Abstract: A method of dredging which comprises suspending dredging apparatus 200 from a vehicle 360. The sediment agitating apparatus comprising a chassis 210, and mounted on the chassis are an extractor, sediment agitating apparatus and respective pumps 220, 230. The dredging apparatus 200 is disposed above, but not in contact with a waterbed 340 to be dredged of sediment 350. The sediment 350 is agitated then extracted with the extractor. The dredging apparatus 200 is moved around the water and the extracted sediment 400 is deposited underwater and above the dredging apparatus 200, so that the sediment 400 is transported and deposited away from an area being dredged by the natural movement of the water. Apparatus and use of the apparatus are also described.

Abstract: A hydraulic excavation apparatus may be used for providing access to a pipeline buried under shallow water or in wetland locations, for example, in order to install an electro-mechanical clamp on the pipeline. This clamp can then be used for connecting externals anodes to the pipeline, for monitoring the level of corrosion protection of the pipeline, or for any other purpose.

Abstract: A method of emptying an undersea fluid transport pipe (2) that is submerged and full of water, by pumping out at least a portion of the water present inside the submerged pipe using a submersible pump unit (6) connected to a point of the pipe, the volume of water pumped out from the inside of the pipe being compensated by a gas injected under pressure into the submerged pipe from a point (18) thereof that is situated higher than the connection point (12; 14) to the submersible pump unit. The invention also provides an installation for performing such a method.

Abstract: An earth working apparatus, for laying a pipe or cable underground. The earth working apparatus comprises a plurality of trenching modules. Each trenching module is arranged sequentially in a first plane and comprises a cutter in communication with a conveyor. In a second aspect, each trenching module cuts a layer of earth and conveys said layer of earth to a collection device or to a collection area.

Abstract: A method of laying underwater pipelines in the bed of a body of water, the method including laying an underwater pipeline along a given path on the bed of the body of water; breaking up a ground mass along the path to a given depth in the bed; and fluidifying the broken ground mass beneath the underwater pipeline to sink the underwater pipeline into the fluidified ground mass.

Abstract: A fluidified inert material spreading device configured to bury a pipeline in a body of water is configured to travel in the body of water in a travelling direction along and over the pipeline, and has a hull, which extends along a longitudinal axis, houses at least one expansion chamber for fluidified inert material, is connected to at least one feed port to feed the fluidified inert material to the expansion chamber, and has a quantity or number of outlet ports configured to release the fluidified inert material from the expansion chamber, close to the pipeline, and which as a whole define a flow cross section greater than the flow cross section of the feed port.

Abstract: An underwater trenching system is mountable on a side of a barge to be propelled by the barge along a waterway, the bed of which contains a trench with a laid pipeline. To remove the excess sediment from the trench the trenching unit delivers pressurized water and air to the trench. A sparge assembly with jet nozzles directs jets of water, breaking up the formation that has built up around the pipeline. The airlift assembly creates a turbulent flow to lift the disturbed sediment and remove it from the created trench.

Abstract: A method of laying underwater pipelines in the bed of a body of water, the method including laying an underwater pipeline along a given path on the bed of the body of water; breaking up a ground mass along the path to a given depth in the bed; and fluidifying the broken ground mass beneath the underwater pipeline to sink the underwater pipeline into the fluidified ground mass.

Abstract: An underwater trenching system is mountable on a side of a barge to be propelled by the barge along a waterway, the bed of which contains a trench with a laid pipeline. To remove the excess sediment from the trench the trenching unit delivers pressurized water and air to the trench. A sparge assembly with jet nozzles directs jets of water, breaking up the formation that has built up around the pipeline. The airlift assembly creates a turbulent flow to lift the disturbed sediment and remove it from the created trench.

Abstract: An underwater trenching system is mountable on a side of a barge to be propelled by the barge along a waterway, the bed of which contains a trench with a laid pipeline. To remove the excess sediment from the trench the trenching unit delivers pressurized water and air to the trench. A sparge assembly with jet nozzles directs jets of water, breaking up the formation that has built up around the pipeline. The airlift assembly creates a turbulent flow to lift the disturbed sediment and remove it from the created trench.

Abstract: An underwater trenching system is mountable on a side of a barge to be propelled by the barge along a waterway, the bed of which contains a trench with a laid pipeline. To remove the excess sediment from the trench the trenching unit delivers pressurized water and air to the trench. A sparge assembly with jet nozzles directs jets of water, breaking up the formation that has built up around the pipeline. The airlift assembly creates a turbulent flow to lift the disturbed sediment and remove it from the created trench.

