US3736677A

US3736677A - Silt dredging method

Info

Publication number: US3736677A
Application number: US00237757A
Authority: US
Inventors: H Loy
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-07-13
Filing date: 1972-03-24
Publication date: 1973-06-05
Anticipated expiration: 1990-06-05

Abstract

A method involving two aspects. One comprises dragging a suitable scraper from a position remote from the shore of a body of water toward it and lifting the scraper, i.e., not dumping it, at the place the silt is to be deposited above its load of silt. The second aspect, which can be used alone or preceding the first comprises dragging the scraper along the bottom of the body of water only in the area to be deepened to loosen and agitate the silt to put it in suspension so that normal currents in the body of water carry it towards the shore. Thereafter, if desired, and with relatively short path of travel, a scraper can pull redeposited silt near the shore onto it.

Description

United States Patent 1 91 Loy [54] SILT DREDGING METHOD [76] Inventor: Henry Albert Loy, 87 North 1 1th W.,

Provo, Utah 84601 [22] Filed: Mar. 24, 1972 [21] Appl. No.: 237,757

Related [1.8. Application Data [62] Division of Ser. No. 54,910, July 13, 1970, Pat. No.

11/1957 Schofield 172/265 5/1918 Pratt ..172/26.5

. Primary ExaminerRobert E. Pulfrey Assistant Examiner-Clifford D. Crowder Attorney-George H. Mortimer [57] ABSTRACT A method involving two aspects. One comprises dragging asuitable scraper from a position remote from the shore of a body of water toward it and lifting the scraper, i.e., not dumping it, at the place the silt is to be deposited above its load of silt. The second aspect, which can be used alone or preceding the first comprises dragging the scraper along the bottom of the body of water only in the area to be deepened to loosen and agitate the silt to put it in suspension so that normal currents in the body of water carry it towards the shore. Thereafter, if desired,,and with relatively short path of travel, a scraper can pull redeposited silt near the shore onto it.

4 Claims, 6 Drawing Figures 3,679,004, granted July 25,

1 SILT DREDGING METHOD REFERENCE TO EARLIER FILED APPLICATION This application is a division of my prior application Ser. No. 54,910 filed July 13, 1970 entitled SILT DREDGING APPARATUS, now US. Pat. No. 1972, for DRAG SCRAPER FOR DREDGING SILT.

BACKGROUND OF THE INVENTION Lakes are fed by rivers and streams carrying silt in suspension that settles out in the relatively quiescent conditions prevailing there. This silt builds up on the bottom of the lake and, over a period of years, raises the level of the water, assuming approximately constant volume of water in the lake, and floods land adjacent to the shore. A somewhat similar build up of silt takes place in portions of the beds of the rivers flowing into and from the lake where the rate of flow of the water is slow compared to the rate where silt is picked up. The problem of silt build up in the beds of lakes and rivers has long been recognized and many devices and methods have been proposed for dredging the beds of rivers and lakes. Many of these devices are complex pieces of equipment that are expensive to manufacture and use.

SUMMARY OF THE INVENTION The present invention relates to a method of dredging silt from lake and river bottoms, preferably using the novel apparatus disclosed herein which is claimed in my said prior application.

The apparatus preferably used in carrying out the method comprises a simple and relatively inexpensive scraper and catamaran for moving the scraper to a position remote from the shore so that it can be pulled in to the shore to deposit the load of silt by merely lifting the scraper above the load. The scraper can also be used to agitate deposited silt a considerable distance from shore to resuspend it in the water that has currents normally moving shoreward where the silt will settle again and can be removed to the shore by rela tively short travel of the scraper. V

FIG. 1 is an isometric view of the scraper from above the right rear corner; I

FIG. 2 is a side view of the right side of the scraper;

FIG. 3 is an isometric view of the interior of the scraper from below looking into it from the front;

FIG. 3a is a detailed view of a portion of the scraper of FIG. 3;

FIG. 4 is an isometric view of the catamaran with the scraper in raised position; and

FIG. 5 is an isometric viewof a toothed blade that may be removably secured to the scraper to loosen compacted silt.

DESCRIPTION OF THE INVENTION The method of the invention involves two aspects which can be practiced independently but preferably are used in combination, one preceding the other, where a lake or large body of water is to be deepened aconsiderable distance from shore. One aspect comprises bringing silt from the bed of a lake or river to the shore and depositing it there, i.e., near or on the shore,

by use of a scraper, preferably the novel scraper described herein, and means to move it repeatedly toward and away from the shore and progresively along it. A second aspect comprises dragging a scraper, again preferably the novel scraper described herein, along the bottom of the body of water only in the area to be deepened to loosen and agitate the silt to put it into suspension in the water so that normal currents in the body of water carry it from the area where agitation suspends it toward the shore where it redeposits or settles out. Thereafter, if desired, and with a relatively short path of travel for the scraper toward and away from the shore, the redeposited silt can be brought to the shore as described in the first aspect of the method of the invention, thus using both aspects of the method in combination, i.e., in sequence, for a single purpose.

