Abstract:
A floating system for collecting floatable debris is provided with curtains that direct the flow of water that contains floatables into the traps of the system while functioning as a pressure relief mechanism for the system which avoids placing excessive hydraulic forces on the system under extreme flow conditions. Inlet flow confining curtains have means for allowing the curtain to lift from the bottom of the waterbody as flow becomes progressively more extreme. The means may include patterns of weights in a series of normally horizontal pockets that are fabricated into the curtain at various distances below the water level that hang down to the bottom of the waterbody under normal conditions. The weights are graduated with the heaviest at the top and the lightest at the bottom. Alternatively, openings or windows are formed in the curtain and covered with mesh to allow flow through the windows while containing floatables larger than the size of the openings in the mesh. Also, a vertical corner of the curtain may have a triangular-shaped pucker pocket that extends from the surface of the water to the bottom of the curtains, which allows the two curtains to lift.

Description:
The present invention generally relates to the collection and removal of floatable debris and, more particularly, to structure for directing water flow into the inlets of the traps of such debris removing systems. 
     BACKGROUND OF THE INVENTION 
     Trash and debris floating on the surfaces of waterways or along shorelines and beaches is a highly visible form of water pollution, which is receiving attention for its adverse, polluting effect and for its unaesthetic appearance on the surfaces of lakes and other water bodies. One type of system for the collecting and removing of floating debris has consisted of arrays of disposable mesh nets installed in receiving bodies of water in the flow path of a sewer outlet, particularly in applications referred to as “Combined Sewer Overflows” or “CSOs”. Such systems are described in Vol. 2, No. 3, of Fresh Creek Technologies, Inc. “Shorelines” newsletter. Systems of this type are effective in collecting floatables or trash for removal and are shown in Fresh Creek Technologies, Inc. Netting Trashtrap™ Product Bulletin. Improvements in such devices are described in U.S. Pat. No. 5,562,819, owned by the assignee of the present application, which provides an underground, in-line apparatus for trapping and collecting debris in a sewer or storm flow conduit, a secondary trap which provides continued protection when primary collection traps are full, a system which signals when primary bags or nets are full and servicing is required, and a trapping facility in which bags or nets may be replaced without loss of trapping protection during servicing. 
     More specifically, the device in the patent referred to above includes an enclosure or chamber with an inlet and an outlet each adapted to be connected to a sewer, storm drain conduit or outflow. A debris removing system is disposed within the chamber between the inlet and the outlet for trapping and collecting water borne debris entering at the inlet and thereby providing for an outflow of substantially debris-free water. The enclosure includes an access opening comprising upper doors or hatches or access hatches in the enclosure sized to allow the debris removing system to be removed and replaced. The debris removing system specifically includes a perforated container having an open end facing the inlet of the chamber. The perforated container includes a netting assembly that traps and collects the trash or floating debris. The container is in the form of a netting assembly having a flexible bag-shaped mesh net attached to a frame. The netting assembly is attached to lifting structure having supports or handles for allowing the frame and net to be lifted out when the net is full of captured debris. In some applications, a bypass weir or screen is provided to normally direct flow from the chamber inlet through the open end of the net while allowing flow to bypass the net and flow to the chamber outlet when the net is full of debris. 
     Sensing and signaling elements are typically provided for sensing and signaling the passage of solid debris around the net when the net is full of debris and is in need of servicing. The sensing and signaling elements may include mechanical structure which permits passage of water, but is displaced by impingement of solid debris flowing around the nets. Displacement of such mechanical structure signals when the net is full of debris, for example, by actuating a visible flag above ground or by actuating an electrical switch which activates an aboveground indicator or remote indicator. The sensing and signaling may include an optical sensor for detecting the passage of debris around the netting assembly. Upon detection of debris, the optical sensor emits a signal indicating that the trap is full of debris. The signal may also activate an aboveground indicator or a remote indicator. 