Abstract: A riser retention apparatus includes a board. A component connector is mounted to the board. A support frame is coupled to the board adjacent the component connector and extends from the board. A riser guide is located on the support frame and operable to engage a riser and guide a riser connector on the riser toward the component connector. A riser retention member is operable to couple to the support frame to provide a retaining force to a riser in order to retain the riser connector in engagement with the component connector. A riser including a plurality of components coupled to it may be coupled to the component connector and the support frame and riser retention member may be used to support the riser and retain the riser in the component connector.

Abstract: A guide device suitable for use in an offshore drilling installation having at least one drilling riser extending from a floating support to the guide device on the seabed. The guide device includes a guide pipe in a buried position, wherein the guide pipe has a front end resting horizontally on the seabed, a curved intermediate portion buried in the subsoil of the seabed at a radius of curvature preferably being greater than 500 m, and an inclined substantially linear rear portion at the rear end of the guide pipe buried in the subsoil of the seabed at a given angle of inclination lying in the range 50° to 60°.

Abstract: A method and apparatus are provided for accessing a cable or pipe (9) buried underwater in a layer of material (10). The method comprises urging a tool (1) through the layer of material (10) by fluidising the material adjacent the tool (1) such that the tool may be positioned at or adjacent the position of the buried cable or pipe.

Abstract: A method and system for laying and burying pipe a seabed using a pipe trenching plow that is advanced along the seabed to form a continuous trench. The pipe trenching plow cuts a pilot hole in the seabed using a cutting apparatus and widens and forms a trench from the pilot hole using expandable spreading side sections. A pipe guiding sled also is used to support and guide the pipe into the trench and a trench box section retains the trench geometry as the pipe trenching plow is continuously advanced in a forward direction. The pipe trenching plow cutting the trench and burying the pipe with minimal turbidity and seabed disturbance.

Abstract: An apparatus for burying cables and pipes in soil includes a support structure adapted for movement across a surface of the soil. A water jetting machine is provided for producing a source of pressurized water. At least two jetting arms are in fluid communication with the source of pressurized water. The jetting arms have vertical adjustment structure for varying at least the vertical position of each jetting arm relative to the support structure so as to adjust for varying soil conditions. A method for burying cables and pipes in soil is also disclosed.

Abstract: An apparatus for forming a trench in a seabed for burying a line generally consisting of a main frame, at least one buoyancy tank mounted on the main frame, a pair of endless track assemblies, each engageable in gripping relation with a side of the line for propelling the frame along the line, a pair of jet legs mounted on the main frame and communicable with a source of fluid under pressure, for ejecting high velocity streams of fluid to dislodge portions of the seabed when the track assemblies grip the line and propel the main frame along the line to form a trench and allow the line to fall therein.

Abstract: A method and apparatus are provided for accessing a cable or pipe (9) buried underwater in a layer of material (10). The method comprises urging a tool (1) through the layer of material (10) by fluidising the material adjacent the tool (1) such that the tool may be positioned at or adjacent the position of the buried cable or pipe.

Abstract: An underwater cable deployment system includes a series of cables, pre-wound on a set of reels, disposed upon a pallet and connected to a distribution hub on the pallet. The pallet is lowered to the ocean floor and a remotely operated vehicle (ROV) is also lowered to the ocean floor to deploy cables to form a predetermined array on the ocean floor. Preferably, the pallet is delivered to the ocean floor in advance by crane with the reel-mounted sensor array cables being deployed later by ROV. Optionally, the ROV may include a jetting package configured to bury the sensor cable as it is being deployed from the reel on the ROV.

Abstract: An underwater self-propelled trenching apparatus for burying a pipeline or the like below the bottom of a body of water having a frame that is positioned on each side of the pipeline, jets in the form of nozzles that spray pressurized streams of water to dig the trench, a set of rollers supported on the apparatus for contacting the pipeline and guiding the apparatus along the pipeline and a plurality of thrusters pivotally supported on the frame for propelling the trenching apparatus along the pipeline including the thrusters having more axes of movement in the horizontal and vertical planes for impelling water entering the thruster out of the thrusters to generate any one of multiple forces applied to the trenching apparatus along a horizontal or vertical plane.

