Patent Description:
Conventional dredging operations are principally performed using one of two dredging techniques. Suction dredging in which a vessel raises sediment to the surface using a suction tube. An example of this technique is discussed in <CIT>. As explained therein, dredges (i.e., dredging-type watercraft) are commonly used to remove sediments, vegetation, and/or debris, from the bottom areas of various types of bodies of water. Such bottom areas are herein described as "water-beds. " For example, dredges may remove silt from a riverbed, sand from a seabed, or other materials from other types of water-beds. Dredges typically comprise a hull which floats on top of the water. A boom with a cutterhead can be pivotally attached to the hull. As such, when the cutterhead is in a lowered position, i.e., with the cutterhead positioned adjacent to the water-bed, the cutterhead can be operated in combination with a pump to stir up and remove a slurry of water-bed material from the body of water. Traditional dredges have implemented cutterheads that include a rotatable cutterbar within a shroud. With the cutterhead positioned adjacent to the water-bed, the rotatable cutterbar grinds into the water-bed and churns water-bed material, such that the water-bed material can be fluidized with the surrounding liquid to form a slurry. In addition, traditional dredges have also included pumps fluidly connected to the cutterhead, such as via a back side of the shroud, such that the dredge is capable of pumping the slurry away from the dredge to a barge or to an adjacent shoreline.

Clam shell dredges are also frequently used. Their mode of operation is discussed in <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>;<CIT>; and <CIT>.

A third, less commonly used, dredging operation is called water injection dredging (WID). This technique fluidizes the bottom material but provides minimal directional force to relocate the material. Absent lateral force generated by the dredging unit, the fluidized sediment fills in bottom depressions only in the direction of the prevailing current, reducing widespread use of this method. A bottom slope also affects the behavior of the sediment wave.

The methods of the present invention provide significant advantages over these three established dredging methods.

As explained in <CIT>, European patent <CIT> describes a method of dredging comprising lowering a casing of a wing shape downwardly towards the area to be cleared, the casing carrying thrust means arranged so that the thrust means is directed downwardly, the orientation of the wing casing being adjusted in the water so that it presents a surface relative to the flow which causes a resultant downward vertical component of force to counteract the upward force provided by the thrust means, the thrust means also directing a lateral wash of water towards the areas to be cleared so that the turbulence created clears the sand, silt or like material covering the area. This method of dredging may be useful for providing a trench across the sea bed. The wing shape casing is towed along a line above the sea bed and the thrust means, which is directed downwards, excavates a trench in the sea bed of a width which depends upon the material of the sea bed, its altitude above the sea bed, the power in the thrusters, its speed over the sea bed, and its pitch angle. In a typical example, the width of trench formed will be of the same order as the width of the wing shape casing. Such a dredger, which is commonly known as a "wing dredger" has been successful in producing a trench of a width sufficient to take a pipeline or, alternatively, to flatten an area of seabed in preparation for works on the seabed. Reference is also made to <CIT> and <CIT> which describe wing dredgers is further detail. The wing dredger is normally suspended below the surface support vessel by means of cables. <CIT> describes use of a wing dredger that is not supported from the surface vessel, avoiding problems associated with waves causing heaving of the vessel.

Conventional dredging techniques move the vessel to the in-situ material for extraction. As may be seen, current practices may not be adequate for all circumstances. There remains a need for more robust, agile systems and methods for dredging, particularly for systems and methods employing a wing dredge suspended from an agile support vessel to move fluidized dredged material to a predetermined extraction area where a second vessel transfers the fluidized material to either a transport barge or to a nearby deposit site. Stated differently, there remains a need in the art for the introduction of material movement as a separate step in the maintenance dredging process and the separation of material movement from extraction (removal from the water) steps. Moreover, there is a need in the art for systems and methods that are effective at relocating large quantities of accumulated sediments in confined areas such as vessel berths. There is also a need for systems and methods that reduce or avoid disruptive maneuvering normally required by conventional dredging vessels. It would be advantageous if systems and methods could be developed that utilize a fluidized sediment technique that introduces a settling period between material arrival and extraction pumping during which gravitational settlement of the dredged material creates a denser extraction stream with less water. It would further be advantageous if the independent collection and extraction processes are also coordinated to minimize vessel maneuvering and interference between movement and extraction operations, and transforms the collection and extraction of dredged material from the intermittent process typical of traditional mechanical dredging to a continuous process, that are suitable for operation in inland, coastal and offshore waters, and that do not use cutters or teeth to move sediment so integrity of underwater pipelines and cables and the like are not threatened. It would be further advantageous to provide systems and methods suffering minimal disruption due to debris and trash within the sediment being dredged, and with road mobility for access to remote bodies of water (reservoirs), or to aid in rapid response to a distant emergency (for example, hurricane disruption) more rapidly. The systems and methods of the present disclosure are directed to one or more of these needs.

In accordance with the present invention, there is provided a method comprising: forming a first fluidized material in a first seabed location by forming a first trench by fluidizing the seabed using a first wing dredger and using an extraction pump for evacuating the first trench, wherein the extraction pump evacuates the first trench in anticipation of deposit of material extracted from a second seabed location, the first trench thus formed serving as a collection area for material extracted from the second seabed location, and to identify debris that could obstruct the extraction pump; forming a second fluidized material and moving it away from the second seabed location using the first wing dredger or a second wing dredger while the extraction pump extracts at least a portion of the first fluidized material from the first trench formed in the first seabed location and delivers at least a portion of the first fluidized material to a surface vessel; and moving the second fluidized material into the first trench using the first or second wing dredger while the extraction pump extracts at least a portion of the second fluidized material from the first trench and delivers at least a portion of the second fluidized material to the surface vessel or other support vessel.

Optionally, the first seabed location is spaced from and roughly parallel to the second seabed location adjacent a dock, wharf, or reservoir wall.

