comprises a 9 km long dual 2-lane carriageway between Tuen Mun and North Lantau, Hong Kong (Figure 1). The alignment commences at the Lung Mun Road and Lung Fu Road Roundabout in Tuen Mun Area 46. It heads southeast on an elevated structure over Lung Mun Road and lands on a new reclamation (referred to as the Northern Landfall (NLF)) adjacent to the Tuen Mun River Trade Terminal (RTT). The alignment turns south and heads into a 5 km long sub-sea tunnel passing under a busy navigation channel between Lantau Island and Tuen Mun – the Urmston Road. After crossing the Urmston Road, the alignment daylights at the eastern edge of the reclaimed Hong Kong–Zhuhai–Macao Bridge, Hong Kong Port (HZMB HK Port) near Hong Kong International Airport at Chek Lap Kok (referred to as the Southern Landfall (SLF)) and then head eastwards on a marine viaduct to connect the North Lantau Highway at Tai Ho Wan of Lantau. Construction of the sub-sea tunnels across the Urmston Road between the HZMB HK Port and Tuen Mun was carried out by two 14m diameter Tunnel Boring Machines (TBMs). The adoption of TBM completely avoided the impact on the busy Urmston Road during construction and minimised the impacts on the marine habitat of the Chinese White Dolphin, within and near the works site of the Figure 1. 1 .General General view view of TM-CLKLof TM-CLKL alignment. alignment. project. Construction of the sub-sea tunnels across the Urmston Road between the HZMB HK Port and Tuen Mun was carried out by two 14m diameter Tunnel31 Boring Machines (TBMs). The adoption of © 2021 The Hong Kong Institution of Engineers HKIE Transactions | VolumeTBM 28, Number completely 1, pp.31-38 •avoided https://doi.org/10.33430/V28N1THIE-2019-0044 the impact on the busy Urmston Road during construction and minimised the impacts on the marine habitat of the Chinese White Dolphin, within and near the works site of the project.

This paper describes the different techniques used for TBM interventions under the sea to change

A W Y CHAN ET AL.

This paper describes the different techniques used for the ground into the TBM excavation chamber. Water flow TBM interventions under the sea to change the worn-out from the face might result in ground material being carried cutting tools at the TBM cutterhead. into the excavation chamber during compressed air works, causing face collapse, with a subsequent ground surface settlement or, in more serious incidents, a sinkhole at the 2. TBM cutterhead intervention strategy during project ground surface above the TBM. design stage As the tunnel alignment is up to 55 m below the sea level with the deepest seabed level at -21 mPD, in order to the wornThe- outdesigned cutting tunnel tools alignment at the TBMfor the cutterhead. TM-CLKL maintain the cutting face stability during each intervention, sub-sea tunnel section was in mixed ground condition with the intervention pressure could be up to 6 bars. 2.the TBM first cutterhead500m in mixed intervention geology of slightly strategy to moderately during projectUnder design such stage a high pressure, the compressed air decomposed granite and completely decomposed granite workers could not stay for a long time and work efficiently (CDG),The followed designed by softtunnel ground alignment condition forwith the CDG, TM -CLKLto carry sub out-sea TBM tunnel cutterhead section interventions was in mixed because, ground conditionalluvial sand, with alluvial the clayfirst and 500m marine in deposit mixed (Figure geology 2). ofunder slightly this pressure, to moderately workers breathing decomposed air would granite likely and With this mixed ground geology, the TBM disc cutters to have the narcosis effect due to high concentration of completelyand cutting toolsdecomposed were subjected granite to wear(CDG), and tear.followed The bynitrogen soft andground that thecondition high concentration with CDG, of oxygen alluvial would sand, alluvialmaintenance clay andof the marine TBM cutterheaddeposit (Figure required 2) regular. With thisalso mixed cause ground oxygen geology,toxicity. In the addition, TBM accordingdisc cutters to and cuttinginspections tools to monitorwere subjected cutter tool wear,to wear replace and worn tear. tools The maintenancethe decompression of the table TBM that cutterheadhad to be approved required by theregular inspectionsand undertake to anymonitor repairs cutt necessaryer tool towear, the cutterhead replace wornauthority tools priorand toundertake use, after the any workers repairs are exposednecessary under to the cutterheaditself, in order itself, to prevent in order the TBM to fromprevent becoming the TBMstuck fromthis highbecoming pressure stuckfor about underground. 1.5 hours of work, The they process have of deployingunderground. workers The process under of pressure deploying to workers the TBM under excavation to decompress chamber for aboutto inspect 2.5 hours the back TBM to atmosphericcutterhead and replacepressure the to theworn TBM-out excavation cutters orchamber cutting to inspecttools is the commonly pressure called and take TBM a rest. cutterhead As it normally intervention takes an hours. During to TBM cutterhead and replace the worn-out cutters or cutting replace a worn-out cutter, for a TBM having more than 100 thesetools mannedis commonly interventions, called TBM cutterhead compressed interventions. air was useddisc tocutters, balance the use the of hydrostatictraditional intervention and earth technique pressures, creatingDuring thesea hyperbaric manned interventions, environment compressed within airthe was excavation for TBM chamber cutterhead of interventions the TBM. will Failure be impractical to balance if not the groundwaterused to balance pressure the hydrostatic would and earthlead pressures,to face creatinginstability impossible.due to the flow of water from the ground into the TBMa hyperbaric excavation environment chamber. within Water the excavation flow from chamber the face mightWorkers result working in ground in a compressed material airbeing environment carried into theof excavationthe TBM. Failure chamber to balance during the groundwater compressed pressure air works, under causing such a highface pressure collapse, will withbe exposed a subsequent to Occupation ground surfacewould lead settlement to face instability or, in more due to seriousthe flow incidents,of water from a sinkholeSafety andat the Health ground (OSH) surface risk due above to the thenarcosis TBM. effects

Figure 2. Geological profile of the TM-CLKL sub-sea tunnels and different modes of hyperbaric works along the alignment. Figure 2. Geological profile of the TM-CLKL sub-sea tunnels and different modes of hyperbaric works along the alignment. 32 HKIE Transactions | Volume 28, Number 1, pp.31-38

As the tunnel alignment is up to 55 m below the sea level with the deepest seabed level at -21 mPD, in order to maintain the cutting face stability during each intervention, the intervention pressure could be up to 6 bars.