Abstract: An ocean plow device and accompanying method which incorporate a passive plow blade and a jetter tool working in conjunction with one another to lower drawbar and increase cable deployment speeds. In order to avoid cavitation due to sand dilation, in one embodiment of the plow device, the jetter tool includes nozzles oriented in a downward and backward direction relative to the plow device which creates a flow pattern to turbulently remove surface soil in front of the jetter tool in a rapid manner. The jetter tool is pivotally suspended from a point in front of the passive plow blade, such that the jetter will be free to find its own equilibrium position. That is, the pivotal mounting enables the jetter tool to rotate upward in harder soils and become fully extended in softer soils in order to reach the equilibrium position. The passive plow blade behind the jetter tool provides a constant burial depth for the cable and also provides protection from side loads encountered during deployment.

Abstract: A method for the penetration of a body (8), having a leading edge (21) and an inclined ground contacting surface (C, D, E) extending upwardly therefrom, into a porous ground material, the pores of the ground material being at least partially filled with water. The method comprises applying a driving force to the penetrating body in the direction of penetration, and discharging from the penetrating body (8) at least one flow of high-pressure gas to the inclined surface so as to facilitate the penetration of the body. Moreover, a penetrating body (8) and a plough assembly both of which can be used in the method. The method and equipment may e.g. be used for embedding drain tubes, pipes, cables or similar objects into a ground material also at a relatively great depth larger than 100 cm. Moreover, the embedding can be performed by employing a relatively high speed and can be performed at a relatively low energy consumption.

Abstract: A device for creating a localized water jet within a body of water allows for the displacement of material from the floor of the body of water. The device includes two powered screws within a jet pipe. The screws are arranged coaxially and their direction of rotation, pitch, and speed of rotation are arranged such that the torque produced by one of the screws tends to counteract the torque produced by the other, allowing for improved control of the device.

Abstract: A self-guided system for trenching water bottoms for the installation of a pipeline. The preferred embodiment of the present invention teaches a system which is configured to be mounted about the pipeline to be buried, and which further contemplates a uniquely configured, forward mounted trenching/drive mechanism incorporating a cutter wheel generally about the width of the desired trench, the mechanism configured to propel the system as well as trench the desired area. An alternative embodiment of the contemplates a frontal high pressure jet array in lieu of the cutter head. The trenching/drive mechanism of the preferred embodiment of the present invention further includes a high pressure spray array mounted about the frontal cutter wheel area, and a suction/mud pump assembly to the rear of the cutter wheel. The high pressure spray array provides the dual purpose function of loosening the area to be trenched, as well as cleaning and removing the trenched matter from the cutter wheel.

Abstract: A system for entrenching an underwater pipeline on a water bottom. The system is comprised of an underwater pipeline positioned on a water bottom; a floating vessel; an elongated tubular entrenching tool having a plurality of tool nozzles; a jetting head having a plurality of nozzles attached to the entrenching tool by a flexible jetting head hose; first and second waterlines; means for connecting the first waterline to the rear end of the entrenching tool and means for connecting the second waterline to the front end of said tool; and means for suspending the entrenching tool below the pipeline. A pump supported on the surface vessel is connected to the waterlines and is utilized to pump a volume of water at a desired pressure through the waterlines to the entrenching tool to create a trench on the water bottom for entrenching the pipeline by the jets of water at the tool and jetting head nozzles.

Abstract: An improved trench-filling device for covering a pipe and filling in a trench dug in a sea bed, characterized in that the device comprises two sets of nozzles (6,7) arranged above and proximate to the sea bed on both sides of the trench (1), the nozzles pointing towards the sea bed and towards the trench and being fed with pressurized water to direct powerful jets of water into the ground making up the sea bed adjacent the trench to deposit into the trench constituent parts of the adjacent ground as the trench-filling device progresses along the trench, and guides (14, 14') provided above to channel the high pressure jet streams created by the nozzles (6,7).

Abstract: A self-guided system for trenching water bottoms for the installation of a pipeline. The preferred embodiment of the present invention teaches a system which is configured to be mounted about the pipeline to be buried, and which further contemplates a uniquely configured, forward mounted trenching/drive mechanism incorporating a cutter wheel generally about the width of the desired trench, the mechanism configured to propel the system as well as trench the desired area. The trenching/drive mechanism of the present invention further includes a high pressure spray array mounted about the frontal cutter wheel area, and a suction/mud pump assembly to the rear of the cutter wheel.

