Lyntas/mining_domain_knowledge_reference_dataset huggingface dataset:
Area: Marine Facilities
The projects marine infrastructure comprises several marine facilities which are within intertidal or sub-tidal waters. These marine facilities can be categorized into 4 main sites consisting of:
 LNG Jetty/Suspension Bridge (including LNG berth structures and the Suspension Bridges SW Anchor Block and SW Tower foundations and associated scour protection armouring);
 Pioneer Dock;
 Materials Off-loading Facility (MOF); and
 Lelu Island Access Bridge.
The construction methodologies will be developed with consideration of minimizing the potential for environmental disturbance.
The LNG Jetty has been divided into two main components consisting of the 
Suspension Bridge which spans over Flora Bank, and the 
Trestle and Berth Structures which make up the balance of the overall LNG Jetty. 

The Suspension Bridge is approximately 1,100m long and is the closest jetty section to the shore. Since the Suspension Bridge spans over Flora Bank, it effectively avoids any form of marine foundations within Flora Bank. 
The Trestle section of the jetty and the Berth Structures are located in deeper waters and are comprised of pile-and deck construction.
Because of the inherently different structures used for the two Jetty components, the construction methodologies will be divided between the 
Suspension Bridge and the
 Trestle/ Berth Structures. 

The Suspension Bridge component will be further divided between the 
Bridges superstructure and the 
Bridges marine foundations consisting of the Southwest Tower and Southwest Anchor Block. 

A comparison will be drawn between viable methods for constructing the Trestle and Berth Structure component.
Area: Marine Facilities
The following definitions describe basic marine terminology used in this report:
 Pile: A pile is a heavy column or post either driven or drilled into the ground or seabed to support the foundations of a structure. Piles are commonly made of either timber, concrete or steel. For the PNW LNG marine facilities, steel pipe piles fabricated from large diameter steel pipe sections welded together to form the final pile length are most practical.
Area: Marine Facilities
 Bent: A bent is part of a bridge or trestle substructure and is comprised of a group of piles, typically installed in a single line, connected at their tops with a pile cap forming a single rigid frame that supports a vertical load. Bents are typically placed transverse to the length of the overall structure and directly support the beams and girders that support the deck of the bridge or trestle.
Area: Marine Facilities
Cofferdam: A cofferdam is a watertight enclosure from which water is pumped to expose the bottom of a body of water and permit construction.
Area: Marine Facilities
Jetty: A jetty is a pier structure built out into the sea or along the shore as part of a port. It typically includes a landing stage at which ships can dock or be moored. For the purposes of the PNW LNG project the LNG Jetty includes the Suspension Bridge, and the Trestle and Berth Structures.
Area: Marine Facilities
Trestle: A long bridge-like structure which typically spans from the shoreline out to berth structures located in deeper navigable waters. The trestle is supported on a series of bents spaced at regular intervals, using large beams or girders to span between the bent foundations. A trestles deck typically includes space for a roadway, pipe supports, and pedestrian walkways.
Area: Marine Facilities
Dolphin (Breasting dolphin) (Mooring dolphin): A dolphin is a man-made marine structure that extends above the water level and is not connected to shore. Dolphins are usually installed to provide a fixed structure when it would be impractical to extend the shore to provide a dry access facility. Typical uses include extending a berth (a berthing dolphin) or providing a point to moor to (a mooring dolphin). The berthing dolphin is equipped with a fender which is used to "cushion" ship impacts whereas mooring dolphins are set a certain distance from the vessel and are equipped with hooks used to secure the vessels mooring lines. For the PNW LNG facilities both berthing dolphins and mooring dolphins are required to securely hold a vessel in the berth. The dolphin structures typically consist of a number of piles set into the seabed and connected above the water level to provide a platform or fixing point. The piles are typically steel pipe piles connected by a reinforced concrete capping or a structural steel frame. Access to a dolphin is typically gained via a catwalk (pedestrian bridge).
Area: Marine Facilities
Caisson: "Caisson" is the French word for "box." A caisson is a huge box or tub made of steel-reinforced, waterproof concrete with a central core that is open from the top. For a wharf facility, the caisson comprises both the foundation and main superstructure of the wharf. For the Suspension Bridge, the caisson becomes the Anchor Block or the pilecap supporting the bridge tower.
Area: Marine Facilities
Dock: A structure extending alongshore or out from the shore into a body of water, to which boats may be moored.