Under such a high pressure, the compressed air workers could not stay for a long time and work efficiently to carry out TBM cutterhead interventions because, under this pressure, workers breathing air would likely to have the narcosis effect due to high concentration of nitrogen and that the high concentration of oxygen would also cause oxygen toxicity. In addition, according to the decompression table that had to be approved by the authority prior to use, after the workers are exposed under this high pressure for about 1.5 hours of work, they have to decompress for about 2.5 hours back to atmospheric pressureand high dosage and taofke oxygen. a rest. In addition,As it normally the risk of takeshaving an houreffect toand re minimiseplace a oxygen worn -toxicity.out cutter, The divers for alive TBM inside having moredecompression than 100 illness disc (DCI) cutters, is high the due useto frequent of traditional a diving interventionbell under the sea technique and can stay forunderwater TBM to workcutterhead interventioncompression ands will decompression be impractical at the if start not and impossible. end of for a month without the need for daily decompression. each intervention. In order to minimise the OSH and DCI When the saturation diving technique is used in the risk forWorkers the compressed working air workers, in a compressed the project consultant, air environment tunnelling under industry such for a TBMhigh pcutterheadressure willinterventions, be exposed to OccupationAECOM, has introducedSafety and the conceptHealth of(OSH) saturation risk diving due to thethe workers narcosis are effectssaturated. and They high work dosage inside ofthe oxygen.TBM In technique as the TBM cutterhead intervention strategy excavation chamber under compressed air but breathe addition,during the projectthe risk design of stage.having AECOM decompression has put down illness mixed (DCI) gas viais anhigh umbilical due to hose. frequent After they compression work in a and decompressionthe provisions of theat thesaturation start anddiving end technique of each in intervention. the hyperbaric In order environment to minim fori sae fewthe hours,OSH theyand DCIwill be risk for theEmployer’s compressed Requirements air workers, of the Contract the whichproject require consultant, the back AECOM, to a hyperbaric has introducedchamber to take the a conceptrest but are of always saturation divingContractor technique to provide asthe the saturation TBM diving cutterhead equipment intervention and under strategy pressure. during These saturated the project workers design can stay stage. and work AECOM hasfacilities put and down design the the provisions TBM to allow of the the use saturation of saturation divingcontinuously technique in ina hyperbaricthe Employer’s environment Requirements for a month of the Contractdiving technique which for require TBM cutterheadthe Contractor interventions to provide if before the saturationthey need to bediving decompressed equipment back toand atmospheric facilities and needed. The use of saturation diving technique for TBM pressure. designcutterhead the interventions TBM to hadallow previously the use been of deployed saturat byion diving technique for TBM cutterhead interventions if needed.only a few The tunnel use projects of saturation around the diving world and technique was the for TBM cutterhead interventions had previously been deployedfirst time in byHong only Kong. a few Figure tunnel 3 shows projects the recommended around the 3.world Statutory and approvalwas the process first time in Hong Kong. Figure 3 showspressure therange recommended for different modes pressure of interventions. range for different modes of interventions. According to the CAP59M Factories and Industrial Undertakings (Work in Compressed Air) Regulations of the HKSAR, no person shall be employed in compressed air at a pressure exceeding 3.45 bars without permission from the Commissioner. In this connection, exemption from the Labour Department was required to carry out hyperbaric works above 3.45 bars. Since the saturation diving technique for TBM cutterhead interventions in TM- CLKL sub-sea tunnels was the first time to be used in Hong Kong with no precedent, the process to obtain an exemption from the authority to use the saturation diving technique for TBM cutterhead interventions was a crucial task before the actual implementation of the saturation diving operation. As soon as the contract was awarded in August 2013, the Contractor commenced understanding the requirements to get the exemption for the saturation hyperbaric works. Since there was neither local guideline nor code of practice for this kind of hyperbaric works in Hong Kong, the Contractor was required to plan the saturation hyperbaric works based on renowned international guidelines and practice and submit a proposal for the authority’s review and consideration. Based on the TM-CLKL tunnel alignment, the Figure 3. Pressure range for compressed air, mixed gasContractor and saturation planned to interventiondeploy three modess. of hyperbaric Figure 3. Pressure range for compressed air, mixed gas and technique for TBM cutterhead interventions. These three saturation interventions. modes of hyperbaric techniques were Air Mode (from 0 bar to 4.2 bars), Trimix Bounce Mode (from 3.45 bars to 5.5 Saturation diving is a technique which was first bars) and Saturation Mode (from 3.45 bars to 6 bars) (Figure adopted for commercial use in 1965 by Westinghouse to 2).6 Air Mode is the conventionally manned intervention replace faulty trash racks at 61 m on the Smith Mountain practice in which the hyperbaric workers breathe normal air Dam in the United States (Kindwall, 1990). Since then, during each intervention. Decompression of the hyperbaric it was used in commercial offshore diving. Whenever workers is required after a period of working time which there is maintenance or repairs required at the offshore varies according to the working pressure. At 4.2 bars, the infrastructures under the sea, deep-sea divers are deployed allowable working time will be up to a maximum of 100 to dive at pressures of over 5 bars or more and stay minutes followed by 147 minutes of decompression. Trimix underwater for a certain period of time to inspect and repair Bounce Mode is similar to Air Mode except the hyperbaric the parts. These deep-sea divers are “saturated”. They workers breathe a trimix gas comprising oxygen, nitrogen breathe a mixture of gas instead of air to reduce the narcosis and helium with a composition of 20/47/33 (O2/N2/He)

