Apparatus for Removing a Layer of Sediment Which Has Settled on the Bottom of a Large Water Body

Abstract

A method and apparatus for removing a layer of sediment which has settled on the bottom of a large water body includes using a structural frame configured to contain a bottom water flow and for containing liquid and suspended particles dispersed during removal of bottom sediment in a suctioning area that is at least about 3 square feet, up to and including 8 square feet, that has support elements and/or silt containing elements, with a plurality of supporting wheels. A sediment removing vacuum unit is operably associated with the structural frame to conduct suctioned bottom water flow through suction lines to a filtering station outside of the water body, such that the water can then be returned to the large water body.

Claims

1. A method of removing a layer of sediment which has settled on a bottom of a large body of water, the method comprising, providing an apparatus that comprises, a structural frame configured to contain a bottom water flow, said structural frame configured to contain liquid and suspended particles dispersed during removal of bottom sediment in a suctioning area that is at least 3 square feet, said structural frame having at least 4 wheels configured to facilitate conveyance across the bottom of the large water body when the structural frame is submerged in the large water body; said structural frame operably connecting to at least one suction line that is at least about 8 feet in length and has a diameter of at least about 2 inches and configured to conduct a suctioned bottom water flow through said suction line; said structural frame having one or more sections that direct silt laden water to an at least one sediment removing vacuum unit; moving the apparatus along the bottom of the large body of water; suctioning sediment-containing water from the bottom of the large body of water using the apparatus; and filtering the suctioned bottom water outside of the large body of water through a filter that is permeable to water to trap debris and to generate filtered water; and returning the filtered water to the large body of water.

2. The method as set forth in claim 1, wherein the step of moving the apparatus comprises employing a motorized mechanism to move the apparatus along the bottom of the large body of water.

3. The method as set forth in claim 1, wherein the step of moving the apparatus comprises employing a floating mechanism to move the apparatus along the bottom of the large body of water.

4. The method as set forth in claim 1, wherein the step of suctioning is performed by a power source selected from the group of an electrical power source and a gas-powered engine.

5. The method of claim 1, wherein the filtering step employs a filtering system that separates water from the silt and debris prior to returning the filtered water to the large body of water.

6. The method of claim 1, wherein the filtering step includes successive filtering treatments to remove ever smaller debris until a desired quality of water is achieved.

7. The method of claim 1, wherein the filter is positioned outside the large body of water.

8. The method of claim 1, wherein the filtering step is conducted in a manner that removes silt and debris that accumulates on the bottom of the very large water body in a more energy efficient manner as compared to methods employed in conventional centralized filtration systems used in conventional swimming pools, wherein said filtering step does not filter the entire volume of water in the very large water body more than once per day.

9. The method of claim 1, further comprising positioning the apparatus a desired distance above the bottom of the large body of water.

10. The method of claim 1, wherein the apparatus comprises more than one sediment removing vacuum unit.

11. The method of claim 1, wherein the energy required to generate the filtered water is a fraction of the energy it would take for the same amount of filtered water running thorough a typical pool centralized filter system.

12. The method of claim 1, further comprising a barrier configured to contain the bottom water flow within the apparatus.

13. The method of claim 1, further comprising avoiding re-suspension of the layer of sediment.

14. The method of claim 1, wherein said filtering step comprises filtering a small fraction of the filtered water that would otherwise be filtered using a conventional water treatment filtration system.

15. The method of claim 1, wherein said suctioning step comprises covering large surface areas of the bottom of a large body of water at high speed and without employing a centralized filter system used in conventional swimming pools.

16. The method of claim 1, wherein said suctioning step comprises confining the liquid and suspended particles dispersed during removal of bottom sediment in a suctioning area that is at least 3 square feet.

17. The method of claim 1, wherein said step of suctioning comprises preventing the thickness of settled material on the bottom of a large body of water from exceeding at least 3 millimeters.