The first aspect of the method of dredging silt from the bottom of a body of water, e.g., a lake or river, in accordance with the invention comprises placing a scraper, preferably the scraper of the invention as described above, on the bottom of the body of water with the front end pointed in the direction of the shore. The distance of the scraper from the shore may be varied and depends on the circumstances and the equipment being worked with. For example, if one is dredging near to shore the scraper may be used with a crane that has vertical and horizontal movement generating means. Then the scraper. is dragged along the bottom toward the shore by using the horizontal movement generating means attached to the

chain

40 or 48 as circumstances require. When the scraper is on the shore at the place where its load of silt is to be deposited, the scraper is moved backward and/or upward away from its load of silt without being turned over, e.g., the vertical movement generating means may lift the scraper to deposit through the open bottom thereof the load of silt it has brought up with it from the bed of the body of water as it was dragged along it. If one is dredging from a considerable distance from the shore, the catamaran 5 is used to take the scraper to the site to be dredged, the winch 66 is operated to lower the scraper to the bottom of the body of water, the catamaran is then moved, either by power supplied from an outboard motor secured to the frame 52 or by a power boat ahead of the catamaran which tows it toward the shore and simultaneously pulls the scraper. When the catamaran is close to the shore the winch is operated to lift it from its load of silt which can then be brought near to or onto the shore as described above.

Another way of operating the scraper 1 involves use of the catamaran 5 anda winch or windlass (not shown) anchored on the shore. The catamaran carries the scraper to the place remote from shore that is to be dredged with the wire rope or chain of the .windlass on shore attached to the

chain

40 or 48. The windlass 68 on the catamaran lowers the scraper to the bottom of the body of water with the front end aimed at the shore. The windlass on shore then reels in the chain or rope pulling the scraper and catamaran to the shore. When the floats 50 reach the shore the reel 68 plays out its rope to permit the scraper to be pulled up on the shore The second aspect of the method is based on the discovery that silt at points distance from the shore of a lake can be moved largely by natural currents in the water to the shore by agitating the silt in the area to be deepened, e.g., a considerable distance away from the shore, to resuspend it in the water. The natural currents then move the suspended silt toward the shore and redeposit it there where it can be pulled up on the shore in the manner described above. In using the scraper 1 for this purpose it is towed along the bottom of the lake in in the area that is to be deepened by a power boat connected to the

chain

40 or 48. Even though the scraper fills up with silt, it still is able to loosen other silt and agitate it to suspend it in the water near the point of agitation. The normal currents of the lake that move toward the shore bring the suspended silt to the shore where much of it redeposits near enough to be removed by crane operation of the scraper as described.

The preferred apparatus for dredging silt comprises a scraper l and a catamaran 5.

The scraper 1 comprises a top wall 10 of rectangular shape, preferably approximately square and while not restricted to any particular size and gauge a convenient and practical size is about 6 feet by 6 feet by :6 inch thick. Secured to the top wall 10 are side walls 12 and a rear wall 14. These walls may be integral with the top wall, i.e., part of the same steel plate, or they may be separate pieces of steel plate of similar gauge suitably welded together along their contacting edges. The side walls may have any suitable width, e.g., about 24 to 26 inches, and the same length as the top wall. The rear wall 14 may be narrower than the side walls, e.g., about 14 to 16 inches wide and the same length as the width of the top wall. There is no front or bottom wall, thus leaving the front and bottom open, as may best be seen in FIG. 3.

Secured to the rear wall 14 is a scraper blade 16 that is sloped downwardly and forwardly at any suitable angle, e.g., at an angle of about 36 to the top wall 10. It preferably has the same length as the rear wall 14 so that it may be secured at its ends to the side walls 12 as well as along its upper edge to the rear wall 14, e.g., by welding. The blade 16 may have any suitable width but it is preferred to make it wide enough to extend a short distance below the plane of the bottom edges of the side walls 12, as may be seen in FIGS. 2 and 3, and a width of about 18 inches is satisfactory for this purpose. v

The front ends of the top and side walls are preferably reinforced by spaced flanges l8 and 20 made from similar steel plate which are suitable secured, preferably by welding, to these walls along their contacting areas.