33 HKIE Transactions | Volume 28, Number 1, pp.31-38 A W Y CHAN ET AL.

instead of normal air via the umbilical hose. Decompression and the Public Emergency Authorities (PEA) of the hyperbaric workers is also required after a period including the Fire Services Department, Hospital of working time which varies according to the working Authority, Hong Kong Police Force; and pressure. At 5.5 bars, the allowable working time will be up (3) a Risk Assessment on the hyperbaric works. to a maximum of 90 minutes followed by 305 minutes of Before getting the exemption to carry out saturation decompression. Under the Saturation Mode, the hyperbaric works in Hong Kong for the first time, there were critical workers breathe trimix gas with a composition of 12/35/53 issues to be resolved which are discussed in the following

(O2/N2/He). They could stay and live under a trimix gas paragraphs. environment in a hyperbaric chamber for up to 28 days. The An Appointed Medical Practitioner (AMP) was percentage of the oxygen, nitrogen and helium in the trimix required for the hyperbaric works. However, there was gas will be adjusted depending on the working pressure no local AMP in Hong Kong with relevant experience in and whether the hyperbaric workers are working inside saturation diving. Therefore, in addition to a local AMP and the TBM cutterhead or living in the hyperbaric chamber. his backup who were employed as required to take care of The workers were able to carry out TBM cutterhead the health of the hyperbaric workers, AMP from overseas interventions for 6 hours a day for 25 days with the last 3 countries, with backup, had to be employed to oversee days for decompression. the saturation works of the project and supervise the local Since the saturation diving technique for TBM AMPs. These AMPs from overseas countries had to apply cutterhead interventions was being deployed for the first for a limited registration, renewable each year, from the time in Hong Kong, there were no competent hyperbaric Medical Council prior to practising in Hong Kong. workers available in the local manpower market. All the Other than the AMPs who were stated in the ITA hyperbaric workers had to be imported to Hong Kong guidelines, an additional trauma surgeon and his backup by applying for working visas from the Immigration were also required to carry out emergency operations Department. In addition, there is no guideline in Hong under a hyperbaric environment in the hyperbaric medical Kong to regulate saturation works. chamber in the event of any serious accidents that might The Contractor therefore planned his saturation works happen during the TBM intervention works. for TBM cutterhead interventions with reference to several The decompression tables deployed for the renowned international guidelines and compliance with trimix bounce mode and saturation mode were not relevant statutory requirements listed in table 1. statutory decompression tables. They were commercial To apply for exemption from the Labour Department decompression tables developed by the hyperbaric to carry out hyperbaric works for the TM-CLKL project, consultant. In order to safeguard the health of the the Contractor prepared a comprehensive submission hyperbaric workers using these commercial decompression containing: tables for decompression, these decompression tables were (1) a method statement for different modes of required to be validated. A validation of the decompression hyperbaric works deployed for the TBM tables using numerical models was therefore conducted by cutterhead intervention; a physiological specialist, which was followed by a full- (2) an Emergency Response Plan detailing the scale physical trial run of the trimix bounce decompression required coordinated actions among the Contractor and saturation decompression with a team of hyperbaric

Table 1. Reference of International Guidelines/Statutory Requirements for saturation works.

Subjects Guidelines / Statutory Requirements 1 Imported French Hyperbaric Workers Hong Kong Labour Law and French Labour Law Hyperbaric work process including airmode, The International Tunnelling Association Working 2 trimix bounce mode and saturation mode Group (2015) Qualifications of the hyperbaric workers, testing and The International Marine Contractor Association 3 certification of the hyperbaric plant and equipment (IMCA) D 018 (2014) The Diving Medical Advisory Committee (DMAC) 4 Medical equipment of saturation works DMAC 15 revision 4 (2014) Hygiene standard of the saturation diving hyperbaric The Diving Medical Advisory Committee DMAC 26 5 chamber (2016) Provision of emergency medical care about saturation The Diving Medical Advisory Committee DMAC 28 6 divers (2014) Requirements for accelerated emergency The Diving Medical Advisory Committee DMAC 7 decompression 31(2013)

34 HKIE Transactions | Volume 28, Number 1, pp.31-38

workers witnessed by the Independent Hyperbaric Advisor appointed by the Highways Department.

Numerous meetings among the Labour Department, Fire Services Department, Hospital Authority, Hong Kong Police Force, the Client – the Highways Department, the Project Consultant – AECOM and the Contractor were organised for the Contractor to address comments from government authorities on the submission. Besides, emergency drills with the Fire Services Department, Hospital Authority and Hong Kong Police Force were held to streamline the emergency actions depicted in the

Emergency Response Plan before the exemption from Figure 4. General view of Living Habitat and Dangerous Goods Store for trimix gas. hyperbaric works over 3.45 bars was granted by the Figure 4. General view of Living Habitat and Dangerous Commissioner for Labour to allow the Contractor to carry Goods Store for trimix gas. out the saturation diving operation for TBM cutterhead Figure 4. General view of Living Habitat and Dangerous Goods Store for trimix gas. interventions.