18. A method of removing a layer of sediment which has settled on a bottom of a large body of water, the method comprising, providing an apparatus that comprises, a structural frame configured to contain a bottom water flow and avoid a re-suspension of sediment outside a vicinity of the structural frame, said structural frame configured to contain liquid and suspended particles dispersed during removal of bottom sediment in a suctioning area that is at least 3 square feet, said structural frame having at least 4 wheels configured to facilitate conveyance across the bottom of the large water body when the structural frame is submerged in the large water body; said structural frame operably connecting to at least one suction line that is at least about 8 feet in length and has a diameter of at least about 2 inches and configured to conduct a suctioned bottom water flow through said suction line; said structural frame having one or more sections that direct silt laden water to an at least one sediment removing vacuum unit; moving the apparatus along the bottom of the large body of water, the apparatus associated with a buoyant or a floatation device; suctioning sediment-containing water from the bottom of the large body of water using the apparatus; and filtering the suctioned bottom water through a filter that is permeable to water to trap debris and to generate filtered water; and returning the filtered water to the large body of water.

19. The method as set forth in claim 18, wherein the step of moving the apparatus comprises employing a motorized mechanism to move the apparatus along the bottom of the large body of water.

20. A method of removing a layer of sediment which has settled on a bottom of a large body of water, the method comprising, providing an apparatus that comprises, a structural frame configured to contain a bottom water flow and avoid a re-suspension of sediment outside a vicinity of the structural frame, said structural frame configured to contain liquid and suspended particles dispersed during removal of bottom sediment in a suctioning area that is at least 3 square feet, said structural frame having at least 4 wheels configured to facilitate conveyance across the bottom of the large water body when the structural frame is submerged in the large water body; said structural frame operably connecting to at least one suction line that is at least about 8 feet in length and has a diameter of at least about 2 inches and configured to conduct a suctioned bottom water flow through said suction line; said structural frame having one or more sections that direct silt laden water to an at least one sediment removing vacuum unit; moving the apparatus along the bottom of the large body of water; suctioning sediment-containing water from the bottom of the large body of water using the apparatus; and filtering the suctioned bottom water outside of the large body of water through a filter that is permeable to water to trap debris and to generate filtered water; and returning the filtered water to the large body of water, and, reducing the amount of settled material on the bottom of a large body of water in a manner that reduces the overall costs and energy required as compared to a conventional swimming pool.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] FIG. 1 shows a schematic, perspective view of one embodiment of the present invention, showing two submerged suction units in operation at the bottom of a lagoon.

[0070] FIG. 2A shows a closer perspective view of one embodiment of a suction units shown in FIG. 1 as used in the present method.

[0071] FIG. 2B shows an embodiment where skis are employed to support and convey the suction unit across the bottom of a large lagoon.

[0072] FIG. 3 is a perspective view of another embodiment where a submerged pump is employed with a long hose connected to a suction unit, with a remote control unit shown that is capable of controlling the suctioning operation.

[0073] FIG. 4 is a side perspective view of a lagoon with a submerged suction unit at its bottom, a filter, pump and sediment container positioned outside the lagoon, and a motorized powered floating unit that is remotely controlled to achieve the suctioning operation.

[0074] FIG. 5 is a perspective view of one embodiment where the suction unit is manually operated, employing a wheel and a silt curtain to perform the suctioning operation.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

[0075] One embodiment of an apparatus of the invention 10 is shown in FIG. 5 in a working environment for removing a layer of sediment which has settled on the bottom of a pond/lagoon. The apparatus comprises a frame and a conduit for conveying slurry from a suction unit 10 (which may include an adjustment means to vary the size of apertures can be made to adjust the ratio of sediment to water removed from the bottom of the pond/lagoon). In certain embodiments, see FIG. 5, a single wheel 16 supports the unit and such unit is electrically powered via a long cord. As shown in FIGS. 2A and 2B, the suction unit 10 may include an inlet port/suction chamber 24 (underneath the housing 18) and an outlet port/discharge opening 26. Preferably, with respect to a manually operated version (see FIG. 5), the housing 18 is in fluid communication with a chamber 12, and then a flexible conduit/hose 20 is in fluid communication, which extends above the level of the pond/lagoon. FIG. 1 shows a perspective view of one embodiment of the present invention, showing two submerged suction units in operation at the bottom of a lagoon, where long extended hoses convey suctioned water to a filter, and where the filtered water is then returned to the lagoon.