     Multiple trap systems are employed in which the enclosure includes side-by-side trap assemblies. Such systems may be configured such that, upon filling of the first trap, the flow and debris can be diverted over a bypass weir disposed between the inlet ends of the first and second traps so that flow is thereby directed through the second trap and overflow debris is trapped and collected. Closure panels may be provided in a stationary frame structure disposed adjacent the inlet ends of the traps in either the single-trap systems or the multitrap systems to restrain debris from flowing through the chamber during servicing. 
     Floating systems for the removal of floatables or trash are positioned in a body of water in front of an outfall such as a stream or storm sewer conduit through which water flows into the waterbody. The systems are oriented with the mouths of the disposable nets facing the outfall. The system includes a structure that floats on the surface of the water to hold the nets horizontally in the water. The flow is directed toward the mouths of the nets through a funnel-shaped structure in front of the floating structure. The energy of the flow drives the floatables into the disposable nets where they are captured and can be removed. The number of nets in a given system is chosen to handle the anticipated flow from the outfall under specified conditions and to avoid excessive flow velocities in the individual nets. 
     Floating systems are installed in waterways that have variable water elevations due to tides or other flow patterns. To prevent floatables from escaping around or under the system, weighted curtains are attached to floating booms attached between the shore headwall, on opposite sides of the outfall, and the front corners of the unit and below the mouths of the nets, with the unit facing the outfall. Under designed flow conditions, these curtains direct the flow from the outfall into the mouth of the disposable nets. The curtains extend or hang vertically from the units and the floating booms to the bottom of the waterbody. The vertical length of the curtains is such that they will reach the water bottom under a specified water elevation such as extreme high tide or the 100-year flood elevation. 
     Under extreme flow conditions, the energy of the flow can place excessive hydraulic forces on the system. Since design of the system for the worst case flow is impractical, a need exists for a method of providing relief to structurally protect the system. 
     SUMMARY OF THE INVENTION 
     A primary objective of the present invention is to provide relief to structurally protect the system under extreme flow conditions and under the worst case flow. 
     According to principles of the present invention, a floating debris collecting system is provided with curtains that direct the flow of water that contains floatables into the traps of the system while functioning as a pressure relief mechanism for the system which avoids placing excessive hydraulic forces on the system under extreme flow conditions. 
     In one embodiment of the invention, inlet flow confining curtains are provided with patterns of weights to cause the curtain to hang in an optimal manner for preventing floatables from bypassing the traps of the system while allowing extreme water flow at depths that are less likely to carry floatables to find a low flow resistance path around the traps. In particular, curtains are provided that are weighted in a manner that causes them to lift off of the water bottom when the velocity of the water and the pressure on the curtains reach predetermined levels. As the lifting occurs, some of the flow of the water pases under the curtains, thereby providing pressure relief. This is achieved by placing weights in the curtain in a series of nominally horizontal pouches or pockets that are fabricated into the curtain at various distances below the water level that hang down to the bottom of the waterbody under normal conditions. The weights are graduated with the heaviest at the top and the lightest at the bottom. This progressive weighting causes the curtain to lift first at the bottom, thus causing the bypass to occur nearest the water bottom, where floatables are less likely to be present, providing pressure relief while minimizing the floatables that escape as the bypass occurs. 
     In another embodiment of the invention, curtains are provided having openings or windows formed therein that are covered with a mesh material of approximately the same aperture as the mesh of the nets. These windows allow flow through the windows while containing floatables larger than the size of the openings in the mesh. The positions and size of the windows are determined so as to provide a desired pressure relief while still directing the flow into the disposable nets of the traps. 
     In a further embodiment of the invention, curtains are provided with the vertical corner that is formed by the junction of the side curtain and the funnel curtain constructed with a triangular-shaped pucker pocket that extends from the lower corner of the floating structure to the bottom of the curtains. This pucker pocket allows the two curtains to lift and open at these corners while still containing the floatables that are more likely borne near the surface of the water. 
     These and other objectives and advantages of the present invention will be more readily apparent from the following detailed description of the of the preferred embodiments of the invention, in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing the common features of a debris removal system of the prior art. 
     FIG. 1A is an underground in-line version of the prior art system of FIG.  1 . 
     FIG. 1B is a floating version of the prior art system of FIG.  1 . 
     FIG. 1C is an end-of-pipe version of the prior art system of FIG.  1 . 
     FIG. 2 is a perspective view of one embodiment of a curtain for a floating system, of the type illustrated in FIG. 1B, for removing floatable debris according to certain principles of the present invention. 
     FIGS. 2A-2C is a series of cross-sectional diagrams through the curtain of FIG. 2 illustrating the shape of the curtain under increasing flow conditions. 
     FIG. 3 is a perspective view, similar to FIG. 2, of an alternative embodiment of curtain for a floating system according to principles of the present invention. 
     FIG. 4 is perspective view similar to FIGS. 2 and 3, of another alternative embodiment of curtain for a floating system according to principles of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates the basic components of one system  10  of the prior art described in the background of the invention above. The system  10  includes one or more traps  12 , illustrated as two in number, separately designated as traps  12   a  and  12   b . The traps  12   a , 12   b  are located within a flow-constraining housing or enclosure  11  between inlet  13  and outlet  14  thereof. The inlet  13  and the outlet  14  are each respectively connected in a known manner to conduits  15  and  16 , which may be storm drain or combined sewer conduits or other structures or the terrain of the site. The traps  12   a , 12   b  each include a netting assembly  19  formed of a bag-shaped mesh net  17  that is attached to a lifting basket  18 . Each of the netting assemblies  19  captures and holds floatable velocity borne debris  20  entering enclosure  11  through inlet  13 . The arrows  25  indicate the direction of water flow. 
     Perforations or openings in nets  17  may vary in size depending on the intended use, with sizes generally in the range of from about 0.1″ to about 2″. Nets  17  are open on the upstream facing end  17   a  thereof, toward inlet  13  of enclosure  11 . Upper support members (not shown in FIG. 1) are attached to lifting baskets  18  for allowing the netting assemblies  19  of traps  12   a , 12   b  to be lifted out of enclosure  11  for periodic removal of captured debris. The netting assemblies  19  are configured such that the nets  17  provide a large filter area for the size of the mouth, thereby minimizing head loss. For example, 80 square feet of net  17  may be provided for a netting assembly mouth area of 6½ square feet, resulting in a pressure drop across each net  17  of three or four pounds. 
     A bypass weir (not shown in FIG. 1) or screen is typically located upstream of traps  12  and on one side of inlet  13  to permit continued flow in the event that the nets  17  of traps  12   a ,  12   b  are filled to capacity with debris. To signal that nets  17  of the netting assemblies  19  of traps  12   a ,  12   b  are in need of replacement or emptying, sensing and signaling mechanisms may be provided. The multiple trap system  10  can be configured to provide continuous and uninterrupted capture of debris through second trap  12   b  after the netting assembly of first trap  12   a  has been filled and during the process of removing and replacing it. While servicing is being performed, movable panels can be positioned in front of each respective trap  12   a  or  12   b  being serviced, as necessary, prior to its removal from enclosure  11 . In this way, the system  10  is protected against passage of floatable debris during net removal and replacement. 
     FIGS. 1A-1C illustrate the basic system  10  of the prior art in three environments. These arrangements are generally described in a publication of the United States Environmental Protection Agency, Office of Water, No. EPA 832-F-99-037, September, 1999, hereby expressly incorporated by reference herein. 
     In particular, in FIG. 1A, an in-line system  10   a  is illustrated in which the two traps  12   a , 12   b  are contained in an enclosure in the form of an underground or subterranean vault  11   a . The vault  11   a  includes its inlet  13   a  and its outlet  14   a  respectively connected to conduits in the form of buried pipes  15   a ,  16   a , for example, of a storm drain. The in-line traps  12   a ,  12   b  each include a netting assembly  19  with a mesh net  17  installed in and held in place by a respective lifting basket  18 . A lifting bridle (not shown) is attached to upper support members  21  of the lifting basket  18  for allowing the netting assemblies  19  of traps  12   a  and  12   b  to be lifted out of vault  11   a  through doors  22   a  for periodic removal of captured debris. A bypass screen  23   a  is located above the traps  12   a , 12   b  to allow flow to divert from the inlet  13   a  to permit continued flow in the event that nets  17  of the traps  12   a ,  12   b  are both filled to capacity with debris. 
     In FIG. 1B, a floating system  10   b  is illustrated that is configured to float in a body of water in front of a stream, pipe or other water source from which enters into the body of water a flow of water containing trash or floatables to be removed by the system. The direction of water flow into and through the system  10   b  is also indicated by arrows  19 . The floating system  10   b  also includes two traps  12   a , 12   b , shown in a floating hull  11   b  that is provided with closed cell foam panels  23  and pontoons to float the hull at the surface  28  of the body of water. The traps  12   a , 12   b  also each include a mesh net  17  held in place within a lifting support  18   a . Because the system  10   b  is floating and the traps  12   a , 12   b  are immersed in water, a less extensive support frame  18   a  is substituted for the lifting basket  18  of system  10   a , described above. 
     In the system  10   b , the hull  11   b  has its inlet  13   b  extending above and below the surface  28  of the water so that trash or floatables at and immediately below the surface enter through it into the interior of the hull  11   b . The hull  11   b  has its outlet  14   b  below the water surface  28  on the back of the hull  11   b . The inlet conduit  15  is formed of a set of curtains  15   b  which hang from below the inlet  13   b  and from floats  24  extending respectively between the hull  11   b  on both sides of the inlet  13   b  to the shore on the opposite sides of the flowing source, connected to buried concrete conduits (not shown) of a storm drain, for example. The curtains  15   b  may extend from the water surface  28  to the bottom  29  of the water body and channel water from the source into the inlet  13   b . The traps  12   a ,  12   b  are supported in the hull  11   b  in a manner similar to the way they are supported in the vault  11   a  described above. They can be lifted out of hull  11   b  through grate doors  22   b  for periodic removal of captured debris from the nets  17  thereof. 
     In FIG. 1C, an end-of-pipe system  10   c  is illustrated in which the two traps  12   a , 12   b  are shown in an enclosure in the form of a surface mounted three-sided concrete headwall and knee wall enclosed cavity  11   c  having an open end that defines its outlet  14   c . The cavity  11   c  has its inlet  13   c  connected to a pipe  15   c  draining into the cavity  11   c . The traps  12   a ,  12   b  each include a net assembly  19  having a mesh net  17 . A fiberglass drain grating  16   c  is provided beneath the netting assemblies  19  to allow flow to exit each net  17  through its bottom to the outlet  14   c  of the enclosure tic. The net  17  of each netting assembly is attached to a lifting structure (not shown), which may be similar to the lifting basket  18  described in FIG. 1A above, or in the form of lifting frame  18   a  described in FIG. 1B above where the traps  12   a , 12   b  are submerged. Door grates  22   c  are provided above the traps  12   a ,  12   b  to permit them to be raised for periodic removal of captured debris. A bypass weir  23   c  may be located above the traps  12   a , 12   b  to allow flow to divert from the inlet  13  to permit continued flow in the event that traps  12   a ,  12   b  are both filled to capacity with debris. 
     Referring more particularly to the floating system  10   b  of FIG. 1B, the flow of water from the outfall into the inlet  13  of the system  10   b  causes pressure against the curtains  15   b  that hang from below the inlet  13  and the floats  24  that extend between the hull  11   b  and to the shore on the opposite sides of the flowing source. Under normal flow conditions, the curtains  15   b  channel substantially all of the inflowing water from the source into the inlet  13  along with the floatable debris it carries. When the flow is extreme, however, the pressure on the curtains  15   b  becomes greater, and either the water finds a way around the curtains and carries floating debris around the traps  12 , or the curtains  15   b  fail. Failure not only allows the flow of debris to bypass the system  10   b  while the extreme flow conditions persist, but leaves the system  10   b  in a nonfunctional and ineffective state when the flow conditions return to normal. 
     FIG. 2 illustrates a curtain  50 , according to one embodiment of the invention, to replace the curtain  15   b  in the system  10   b  of FIG.  1 B. The curtain  50  may be one continuous piece, or may be formed in segments, one hanging from each of the floats  24  and one from below the traps  12 . Preferably, the curtain  50  is assembled in segments that are joined with the pucker pocket feature described in connection with FIG. 4 below. The curtain  50 , when hanging from the floats  24  to the bottom  54  of the waterbody, substantially prevents the flow of water therethrough. The curtain  50  has weights distributed over its surface, such as, for example, an array of weights fixed to the curtain in a row or a plurality of rows, as illustrated as three rows of weights  51 ,  52  and  53 . The weights  51 - 53  are attached to the curtain in a way that weight can be added or reduced for the best performance of the curtain, for example, by providing pockets  49  in the curtain into which weights can be inserted or removed. A continuous flexible weight such as a chain can replace the one or more rows. In the illustrated embodiment, the weights  51  of the top row are the heaviest, with the weights  52  of the second row being lighter and the weights  53  of the bottom row being the lightest. Fewer or more than three rows of weights may be used, depending on the depth of the waterbody and flow conditions. 
     The function of the curtain  50  bearing the weights  51 - 53  is illustrated in FIGS. 2A-2C, in which FIG. 2A shows the curtain  50  under normal flow conditions, as represented by the arrow  55 , with the curtain  50  hanging from the float  24  to the bottom  54  of the waterbody. As the flow increases, as illustrated by the arrow  56  in FIG. 2B, the force of the flowing water overcomes the force of the bottom row of weights  53  and the curtain  50  begins to lift from the bottom  54 , allowing excess flow to begin to flow under the curtain  50 , as represented by the arrow  57 . As flow reaches extreme conditions, as illustrated by the arrow  58  in FIG. 2C, the effects of the heavier weights  52  and  53  are progressively overcome by the force of the flowing water and substantial excess flow thereupon occurs between the bottom of the curtain  50  and the bottom  54  of the waterbody, as represented by arrow  59 . 
     FIG. 3 illustrates an alternative curtain  60  to replace the curtain  15   b  in the system  10   b  of FIG.  1 B. The curtain  60  may be one continuous piece as illustrated in FIG. 1B, and is shown in FIG. 3 as hanging from the floats  24 , or may be formed in sections. The curtain  60  may also include the weights such as in the curtain  50  of FIG.  2 . The curtain  60 , when hanging from the floats  24  to the bottom  54  of the waterbody, prevents most of the flow of water therethrough. However, the curtain  60  has one or more openings therein, such as, for example, an array of windows, shown arranged in a plurality of rows, illustrated as three rows of windows  61 ,  62  and  63 . The windows  61 - 63  may be of various configurations, numbers and arrangements. Each window is covered with a mesh  64  with openings therein of the same approximate size as, and preferably not larger than, the openings in the mesh of the nets  12   a ,  12   b . The function of the curtain  60  having the windows  61 - 63  therein is to allow a flow of water from below the surface of the waterbody to flow through the windows  61 - 63 , particularly when the flow rate becomes large, and thus relieves the hydraulic pressure on the curtains  60  and the system. Under normal flow conditions, few floatables are found in water below the surface, but at higher flow rates when floatables are found at greater depths, such floatables are traped by the mesh covering the windows as the flow of water proceeds through the windows. 
     FIG. 4 illustrates a curtain  65  having another feature for handling extreme flow conditions that can be used alone with the curtain  15   b  of FIG. 1B or in combination with the features of the curtains  50  and  60  of FIGS. 2 and 3. The curtain  65  is a continuous curtain or a curtain with separate segments that are joined into a continuous curtain. In either case, joints  66  exist at the lower ends of the junctions where the floats  24  attach to the hull  11   b . At the bottom of the curtain  65  at each of the joints  66 , a pucker pocket  67  is provided in the flow resistant material of which the curtain is made. The pockets  67  allow the curtain to rest on the bottom  54  of the waterbody when the flow is nominal, but allows a lower end  68  of the curtain  65  to deflect back and lift from the bottom  54  when the flow is high in a manner similar to the bottom of the curtain  50  in FIG.  2 C. 
     Other applications of the invention can be made. Those skilled in the art will appreciate that the applications of the present invention herein are varied, and that the invention is described in preferred embodiments. Accordingly, additions and modifications can be made without departing from the principles of the invention.