4. Implementation of saturation diving technique for TBM cutterhead interventions

4.1 Setup for saturation diving operation

The Employer’s Requirements for the project required the Contractor to provide saturation diving equipment Figure 5. Layout of Living Habitat. and facilities and design the TBM to allow the use of On the TBM, a built-in electrical winch and hoist system was designed to lift and handle the TUP the saturation diving technique for TBM cutterhead Figure 5. Layout of Living Habitat. shuttle carrying the saturation workers from the specialised vehicle to the TBM gantry platform and a interventions if needed. scissor lift was equipped within the TBM to lift the TUP shuttle for connection to the TBM man lock by Figure 5. Layout of Living Habitat. On site, an area near the tunnel portal was reserved meansOn of the a specialTBM, a connectionbuilt-in electrical flange winch (Figure and 6 hoist). The system saturation was designed workers to were lift and then handle able theto workTUP in the shuttleTBM excavationcarrying the chamber saturation for workers cutterhead from intervention the specialiss.ed vehicle to the TBM gantry platform and a for construction of a living habitat (Figure 4), a compound scissor lift was equipped within the TBM to lift the TUP shuttle for connection to the TBM man lock by means ofOn a special the connectionTBM, flangea built-in (Figure 6 ).electrical The 10saturation workerswinch were and then hoistable to work in the which housed the hyperbaric chambers including a TBM excavation chamber for cutterhead interventions. living chamber where the saturation workers lived under system was designed to lift and handle the TUP shuttle carrying the saturation workers from10 the specialised vehicle pressure in a trimix gas environment; a medical chamber where medical treatment or surgical operations could be to the TBM gantry platform and a scissor lift was equipped conducted under pressure, a wet pod equipped with shower within the TBM to lift the TUP shuttle for connection and toilet facilities for use under pressure by the saturation to the TBM man lock by means of a special connection workers, a decompression chamber where the saturation flange (Figure 6). The saturation workers were then able workers were able to stay for the 3-day decompression, and to work in the TBM excavation chamber for cutterhead two Transfer Under Pressure (TUP) shuttles which were interventions. used to transport the saturation workers under pressure to the TBM for cutterhead interventions. These saturation workers were under round-the-clock surveillance by a team of technicians managed by an experienced Hyperbaric Operation Supervisor via a centralised control panel and gas panel where the storage pressure, storage temperature and trimix gas content were monitored (Figure 5). A Dangerous Goods store was also constructed in the close vicinity to the living habitat for trimix gas storage. The whole compound was equipped with fire-fighting installations approved by the Fire Services Department.

Figure 6. Provisions in the TBM for the saturation diving operation.

4.2Figure Medical 6. Team Provisions for Saturation in the Diving TBM Operation for the saturation diving operation. In the ITA guidelines, an AMP was required to take care of the health issues of the hyperbaric workers. In the IMCA guidelines, in a team of four saturation workers, two of them were required to be diving medics who were able to carry out first aid treatments in the event of any incident prior to treatments by the AMP.

The medical team for hyperbaric works in the TM-CLKL project comprised an AMP from overseas, who had the medical experience of saturation diving works, as a consultant to oversee the health of the saturation workers of the project and supervise the local AMP. 35 HKIE Transactions | Volume 28, Number 1, pp.31-38 The local AMP had to assist the overseas AMP to carry out daily health surveillance of the saturation workers while those workers were living in the hyperbaric environment and conduct medical checks of the saturation workers after they had finished the 3-day decompression at the end of the saturation cycle. Since there were occasions that the overseas AMP or local AMP was engaged or otherwise not available, a backup overseas AMP and a backup local AMP was required to take up the duties of the principal AMP.

A local trauma surgeon and a backup trauma surgeon were also appointed by the Contractor, who would be required to undertake surgical operations on the saturation workers in the event of incidents in the hyperbaric medical chamber under the hyperbaric environment.

As the diving medics were not legally authorised to carry out medical injections if needed during an incident, hyperbaric site nurses, working on shift, were employed who were able to work under hyperbaric environment, in the event of an emergency, to carry out nursing duties prior to the arrival of the local AMP.

4.3 Saturation Diving Operation

According to the IMCA guidelines, saturation workers were recommended to stay under

A W Y CHAN ET AL. hyperbaric environment for a cycle of 28 days including the decompression period. After completing the cycle, the saturation workers should take a rest of 28 days before beginning another saturation cycle. In addition, the same saturation workers were not recommended to work under pressure for more than 180 days within a year. Therefore, to carry out TBM cutterhead interventions for TM-CLKL project, a saturation diving team composed of over 50 staff members was employed which included 6 hyperbaric 4.2. Medical Team for Saturation Diving Operation doctors,then go3 nurses, to 3the hyperbaric TUP operation shuttle, supervisors, which 12 lifewould support besupervisors carried and technicians,by a and 30 saturation workers. specialised vehicle and travel from the living habitat all To start a saturation cycle, a team of four saturation workers were compressed and stored under In the ITA guidelines, an AMP was required to take pressurethe way in the to living the chamber. TBM When (Figures the two TBMs7 and were 8). excavating Upon in arrivalthe mixed atground the where daily care of the health issues of the hyperbaric workers. In the interventionTBM, thes to changetailored the cutters made were TUP required, handling two teams ofsystem four saturation on theworkers TBM were required to be stationed in the living chamber. IMCA guidelines, in a team of four saturation workers, two would lift the TUP shuttle and mount it to the manlock Whenever an intervention was required for the TBM cutterhead, the team of four saturation of them were required to be diving medics who were able workersfitted wouldwith then a goflange to the TUP to shuttle,ensure which air-tightness. would be carried byThe a speciali saturationsed vehicle and travel from the living habitat all the way to the TBM (Figures 7 and 8). Upon arrival at the TBM, the tailored to carry out first aid treatments in the event of any incident madeworkers TUP handling would system then on the go TBM into would the lift theexcavation TUP shuttle and chamber mount it to the and manlock fitted prior to treatments by the AMP. withstart a flangechanging to ensure theair-tightness. worn-out The saturation cutters. workers would then go into the excavation chamber and start changing the worn-out cutters. The medical team for hyperbaric works in the TM- CLKL project comprised an AMP from overseas, who had the medical experience of saturation diving works, as a consultant to oversee the health of the saturation workers of the project and supervise the local AMP. The local AMP had to assist the overseas AMP to carry out daily health surveillance of the saturation workers while those workers were living in the hyperbaric environment and conduct medical checks of the saturation workers after they had finished the 3-day decompression at the end of the saturation cycle. Since there were occasions that the overseas AMP or local AMP was engaged or otherwise not

available, a backup overseas AMP and a backup local AMP Figure 7. Transport of the TUP shuttle from the Living Habitat to the TBM. was required to take up the duties of the principal AMP. Figure 7. Transport of the TUP shuttle from the Living A local trauma surgeon and a backup trauma surgeon Habitat to the TBM. were also appointed by the Contractor, who would be required to undertake surgical operations on the saturation (a) workers in the event of incidents in the hyperbaric medical chamber under the hyperbaric environment. 12