[0076] Various patents and patent publications are hereby incorporated by reference to provide written description and support and for enablement purposes with respect to the varied and numerous embodiments of the present invention as encompassed by the scope of claims herein. These include U.S. Pat. No. 4,957,622 to Mims; U.S. Pat. No. 6,432,303 to Chesner; U.S. Pat. Nos. 7,370,445, 5,864,919 to Pineda; U.S. Pat. No. 5,317,776 to DeMoura; U.S. Pat. No. 7,314,571 to Lovestead et al; U.S. Pat. No. 7,234,657 to Doering et al; U.S. Pat. No. 4,454,993 to Shibata et al; 20080313827 to Paxton; 20050247613 to Bishop; U.S. Pat. No. 7,520,015 to Ajello; U.S. Pat. No. 7,552,551 to Kohutko; 20080109972 to Mah; U.S. Pat. No. 7,676,966 to Taplin; U.S. Pat. No. 6,383,383 to Novak; U.S. Pat. No. 4,642,919 to Werner et al.; U.S. Pat. No. 7,181,871 to Sower; and U.S. Pat. No. 6,953,321 to Roudnev et al.; U.S. Pat. No. 7,806,347 to Hanke et al.; U.S. Pat. No. 7,805,793 to Paxton; 20040111825 to Kaufman et al.; 20030221412 to Harrington; 20070190591 to Grech; 20100096324 to Roberts; U.S. Pat. No. 7,686,951 to Wagner, et al.; U.S. Pat. No. 7,270,746 to Wang; U.S. Pat. No. 7,708,149 to Pank et al.; U.S. Pat. No. 5,095,571 to Sargent; U.S. Pat. No. 7,465,129 to Singleton; U.S. Pat. No. 7,814,926 to Hoffmeier, et al. and U.S. patents application Nos. 20070065316; 20070183905; 20070199595; 20070286752; 20080054088; 20080044293; 20080056911; 20080105311; 20120024794 and 20080217229. U.S. Pat. Nos. 7,820,055; 8,070,942; 8,062,514; 8,790,518; 9,708,822; 9,470,007; 9,080,342; 8,465,651; 9,062,471; 8,753,520; 9,957,693 and 9,470,008 are also hereby incorporated by reference to provide further written support and enablement for various embodiments of the present invention.

[0077] According to another aspect of the present invention, a sediment removal system for removing sediment from a body of water comprises a suction conduit having an inlet portion defining an inlet opening/suction chamber 24, at least one retention container/filter 30 adapted to retain sediment removed from a body of water, and a suction pump 33 adapted to draw sediment and water through the suction conduit/hose 20 and into the at least one retention container/filter 30. A retention/storage container 36 (see FIG. 4) may also be employed to contain filtered sediment for later disposal.

[0078] In a preferred embodiment, the material that has settled to the bottom of the pond is not to be unduly disturbed before being suctioned, thus allowing more of the sediment to be removed and preventing further contamination of the pond water. Thus, the method of the present invention is particularly directed and focused to achieving in a controlled manner removal of debris from a pond/lagoon bottom without generating unwanted turbidity.

[0079] In still other embodiments, a mulcher-type of mechanism (not shown), similar to those employed in leaf blower systems, can be associated with the suction import end of the unit so that leaves and other debris that can be reduced in size (to a size that does not interfere with the impeller movement of the vacuum or pump employed). This provides a way to largely dispense with the herein described bagger mechanisms for large debris and leaves. In some embodiments, a combination of such systems can be provided on a unit so that the operator has options in what mechanisms can be employed for particular uses. Such mechanisms typically include vanes which provide serrations or debris-engaging structure for further mulching debris. Incorporated herein are the following patents for this particular aspect of the present invention: U.S. Pat. No. 6,629,818 to Svoboda; U.S. Pat. No. 5,791,568 to Keim and U.S. Pat. No. 5,794,864 to Hammett, et al.

[0080] Thus, in certain embodiments, a cutter pump (not shown) is employed to address mulching of debris so that impeller devices are not adversely affected by debris clogging the vacuum operation. Various types of pulverizing means for receiving said solids and for reducing the solids to particulate sizes can be employed. For example, water enters a chamber from an inlet, an aperture control the water flow as it leaves the chamber and enters a passageway, with such passageway controlling the water flow. Separated heavier solid waste settles into a sump and pre-filtered lighter suspended solid waste is carried by the water flow to be filtered by a filter member. A cutter pump (not shown) subassembly can be employed that is adapted for cutting and pumping a liquid containing entrained solids, such as slurry. Pumps of this kind are used to transport fiber suspensions and various sludges such as sewage, paper, cloth products, and plastics. Preferably, head capacity, i.e., pressure differential from suction to discharge, is maintained at desirable levels so that the chopping action does not unduly restrict the flow of the water.

