Lyntas/mining_domain_knowledge_reference_dataset huggingface dataset:
Area: Marine Facilities
Concrete foundation construction would progress similar to onshore construction after completing pile installation. The connection between the piles and pile caps consists of a reinforced concrete plug inside each pile head with the reinforcement cage extending up into the mass concrete of the pilecap. Construction of the pilecaps and other concrete elements would consist of placing reinforcement, constructing formwork, and pouring concrete in a series of lifts separated by construction joints. Supply of the large volumes of concrete required for the foundations will need to be conducted via barge. As a result, concrete supply and hence concrete placement will be affected by tidal restrictions and may impose longer construction times. Considering the large volumes of concrete required for the bridge foundations, there are two possible methods for supplying concrete to the work face; one involves concrete produced by an onshore batch plant and delivered to the work face via concrete trucks on a barge, and the other involves using an actual floating batch plant located adjacent to the work site. For the first method, the barges will be loaded with a pump truck and several concrete trucks and will travel from the construction batch plant located on the mainland to the work front at approximately 1-hour intervals. 
Figure 2-5 shows a typical barge loaded with a pump truck and several concrete trucks. This method is generally slower and is restricted by a delivery window of about 2-hours which represents the time the concrete is allowed to sit in the trucks. As mentioned previously, considering the volume of concrete required, it is estimated that at least six barge runs carrying at least four 10 m3 concrete trucks and one concrete pump truck would be required to meet the needed concrete volumes and meet the schedule.
The floating batch plant method on the other hand is more efficient at supplying concrete to the work face, however it is more susceptible to tidal and weather related down times.
The contractor will need to the weigh the pros and cons of either method or may choose to use a combination of both, depending on seasonal weather conditions


Prior to casting the top portion of the Anchor Block, the suspension cable anchorage assemblies and splay saddles are installed and secured into the Anchor Block. These are large assemblies of prefabricated structural steel that will be transported to the foundation on barges and installed with the barge crane. Finishing works on the Anchor Block will be completed after the main suspension cables have been installed and adjusted.
Area: Marine Facilities
Cofferdam removal can commence once the required foundation concreting works are above the high water level. Excavated material can be placed back within the cofferdam allowing for the removal of internal bracing layer by layer. The steel sheet piles can be removed with a vibratory hammer. Consideration for leaving the sheet piles in place below the top of the footing to help with scour prevention should be made.
Area: Marine Facilities
Placement of scour protection around the perimeter of the Anchor Block would be conducted soon after removal of the cofferdam. Due to the shallow waters around the Anchor Block, the scour protection would be placed via marine-based methods using tidal windows and a flat deck barge equipped with an excavator or front end loader and a stockpile of riprap. The excavator or front end loader would place the scour protection to the appropriate thickness.
Area: Marine Facilities
Construction of the SW Anchor Block will consume a considerable amount of the construction schedule and will be on the critical path. It is estimated to take approximately 24 months to construct the Anchor Block, with the following breakdown:
 3 months to construct the cofferdam
 10 months to install the piles and rock sockets
 6 months to install the concrete Anchor Block mass concrete
 3 months to install the rock anchors (work can overlap with constructing the mass concrete Anchor Block)
 2 months to install the suspension cable anchorage assemblies and splay saddles
Area: Marine Facilities
2.1.2.1 Overview
The preliminary foundation design for the South West (SW) tower consists of 4 rows of 7 piles each (total of 28). The piles in the outer periphery of the pile group are battered at a 1:10 slope. The piles are 1800 mm diameter steel pipes, filled with concrete with rock socketed ends. The rock bed at the SW tower location is approximately 100 m below Low Water Level.
The approximate mud line and rock bed top level have been taken from Bore Hole BH  33. The approximately 100 m long piles will be vibrated through the overburden material into the bedrock. A drilled rock socket of 6 m length will be provided. The pile is filled with concrete over its entire length and connected rigidly to the pile cap. The cap provided is 36.4 m × 20.2 m × 4 m deep. A 13 m high concrete tower base extends from the pile cap to the underside of the superstructure. The tower base consists of two 4 m x 8.5 m columns connected with a 1 m thick infill wall for transverse rigidity. This foundation design is only preliminary and will change prior to the completion of a final design that is ready for construction.
Area: Marine Facilities
Construction Access
Similar to the SW Anchor Block, there are several potential options for providing the required access to construct the tower foundation. The south edge of the footing cap however, is directly adjacent to Flora Bank and therefore there will be limited to no access on the south side of the foundation to avoid disturbance to Flora Bank.