4.3. Saturation Diving Operation Figure 8. Special vehicles for trimix gas delivery and TUP shuttle delivery. (b) According to the IMCA guidelines, saturation workers The allowable daily working time inside the TBM excavation chamber depended on the were recommended to stay under hyperbaric environment for a cycle of 28 days including the decompression period. intervention pressure but in general was 6 hours a day. It was divided into two sessions with a 30-minute After completing the cycle, the saturation workers should meal break inside the man lock. take a rest of 28 days before beginning another saturation cycle. In addition, the same saturation workers were not After completing 6 hours’ work, the saturation workers would return from the TBM excavation recommended to work under pressure for more than 180 chamber to the TUP shuttle, which was again carried by the same specialised vehicle from the TBM back days within a year. Therefore, to carry out TBM cutterhead to the living habitat. The saturation workers would then take a shower in the Wet Pod and return to the interventions for TM-CLKL project, a saturation diving living chamber to take a rest. team composed of over 50 staff members was employed whichFigure included 8. 6 Special hyperbaric veh doctors,icles 3for nurses, trimix 3 hyperbaric gas delivery andThe TUP team shuttle would delivery stay in. the living chamber for 25 days, with intervention works at the TBM operation supervisors, 12 life support supervisors and wheneverFigure 8. Special required. vehicles During for trimix the gaslast delivery 3 days, and the TUP saturation team would stay inside the decompression shuttle delivery. technicians, Theand 30 allowablesaturation workers. daily working time insidechamber the to TBMundertake excavation the 3-day chamberdecompression depended cycle. Whenon the the decompression process was finished, the To start a saturation cycle, a team of four saturation local AMP would conduct medical checkups, including Doppler monitoring to check the bubbles inside intervention pressure but in general was 6 hours a day.The Itallowable was divided daily working into two time sessions inside the with TBM a 30-minute workers were compressed and stored under pressure in the the body, before the team was allowed to leave the site. livingmeal chamber. break When inside the thetwo manTBMs lock. were excavating in excavation chamber depended on the intervention pressure the mixed ground where daily interventions to change the but in general was 6 hours a day. It was divided into two After completing 6 hours’ work, the saturationsessions withworkers a 30-minute would meal return break insidefrom the the man TBM lock. excavation cutters were required, two teams of four saturation workers 5. Achievements were chamberrequired to tobe thestationed TUP in shuttle, the living which chamber. was again carriedAfter by thecompleting same specialised 6 hours’ work, vehicle the fromsaturation the TBM back toWhenever the living an intervention habitat. Thewas requiredsaturation for theworkers TBM wouldworkers then would take return a shower from the in TBM the excavationWet Pod chamberand return to the to the DuringTUP shuttle, the construction which was again of the carried 5 km by long the sameTM- CLKL sub-sea tunnels, the air mode intervention was cutterhead,living thechamber team of to four take saturation a rest. workers would deployed at the approach tunnels at both the Northern Landfall and Southern Landfall for about 1 km, whereas the trimix bounce inspection followed by the saturation intervention was deployed for about 4 36 The team would stay in the living chamberkm of forthe subsea25 days, tunnels. with Aintervention total of 18 saturationworks at cyclesthe TBM were conducted (Hydrokarst Group, 2019) for HKIE Transactions | Volume 28, Number 1, pp.31-38 whenever required. During the last 3 days, thewith saturation more than team 1,200 would-disc cutters stay insidechanged the for decompression both TBMs and there was a zero case of decompression chamber to undertake the 3-day decompressionillness cycle. reported. When the decompression process was finished, the local AMP would conduct medical checkups, including Doppler monitoring to check the bubbles inside the body, before the team was allowed to leave the site. 6. Conclusion

With no decompression illness reported during the whole period of sub-sea tunnelling works, the 5. Achievements saturation diving technique was successfully implemented in the TM-CLKL project and it proved to be a safe technique for TBM interventions to minimise OSH risk for hyperbaric works. The experience During the construction of the 5 km long TM-CLKL sub-sea tunnels, the air mode intervention was gained in this project had therefore been incorporated into the updated version of the ITA Working deployed at the approach tunnels at both the NorthernGroup No. Landfall 5 version and 3 issued Southern in March Landfall 2018 for (Th aboute International 1 km, Tunnelling Association Working Group, whereas the trimix bounce inspection followed2018) by the saturation intervention was deployed for about 4 km of the subsea tunnels. A total of 18 saturation cycles were conducted (Hydrokarst Group, 2019) for with more than 1,200-disc cutters changed for both TBMs and there was a zero case of decompression illness reported. Acknowledgements

The authors are grateful for the support from the Highways Department, Labour Department, Fire 6. Conclusion

With no decompression illness reported during the whole period of sub-sea tunnelling works,13 the

saturation diving technique was successfully implemented in the TM-CLKL project and it proved to be a safe technique for TBM interventions to minimise OSH risk for hyperbaric works. The experience gained in this project had therefore been incorporated into the updated version of the ITA Working Group No. 5 version 3 issued in March 2018 (The International Tunnelling Association Working Group, 2018)

Acknowledgements

The authors are grateful for the support from the Highways Department, Labour Department, Fire

Services Department, Hong Kong Police Force of the HKSARG and the Hospital Authority. However, the content of this paper does not necessarily reflect the views and policies of these supporting organisations, nor does the mention of trade names and commercial products constitute endorsement or recommendations for use.

Notes on Contributors specialised vehicle from the TBM back to the living habitat. Notes on Contributors The saturation workers would then take a shower in the Wet Ir Albert W Y CHAN Pod and return to the living chamber to take a rest. Ir Albert W Y Chan received his B.Sc. The team would stay in the living chamber for 25 andAlbert M.Sc. received degree his in BSc Civil and MScEngineering degree in Civil Engineering from The University of Hong Kong in 1988 and 1996 respectively. He has more than 30 years of days, with intervention works at the TBM whenever fromexperience The University in delivering of civil Hong works Kong projects in in Hong Kong. For tunnel projects, he required. During the last 3 days, the saturation team would 1988was and involved 1996 inrespectively. the Harbour AreaHe has Treatment more Scheme Stage 1 and Stage 2A as well stay inside the decompression chamber to undertake the Services Department, Hongthanas Kong 30the yearsTsuen Police ofWan Force experience Drainage of the HKSARG Tunnel in delivering project. and the Hospital Authority. However, the content of this paper does not necessarily reflect the views and policies of these supporting 3-day decompression cycle. When the decompression civilAlbert works is currently projects Chief in Hong Engineer Kong. of the For East Development Office, Civil organisations, nor does theEngineering mention of trade and Developmentnames and commercial Department. products He was constitute Senior endorsementEngineer in theor Major process was finished, the local AMP would conduct recommendations for use.tunnel Work projects,s Project Management he was involved Office (Special in the Duties) of the Highways Department medical checkups, including Doppler monitoring to check Harbour Area Treatment Scheme Stage managing the Tuen Mun–Chek Lap Kok Link project including the construction of the bubbles inside the body, before the team was allowed to Notes1 and on StageContributors 2A as wellthe subas the-sea Tsuen tunnel Wanuntil itsDrainage completion. Tunnel leave the site. project. Ir Charles H C YEUNG Albert is currently ChiefIr Albert Engineer W Y CHAN of the East Development Charles received his BSc degree in Civil Engineering from The University of ServicesOffice, Department, Civil Engineering HongAlbertHong Kongreceived Kong and Police hisinDevelopment BSc1988 Force and and MSc of diplôme thedegree Department. HKSARG ind’ingénieur Civil Engineering and from the Hospital L’Ecolefrom The NationaleUniversityAuthority. des However, Travaux 5. Achievements He was Senior Engineerof PublicsHong Kong dein inl’Etat the 1988 Majorin and France 1996 Worksrespectively. in 1990 Projectrespectively. He has more Hethan has 30 yearsmore of than 30 years of the content of this paperexperience does innot delivering necessarily civil works reflect projects the in Hongviews Kong. and Forpolicies tunnel projects,of these he supporting organiManagementsations, nor doesOffice wastheexperience involved (Specialmention in in ofthe Duties) tunnel tradeHarbour namesprojects Areaof the Treatmentand involving Highways commercial Scheme drill Stageand products blast 1 and, andStageconstitute TBM. 2A as Thewellendorsement tunnel or During the construction of the 5 km-long TM-CLKL recommendationDepartment managings for use.as projectsthe the Tsuen Tuen he Wan has Mun–ChekDrainage been involved Tunnel Lap project. include Kok RouteLink 3 Tai Lam Tunnel, KCR West Rail AlbertTai isLam currently Tunnel, Chief KCR Engineer Lok ofMa the Chau East DevelopmentSpur Line, MTR Office, Kowloon Civil Southern Link, sub-sea tunnels, the air mode intervention was deployed project including theEngineering MTRconstruction Express and Development Railof the Link, sub-sea Department. Tuen tunnelMun –HeChek untilwas SeniorLap Kok Engineer Link inNorthern the Major Connection Works Project Management Office (Special Duties) of the Highways Department at the approach tunnels at both the Northern Landfall and Notesits completion. on Contributors Sub-sea Tunnel Section. managing the Tuen Mun–Chek Lap Kok Link project including the construction of Southern Landfall for about 1 km, whereas the trimix the sub-sea tunnel until its completion. IrCharles Albert isW currently Y CHAN Senior Resident Engineer (Tunnel) in Hyder-Meinhardt JV bounce inspection followed by the saturation intervention IrIr Charles H C HYEUNG C Yeung received his supervising the Contract of Trunk Road T2 sub-sea tunnels. He was Senior was deployed for about 4 km of the subsea tunnels. A total B.Sc.CharlesAlbertResident degree received received Engineer inhis his BScCivil BSc (TBM) degree andEngineering MSc inin Ci AECOM vildegree Engineering infrom between Civil from Engineering 3 The December University from 2013 ofThe and University 31 of 18 saturation cycles were conducted (Hydrokarst Group, TheHongofDecember HongUniversity Kong Kong in 19882019 in and1988of supervising diplômeHong and 1996 d’ingénieurKong the respectively. Contract in from1988 ofL’Ecole He the has Tuen Nationalemore Mun than des– 30Chek Travaux years Lap of Kok Link 2019) for with more than 1,200-disc cutters changed for andPublicsexperienceNorthern diplôme de l’Etat Connectionin deliveringind’ingénieur France in Subcivil 1990-sea worksfrom respectively. Tunnel projects L’Ecole Section He in has Hong. more Kong. than 30 For years tunnel of projects, he experiencewasIr Andy involved in J. tunnel WESTMORELANDin the projects Harbour involving Area Treatmentdrill and blast Scheme, and TBM. Stage The 1 and tunnel Stage 2A as well both TBMs and there was a zero case of decompression Nationaleprojectsas the Tsuenhe has des beenWan Travaux involved Drainage includePublics Tunnel Route project.de 3 l’Etat Tai Lam Tunnel, KCR West Rail Andy has more than 35 years of experience in the tunnelling industry, starting with illness reported. inTai AlbertFrance Lam isTunnel, currently in 1990 KCR Chief Lok respectively. Ma Engineer Chau Spur of the Line,He East hasMTR Development Kowloon Southern Office, Link, Civil the Singapore MRT in 1983, the Channel Tunnel Project in 1988 and the moreMTREngineering Expressthan Rail 30and Link, yearsDevelopment Tuen of Mun experience Department.–Chek Lap Kok Hein Link was Northern Senior Engineer Connection in the Major SubWorkStorebaelt-seas Tunnel Project Project Section. Management in Denmark Office in (Special 1991 before Duties) settling of the inHighways Hong Kong Department in 1995 . In

tunnel managingHong projects Kong, the Tuenhe involving has Mun been–Chek involved drill Lap and Kok in a blast,Link number project of includingmajor tunnelling the construction projects of and the Charles is currently Senior Resident Engineer (Tunnel) in Hyder-Meinhardt JV 6. Conclusion and TBM. The tunnelthedevelopment projects sub-sea tunnel he of has hyperbaricuntil been its completion.involved tunnelling. include Andy was Chief Resident Engineer (TBM) supervisingfor AECOM the Contract between of Trunk30 August Road T22013 sub -andsea tunnels.31 December He was Senior2019 supervising the Route 3 Tai Lam Tunnel,ResidentIr Charles EngineerKCR H CWest (TBM)YEUNG Rail in AECOM Tai Lam between Tunnel, 3 December 2013 and 31 Contract of the Tuen Mun–Chek Lap Kok Link Northern Connection Sub-sea With no decompression illness reported during the KCR Lok Ma ChauDecember Spur 2019Line, supervising MTR Kowloon the Contract Southernof the Tuen Mun–Chek Lap Kok Link NorthernCharlesTunnel Connection received Section hisand Sub BSc -issea currently degree Tunnel inSection inCi avil similar. Engineering role for from Hyder The- UniversityMeinhardt of JV on the whole period of sub-sea tunnelling works, the saturation Link, MTR Express IrHong T2AndyRail Trunk Kong J.Link, WESTMORELAND Road in Tuen1988 Sub and Mun–Chek-Sea diplôme Tunnel d’ingénieur Project.Lap Kok from L’Ecole Nationale des Travaux diving technique was successfully implemented in the Link Northern ConnectionAndyPublics has moredeSub-sea l’Etat than in 35 Tunnel France years of inSection. experience 1990 respectively. in the tunnelling He has industry, more than starting 30 years with of theexperience Singapore inMRT tunnel in 1983, projects the Channelinvolving Tunnel drill Projectand blast in ,1988 and andTBM. the The tunnel TM-CLKL project and it proved to be a safe technique for Charles is currentlyStorebaelt projectsSenior Projecthe Resident has beenin Denmark involvedEngineer in 1991 include (Tunnel) before Route settling 3in Tai in LamHong Tunnel,Kong in KCR1995. WestIn Rail TBM interventions to minimise OSH risk for hyperbaric Hyder-Meinhardt HongJVTai supervising LamKong, Tunnel, he has beenKCR the involved LokContract Ma in Chau a number of Spur Trunk of Line, major MTR tunnelling Kowloon projects Southern and the Link, works. The experience gained in this project had therefore Road T2 sub-sea tunnels.developmentMTR Express He ofwas hyperbaric Rail Senior Link, tunnelling. TuenResident Mun Andy– EngineerChek was Lap Chief Kok Resident Link Northern Engineer (TBM)Connection forSub AECOM-sea Tunnel between Section. 30 August 2013 and 31 December 2019 supervising the Contract of the Tuen Mun–Chek Lap Kok Link Northern Connection Sub-sea been incorporated into the updated version of the ITA (TBM) in AECOM between 3 December 2013 and 31 Working Group No. 5 version 3 issued in March 2018 December 2019 supervisingTunnel Section the and Contract is currently of in the a similar Tuen role Mun– for Hyder- Meinhardt JV on the T2Charles Trunk Roadis currently Sub-Sea Senior Tunnel Resident Project. Engineer (Tunnel) in Hyder-Meinhardt JV (The International Tunnelling Association Working Group, Chek Lap Kok Linksupervising Northern the Connection Contract of TrunkSub-sea Road Tunnel T2 sub- sea tunnels. He was Senior Resident Engineer (TBM) in AECOM14 between 3 December 2013 and 31 2018). Section. December 2019 supervising the Contract of the Tuen Mun–Chek Lap Kok Link Northern Connection Sub-sea Tunnel Section. Ir IrAndy Andy J. J. WestmorelandWESTMORELAND has more than Acknowledgements 35Andy years has of more experience than 35 years in ofthe experience tunnelling in the tunnelling industry, starting with the Singapore MRT in 1983, the Channel Tunnel Project in 1988 and the industry,Storebaelt startingProject in Denmarkwith the in 1991Singapore before settling in Hong Kong in 1995. In Hong Kong, he has been involved14 in a number of major tunnelling projects and the The authors are grateful for the support from the MRT in 1983, the Channel Tunnel Highways Department, Labour Department, Fire Services Projectdevelopment in 1988 of hyperbaricand the Storebaelt tunnelling. AndyProject was Chief Resident Engineer (TBM) for AECOM between 30 August 2013 and 31 December 2019 supervising the Department, Hong Kong Police Force of the HKSARG and in ContractDenmark of the in Tuen 1991 Mun before–Chek Lap settling Kok Link in Northern Connection Sub-sea the Hospital Authority. However, the content of this paper HongTunnel Kong Section in and1995. is currently In Hong in a Kong,similar rolehe for Hyder- Meinhardt JV on the does not necessarily reflect the views and policies of these hasT2 been Trunk involved Road Sub -Seain a Tunnel number Project. of major supporting organisations, nor does the mention of trade tunnelling projects and the development of hyperbaric names and commercial products constitute endorsement or tunnelling. Andy was Chief Resident Engineer (TBM) for recommendations for use. AECOM between 30 August 2013 and 31 December 2019 supervising the Contract of the Tuen Mun–Chek Lap Kok Link Northern Connection Sub-sea Tunnel Section and is currently in a similar role for Hyder- Meinhardt JV on the 14 T2 Trunk Road Sub-Sea Tunnel Project.

37 HKIE Transactions | Volume 28, Number 1, pp.31-38 A W Y CHAN ET AL.

Ir S W FOK Ir SS W obtainedFok obtained his BSc and his BA B.Sc. degrees. and He hasBA 43 -year[6] solid constructionThe Diving Medical Advisory Committee (2016). degrees.experience He has in Hong 43-year Kong solidinvolving construction in an extremely wide rangeSaturation of both marine diving and chamber hygiene, DMAC 26 Rev. 1. land-based structures including bridges, viaducts, roads, drains, and high-tech experiencebuildings. Hine alsoHong has extensiveKong involving experience in in TBM tunnelling,[7] The marine International Marine Contractor Association an extremelyreclamation, sitewide formatio rangen blastingof both and marine heavy foundations , i.e.(2014). bored piling, Code rock of Practice for the initial and periodic andsocket land-based H-piles, diaphragm structures walling, including top down construction andexamination, deep excavation testing for and certification of diving plant tunnellingIr S W and FOK basement structures. He is Principal Resident Engineer of AECOM bridges,supervising viaducts, the construction roads, drains, phase ofand the high-Tuen Mun–Chek Lapand Kok equipment Link project. D 018 Rev. 1. tech Sbuildings. W obtained He his also BSc has and extensive BA degrees. He[8] hasThe 43 -Internationalyear solid construction Tunnelling Association Working experienceexperience in TBM in Hong tunnelling, Kong in marinevolving in an extremelyGroup (2015). wide range Guidelines of both for marine Good andWorking Practice Irland Conrad-based C W structuresNG including bridges, viaducts, roads, drains, and high-tech reclamation, site formation blasting and heavy foundations, in High Pressure Compressed Air, 5(2). buildings. He also has extensive experience in TBM tunnelling, marine i.e. bored piling, rockIr socketConrad C H-piles, W NG received diaphragm his BSc degreewalling, in Civil Engineering[9] The from International The Tunnelling Association Working Universityreclamation, of Hong site Kong formatio in 1982. Hen blastingis currently and Vice heavy President foundations of AECOM who, i.e. bored piling, rock top down construction and deep excavation for tunnelling Group (2018). Guidelines for Good Working Practice hassocket over 38 H years-piles, of local diaphragm experience walling,in planning top and downfeasibility construction study, design andand deep excavation for and basement structures.documentation, He is Principal project management, Resident Engineer and construction and contractin High administration Pressure Compressed Air, 5(3). oftunnelling various highway and and basement tunnel infrastructure structures and. Hemajor is multi Principal-disciplinary Resident projects Engineer of AECOM of AECOM supervisingincludingsupervising the construction Tseung theKwan construction Ophase Tunnel, of Route the phase Tuen8 between of the Cheu Tuenng Sha Mun Wan– andChek Sha Lap Kok Link project. Mun–Chek Lap Kok LinkTin, Central project.-Wan Chai Bypass and Island Eastern Corridor Link, Tuen Mun-Chek Lap Kok Link, Tseung Kwan O-Lam Tin Tunnel, Cross Bay Link, and Lok Ma Chau Loop. Mr Fabrice GUEDONIr ConradIr Conrad C W C Ng W receivedNG his B.Sc. degree in Civil Engineering from The Fabrice was Project DirectorUniversityIr of ConradDragages of Hong –CBouygues W KongNG Joint received in Venture, 1982. his Hethe BScContractor is degree for thein ContractCivil Engineering of the from The Tuen Mun–Chek Lap Kok LinkUniversity Northern Connection of Hong Sub Kong-sea Tunnelin 1982. Section He between is currently 23 January Vice 2017 President and of AECOM who 10 July 2019. currently Vice President of AECOM who has overhas over38 years 38 years of local of local experience experience in in planning and feasibility study, design and planningdocumentation, and feasibility project study, management, design and and construction and contract administration documentation,of various projecthighway management, and tunnel infrastructureand and major multi-disciplinary projects constructionincluding and Tseung contract Kwan administration O Tunnel, Route 8 between Cheung Sha Wan and Sha Tin, Central-Wan Chai Bypass and Island Eastern Corridor Link, Tuen Mun-Chek of various highway and tunnel infrastructure and major Lap Kok Link, Tseung Kwan O-Lam Tin Tunnel, Cross Bay Link, and Lok Ma multi-disciplinary projects including Tseung Kwan O Chau Loop. Tunnel, Route 8 between Cheung Sha Wan and Sha Tin, Mr Fabrice GUEDON Central-Wan Chai Bypass and Island Eastern Corridor

FabriceLink, was Tuen Project Mun-Chek Director Lap of Kok Dragages Link, –TseungBouygues Kwan Joint O-Lam Venture, the Contractor for the Contract of the Tuen TinMun Tunnel,–Chek Cross Lap Kok Bay LinkLink, Northernand Lok Ma Connection Chau Loop. Sub-sea Tunnel Section between 23 January 2017 and 10 July 2019. Mr Fabrice Guedon was Project Director of Dragages– Bouygues Joint Venture, the Contractor for the Contract of the Tuen Mun–Chek Lap Kok Link Northern Connection Sub-sea Tunnel Section between 23 January 2017 and 10 July 2019.

References [1] Hydrokarst Group (2019). Saturation works for maintenance operations in TBM - 15Hong Kong. [YouTube video] Available at: https://www.youtube. com/watch?v=cvAHuhFA3rA. [Accessed on 11 March 2021]. [2] Kindwall E P (1990) ‘A short history of diving and diving medicine’, in Bove, A. A. and Jefferson, C. D. (eds.) Diving medicine (2nd edn). WB Saunders Company, pp. 6-7. [3] The Diving Medical Advisory Committee (2013). Accelerated emergency decompression (aed) from saturation DMAC 31. [4] The Diving Medical Advisory Committee (2014). Medical equipment to be held at the site of an offshore diving operation, DMAC 15 Rev. 4. [5] The Diving Medical Advisory Committee (2014). The provision of emergency medical care for divers in saturation, DMAC 28 Rev. 2.

15 38 HKIE Transactions | Volume 28, Number 1, pp.31-38