Optionally, the method comprises forming a third fluidized material at a third seabed location and moving it into the first or second trench using the first wing dredger while extracting at least a portion of the third fluidized material from the first or second trench and delivering the at least a portion of the third fluidized material to the surface vessel, the other support vessel, or another vessel.

The present invention also provides a method for relocating sand waves comprising the method of the present invention as defined above.

The present invention also provides a method for pre-trenching marine pipelines and cables comprising the method of the present invention as defined above.

The present invention also provides a method for removing cover from marine archaeological sites comprising the method of the present invention as defined above.

The present invention also provides a method for disposal of contaminated seabed, reservoir, and inland waterway bottom materials in an environmentally acceptable manner comprising the method of the present invention as defined above.

The present invention also provides a method for maintaining canal locks, dams, and reservoirs comprising the method of the present invention as defined above.

The present invention also provides a method for sediment nourishing of intertidal zones, mudflats and marshes comprising the method of the present invention as defined above.

The present invention also provides a method for reclamation of silted reservoirs comprising the method of the present invention as defined above.

Optionally, at least one of the surface vessel and another vessel comprises a hull, wherein the hull is disassembled and transported on one or more trucks or in one or more shipping containers.

The manner in which the objectives of this invention and other desirable characteristics can be obtained is explained in the following description and attached drawings in which:.

It is to be noted, however, that <FIG> of the appended drawings may not be to scale and illustrate only typical system embodiments, or components of systems in accordance with this disclosure. Furthermore, <FIG> illustrate only six of many possible methods of this invention. Therefore, the drawing figures are not to be considered limiting in scope, for the invention may admit to other equally effective embodiments. Identical reference numerals are used throughout the several views for like or similar elements.

In the following description, numerous details are set forth to provide an understanding of the inventive methods. However, it will be understood by those skilled in the art that the systems and methods disclosed herein may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.

The present disclosure describes apparatus, systems, and methods for moving fluidized material from one subsea location to another location, and in some embodiments removal of the material from the subsea environment to a disposal or a separation facility. The methods of the present invention employ a wing dredger (sometimes referred to herein as a "wing material movement tool", or simply as a "wing tool"), suspended from an agile support vessel, to move the dredged material to a predetermined extraction area where a second vessel transfers the fluidized material to either a transport barge or to a nearby deposit site. The introduction of material movement as a separate step or feature in the maintenance dredging process and the separation of material movement from extraction (removal from the water). Combinations of multiple wings and support vessels, pumps and support vessels, disposal barges and/or separation systems may be combined into coordinated systems and methods of this disclosure to complete various work scopes.

The methods of the present invention feature one or more wing dredger. The wing dredger is particularly effective at moving large quantities of accumulated sediments in confined areas such as vessel berths. A wing dredger, together with a separate extraction pump, performs the role normally filled by a single extraction vessel. However, the methods of the present invention more than compensate for this apparent lack of efficiency in several ways. Through use of a wing tool and a support vessel dedicated to the wing tool, avoid much of the disruptive maneuvering normally required by conventional dredging vessels. Instead, the wing tool moves material in swaths measuring from about <NUM> to <NUM> (<NUM> to about <NUM> ft). over long runs by using directional turbidity to fluidize and move the sediment. Certain embodiments may comprise a "gang" configuration of wing tools similar to those used to mow wide median strips next to major highways or to snow-plow major highways where each wing would be controlled by a separate vessel. In certain "shallow water" embodiments, a comparatively smaller wing may be employed. A wing with more than two thrusters is also feasible, but these embodiments may require a large vessel which would defeat the purpose of working in small spaces and making road transport impractical. The minimum swath of about <NUM> (<NUM> feet) wide may be produced by employing a wing tool with a single thruster cone diameter.

Certain system and method embodiments of the present disclosure employ an extraction vessel operating independently of the wing tool(s) to pump the moved or relocated material to either a transport barge or nearby deposit site. Process efficiency is enhanced by providing a settling period between material arrival in the depression, collection area, or trench and extraction pumping from that depression during which gravitational settlement of the dredged material creates a denser extraction stream with less water. The independent collection and extraction processes may also be coordinated to minimize vessel maneuvering and interference between movement and extraction operations. Although systems and methods of this disclosure may operate in intermittent mode (batch or semi-continuous modes), the wing tool(s) and separate extraction pump(s) allow continuous collection and extraction of dredged material.

The primary features of the methods of the present invention will now be described with reference to the drawing figures, after which some of the construction and operational details, some of which are optional, will be further explained. The same reference numerals are used throughout to denote the same items in the figures.

<FIG> is a perspective schematic illustration view of an embodiment <NUM> comprising a wing work vessel <NUM>, sometimes referred to herein as a first vessel, and wing material movement tool <NUM> useful in systems and methods of the present disclosure. Wing tool <NUM> includes a port and starboard thrusters <NUM>, <NUM>, port thruster stabilizers 10A, 10B, and starboard thruster stabilizers 12A, 12B. In embodiment <NUM>, first vessel <NUM> includes port and starboard wing suspension winches <NUM>, <NUM>, and port and starboard A-frame winches <NUM>, <NUM>, as well as an A-frame rotation mechanism <NUM>. A power and instrument umbilical (not illustrated) would also be included connecting wing tool <NUM> and first vessel <NUM>. Work vessel <NUM> is illustrated schematically moving forward or stationary heading into a tidal flow. The tidal flow may be in a river, estuary, or at sea. Wing tool <NUM> is suspended at an appropriate distance from the sediment via a pair of cables operated by winches <NUM>, <NUM>, one cable extending from each side of vessel <NUM> and there is provided a further cable <NUM> from adjacent the bow of vessel <NUM>.