Abstract: A system for excavating and rehabilitating underground pipelines. The system including an earth removal unit, a coating removal unit and a defect detection unit each of which is self-propelled to ride on and/or along underground pipelines. The earth removal unit includes an adjustable housing adapted to be mounted about an exposed portion of the underground pipeline. The earth removal unit further includes front and rear wheel assemblies adapted to engage the top surface of the underground pipeline. A plurality of endless belts are suspended from the housing so that they assume a position beneath the underground pipeline. The endless belts are independently operable and include a plurality of cutting/digging elements. The endless belts are offset in both the horizontal and vertical directions with respect to the underground pipeline. The coating removal unit includes at least one endless chain for removing the deteriorated coating on the underground pipeline.

Abstract: The invention relates to an apparatus for relocating sedimentary materials particularly from the bottom of water channels. The invention utilizes a water jet fluidizer to displace sedimentary materials and to suspend them in a water flow. The water flow containing the suspended, dispersed sedimentary material is contained within a shaped duct means and re-directed as a uni-directional flow, so that re-deposition of the displaced sediments is controlled. The apparatus includes a manifold having parallel water jets spaced apart in a transverse direction along it; a parallelogram linkage for controlling the position of the manifold; a hose for supplying water under pressure to the manifold; and a duct means arranged opposite the manifold for directing the flow of dislodged sedimentary material in suspension. The apparatus preferably is supported on wheels and is controlled by the linkage from a boat. In shallow water, the device may be supported on a hand controlled trolley.

Abstract: A self-guided system for trenching water bottoms for the installation of a pipeline. The preferred embodiment of the present invention teaches a system which is configured to be mounted about the pipeline to be buried, and which further contemplates a uniquely configured, forward mounted trenching/drive mechanism incorporating a cutter wheel generally about the width of the desired trench, the mechanism configured to propel the system as well as trench the desired area. The trenching/drive mechanism of the present invention further includes a high pressure spray array mounted about the frontal cutter wheel area, and a suction/mud pump assembly to the rear of the cutter wheel. The high pressure spray array provides the dual purpose function of loosening the area to be trenched, as well as cleaning and removing the trenched matter from the cutter wheel.

Abstract: A water jet system for trenching of a cable or a pipe below the floor of a river, lake, gulf or ocean bottom. Two opposed water jet legs are carried on a carriage forward of venturi tubes for disposing of the trenched bottom. The carriage includes a hydraulically powered track system for advancing along the length of the cable or pipeline. The water jets are a plurality of nozzles mounted in a rotating tube at different angular directions. When the nozzle tube rotates within the housing and the nozzles pass by different openings at different heights, the jets' high pressure water shoot forth. The high pressure action of the streams of water loosen the sediment below the floor of the body of water, which is subsequently carried away by air or water action through venturi tubes which are positioned behind the jet legs. The jet legs and carriage are positioned, controlled and powered from a work vessel on the surface of the water.

Abstract: A machine and method are provided for reconditioning pipelines. The machine comprises parts and modules which are easily stowed, manually portable into and out of excavations, and easily installed together to form a machine for reconditioning the outer surface of pipelines. A frame construction capable of assembly around a pipeline is provided. A travel module is attachable to the frame to move the frame along the pipeline. A traction module is attachable to the frame to provide substantially constant traction during travel regardless of surface irregularities. A ring construction is provided for placement around the pipeline and rotation about rollers attachable to the frame that engage the inside of the ring construction. Retaining arms and reconditioning devices can be mounted on the ring construction and a rotating module is attachable to the frame to engage and rotate or oscillate the ring construction around the pipeline.

Abstract: For excavation of a clay seabed, particularly in a coffer dam to expose a buried pipeline, a minimum of three water nozzles producing water jets and the associated effects 16, 17 and 18 are used. The nozzles are mounted on a disc 12 which can move horizontally and vertically and which rotates in a horizontal plane. The effect 18 (if operated alone) would produce a trench 22 having sloping sides. The two effects 16, 17 enable a trench having vertical sides to be cut and enable the disc 12 to be moved downwardly until obstructed by the base of the trench. The three nozzles are equiangularly spaced about the axis. The rotation of the disc 12 makes the effect of the nozzles possible.