Area: Marine Facilities
Wharf: A structure built typically along the shoreline of deeper navigable waters so that ships may be moored alongside to receive and discharge cargo and passengers.
Area: Marine Facilities
Spud: A spud is a retrac Table leg or underwater column that is deployed from a dredge or marine derrick barge and is used for staying or maintaining the barge in position as construction proceeds.
Area: Marine Facilities
Fender: A fender is a rubber component that is attached to wharves, berthing dolphins, and other marine structures where vessels can make contact with the structure. The fender absorbs the impact energy of berthing (incoming) vessels and hence protects the structure and ship from damage. A fender is formed of rubber which absorbs berthing energy by virtue of the work required to deform it elastically by compression, bending or shear or by a combination of such effects. Because a fender is made of rubber it makes little to no noise as it is compressed or stressed by a berthing vessel.
Area: Marine Facilities
The bridge marine foundations are shown on concept drawings prepared by Infinity Engineering Group Ltd. (Infinity). Two major marine foundations are required for the proposed Suspension Bridge located at the SW Tower and SW Anchor Block
Area: Marine Facilities
Conceptual Foundations Overview
The preliminary design for the South West (SW) Anchor Block consists of,
 a 45 m x 44 m x 21.3 m deep concrete cap 
Supported by an 8 x 8 grid of 1800 mm diameter concrete filled pipe piles.
Area: Marine Facilities
The Anchor Block cap is hollow to accommodate a splay chamber where the bridges cable strands are anchored to the cap.
The piles are battered at a 4:10 slope in the bridge longitudinal direction. The piles are approximately 65 m long, determined from borehole 34, and are driven through the overburden material down to bedrock. All of the piles are anchored into the bedrock with rock sockets with an embedment of 6.0 m. Out of the 64 total piles, there are 32 tension piles each anchored with 31-strand rock-anchors embedded 25 m into the bedrock. This foundation design is only preliminary and will change prior to the completion of a final design that is ready for construction.
The depth to rock at nearby boreholes B-33 and B-34 was determined as 70 m and 44 m, respectively, from the mudline. The bedrock is primarily overlain by poor quality material with only limited depths (~5 m) of more competent soil immediately above it. Further details are available in the Draft Geotechnical Recommendations for Trestle and Berthing Area of Pacific Northwest LNG (PNWLNG) Project by Fugro dated October 11, 2013.
Area: Marine Facilities
Construction Access
Providing adequate access to the marine foundations is a primary consideration. This is especially so, considering the marine foundations for the bridge are fairly sizable, and will require not only a significant amount of working area for construction, but also a fairly significant portion of the overall bridge construction schedule.
Several potential options for providing the required amount of temporary construction access have been considered including methods such as:
 Self-elevating platforms (jack-up barges);
 Temporary working platforms supported on temporary piles;
 Temporary working platforms supported on the permanent piles;
 Marine-based methods using floating equipment; and
 Temporary/permanent Man-Made Islands.
A discussion of each option is provided below; challenges for each exist and their viability would need to be confirmed during the detailed design process. Once in place, each access option would need to be supplied, to varying degrees, with crew and materials by barges and vessels subject to tidal and other environmental restrictions such as wind, sea state and visibility.
Area: Marine Facilities
Jack-Up Barge
A jack-up barge comes equipped with legs or spuds which can be lowered to sit on the seabed and used to lift the hull of the barge up above the sea level providing a large fixed working platform unaffected by tides and swells as shown in Figure 2-1. Jack-up barges are fairly common in marine construction and can be located at each foundation location.
The barges can be equipped with large cranes sufficient to support the anticipated pile driving, cleanout, and concrete foundation installation anticipated for the bridge marine foundations. The challenge at this site is the significant depth of weak materials above the bedrock. The bearing capacity of the seabed may be insufficient to support the concentrated loads from the spuds when the barge is elevated, causing the spuds of the barge to sink deep into the mud. This will make extending and retracting the spuds very difficult if not impossible. Also many jack-up barges do not have legs of sufficient length or size to be utilized at this location. Although there are rigs with legs up to and in excess of 80 m in length, none are currently believed to be within local contractor fleets.