<FIG> are perspective schematic illustration views of two possible modes of operation of the wing material movement tool illustrated schematically in <FIG>, with <FIG> illustrating a "bulldozer" mode of operation, while <FIG> illustrates a "tractor" mode of operation. In each of <FIG> the arrow indicates direction of movement of first vessel <NUM>, wing tool <NUM>, and a cylindrical fluidized bed of material <NUM>, and wing tool <NUM> is tilted so as to allow port and starboard thrusters <NUM>, <NUM> to create movement of the cylindrical fluidized bed of material.

<FIG> are perspective schematic illustration views of three possible adjustments for optimal material movement by the wing material movement tool illustrated schematically in <FIG> illustrate lateral movement; <FIG> illustrates altitude movement; and <FIG> illustrates adjustment of power of the thrusters may be adjusted (the solid arrow indicating more power than the dotted line arrow).

<FIG>, <FIG> are schematic plan illustration views of one system and method embodiment. <FIG> illustrates a first step, a first depression or trench <NUM> is formed by wing tool <NUM> and first vessel <NUM>. A hopper or barge <NUM> acts as a second vessel, and an extraction pump <NUM> is idle at this stage. A vessel unloading area <NUM> (such as on a wharf) is illustrated, and as illustrated in the graph to the right of <FIG>, a silted area of reduced depth exists adjacent vessel unloading area <NUM>. The graph also illustrates a level of depression of trench <NUM>, a line L1 represents pre-dredged birth level, and dashed line L2 indicates dredged level. A federal channel <NUM> is also illustrated, as will be explained herein. <FIG> illustrates wing tool <NUM> and first vessel <NUM> excavating the silted, reduced depth area adjacent the wharf, forming a second trench <NUM>, and further illustrates extraction pump <NUM> pumping silt, sand, and other dredged materials onto barge or hopper (second vessel) <NUM> via an extraction pump discharge conduit <NUM>. <FIG> illustrates a fulling dredged second trench <NUM>, and wing tool <NUM> and first vessel <NUM> moving in the direction of horizontal arrows, with the cylindrical fluidized bed of material moving in a direction indicated by non-horizontal arrows toward first trench <NUM>. Finally, <FIG> illustrates wing tool <NUM> and first vessel <NUM> excavating the federal channel <NUM> (on the left the wing tool <NUM> and first vessel <NUM> operating in bulldozer mode, while on the right side they operate in tractor mode). The primary difference between <FIG> is that second vessel <NUM> moves from below first trench <NUM> to above first trench <NUM> to accommodate wing tool <NUM> and support vessel <NUM> which simultaneously move from above to below first trench <NUM>. Material from federal channel is moved into second trench <NUM>, and extraction pump <NUM> pumps material out of second trench <NUM> via extraction pump discharge conduit <NUM> onto or into second vessel <NUM>. Material from second vessel may then be moved onshore for feeding to one or more separation units (not illustrated) for one-phase, two-phase, or three-phase separation.

<FIG> is a schematic perspective view of a wing material movement tool <NUM> useful in systems and methods of the present disclosure being retrieved onto a work vessel, with the sheltered water (vs. open water) configuration of the tool being shown.

<FIG> is a perspective schematic illustration view of a wing tool <NUM> of similar type as shown in <FIG> being employed to form a cylindrical fluidized bed of material <NUM> in accordance with systems and methods of the present disclosure. As explained in <CIT>, wing tool <NUM> is provided with two closed vertical bores which are laterally spaced from each other, each housing a thruster in the form of a motor driven propeller mounted substantially in the plane of wing tool <NUM> and the two propellers are driven in opposition to reduce the effects of centrifugal/centripetal forces. Two contra-rotating vertical jet vortices <NUM>, <NUM> are created and where they meet, very high forces are created which increase sediment penetration.

<FIG> are schematic plan, side elevation, and end elevation illustration views, respectively, of a wing tool embodiment <NUM> suitable for use in systems and methods of the present disclosure in open water configuration. Wing tool embodiment <NUM> includes a forward section <NUM>, a hull center section <NUM>, and an aft section <NUM>. Both of the forward and aft sections <NUM>, <NUM> are air-tight and water-tight compartments, while hull center section <NUM> is free-flooding. Hull center section <NUM> includes an instrument compartment <NUM> for scanning sonar, sonar altimeter, dual axis inclinometer, communication with the first vessel or other vessels, and possibly other instruments. The positions of port and starboard thrusters <NUM>, <NUM>, as well as port stabilizers 10A, 10B, and starboard thruster stabilizer 12A, 12B are illustrated. A curved bottom surface <NUM>, as well as forward end <NUM> and aft end <NUM> of the wing tool produce the counter-balancing downward force (or downward component of force) necessary to maintain position when the thrusters are activated, as explained herein. Curved bottom surface <NUM> includes two openings or ports for the thrusters, as detailed in embodiment <NUM>, <FIG>.

<FIG> are schematic plan, side elevation, and end elevation illustration views, respectively, of another wing tool embodiment <NUM> suitable for use in systems and methods of the present disclosure in sheltered water configuration. Wing tool embodiment <NUM> is devoid of forward and aft air- and water-tight sections, but includes first side plate or plates <NUM>, second side plate or plates <NUM>, top plate or plates <NUM>, first end plate or plates <NUM>, and second end plate or plates <NUM>. If multiple metal plates are used they may be welded construction. Another difference from embodiment <NUM> is that in the sheltered water configuration of embodiment <NUM> thruster stabilizers 10A, 10B, 12A, and 12B are parallel to the long axis of the wing tool. Hull center section <NUM> includes an instrument compartment <NUM> for scanning sonar, sonar altimeter, dual axis inclinometer, communication with the first vessel or other vessels, and possibly other instruments.

<FIG> are schematic perspective and schematic perspective longitudinal cross-sectional views, respectively, of another wing tool embodiment <NUM> suitable for use in systems and methods of the present disclosure in sheltered water configuration. Wing tool embodiment <NUM> is similar to embodiment <NUM>, but further includes four lifting eyes <NUM> welded to side plates <NUM>, <NUM>, and a gimbal connection <NUM> operated by hydraulic/electric cylinders <NUM>, <NUM>. A pair of central gimbal lifting eyes 86A, 86B secure gimbal connection <NUM> to a piece <NUM> of a framework of the wing tool. The framework comprises multiple tubular elements, typically steel, which may have rectangular, triangular, or circular cross-section, or combination thereof, arranged as illustrated in in <FIG>, <FIG>, and <FIG>and welded to form the framework. Referring to <FIG>, curved bottom plate <NUM> has passages for thruster support outlets <NUM>, <NUM>. A set of curved ribs <NUM> are welded or otherwise secured on one side to framework elements <NUM> and the other side to curved bottom plate <NUM>. Note there are several differences between embodiments <NUM> and <NUM> and the original wing tool described in European Pat. <CIT> and/or <CIT>. There is only a single suspension cable connected to the center of gravity of the unit. Lateral stabilization may be created by cables back to the service vessel (as illustrated in <FIG>). Control of pitch and roll attitudes of the wing tool in these embodiments is by mechanical or hydraulic actuators located at the enter section of the wing tool, and the structure is now composed of a frame over which is welded cover plates. Formerly known wing tools consisted of only cover plates welded together. The use of a frame and plate construction simplifies fabrication and reduces weight.

<FIG>, and <FIG> are schematic perspective, top plan, side elevation, bottom plan, and end elevation views, respectively, of the wing tool embodiment <NUM> of <FIG>, with thrusters and thruster stabilizers removed. Additional lifting eyes <NUM> are illustrated welded to end plates <NUM>, <NUM>. A pair of thruster connecting flanges <NUM>, <NUM> are welded or otherwise secured to upper plate <NUM>. Hydraulic/electric cylinder mounts <NUM> (<FIG>) are welded to supports <NUM> for same, which are in turn welded to the framework or to respective side plates <NUM>, <NUM> and/or top plate <NUM>.

<FIG>, <FIG> are schematic top plan, end elevation, side elevation, transverse cross-sectional, and bottom plan views, respectively, of the wing tool embodiment <NUM> of <FIG>, <FIG>, <FIG>, and <FIG> with thrusters, thruster stabilizers, and structural plates removed, so that the multiple framework tubular elements <NUM> may be viewed. As is most apparent from viewing <FIG>, the pair of gimbal lifting eyes 86A, 86B have a notched lower end so that they fit to and may be welded to one of the framework tubulars 88A, and a pair of gimbal lifting eye supports 108A, 108B, which are simply plate pieces each having a pair of vertical notches, are welded to the tubular support element 88A (<FIG>) and to gimbal lifting eyes 86A, 86B. Also illustrated schematically in <FIG> are a pair of upper thruster supports 110A, 110B, which are similarly welded to respective tubular elements <NUM> of the framework.

Certain systems and methods, not necessarily in accordance with the present invention, comprise three pieces of operating equipment: <NUM>) one or more wing tools, such as described in <CIT> and/or <CIT>, and/or European Pat. <CIT> and/or <CIT>; <NUM>) one or more extraction pump(s) and work boat units, particularly systems and methods where local authorities or clients require removal of sediment from the water, this unit allowing sediment to be relocated either to a transportation barge (scow) for remote deposit or to a nearby deposit site; and <NUM>) one or more separation plants (mobile or non-mobile, onshore or on a vessel) that may include one or more separation units to separate sand from fine grain materials (silts and clays) and entrained water, which may be required for projects that specify the need for beneficial use of the sediment.

<CIT> and <CIT> disclose one suitable wing tool and method of dredging a trench or other shape depression for sediment collection, concentration and extraction characterized by lowering a support member carrying one or more thrusters so that the thrusters are directed downwardly towards an area to be cleared, adjusting the orientation of the support member in the water so that it presents a surface relative to the thruster flow which causes a resultant downward vertical component of force, and operating the thrusters to direct a stream of turbulent water towards the area to be cleared, whereby the turbulence created sets the sand, silt and like material covering the area in suspension in the water as a dense mudflow so as to be carried away from the area by the flow of the water, the weight of the support member and the resultant downward force component in use being designed to provide a downward force in excess of the upward force caused by the thrusters. In certain embodiments, the support member is lowered from a vessel. Although it can be dynamically held in position by one or more thrusters or mounted on a trestle sitting on the sea or riverbed or on a floating pontoon, it will normally be set in its correct orientation by the adjustment of, for example, cables, chains or telescopic arms. The vessel may initially be stationed immediately downstream of the area to be cleared, where after the vessel is moved forward to cover the complete area at a controlled speed, this movement acting to increase the resultant downward force component on the support member. The support member can be designed to work in opposite directions, so that the vessel can then be turned and retraced over the area, after re-setting the orientation of the support member by adjustment of the cables. The '<NUM> patent also discloses dredging apparatus for carrying out the methods comprising, a support member having one or more thrusters mounted thereon, orientation components to orient the support member to maintain the thrusters in a downward attitude, the support member providing a face against which the water flow can act to provide a stable and controllable downward component of force, the arrangement being such that in use, the weight of the support member together with the resultant force component produced provide a downward force which exceeds the upward force provided by the one or more thrusters. The orientation components to orient the support member preferably comprises cables or the like connected to the support member at at least three spaced points. The orientation components may be mounted to an associated vessel. Preferably, the support member is generally in the form of a wing comprising a casing (in certain embodiments having ballast tanks to adjust its weight, depending upon the working depth and the type of material to be cleared), the casing also having at least one closed bore passing between its upper and lower faces, in which the one or more thrusters is located. In some configurations, the casing is provided with an angled face at least along one (leading) edge thereof which, at least in part, causes the resultant downward force component in use; this component can be varied by appropriately tilting the casing so that its upper surface is angled to the horizontal. The one or more thrusters may comprise one or more propellers, each mounted within a closed bore, to rotate substantially parallel to the plane of the casing, in which case drivers for the propeller(s) are mounted on the casing and may be driven from an energy source on board the vessel by a cable, hose or the like. The energy source may be an electric generator and the driver electric motors. Alternatively, the source of energy may be a hydraulic pump on board the vessel and pressure fluid may be circulated through the drive unit via flexible hoses, the drive unit comprising a hydraulic motor including gearing which meshes suitably with gearing on the or each propeller shaft. The support member may be provided with transducers, and/or sonar, or like devices, directed downwardly so that, in use, electrical signals indicative of the working distance, and work progress can be transmitted to a suitable display on board the vessel.