Abstract: A machine and method are provided for reconditioning pipelines. The machine comprises parts and modules which are easily stowed, manually portable into and out of excavations, and easily installed together to form a machine for reconditioning the outer surface of pipelines. A frame construction capable of assembly around a pipeline is provided. A travel module is attachable to the frame to move the frame along the pipeline. A traction module is attachable to the frame to provide substantially constant traction during travel regardless of surface irregularities. A ring construciton is provided for placement around the pipeline and rotation about rollers attachable to the frame that engage the inside of the ring construction. Retaining arms and reconditioning devices can be mounted on the ring construction and a rotating module is attachable to the frame to engage and rotate or oscillate the ring construction around the pipeline.

Abstract: Scavenging apparatus for embedding cables or the like into the soil of waters, comprising an elongated scavenging sword being adapted to be attached at different heights to an embedding vessel movable on the soil of waters or to a surface water vessel, the sword having a guide channel extending through the sword from the top to the bottom in the rear area thereof for the guidance of the cable and its depositing on the bottom of the trench scavenged free, the sword further including a water channel extending through from the top to the bottom in the front region thereof and connected to a pressurized water supply at the upper end and to a set of scavenging nozzles located at the front side of the scavenging sword, and a vibrator for the scavenging sword, the vibrator being connected to an energy source located on the vessels by energy supply lines, with the vibrator being located with the scavenging sword near the sole of the sword and the energy supply lines for the vibrator extend inside the sword.

Abstract: A freighter or coaster is temporarily converted for cable laying by an accommodation and power module, a stern side thruster and control and deployment equipment, all of which is removable after completion of the lay for the vessel to return to its normal operation.

Abstract: An underwater trenching system comprises a closed trenching system that vacuums up sediment removed during the trenching operation and deposits that same sediment into the trench, thereby burying a pipeline that has settled into the trench. The invention provides a trenching sled having high pressure water jets for digging and a vacuum head and lines for sucking the resulting sediment into a surge tank on a barge, from which it is re-deposited by a bury sled.

Abstract: A method and apparatus for simultaneously digging a trench in the bottom of a body of water and laying a pipe from a barge therein. The plow is provided with vertical side plates to assist in molding the side of the cut trench so an inclined ramp can move the soil upwardly where it is diverted to each side of the trench. The pipe being laid is extended from a working barge through a hiatus at the aft end of the trenching device. The position of the pipe in the hiatus is monitored and that information is used to properly position the barge with respect to the trenching machine. In one embodiment a gas/oil spring supports the lower horizontal roller at the bottom of the hiatus.

Abstract: An embedding apparatus for optionally cutting through different densities of soil and rock in order to embed cable in a waterbed. The apparatus comprises a low pressure jet assembly for cutting into the soil, a rock-cutting assembly with teeth for cutting into soft rock; a rock-embedment depressor with a rotary saw blade assembly for cutting into relatively harder rock; and a depth sensor device. The low pressure jet assembly is part of a pivotal soil embedment depressor and liquifies the soil without any permanent soil displacement. The rock embedment depressor is selectively attachable to the soil embedment depressor, and has jets connected to a source of pressurized fluid to provide an hydraulic cushion thereunder and to clear the rock debris for the embedment of the cable.

Abstract: A method for progressively producing an underwater laying-out channel (3) for an object (53) to be laid out, like a cable or the like, in an underwater ground by flushing and by mechanically loosening ground formations (7) which are resistive against flushing, by means of a mechanical loosening device (31) having a given maximum working depth, characterized by lowering the mechanical loosening device (31) to the ground formation (7) which is resistive against flushing, and advancing, in an advancing direction, the mechanical loosening device through the ground formation which is resistive against flushing, with the working depth being effective from the surface of that ground formation.

Abstract: A self-propelled underwater bed cable burying machine is disclosed, which comprises a bottom running gear body with a high pressure water generator mounted therein and an arm-shaped water jet trenching unit mounted the base end capable of revolution in a horizontal plane on a front portion of the running gear body and having a multiple joint degree of freedom. The arm-shaped water jet trenching unit includes an elbow arm having at least one portion capable of being bent in a vertical plane. The elbow arm having a U-shaped hand provided at the free end for capturing and holding an underwater cable. The U-shaped hand having finger portions each provided at least one cable sensor and a trenching water jet nozzle communicating with the high pressure water generator.

Abstract: A method for progressively producing an underwater laying-out channel (3) for an object (53) to be laid out, like a cable or the like, in an underwater ground by flushing and by mechanically loosening ground formations (7) which are resistive against flushing, by means of a mechanical loosening device (31) having a given maximum working depth, characterized by lowering the mechanical loosening device (31) to the ground formation (7) which is resistive against flushing, and advancing, in an advancing direction, the mechanical loosening device through the ground information which is resistive against flushing, with the working depth being effective from the surface of that ground formation.

Abstract: A deep trench is excavated into a sea bottom. The trench is filled with a slurry, e.g. clay and water, to maintain trench integrity for a period of time. A pipeline is subsequently lowered to the trench bottom by either gravity settlement, jet down using water jets, or vibration.

Abstract: Apparatus and a method for progressively forming a subsea trench and for laying a pipeline in that trench are provided. The apparatus includes a towable sled for supporting the pipeline as it is being laid in a subsea trench that is being created by fluid jetting, mechanical cutting or a combination of both, using jetting and cutting devices mounted on the sled. In the preferred embodiment, the jet device proceeds the mechanical cutter on the sled and is vertically adjustably mounted so it can be raised out of the way while the mechanical cutter is in use.

Abstract: An underwater trenching apparatus for burying pipeline and the like including a frame for positioning about the pipeline to be buried, a drive roller system operatively connected to the frame for driving the frame along the pipeline and including at least one pair of opposed rollers, each of the rollers having a curved pipe contact surface having a radius less than the radius of the pipeline to be buried and configured to grasp about 40 percent of the circumference of the pipe, the arms to which the rollers are mounted pivot about a shaft which is removably mounted to the frame, and a cutting system attached to the frame for cutting a trench, the cutting system includes at least one pair of rotating discs rotating about a horizontal axis, and having water nozzles extending out from them, the water forced out of the nozzles scoops the seabed and disperses it up, away from the bottom of the trench. The pair of discs are mounted so that they can be moved up and down as well as rotated in and out.

Abstract: A process and apparatus are provided for the simultaneous trenching and installation of submarine pipelines. The apparatus is based on a single unit which includes an excavating portion, an attached ditch sidewall retention shield, and a pipeline installation guide. The excavator creates a trench of a slightly larger cross section than required, the shield prevents the trench from closing due to the collapse of the sidewalls, and the pipe guide causes the pipeline to be deflected into that portion of the trench protected by the shield. The pipeline is fabricated on the surface of the sea or on floating ice, and is supported and guided to enter the forward portion of the shield by a stinger or other means, when required.

Abstract: A trenching machine for digging a trench beneath a pipeline lying on the floor of a body of water, with a pair of laterally spaced vertical cutting members, shown to be a series of water jets, positioned at each end of the machine. The cutting members are laterally adjustable to move apart and tilt with respect to the vertical centerline of the machine. The cutting members are also arranged to oscillate about a vertical axis. Fore and aft side rollers are longitudinally spaced under the framework of the machine and are arranged to contact the pipeline to drive the machine along the pipeline and to stabilize the machine in its upright operating position over the pipeline. The rollers have selectively adjustable hydraulic biasing cylinders associated with each set of rollers to maintain a constant gripping force between the rollers and pipeline. The rollers are selectively reversibly driven to provide back and forth operation of the trenching machine.

Abstract: A self-propelling device for burying and digging up subsea conduits laid on beds of an incoherent material. The device has:disintegrating members using high pressure water jets to create a slurry of material,digging members having suction members which draw the suspension prepared by the disintegrating members, thus leaving a trench behind, anddisplacement members for moving the device on the seabed astride the conduit.

Abstract: This invention relates to the self-propelled underwater trenching apparatus and method for burying pipelines, cables and the like with minimum underwater diver supervision. The apparatus includes a frame having frame members positioned about the pipeline and buoyancy tanks with variable positions. Drive rollers are connected to the frame members for drive engagement with the pipeline. The frame members are movable by power rams about vertical and horizontal pivots selectively to engage or disengage the drive rollers with the pipeline. Oscillating water jet nozzles are secured to the apparatus for preselected sweeping movement to cut away the bottom formation to enable the pipeline to be buried in the trench so formed.

Abstract: Submersible backfill machine for covering a submerged conduit disposed within a trench in a seabottom with material from the sea bottom, which includes a sled positionable over the conduit on the sea bottom. A pump is supported by the sled and is connected to an intake head that is adapted to pick up sea bottom material entrained in water drawn into the pump. A dispersion nozzle is connected to the discharge side of the pump to cause the entrained sea bottom material to settle into the trench and cover the conduit.