Area: Marine Facilities
 Construction Process
The SW Tower foundation will be constructed in the same manner as the SW Anchor Block, by installing a cofferdam around the perimeter of the foundation, installing piles and rock sockets and finally concreting the pile cap. Scour protection would be placed shortly after removal of the cofferdam once the concrete foundation is complete. The equipment used will be the same as that for the Anchor Block and the number of daily barge transits will be similar. The volume of concrete required for the tower foundation however, is significantly less than the Anchor Block, so concreting will take less time and require less barge traffic. For the 4 month period where concrete would be poured for the SW Tower foundation, at least two concrete supply barges would be required to work in rotation to make, on average, one delivery per day in order to meet the quantities of concrete required. In practice the EPC contractor will attempt to maximize the concrete deliveries for any given work shift to provide a somewhat continuous concrete placement. The actual number of daily concrete supply trips may be as high as eight or more, depending on tidal restrictions. Concrete placement for the SW Tower should be coordinated to not overlap with concrete placement for the SW Anchor Block. This will allow for the least amount of concrete supply equipment required for the bridge foundations.
Similar to the Anchor Block, the concrete caisson method is a possible alternative to the use of cofferdams. However for the same issues and concerns surrounding the use of concrete caissons for the Anchor Block foundation, use of this method for the tower pilecap was not given much consideration past the initial concept development.
The concrete tower base will be constructed on top of the pile cap within the cofferdam using the same concreting methods as the pile cap. The pile cap will be used to anchor a tower crane that will be used to construct the steel portion of the tower. As a result, the cofferdam should be left in place at least until the tower crane base is installed.
Area: Marine Facilities
Construction Schedule
Construction of the SW tower foundation will be on the critical path. It is estimated to take approximately 16 months to construct the foundation, with the following breakdown:
 3 months to construct the cofferdam
 9 months to install the piles and rock sockets
 2 months to install the concrete pile cap
 2 months to install the concrete tower base
Area: Marine Facilities
Overview

The 128 m long portion of the towers above the concrete base are composed of structural steel legs connected with cross-bracing. The towers are 125 m high above deck level. The thick walled steel boxes are 2.2 m wide and vary in length from 5.5 m at the top to 7.0 m at the bottom. Each segment is approximately 5.0 m in height. The connections between the leg segments as well as the connections of cross members to the main tower legs are bolted splice connections detailed for repetition and ease of on-site installation. Saddles that carry the main suspension cables are positioned on top of the towers. Typically of cast steel, the saddles can also be custom fabricated using built up plates. They will be equipped with rollers to allow the main cables to shift/adjust under construction and normal loads.
Area: Marine Facilities
Construction Access
Construction of the steel tower is done mainly from a tower crane and temporary work platforms supported off the permanent tower legs at required locations. The tower crane is supported on the permanent footing cap and is self-climbing (i.e. it increases in height as the tower height increases). The tower crane is braced to the permanent tower legs as its height increases. Figure 2-6 below shows a typical tower crane used for bridge tower construction
Area: Marine Facilities
Temporary work platforms are installed to the tower segments before they are erected to provide access to the bolted connections. Work platforms are installed at the top of the tower legs to facilitate installation of the suspension cable saddles. The work platforms at the top of the towers typically remain in place for future maintenance and inspection of the cable saddles. Temporary stair scaffolding is typically provided the full height of the tower to provide access to the temporary work platforms.
Area: Marine Facilities
Construction Process
Construction of the steel tower segments consists mainly of lifting prefabricated structural steel segments off the barge and onto previously installed segments using the tower crane.
There are two tower legs for the SW tower braced to one another by structural steel bracing.
Tower segments are spliced together with bolted connections. Bracing members are bolted to the tower leg segments as the tower erection progresses. Steel segments are typically trial assembled at the fabrication facility to ensure member fit-up and ease of installation on site.
During trial assembly, adjacent segments are assembled using the final splice plates and about half the number of bolts required in the final connection. Corrections are made so that the segment fit-up and finally geometry is met. Finally, the pieces are marked, disassembled and shipped to site. Temporary working platforms will be pre-installed to the tower segments on site. This work will likely take place on the mainland to avoid having to install the platforms on a barge or high in the air.
Area: Marine Facilities
Construction Schedule
The tower segments, with work platforms already installed, will be delivered using material supply barges with an anticipated delivery frequency of one barge per week. Construction of the SW Tower is estimated to take approximately 6 months.
Area: Marine Facilities
Overview
The main suspension cables are fabricated from numerous small diameter (5 to 6 mm) high strength parallel wires that are galvanized. Cable clamps are provided every 10 m and serve two purposes. First the cable clamps are used to compact the parallel wires into a tight bundle of circular shape and minimum diameter. Second, the vertical hanger cables used to support the deck are connected to the cable clamps.
The vertical hanger cables that support the bridge deck from the main suspension cable consist of high strength wire ropes that connect to the cable clamp at the top and will utilize a stressable anchor socket at the lower connection to the superstructure. The stressable anchor sockets at the lower end will provide for adjustability to address fabrication and erection tolerances. The anchor sockets are connected to the superstructure steel girder by a steel pin with the adjustability coming from the threaded anchor socket itself.
Area: Marine Facilities
Construction Access
The majority of the construction for the main suspension cable happens from a hanging catwalk system suspended from the suspension cable itself. Hence, there is very little marine based traffic required while constructing the main suspension cable. Barges will only be required for supplying materials for the catwalk system.
Area: Marine Facilities
Construction Process
The main suspension cable starts by stringing a small diameter pilot cable from the SW Anchor Block to the NE Anchorage. The pilot cable can be carried from one anchorage to the other by helicopter or by boat and then hoisted to the top of the towers using the tower cranes. Once the pilot cable is installed, it is then used to pull successively larger cables over the towers to the opposite anchor block. Through this means, multiple cables will be installed to allow for catwalks to be erected about 1.5 m below the proposed suspension cables over the full length of the bridge. The catwalks are an access walkway used by ironworkers to facilitate main suspension cable installation. After completion of the catwalks, the main suspension cables are installed by continuously pulling individual wires back and forth from anchorage to anchorage until the required number of wires is achieved (aerial spinning). The reels of wires are delivered to Lelu Island and will be fed to the spinning process from immediately behind the NE Anchorage. Figure 2-7 shows a suspension cable during the spinning process.

The cable spinning is done using equipment supported by the cables themselves, thus no floating construction equipment is required during the cable installation process. After the requisite number of wires is installed, the bundles of wires are compacted into a circular pattern and the cable clamps are installed. The cable clamps serve to maintain the circular shape of the cable and for attaching the vertical hanger cable. A typical cable
Area: Marine Facilities
With the main suspension cable and cable clamps completed, cable cranes that ride on top of the suspension cable are installed. The cable craned will be used to install the vertical hanger ropes and the bridge deck segments.
After the superstructure has been constructed, finishing work on the main suspension cable is done. This includes final cable compaction, installation of cable wraps for corrosion protection and catwalk removal. As shown in Figure 2-9 this work is done from the catwalks and the newly installed superstructure, thus requiring no support from marine equipment.
Area: Marine Facilities
Construction Schedule
It is expected that installation of the main suspension cables lasts approximately 8 months and must be completed before the superstructure segments can be installed. Cable finishing works is expected to last approximately 8 months and will begin after the superstructure is complete. During work on the main suspension cables there will be very little construction marine traffic, although crews will be continuously working above any marine traffic navigating below the suspension bridge.
Area: Marine Facilities
Overview
The suspended portion of the deck extends from the NE Tower to the SW Anchor Block (total length of 1490 m). Structurally the deck is composed of an orthotropic steel box girder supported on either side with the two suspension cable planes. The deck is suspended with four hanger cables spaced approximately 10 m apart along the longitudinal axis of the bridge.
The orthotropic steel box is aerodynamically shaped for wind stability. Each segment is approximately 20 m long and is connected to adjacent segments by fully bolted splice connections. Each segment weighs approximately 200 metric tons.
Area: Marine Facilities
Construction Access
The steel box deck segments are lifted into position using a cable crane that travels along both suspension cables. The deck segments are delivered on a barge directly under their intended final position. Since the main span of the suspension bridge spans over the Flora Bank, all deck segments within the main span will need to be barged into position during high tides (water depths greater than 4 m). Once the segment is lifted off the barge (approximately 1 hour), the barge is no longer required and can be taken away from the Flora Bank. All other work for installing the deck segment can be done above water without any tidal restrictions.
A below-the-deck gantry will be used to facilitate installation of the bolted connections along the underside of the deck. This gantry will travel along the deck maintaining its position at the leading edge of deck construction.
Area: Marine Facilities
Construction Process
The cable crane will hoist each segment from the barge into its final position where four hanger ropes will be attached. The segment is bolted to the previously installed segment and the cable crane is released. The cable crane walks itself up the suspension cable and sets itself into position for the next segment and the process repeats until all segments are installed. Figure 2-10 shows installation of a deck segment of similar shape as that proposed for this bridge.
Area: Marine Facilities
Construction Schedule
It is expected that construction of the suspended superstructure will last approximately 9 months. With an estimated 75 deck segments, it is anticipated that each deck segment will take approximately three to four days to install, with only one of these days involving marine traffic to transport the segment to its final position. Only those areas which are within a safety radius of the deck section being lifted will be restricted from traffic underneath the bridge. The balance of the passage underneath the bridge should remain open to marine traffic throughout the duration of the suspended superstructure construction. The erection of deck sections will be conducted at high tide to mitigate the possibility of grounding the supply barge onto Flora Bank. The erection of deck sections will also need to be timed to occur during minimal wind conditions.
There is an estimated 8 months of additional finishing work to take place on the suspension cables and bridge deck once the suspended superstructure is complete. However, all of this work will be within the confines of the new bridge and will pose minimal interruption to normal marine traffic.
Area: Marine Facilities
The construction methodologies described in this section are suitable for pile-and-deck structures as required for the LNG Jetty Trestle and Berth Structures component. Pile-and deck structures are commonly used for marine facilities in British Columbia. For this type of structure, individual support piles are either driven into overburden sediments, if the overburden sediments are deep enough, or drilled into bedrock. The piles provide support to a pile cap and deck superstructure.
The trestle structural configurations as given in the Environmental Assessment submission and the various FEED contractor bid submissions are all pile-and-deck type structures with some variations with respect to materials and member sizes. In general, the various designs for the trestle can be described as a deck superstructure supported on steel pipe pile bents installed at 36 m spacing. The pipe piles vary from 914 mm to 1219 mm in diameter and are either seated on the bedrock or socketed into the underlying bedrock. Each bent has at least 4 piles, including vertical and battered piles, and has a steel box beam or precast concrete pile cap which spans perpendicular to the trestle alignment. The pile caps in turn support steel box beams or precast concrete girders which span between the bents and form the main trestle superstructure and vehicle roadway. The pipe racks consist of steel truss assemblies spanning between the bents and are installed adjacent to the roadway. A typical LNG trestle structure is shown in Figure 3-1.

The two principal methods proposed for constructing the LNG Jetty Trestle and Berth
Structures are:
 The Marine-Based Method, which uses floating equipment; and
 The Cantilever Method, which uses a mobile construction platform that progresses above the water supported by the very trestle foundations that it installs.
Although either method may be used to construct the entire Trestle, as discussed in the following sections, the floating Marine-Based Method is more effective in deeper water, whereas the Cantilever Method is more efficient and quicker in shallow waters, since marine based equipment will be restricted to tidal windows and hence longer construction times.
Area: Marine Facilities
Floating Marine-Based Method
Where the water depths are sufficient enough to not limit construction to tidal windows, marine derricks and floating equipment may be used to install the Trestle and Berth Structures. There is less likelihood of barges grounding in deeper waters where the seabed is sub-tidal. Also sub-tidal habitat is less sensitive to disturbance. In shallow waters, the work would be limited to tidal windows and the risk of equipment grounding and disturbing the sensitive inter-tidal habitat is greater. Also the cost of construction will be higher and take longer due to the constant interruption of work to accommodate tidal windows.
For this construction method, the cranes, equipment and materials are all brought to the work site on floating flat deck barges. In general, the methods and techniques used to install and drill piles are similar to the Cantilever Method with the exception that the crane is on a floating platform and not a fixed one. As such, the construction activities are more susceptible to delays due to sea state and environmental conditions. In addition, temporary piles and false work may be required to support templates for accurately installing the permanent piles.
Placement of scour protection around the perimeter of each pile for either the Trestle or the Berth Structures would be conducted soon after installation of the piles and before the installation of the main deck elements to allow easier access for floating equipment. For structures located in shallow waters, the scour protection would 

be placed via marine-based methods using tidal windows and a flat deck barge equipped with an excavator or front end loader and a stockpile of riprap. The excavator or front end loader would place the scour protection to the appropriate thickness around each pile. For structures in deeper waters, in lieu of an excavator, a marine derrick fitted with a clamshell grab may be used for more accurate placement of the scour protection.