[0081] Preferably, the cutting action is carried out in line with the natural flow of the water passing through the pump. Other embodiments, however can employ other pump systems, such as that disclosed in U.S. Pat. No. 4,145,008, issued to Wolferd and incorporated herein by this reference, where a pump is shown in which the chopping action of the pump is provided by a blade spinning perpendicularly to the direction of fluid flow.

[0082] Another aspect of the present invention in particular embodiments is directed to a carriage for facilitating the conveyance of a suctioning unit across the bottom of a pond/lagoon. Thus, provision of a wheeled 16 or slatted/ski 22 carriage (see FIGS. 2A and 2B) that can retro-fit existing suction devices, including those of the prior art as referenced herein, enables one to better accomplish the removal of silt and debris from the bottom of a pond/lagoon. For example, in one embodiment a sled having skis 22 is attached to the bottom side of a silt enclosure or housing 18 and comprises the combination of both surface conveyance devices, such as wheels 16, castors, slats or skis 22, etc. in combination with a vacuum unit 10 with a suction chamber 24 through which pond/lagoon bottom debris can be suctioned off the bottom of the pond/lagoon. Preferably such a carriage/housing 18 is employed with a submersible pump apparatus 33 positioned at the bottom of a body of water, whether such device is remotely controlled 42 (and thus does not necessitate a person actually entering the pond/lagoon to use the device)or wherein an individual manually conveys the device across desired sections of a pond/lagoon bottom (see FIG. 5). In certain embodiments, the system can be remote controlled 42 in various respects, including directing the traveling of the unit 10 across a pond/lagoon floor bottom.

[0083] In other embodiments, where a water pump system 33 is employed that uses one or more powerful water intake units that remove or draw out massive amounts of water in a very short time, the pull or suction of water by these pumps 33 generates a high velocity water flow (vortex) near the pump intake unit 33. The high rate of water flow is sufficiently strong that aquatic life, such as fish, turtles, etc. cannot escape the water current generated, and are sucked into the pump system. Therefore, regrettably, during water pumping operations, water is not the only element removed, but in addition, fish and other aquatic life is also drawn out indiscriminately. Accordingly, preferred embodiments of the present invention uses a protective screen (not shown) to preclude aquatic life from being ingested into the pump stream. When the pumping rate of the water is increased, then the size of the screen is commensurately increased and thus, a large volume of water may flow over a larger surface area, neutralizing, maintaining, or in fact, reducing the actual approach velocity of the water near the protective screen, despite an increase in the rate of water pumped.

[0084] One will appreciate that while the present invention can be immersed and placed at the bottom floor of the body of water, it can also be floated by a buoyant or a floatation device (not shown). In one embodiment (see FIGS. 2A and 2B), downward-facing (via the housing 18) inlet ports/suction chambers 24 are configured as defined suction areas that are positioned to contain the suctioned water flow, and are suspended at an elevation above the bottom of the pond/lagoon, (depicted as dotted lines in FIGS. 2A and 2B), with such suspension adapted to be shortened or lengthened to adjust the height above the bottom of the pond/lagoon. In other embodiments, the buoyancy of the device may be changed to adjust the height above the bottom of the pond/lagoon.

[0085] In various embodiments, a portable frame comprising a screen (not shown) is employed to wrap around the portable frame, thus providing a low profile of the portable frame to permit drafting in shallow water situations, and decreases the overall weight of the device 10. Several various different embodiments of a suction unit 10 may be enclosed or housed within screened environments, thus facilitating the suctioning of silt and small debris without risking suctioning aquatic life and larger debris. Efficient removal of small particles is a critical component of any filtering system 30 when filtering cloudy water.