Preferably the side walls 12 have secured thereto, e.g., by Welding along the contacting areas, an outwardly extending shoe 22 which desirably is about the same length and gauge as the side wall. The shoes 22 should be secured to their respective side walls adjacent to but spaced from the bottom edges thereof, e.g., some or 6 inches from the bottom edges, and they may have any desired width that will serve to prevent the scraper from sinking too deeply into loose silt it is to remove by scraping along the bottom of a body of water. A width of about 5 inches has been found to be suitable for the shoes of a scraper of the dimensions and weight described above. The front ends of the shoes 22 are preferably secured to the

flanges

18 and 20 which desirably terminate at the shoes at their lower ends as seen in FIGS. 1, 2 and 3. The lower front comer of each side wall is preferably cut off at an angle below the shoe 22 to form a sloping front end 24. The lower rear comer of each side wall is also preferably cut off to form a sloping rear end 26 to which the ends of the scraper blade 16 may be secured, e.g., by welding.

As the scraper is dragged forwardly along the bottom of the body of water being dredged it is desirable to provide water escape openings or holes to facilitate filling the body of the scraper full of silt. Such openings may be provided in the rearward part of the scraper, e.g., in the top wall as shown at 28 and in the upper part of the rear wall 14 as shown at 30, i.e., adjacent to the juncture of the top and rear walls.

Means are provided for pulling the scraper in a forward direction including

U-shaped hooks

32, 34, 36 and 38 inserted into holes drilled in the flange 1 8 with their ends welded to flange 20 as shown in FIGS. 1, 2 and 3. A chain 40 of suitable length is provided which has its ends secured by

hooks

32 and 38 to' opposite sides of the scraper adjacent to the bottom ends of the

flanges

18 and 20. These hooks are passed through an end link in each end of the chain 40 before they are secured as described to the flanges. The chain 40 then runs up the respective flange 18 to

hooks

34 and 36 which secure it at these intermediate points to the upper end of the flanges, again by passing through a link that is large enough to receive the hook as well as the other two links which aresecured to it. The bight or connecting part of the chain 40 is long enough to form a V on top of the scraper 1 when laid on it, as seen in FIG. 1, with the apex at about the center of the top wall 10.

At the rear end of each shoe 22 a U-shaped hook 42 (only one shown in the drawing) is suitably secured, e.g., by welding, with the end link of a chain 43 held within the bight of the hook which extends beyond the end of the shoe 22, as seen in FIG. 1. This chain is somewhat longer than the distance between the hooks 42 and may serve a number of functions including a drag to stir up silt to suspend it, a pull chain to draw the scraper backwards, a lift chain for the back end of the scraper, used either alone or together with the front chain 40 so as to give the scraper any desired angle of inclination relative to the horizontal, and the like.

Near the center of the rear wall 14 and at its upper edge, a U-shaped hook 44 may be provided which is suitably secured with the bight thereof above the surface of the top wall 10. To the top wall 10 approximately midway between the side walls and somewhat forward of the center of gravity an eye plate 45 may be suitably secured, e.g., by welding. In a preferred embodiment having a top wall about 6 feet square, the eye plate 45 may be centered some 28 inches from the back and 44 inches from the front which is still somewhat in front of the center of gravity so that if the scraper is lifted by the eye plate the front end will be somewhat higher than the back end, as seen in FIG. 4. These means make it possible to lift the scraper in a number of ways, e.g., by an upward lifting force on 45 alone, or an upward lifting force on both 44 and 45, or an upward lifting force on chain 40, chain 43 or both 40 and 43. Hook 44 may also serve to hold chain 43 up while the scraper is being moved, if this position is desired.

Additional means for moving the scraper forward with the pulling force at the proper height for varying conditions of the deposit on the lake or river bed includes a bar 46 having a hook 47 at each end and a chain 48 connected at its ends to said hooks which may be removably connected to selected links of chain 40 between the

hooks

32 and 34 and 36 and 38 respectively, as may be seen in FIGS. 3 and 3a.