Wing tool / vessel relationship - <CIT> and <CIT> focused only on the wing tool. The intent was to use a locally available supply boat as the platform from which to suspend and control the wing tool. However, we have now discovered that when pursuing markets in which road / rail mobility is essential, the ability to relocate the entire spread quickly and inexpensively are important considerations. That causes two philosophical changes (and associated hardware requirements for those embodiments where road / rail mobility is important): we designed a specially designed (there are no "local") vessel that can be broken into modules for transport to remote locations.

The modular vessel has three purposes: <NUM>) to support the wing tool during tow in the water to the use site; the wing tool will be suspended in the water during tow to gain the lowest possible center of gravity for best vessel stability; this also keeps all lifting gear low to the water; <NUM>) to position and maneuver itself to put the wing tool in the correct location and with the correct attitude to maximize the amount of sediment moved; and <NUM>) to support total process efficiency by improving agility during maneuvers to minimize lost time during operations; although in most embodiments instructions come from the vessel (it is manned), instrumentation on the fluidizer will produce the information which allows the modular vessel to adjust itself to achieve optimum wing tool performance. As noted previously, the primary purpose of the vessel is to place the wing tool in the optimum location and at the best orientation to maximize sediment movement.

As noted previously, in certain embodiments the wing tool structure may be made more efficient, lighter and less expensive by incorporation of a structural framework that is plated on all sides (except the top of the center section to allow free motion of the gimbal, single point suspension). This is easier to build and so can be licensed to multiple fabricators. An all-plate design can still be considered an option. In addition to the four point suspension from the vessel originally contemplated, certain embodiments may eliminate the four point suspension in lieu of a single point suspension that, through hydraulic (or electrically driven screw turnbuckles mounted on the wing tool) can pitch and roll the wing tool during submerged operation from controls on the vessel.

A hydraulic or electric extraction pump transfers the dredged material from the collection point to either a hopper barge for transport to a deposit site (conventional dredging) or to separation plant from which beneficial disposal of the three streams is initiated, or through reservoir outlets or above/around dams. Suitable extraction pumps may be suspended from a second, independent, work boat to increase the efficiency of the dredged material removal operation and may move the collected materials to deposit areas more than <NUM> (<NUM> feet) from the pump intake. If space is available on the wharf, trailers on which the separation and dewatering units may be located there, and if not, the extraction line may be connected to a boost pump to extend the distance between pump and separation plant to lengths limited only by pipeline access ways and project economics to, allowing the plant to be positioned in an area of lower activity, perhaps near a rail siding or at a location with easy access to hopper barges for efficient transportation of sand and dewatered fine grain materials to purchasers or to deposit sites. Suitable extraction pumps include, but are not limited to, those known under the trade designation EDDY PUMP available commercially from Eddy Pump Corporation, El Cajon, California. One set of suitable extraction pumps may be those listed in Table <NUM>, available from Eddy Pump Corporation. Submersible pumps known under the trade designation EDDY PUMP may either be electrically or hydraulically driven and may include water jetting ring agitators. Unlike other dredge pumps, pumps known under the trade designation EDDY PUMP do not have an impeller, but instead have a heavy duty geometrically designed rotor that creates a synchronized eddy current similar to a tornado. Pumps known under the trade designation EDDY PUMP can be attached by cable and suspended from a crane, excavator, floating barge with a-frame or other devices for optimal solids pumping. High chrome versions of pumps known under the trade designation EDDY PUMP exhibit reduced clogging and erosion when compared with conventional pumps or having downtime associated with maintaining critical tolerances. The "cable deployed" versions can be fitted with pumps ranging in size from <NUM>-inch through <NUM>-inch discharge size pumps. Production measures at <NUM>,<NUM>-<NUM> cubic meters (<NUM>-<NUM> cubic yards) per hour of material, at distances over <NUM> (<NUM> feet).

The water jetting ring can be configured in ways to break up the most consolidated material while feeding pumps known under the trade designation EDDY PUMP. The Eddy Pump Corporation offers versions with instrumentation allowing view reach, depth, and GPS location, allowing precision dredging in real time by allowing an operator to track precisely where they are dredging at all times.

(conversion factors: <NUM> gpm = <NUM>×<NUM>-<NUM> l/s; <NUM> inch = <NUM>,<NUM>; <NUM> yd<NUM>/h = <NUM><NUM>/h).

Units (mobile or non-mobile) that separate sand from fine grain materials (silts and clays) and entrained water may be required for projects that specify the need for beneficial use of the sediment. Suitable mobile units include, but are not limited to, separation systems provided by TriFlo International, Willis, Texas, which are characterized by modular units, such as the model "Environmental System" ES <NUM> which is designed to be mounted on a standard <NUM> foot trailer for road mobility. Certain units available from TriFlo International may be "containerized", meaning that they are designed to be transported within a <NUM> to <NUM> foot standard ISO certified containers and include mechanical separation technology including elliptical and linear shakers as well as ten, four, and/or two inch hydrocyclones. One separation unit that may be useful in systems and methods of the present disclosure is a two phase de-sanding unit, which optionally may include a removable equipment skid for non-routine maintenance. Another suitable separation unit may be a three phase cleaning unit (dewatering, desilting, and desanding), with an optional hopper that may be added for small batch mud treatment. A single phase de-silting unit may be another suitable separation unit. In certain embodiments, a de-sanding unit and a desilting unit may be operated in series for three phase cleaning. Flow rates through these units may range from about <NUM>-<NUM>/min (<NUM>-<NUM> gpm).

Features of the methods of the present invention include:.

Wing material movers (wing tools) can also be used independently to perform other tasks such as:.

The methods of the present invention provide an integrated approach to dredging of reservoirs, inland waterways, and port facilities in an environmentally friendly manner. The application of innovative technology improves dredging efficiency and provides opportunities to improve marginally functioning port facilities at competitive costs. The systems of the present disclosure are designed to economically address projects where the volume of materials removed may range from about <NUM>,<NUM> to <NUM>,<NUM> cubic metres (<NUM>,<NUM> to about <NUM>,<NUM> cubic yards), but can be used for larger projects (more than <NUM>,<NUM> cubic metres (<NUM>,<NUM> cubic yards) removal).

The methods of the present invention have minimal environmental impact; provide for beneficial use of sediments (for example, beneficial disposal of dredged materials also eliminates dependence on use of limited United States Army Corps of Engineers (USACE) placement capacity); maximize berth availability by efficient removal of dredged materials and by agile marine equipment that can rapidly relocate to allow use of the berth; safe for use around wharves, docks, other waterfront structures and pipelines or cables (no blades or teeth); rapid mobilization and demobilization due to road transportable components; cost competitive with traditional dredging methods, allowing the flexibility to economically schedule smaller or emergency projects as required.

As mentioned previously, certain embodiments may include additional tools for locating, and possibly removing, underwater debris (like trees, cars, shopping trolleys and wire ropes) after it is exposed by blowing the covering sediment away. A good example would be grabbers to remove trees that clog up the outlets to reservoirs after sediment is blown away; this is currently performed by divers, which is very expensive and very unsafe. Accordingly, certain systems and methods for small reservoirs and reduced sediment quantities may include one or more of the following features:.

We believe that methods having one or more of these features for small reservoirs and reduced sediment quantities will have the following advantages: potential to avoid periodically defined complete system mobilizations; smaller and less expensive vessels for use during long-term maintenance; reduced marine personnel after vessel automation is approved; the personnel will be local and less costly than travelers; the operation will also support the local economy; keeping local workers employed year-round will be only marginally more expensive than hiring temporary employees and training them yearly; another task of the site group would be to maintain the USGS sediment measurement instruments annually; in the long term, permanent facilities will be less expensive than yearly erection and temporary facilities removal.

As noted herein, systems may comprise three major elements:
The wing tool, which functions as a levelling / trenching tool, is suspended from a dedicated work vessel. The wing tool fluidizes the dredged material in swaths up to <NUM> (<NUM> feet) wide and moves it to a predefined material collection location. When material removal is required, a large hollow, trench, or depression is created in the bottom sediment before dredging starts. That depression acts as a natural collector for the fluidized sediment as well as a "sump" in which heavier sediments concentrate for removal of a more consistently dense suspension of sand and fine grain materials. Greater density increases the efficiency of both the marine excavator pump and the downstream separation plant. The dredged material is fluidized and relocated by one or more, in some instances two downward pointing, variable thrust, ducted, counter-rotating, impellers. The action of these thrusters forms a dense wave, or density current, at the sediment-water interface. The heading of the wing, relative to the heading of the vessel, determines the width of the sediment path fluidized (from a pipeline trench to a full <NUM> (<NUM> foot) swath). The angle of the thrusters relative to the bottom determines the direction of the lateral force imparted to the fluidized sediment. This amount of force applied to the sediment is adjusted by the distance between the wing and the bottom and by the speed of the thrusters. It is safe to use the wing around buried facilities such as pipelines and cables and it can work in close proximity to waterfront facilities such as wharf faces.

A hydraulic or electric extraction pump transfers the dredged material from the collection point to either a hopper barge for transport to a deposit site (conventional dredging) or to separation plant having one or more separation units from which beneficial disposal of the three streams or phases (sand, silt, and water) is initiated. The pump is suspended from a second, independent, work vessel to increase the efficiency of the dredged material removal operation. The pump can move the collected material more than <NUM> (<NUM> feet) from the pump intake and further if a booster pump is inserted in the discharge line. If space is available on adjacent land, the trailers on which the separation and dewatering units are mounted may be located there, if not, a booster pump may be inserted in the discharge to extend the distance between pump and separation plant allowing the plant to be positioned in an area of lower activity, for example, near a rail siding or at a location with easy access to hopper barges for efficient transportation of sand and dewatered fine grain materials to purchasers or to deposit sites.

The separation unit (sometimes referred to herein as a separation plant comprising one or more separation units) may comprise several sub-units:.

During the separation processes, clean sand may be piled near the plant for removal by truck, rail or hopper barge and the dewatered (and dried) fine grained materials cake may be accumulated separately for removal also by truck, rail or hopper barge. These substances may be handled according to pre-dredge permit conditions.

Two questions are frequently asked:
Will fluidized material enter the water column for wide dispersion by local currents? No, the wing tool fluidizes the sediment, forming a dense wave at the sediment-water interface. It has been demonstrated that the wave does not re-entrain sediment into the water column. This phenomenon has been verified by Acoustic-Doppler Current Profiler studies and by dissolved solids sampling and analysis around and above the sediment wave and adjacent to an operating wing tool.

Will sediment at the sediment-water interface migrate in an uncontrolled manner? No. There has been concern that dredged material will migrate into a federal channel or other undesired channel. As the wing tool imparts a directional flow to the sediment, the wave remains cohesive and moves across the bottom in a rolling cylinder of from approximately <NUM> to <NUM> feet in diameter. The resulting transport distance depends on: the lateral force imparted by the wing tool, the action of the local currents, the density and composition of the sediments, and the slope and smoothness of the water-bed. The sediment will tend to flow into depressions in the water-bed, but only those depressions in the direction imparted by the wing tool, and will cease flowing due to friction forces and gravity when the wing thrusters are stopped.

In addition to precision dredging of port facilities, systems may also be used for:.

One or more sensor(s) may be mounted onto and/or into the wing tool through a variety of ways depending on the sensor being installed, openings available in the wing tool, and the level of accuracy required. Software either intrinsic to the sensor or installed remotely on a computer type device, may convert the measurements into usable calculated information. The usable calculated information may be displayed locally at the device and/or remotely on a computer type device.

Sensors installed on the wing tool or work vessel may, in certain embodiments, be powered from within an instrument display or other human/machine interface (HMI) itself, for example using batteries, Li-ion or other type. In other embodiments the display/HMI may be powered from an instrument cable providing power to the sensor, perhaps by a local generator, or grid power. A display/HMI on a work vessel allows an operator to interface with the sensor. In certain embodiments the operator will be able to take measurements, view or read these measurements and reset the instrument for subsequent measurement taking. If the display/HMI is connected to a power cable, then measurements may be taken remotely, stored and reset as necessary. In addition to instrument-assisted operation, certain systems may be fully instrument-controlled operation in situations where safety is not compromised in the event of surprises in the sediment or by equipment malfunction.

In certain embodiments, a movable Time-of-Flight (TOF) or LIDAR scanner may be installed on the wing tool, such as disclosed in <CIT>, which discloses systems and methods for conducting autonomous underwater inspections of subsea and other underwater structures using a 3D laser mounted on an underwater platform such as AUV, an ROV or a tripod. The systems and methods described in the '<NUM> patent can be used for scanning underwater structures to gain a better understanding of the underwater structures, such as for example, for the purpose of avoiding collision of a wing tool with the underwater structures and for directing inspection, repair, and manipulation of the underwater structures. Newton Labs (Renton, Washington) offers underwater scanners featuring sophisticated, Newton-developed software working in concert with a laser scanner and a high-resolution video camera. The software compensates for refraction, turbidity and suspended particles, resulting in the generation of a dense point cloud of the scanned area that, when processed by industry standard <NUM>-D software, results in a fully measurable CAD file. All Newton underwater scanner models operate by laser triangulation. The projected laser line sweeps the target surface and the high resolution camera captures and records any deformation of the line as a point cloud enabling ultimate <NUM>-D computation. Scanners are designed to scan and capture much larger target areas, by combining several point clouds together to form larger composites. Laser light color is maximized for water penetration. The specific wavelength of the laser allows for highest possible efficiency underwater transmission. The scanner camera only accepts the specific color produced by its own laser and LED lights, greatly reducing any contamination from stray light in the scanning environment. Useful underwater scanners include those known by model numbers M210UW and M310UW. In certain embodiments, the scanner does not require an external mechanism within the housing to make it sweep through the require angle. The M series scanners have an internal ability to sweep through the required path via a "push button" on a control consol.

The wing tools and any underwater sensors, housings, and couplings are all made of material capable of withstanding prolonged exposure to the underwater environment in which they are used. In certain embodiments power would be supplied to the sensor(s) at a voltage and current that enables the device to be intrinsically safe. By "intrinsically safe" is meant the definition of intrinsic safety used in the relevant IEC apparatus standard IEC <NUM>-<NUM>, defined as a type of protection based on the restriction of electrical energy within apparatus and of interconnecting wiring exposed to the potentially explosive atmosphere to a level below that which can cause ignition by either sparking or heating effects. For more discussion, see "AN9003 - A User's Guide to Intrinsic Safety", retrieved from the Internet July <NUM>, <NUM>.

Certain embodiments may employ a 3D time of flight sensor. Such sensors may be exemplified by those described by Texas Instruments. 3D time of flight products, tools and development kits enable machine vision with a real-time 3D imaging depth camera. From robotic navigation to gesture recognition and building automation, TI's 3D time of flight chipsets allow for maximum flexibility to customize a camera's design. 3D time of flight operates by illuminating an area with modulated IR light. By measuring the phase change of the reflected signal the distance can be accurately determined for every pixel in the sensor creating a 3D depth map of the subject or scene.

One suitable TOF sensor is the sensor known under the trade designation "OPT8241 time-of-flight (TOF) sensor" available from Texas Instruments (TI). The device combines TOF sensing with an optimally-designed analog-to-digital converter (ADC) and a programmable timing generator (TG). The device offers quarter video graphics array (QVGA <NUM> × <NUM>) resolution data at frame rates up to <NUM> frames per second (<NUM> readouts per second). The built-in TG controls the reset, modulation, readout, and digitization sequence. The programmability of the TG offers flexibility to optimize for various depth-sensing performance metrics (such as power, motion robustness, signal-to-noise ratio, and ambient cancellation). Features of the TOF sensor known under the trade designation "OPT8241 time-of-flight (TOF) sensor" available from Texas Instruments (TI) are provided in Table <NUM>.

The separation unit(s) may include filter media. Efficiency of separation in the separation unit, if it includes filter media, may be characterized by turbidity and silt density index (SDI) of the final processed water stream. SDI is a measurement of the fouling potential of suspended solids and may be determined by test method ASTM D4189 - <NUM>(<NUM>). Acceptable values depend on the filter media and even the filter media manufacturer of the "same" media, as well as temperature of the water being tested. Turbidity is a measurement of the amount of suspended solids. SDI and turbidity are not the same and there is no direct correlation between the two. According to the Water Treatment Guide, a publication of Applied Membranes, Inc. , in practical terms, however, many filter media show very little fouling when the feed water has a turbidity of less than <NUM> NTU. Correspondingly these filter media show very low fouling at a feed SDI of less than <NUM>. SDI may be reduced by injecting a coagulant that is compatible with the filter media, before the media filter. A dispersant may keep particles from fouling the media.

A wide variety of probes are available to measure turbidity -- the degree to which light is scattered by particles suspended in a liquid. The measured turbidity, however, depends on the wavelength of light and the angle at which the detector is positioned. In certain embodiments, turbidity values of processed water from a hydrocyclone, or the effluent (filtrate) from a filter material, may range from about <NUM> to about <NUM> NTU, or from about <NUM> to about <NUM> NTU, or from about <NUM> to about <NUM> NTU, or from about <NUM> to about <NUM> NTU, or from about <NUM> to about <NUM> NTU. "NTU" refers to "Nephelometric Turbidity Unit" (NTU) and employs a sensor that measures scattered light at <NUM> degrees from an incident white light beam, according to EPA method <NUM>.

<FIG>, <FIG>, <FIG>, <FIG>, <FIG>, and <FIG> are logic diagrams of six non-limiting method embodiments <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

Method embodiment <NUM> (<FIG>) comprises a method (box <NUM>) comprising forming a first fluidized material in a first seabed location (for example, a portion of seabed spaced from and roughly parallel to a dock) by fluidizing a trench or other shaped collection area using a first wing tool or a suitable extraction pump, the area thus formed serving as a collection location for material extracted from a second seabed location (for example a seabed space adjacent a dock face), and to identify debris that could obstruct a pump (box <NUM>); forming a second fluidized material and moving it away from the second seabed location (dock face) using the first wing tool or a second wing tool while the pump extracts at least a portion of the first fluidized material from the trench formed in the first seabed location and delivers the at least a portion of the first fluidized material to a surface vessel (box <NUM>), and moving the second fluidized material into the trench using the first wing tool while the pump extracts at least a portion of the second fluidized material from the trench and delivers the at least a portion of the second fluidized material to the surface vessel, to an onshore location for disposal or beneficial upgrading, to a location over or around a dam into the downstream river bed, or other support vessel (box <NUM>).

Method embodiment <NUM> (<FIG>) comprises a method (box <NUM>) comprising forming a first fluidized material in a first seabed location (for example, a portion of seabed spaced from and roughly parallel to a dock) by fluidizing a trench or other shaped collection area using a first wing tool, the area thus formed serving as a collection location for material extracted from a second seabed location (for example a seabed space away from a dock face), and to identify debris that could obstruct a pump (box <NUM>); forming a second fluidized material and moving it away from the second seabed location (dock face) using the first wing tool or a second wing tool while the pump extracts at least a portion of the first fluidized material from the trench formed in the first seabed location and delivers the at least a portion of the first fluidized material to a surface vessel (box <NUM>); moving the second fluidized material into the trench using the first wing tool while the pump extracts at least a portion of the second fluidized material from the trench and delivers the at least a portion of the second fluidized material to the surface vessel or other support vessel (box <NUM>), and forming a third fluidized material at a third seabed location (for example, a federal channel) and moving it into the trench using the first wing tool while the pump extracts at least a portion of the third fluidized material from the trench and delivers the at least a portion of the third fluidized material to the surface vessel, to an onshore location for disposal or beneficial upgrading, to a location over or around a dam into the downstream river bed, or the other support vessel, or another vessel (box <NUM>).

Method embodiment <NUM> (<FIG>) comprises a method (box <NUM>) comprising fluidizing a portion of material of a seabed sand wave using a first wing tool (box <NUM>), moving the fluidized portion of material away from, or to the side of, the seabed sand wave to produce a level sand surface traversing the sand wave (box <NUM>), and installing a pipeline across the level sand surface (box <NUM>).

Method embodiment <NUM> (<FIG>) comprises a method (box <NUM>) comprising removing a cover portion of material from a subsea archeological site using a wing tool (box <NUM>); removing a second portion of material from the archeological site using a submersible pump, the submersible pump extracting sand and small artifacts such as coins and ornaments, and preserving the archeological site for diver conducted examination and extraction by hand (box <NUM>); and routing the extracted sand and small artifacts through screens to recover the small artifacts (box <NUM>).

Method embodiment <NUM> (<FIG>) comprises a method (box <NUM>) comprising removing a cover portion of material from a subsea buried pipeline or cable for repair or recovery using a wing tool (box <NUM>); repairing or removing the subsea buried pipeline or cable (box <NUM>), and moving seabed material over the repaired subsea buried pipeline or cable using the wing tool (box <NUM>).

Claim 1:
A method comprising:
forming a first fluidized material in a first seabed location by forming a first trench (<NUM>) by fluidizing the seabed using a first wing dredger (<NUM>) and using an extraction pump for evacuating the first trench, wherein
the extraction pump evacuates the first trench in anticipation of deposit of material extracted from a second seabed location (<NUM>), the first trench thus formed serving as a collection area for material extracted from the second seabed location, and to identify debris that could obstruct the extraction pump (<NUM>) ;
forming a second fluidized material and moving it away from the second seabed location (<NUM>) using the first wing dredger or a second wing dredger while the extraction pump extracts at least a portion of the first fluidized material from the first trench formed in the first seabed location and delivers at least a portion of the first fluidized material to a surface vessel (<NUM>); and
moving the second fluidized material into the first trench (<NUM>) using the first or second wing dredger while the extraction pump extracts at least a portion of the second fluidized material from the first trench and delivers at least a portion of the second fluidized material to the surface vessel (<NUM>) or other support vessel.