[0086] In another aspect of the invention, a method is provided for suctioning debris from the bottom of a pond/lagoon that comprises the acts of: submerging a suction system 10 having a screen (not shown) of a predetermined size that precludes aquatic life of more than about 1 inch in size from passing therethrough; elevating the intake/inlet ports/suction chambers 28 above the pond/lagoon bottom to a predetermined degree; connecting the outlet 26 via a hose 20 to first or second pump 33 located outside the pond/lagoon; and powering on the pump 33 to draw water upward through the system, thus achieving desired removal of silt laden water without substantial loss of aquatic life. In one embodiment, a submerged wheeled system 10 is adjustable for a height above the pond/lagoon bottom, with such system connected to hoses 20 or tubes and functionality connected to a separate power supply (not shown). The conveyance system preferably uses a removable ski 22, wheels 16, etc. (See FIGS. 2A and 2B) to customize the conveyance device, and may further include telescoping, locking, and adjustable height of wheels 16, skis 22, to position the suctioning action a desired distance above the bottom of the pond/lagoon. Such conveyance system facilitates one to be able to avoid unseen obstacles on the pond/lagoon bottom, such as rocks, aerators, potted plants, underwater structures, etc.

[0087] As described herein a housing 18 is particularly desired to entrap silt from going into surrounding waters. Thus, a housing 18 employing a type of a silt curtain/silt constraining enclosure 38 is designed to control the settling of solids (silt) to provide a controlled area of containment. Reduction of turbidity and confining it to a specified area around the suction device 10 has not been employed by prior art pond/lagoon suctioning systems. The use of such a silt containing housing 18 during suctioning operations provides for improved settling for suspended solids. Incorporated herein in their entireties by this reference are: U.S. Pat. No. 6,953,528; and U.S. Publication No. 20050016930 to Nesfield.

[0088] In certain embodiments, the present invention employs various known aspects of dredger designs to accomplish the particular purposes as set forth herein. For example, a Cutter Suction Dredger, Grab Dredger, Dustpan Dredger and trailing suction hopper dredgers can be variously employed.

[0089] In one embodiment, the above described suctioning device 10 (especially those that employ two or more pumping units 33) is used in conjunction with an elongate enclosure (not shown) having mesh sides and defining a closed interior for the collection of water and a mesh exterior for preventing undesired sized particulate penetration into the closed interior.

[0090] Preferably a perforated plate arrayed over a cylindrical body is used where a housing comprising a screen for removing debris from water as water is suctioned from the bottom surface of a pond/lagoon, a suction chamber 24 positioned within the housing 18 and a discharge opening 26 for discharging water out of the suction chamber 24 to feed a suction pipe/hose 20 that is connected to a pumping unit 33. A control zone containing liquid and suspended particles dispersed during removal of bottom sediment surface is provided via a housing 18 that surrounds a desired suctioning area, preferably at least about 1 square foot around the suctioning action, more preferably about 2 square feet, and more preferably about 3 square feet around the suctioning action. Silt curtains and other silt constraining enclosures 38, such as transparent panels (not shown), are preferably employed to form around such housing 18 so as to facilitate some visual assistance of an operator of the suctioning unit 10. Such silt constraining 38 housing 18 may also have one or more sections/chambers 24 within the outer confines of the housing 18 to further reduce turbidity and to direct silt laden water to the suctioning unit outlet port 26. Thus, barrier walls/silt constraining enclosures 38 comprised of individual movable sheets capable of contouring to the bottom of the surface of the waterway can be used in containing liquid and suspended particles dispersed during suctioning operations. These features are designed to reduce sediment dispersion resulting from cutterblade, jetting, or raking mechanisms that may also be used in concert with the suctioning units 10 of the present invention. Various curtains 38 (flexible, impermeable canvas or rubber-like sheets) assist in isolating the area of suctioning.

[0091] Very large artificial water bodies are typically built without centralized filtration systems and there is, therefore, a need for providing low cost and efficient bottom cleaning methods and devices for very large water bodies, such as manmade lagoons, ponds, lakes, etc. whether they have natural bottoms, lined bottoms, or bottoms that permit only a limited amount of leakage. The present invention satisfies this need. In certain embodiments of the present invention, a method for removing a layer of sediment that has settled on the bottom of a large body of water employs a suctioning device 10 that employs a large (at least 3 square feet) expansive suction area configured to provide a structural frame having structures 24 that direct a bottom water flow within the suctioning device and that avoids the re-suspension of sediment from the bottom water flow in the vicinity of the suctioning device 10. A plurality of wheels 16 (e.g. at least four or more) are configured to provide support and/or suction height of the suctioning device 10. More than one apparatus can be employed at the same time in a lagoon (see FIG. 1) so as to speed up the suctioning operation of the entire lagoon.