Referring now to FIG. 4, the catamaran 5 comprises two floats 50 which may be elongated hollow cylinders with tapered ends made of any suitable material and of sufficient length and diameter that they displace a volume of water equivalent in weight to the weight of the scraper and catamaran without sinking too deeply into the water. The floats 50 are spaced apart a distance larger than the width of the scraper by a frame 52 which comprises side bars 54 running along the floats a distance greater than the length of the scraper 1 to which they are secured by any suitable means, e.g., bands 55, and cross bars 56 at the front and rear ends of the side bars to which they are suitably secured, e.g., by welding. Spacing bars 57 may also be provided between bands 55 to which they are secured at their ends. Between the ends of the side bars 54 are uprights 58, the lower ends of which may be secured, e.g., by welding, to the side bars. A top bar 60 is suitably secured to the upper ends of the upright bars 58. Braces 62 are secured to the uprights 58 and the side bars 54 to hold the uprights and side bars in approximately right angular relation to the uprights 58. A winch 66 is mounted on the top bar 60 which comprises a rotatable reel 68 mounted near the center of the top bar and a drive means 70 for the reel which may be of any suitable kind, e.g., an electric motor, a crank or the like. A wire rope 72 or the like has one end wound on the reel 68 and the other end may be secured to the scraper, e.g., to eye plate 45.

When the scraper I is lifted solely by the eye plate 45, and the plate is located somewhat forward of the center of gravity as described above, the scraper tilts to somewhat of an angle as seen in FIG. 4. If it is desired to give the scraper a horizontal position when it is lifted, a lifting force can be applied also to hook 44, either by a separate wire rope and reel or by suitably connecting a single lifting rope to both positions, as those skilled in this art will readily understand. Similarly a lifting force may be applied to the centers of

chains

40 and 43, if desired.

In some lake and river beds the deposits of silt become compacted so that a plain scraper blade such as 16 does not readily loosen and scoop it up when the scraper is pulled forwardly. In such cases it is preferred to secure to the lower edge thereof a toothed blade such as shown 11 FIG. 5 which comprises a steel bar 80, e.g., 5 inchesX6feet having a plurality of teeth 82 welded therto which may be made of suitable steel, e.g., A X 2 X 15 inches, preferably with a sharpened front edge 84. The toothed blade may be secured to the lower edge of the scraperblade 16 in any suitable manner, e.g., by a plurality of bolts passing through openings 86 in the bar 80 and aligned openings in the scraper blade 16.

Although the method of the invention has been described and exemplified in connection with certain specific and preferred apparatus, modifications and variations can be made as those skilled in the art will appreciate without departing from the principles of the invention set forth hereinabove.

Having thus described and exemplified the invention, what is claimed is:

l. A method of dredging silt comprising dragging a scraper having top, side and rear walls and an open front and bottom with a forwardly and downwardly sloping scraper blade at the rear along the bottom of a body of water from a position remote from a shore to ward it, supporting a substantial part of the weight of the scraper on the surface of the silt outside the side walls and a substantial distance above the lower edges thereof during said dragging to control the depth of penetration of the scraper into the silt,.and moving the scraper from its load of silt without being turned over at the place the silt is to be deposited.

2. The method as set forth in claim 1 in which the scraper is moved repeatedly toward and away from the shore and progressively along it.

3. The method of deepening a lake or like body of water in which normal currents are toward the shore comprising agitating the silt at the bottom in the area to be deepened to suspend it in the water so that normal currents therein carry it toward the shore and redeposit it nearer to the shore, and bringing the redeposited silt to the shore by dragging a scraper having top, side and rear walls and an open front and bottom with a forwardly and downwardly sloping scraper blade at the rear along the bottom of said body of water where said silt has redeposited from a position remote from said shore toward it, supporting a substantial part of the weight of the scraperon the surface of the silt outside the side walls and a substantial distance above the lower edges during said dragging to control the depth of penetration of the scraper into the silt, and moving said scraper from its load of siltat said shore.

4. The method as set forth in claim 3 in which the scraper is moved repeatedly toward and away from the shore and said slit is deposited thereon.

Claims

1. A method of dredging silt comprising dragging a scraper having top, side and rear walls and an open front and bottom with a forwardly and downwardly sloping scraper blade at the rear along the bottom of a body of water from a position remote from a shore toward it, supporting a substantial part of the weight of the scraper on the surface of the silt outside the side walls and a substantial distance above the lower edges thereof during said dragging to control the depth of penetration of the scraper into the silt, and moving the scraper from its load of silt without being turned over at the place the silt is to be deposited.

3. The method of deepening a lake or like body of water in which normal currents are toward the shore comprising agitating the silt at the bottom in the area to be deepened to suspend it in the water so that normal currents therein carry it toward the shore and redeposit it nearer to the shore, and bringing the redeposited silt to the shore by dragging a scraper having top, side and rear walls and an open front and bottom with a forwardly and downwardly sloping scraper blade at the rear along the bottom of said body of water where said silt has redeposited from a position remote from said shore toward it, supporting a substantial part of the weight of the scraper on the surface of thE silt outside the side walls and a substantial distance above the lower edges during said dragging to control the depth of penetration of the scraper into the silt, and moving said scraper from its load of silt at said shore.