As given in Section 2.1.1.4 the overall schedule duration for construction of the SW Anchor Block foundation is 24 months. One or two Jack-up barges could be deployed to conduct construction operations on the foundation. With the exception of extreme sea states or weather conditions, it is anticipated that the jack-up barge(s) would stay in position for most of the foundation construction. The jack-up barges would need to be supplied by one or two supply barges carrying equipment or various construction materials. To resupply the work front and to accommodate the tidal windows, the supply barges would transit every day between an onshore staging area and the work site. For the 6 month period where concrete would be poured for the Anchor Block, at least three concrete supply barges would be required to work in rotation to make on average six deliveries 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. The EPC contractor may have to work double shifts during this 6 month period to accommodate tidal windows and meet the schedule.
Area: Marine Facilities
Temporary Working Platform Supported on Temporary Piles
With this method, the temporary pile supported working platform provides a fixed structure upon which a crane and equipment can be placed to install the bridge foundations. The platform would be supported on a series of additional temporary piles and would be required to extend around the perimeter of the foundations in order to provide adequate access for constructing the foundations. An example of a temporary work platform supported on temporary piles is shown in Figure 2-2.
The platform(s) would allow the construction work to continue independent of the tides. The cranes and equipment would remain on the platform for the duration of the foundation construction. Similar to the Jack-up Barge method the crews on the working platform would need to be supplied by one or two supply barges carrying equipment or various construction materials. To resupply the work front and to accommodate the tidal windows, the supply barges would transit every day between an onshore staging area and the work site. For the 6 month period where concrete would be poured for the Anchor Block, at least three concrete supply barges would be required to make up to six deliveries per day.
For this option the working space would likely be kept to the absolute minimum in order to limit the amount of construction required for the temporary platform. The restricted space would inhibit the ability to store material and equipment which may lead to more frequent barge supply trips.
Completely removing the temporary piles installed for the platform after foundation construction would be challenging and potentially unrealistic. Consideration for leaving them in place or potentially cutting them off at the mudline would need to be evaluated
Area: Marine Facilities
Marine-Based Floating Equipment
For the floating marine-based construction method, the cranes, equipment and materials are all brought to the work front on floating flat deck barges. The primary piece of equipment required for marine-based construction is the marine derrick, which is essentially a flat deck barge that has a duty-cycle crawler crane mounted on it. A typical marine derrick is shown in Figure 2-3.

It is expected that there will be two to four barges positioned at each foundation location during construction; one or two marine derricks and one or two flat deck scows for material storage and acting as a work platform to perform miscellaneous tasks. Marine derricks and scows operated by local marine contractors vary in size and can be as large as 60 m long and 20 m wide. To resupply the work front and to accommodate the tidal windows, the marine derricks and scows would transit every day between an onshore staging area and the work site. Alternatively one or more supply barges could also be used for transporting materials from the mainland to the work front depending on construction requirements.
For the 6 month period where concrete would be poured for the Anchor Block, at least three concrete supply barges would be required to make up to six deliveries per day to meet the quantities of concrete required. To maintain somewhat continuous concrete placement, the EPC contractor may have to work double shifts during this 6 month period to accommodate tidal windows and meet the schedule.
The shallow water depths adjacent to the bridges marine foundations necessitate any marine-based construction to be limited to tidal windows and weather delays. This would extend the construction period significantly as well as drive up construction costs, and therefore floating marine-based methods have a significant disadvantage compared to other options which are not tidal-dependent. This is especially so, when considering the sizable efforts required for constructing the bridge foundations. Additionally, the risk of equipment grounding and unintentionally disturbing sensitive habitat is of concern. Also if the marine derricks are spud barges, the use of spuds to anchor the barge into position will add to the habitat disturbance.
One advantage that marine-based-methods have over other methods is that additional crews and equipment can be readily deployed on multiple work fronts to mitigate delays.
Area: Marine Facilities
Temporary/Permanent Man-Made Islands
Due to the shallow water depths at the proposed bridge foundations, the construction of a man-made island at each foundation location was considered as a means to provide uninterrupted construction access. Following construction of the bridge, the islands could be removed, in case of temporary islands, or left in place permanently. The amount of material removed and the desired final elevation of the islands would be dependent on the intent of any offsetting measures such as the creation of additional inter-tidal habitat or the planting of additional eelgrass beds or riparian vegetation.
However, the islands would require placement and possibly reclamation, of a significant volume of material in the marine environment. The resulting footprint of the man-made islands on the marine floor would be considerable and at the SW Tower foundation would likely extend onto Flora Bank. Due to this large habitat disturbance footprint, the man-made island option was discounted and withdrawn from further consideration.
Area: Marine Facilities
Construction Safety Zone and Navigation Protection
Regardless of the method selected to gain access for constructing the bridge foundations, there should not be an impediment to marine traffic. The work faces will occur in relatively small areas in open waters away from or adjacent to approach channels and will be surrounded by a cofferdam. A safety zone would be enforced around the cofferdam, and work site in general which would prohibit vessels from approaching closer than 50 m. Work site restrictions would be promulgated through a variety of channels, such as Notices to Mariners, in accordance with the Marine Communication Plan. As a participant in the Port of Prince
Ruperts Construction Coordination Committee for de-confliction with other users, PNW LNGs
Marine Communications Plan will be used to alert mariners to project activities, hazards and safety measures such as enforced safety zones and marine route closures.
Area: Marine Facilities
Construction Process
Once equipment access and a working area at the foundation locations have been provided either through the use of a Jack-up barge, temporary work platforms, etc., the construction of each marine foundation is presumed to generally follow a similar process. This consists of cofferdam installation, pile installation, concrete work on the Anchor Block or pilecap, concrete pedestal/tower base construction, cofferdam removal, and placement of scour protection. Each activity is described in more detail below.
Area: Marine Facilities
Cofferdam installation is required around each of the marine foundations to allow dewatering and excavation to the depth of the concrete pile cap soffit to facilitate concrete works and construction. It is anticipated the cofferdams would be constructed of steel sheet piles driven to depth in the soft sediments and extending up beyond the high water level. Internal bracing within the cofferdam would be used to support the sheet piles against external pressures. If the size of the foundations, particularly at the SW Anchor Block location, and the poor soil at the site preclude the use of a single sheet pile cell, utilizing a ring of self-supporting sheet pile cells may be an option. After sheet pile installation, a steel template is installed inside the cofferdam to correctly position the piles. The bottom of the concrete foundations will be located to sit approximately at or slightly above the existing mudline to avoid the need for any overburden excavation from inside the cofferdam.
After the piles are installed, the steel template can be removed. Finally a concrete seal is constructed, via tremie pouring, at the bottom of the excavation to allow for dewatering.
After the cofferdam is dewatered the piles are cut off at the bottom of the Anchor Block.
Area: Marine Facilities
Pile installation commences after the cofferdam is excavated and the steel pile template has been installed.
The proposed construction method for pile installation involves the following steps:
? Set the pile into the sediments by gravity;
? Vibrate the pile open-ended though the sediment until the tip reaches bedrock;
? When the pile reaches bedrock, seat the pile into the bedrock with an impact hammer;
? Extract sediments inside pile with a grab hammer or airlift methods;
? Drill a hole in the bedrock with the drill inside the pile which is acting as a casing; and
? For a rock doweled pile, advance pile into under-reamed hole and then grout pile; or alternatively for a rock socket pile, do not advance pile but insert rebar cage and pour tremie concrete into bottom of hole.
Pile driving and drilling including clean out and socketing, for the proposed 1800 mm diameter pipe piles is similar, only on a larger scale, to the trestle foundations as outlined in Sections 3.4 and 3.5. Any overburden material removed from inside the piles will be stockpiled on a barge and disposed of on land as discussed in Section 3.4.
One difference between the trestle piles and the Anchor Block piles is that the Anchor Block piles are filled with concrete over their full length. Thus, instead of stopping the concrete after the rock socket is complete, the concrete pour will continue until the pile is filled to the top. Since the pile driving operations are within the confines of the cofferdam, the effects to the surrounding marine life will be minimal. The piles will be approximately 65 m long and will require welded field splices. Field splices can either be done on a barge with the pile in a horizontal position or in-situ, depending on the size of crane used.

In addition to the rock sockets, rock anchors need to be installed for the 32 tension piles.
The rock anchors consist of 31-strand tendons that are embedded 25 m into the bedrock and anchored within the Anchor Block. After drilling for the rock sockets, a smaller diameter drill bit is used to drill into the bedrock to the required depth. The strand anchors and an inner casing are lowered to the bottom of the drilled shaft. Concreting for the rock sockets is completed and the piles are filled with concrete. The rock anchors are completed by injecting grout from the bottom of the shaft upwards to a depth required to fully develop the anchor force. The strands are stressed from within the Anchor Block and the remaining length of the shaft is grouted to protect the anchors from corrosion.