[0092] The structural frame 18 of the apparatus 10 is operably connected to at least one suction output port or discharge opening 26, that is configured to conduct a suctioned bottom water flow through a suction line/hose 20, which conveys the suctioned bottom water flow and concentrate out of the water body where suctioned water can be filtered 30 and then returned 32 to the water body. Such hose 20 is operably connected to at least one sediment removing vacuum unit 33, preferably located just outside of the large body of water. Preferably the one or more sediment removing vacuum units 33 have one or more segments of PVC or plastic pipe 44 that are at least 1 inch in diameter. The suctioned water with sediment therein is then passed through a filter 30, such filter 30 being permeable to water and of a predetermined size to trap debris. Sediment removed from the filtered water is preferably contained, at least for some period of time, in a storage container 36. The filtered water is preferably then returned 32 to the large body of water.

[0093] In preferred embodiments, methods and devices are employed for suctioning precipitated impurities in a manner that avoids re-suspension of the settled impurities and doing so while being able to cover large surface areas in short periods of time. Preferred embodiments employ a method using a suctioning device 10 designed for cleaning the bottom of artificial water bodies, where the devices move along the bottom of the artificial water bodies, suctioning the bottom water flow in order to remove any solids found on the bottom thereof.

[0094] In contrast to prior suction technologies that employ long and thin suction openings that often create sediment clouds that generate cleaning and suctioning inefficiencies, the embodiments of the present invention are configured to have much larger suction areas, such as at least about 3 square feet, and preferably even larger, such as 8 square feet, to accomplish desired suctioning of the bottom surfaces of very large bodies of water. Preferably, embodiments of the present invention 10 are relatively light in weight as compared to prior art suctioning devices, preferably light enough not to deform the bottom surface of a large body of water. Preferred embodiments provide a suction method and device able to efficiently suction the debris from the bottom of a large body of water at high speed and over irregular bottoms, without relying upon a centralized filter system such as those used in traditional pools.

[0095] Very large artificial water bodies may have plastic liners over the natural terrain that may be covered with sand, clay, or compacted materials, which generates an irregular bottom, with some of such bottoms leaking certain amounts of water therethrough. Various embodiments of the present invention are directed to methods and systems that employ a large suctioning device 10 for suctioning debris from the bottom of large artificial water bodies with bottoms having plastic liners that do not have centralized filtration systems.

[0096] Preferably, the method and apparatus 10 employed uses a suctioning system that is supported, either with structures like curtains 38, wheels 16, brushes, etc., to enable the suction device 10 to suction up and also confine sediments so that there is a reduction in the dispersion and re-suspension of settled debris. In one embodiment, the suctioning device 10 is at least about three square feet in area, but is able to further concentrate suction power by using a series of suction points/chambers 24. The suctioning apparatus 10 is connected to suction lines 20, preferably at least about 2 inches in diameter and that are directed towards a suctioning vacuum device 33, itself connected to a filtration system 30 outside of the large body of water.

[0097] The suction device 10 can be provided with a plurality of structures/chambers 24 to allow for the redirecting of a bottom water flow to achieve efficient suction of the bottom water flow. The geometry and strategic placement thereof can vary and may include structures, such as curtains 28, barriers, etc. configured and positioned to contain the suctioned water flow within the suction device 10 to avoid re-suspension of a bottom water flow in the vicinity of the suction device 10.

[0098] In certain embodiments, a mobile suction device 10 as described herein is used to suction a portion of water containing debris to prevent the thickness of settled material on the bottom of a large body of water from exceeding at least 3 millimeters, more preferably more than 5 mm. Such suctioned water is filtered outside the large body of water and then the filtered water is returned 32 to the large body of water. The energy required to suction and filter such water is a fraction of the energy it would take for the same amount of water running thorough a typical pool centralized filter system.

[0099] In some embodiments, the suction unit 10 is large and flexible, making it easier to conform to the bottom surface of a large water body. The suction unit preferably has structures, such as inlet ports/suction chambers 24 (depicted as dotted lines beneath the housing 18 in FIGS. 2A and 2B), configured and positioned to contain the suctioned water flow within a defined suction area in a manner that assists in avoiding re-suspension of sediment from a bottom water flow in the vicinity of the suction unit 10.

[0100] The present disclosure includes that contained in the appended claims as well as that of the foregoing description. Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention.