Abstract:
A floating debris removal system has a bypass or overflow grate that is hinged at the top and positioned to swing downstream under certain conditions. The grate is fastened with a shear ring that will break when sufficient force is generated against the grate by the flow of overflow water and debris through the system. A plow-shaped member pivots off upwardly as flow increases. The member has a plow-shaped blade that spreads the flow across the inlet of the trap of the system to reduce the velocity of the flow. The shape and weight of the blade are selected for optimal function under a range of water levels and flow velocities, and can be altered to perform best for different installations. Debris pits are provided before or after the traps of the system to collect small suspended debris that is not removed by the traps. The pits are sized and configured to slow the velocity of the flow of that the suspended debris settles into the pits. Guide pits on the traps ride in vertical rails to facilitate loading and removal of the traps in the system, while a third plate-like rail on the face of a service ladder guides the downstream end of the traps, while simplifying the overall construction, minimizing surfaces on which dirt can collect, and conserving space.

Description:
The present invention relates to the collection and removal of floating debris from water flows, and particularly from combined sewer overflows. 
     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 of 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 if full of captured debris. In some applications, a bypass weir or screen is provided to normally direct flows 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 debris removal systems are designed to predefined peak flow rates established through monitoring and modeling based on maximum size reported storms for certain historic periods. Such modeling does not necessarily take into account the actual maximum possible amount of flow due to future record storms or particularly localized concentrations of precipitation or water flow concentration due to changing surface conditions. Bypass devices have been provided in such systems to release excessive pressures, but localized fluctuations in the flow patterns can cause imbalance forces causing premature triggering of such bypass devices. Ideal control of these devices in such situations has been lacking in the prior art. 
     Further, in such systems, removal from the water stream of suspended solids, particularly small suspended solids, has not been provided. In addition, in all systems of the prior art, the changing of the nets of the trap in the main contributor to the cost of servicing and maintaining the system. Accordingly, improvements in such systems that contribute to the efficiency of the net-changing task are continuously needed by such systems. 
     Accordingly, needs exist for improvements in such floating debris removal systems that will address the problems set forth above. 
     SUMMARY OF THE INVENTION 
     A primary objective of the present invention is to provide floating debris removal systems with the ability to handle extreme flow conditions, and, more particularly, to do so without disabling the debris removal capability of the system. 
     A secondary objective of the present invention is to provide such systems with the ability to more effectively remove debris from the water stream, including particularly the removal of suspended solids, such as small suspended solids. 
     It is a further objective of the invention to provide such debris removal systems with more efficient structures for changing of the nets of the trap. 
     According to certain principles of the present invention, a floating debris removal system is provided with a bypass weir or overflow screen or grate that is hinged at the top and positioned to swing downstream under certain conditions. The screen is fastened to fixed structure at the bottom with a shear ring or other shear device that will break when sufficient force is generated against the screen by the flow of overflow water and debris through the system. 
     According to other principles of the invention, one or more velocity dissipating members is provided adjacent the inlet. In the illustrated embodiment, one or more plow-shaped members is pivotally connected above the inlet of the system to pivot off of the bottom and open upwardly as flow increases. The plow-shaped member has, for example, a plow-shaped blade that spreads the flow across the inlet of the trap of the system to dissipate the energy of the flow and thereby reduce the velocity of the flow. The shape and weight of the blade are selected for optimal function under a range of water levels and flow velocities. The blade can be altered to perform best for different installations. 
     According to certain aspects of the invention, collection pits are provided before or after the traps of the system to collect small suspended solids or sediments that are not otherwise removed by the traps. The pits are sized and configured to promote the settling of suspended solids or sediments into the pits that may include objects smaller than the mesh of the nets of the traps. 
     In accordance with further aspects of the invention, the traps are provided with guide pins at the upstream of the traps of the frame thereof adjacent the mouths of the nets. The pins ride in vertical rails to facilitate loading and removal of the traps in the system. A third plate-like rail, preferably on the face of a service access ladder, helps guide the downstream end of the traps, while simplifying the overall construction, minimizing surfaces on which dirt can collect, and conserving space. 
    
    
     These and other objectives and advantages of the present invention will be more readily apparent from the following detailed description 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 . 
     FIGS. 2A and 2B are cross-sectional views of a system similar to that of FIG. 1A embodying certain features of the present invention. 
     FIGS. 3A and 3B are cross-sectional views similar to FIGS. 2A and 2B of a system similar to that of FIG. 1A embodying other features of the present invention. 
     FIGS. 4A-4B are cross-sectional views similar to FIGS. 2A-2B and  3 A- 3 B of a system similar to that of FIG. 1A embodying still other features of the present invention. 
     FIG. 4C is a diagrammatic top view of a portion of FIG.  4 A. 
     FIG. 5 is a perspective view of a system similar to that of FIG. 1A illustrating yet other features 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 a 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  11   c.  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. 
     One aspect of the present invention is embodied in the system  100  illustrated in FIGS. 2A and 2B. The system  100  is similar to debris removal systems  10  of FIG. 1, particularly to version  10   a  and  10   c  thereof, which are illustrated in FIGS. 1A and 1C, but the features of the invention are adaptable to other versions of the system  10 . As illustrated in FIG. 2A, system  100  includes in-line trap  12  within the subterranean vault  11   a.  The vault  11   a  includes inlet  13  and outlet  14  each respectively connected to conduits  15  and  16  of a storm drain or sewer conduit. Flow through the system  100  is in the direction indicated by the arrow  101 . The trap  12  includes a mesh net  17  that is attached to frame structure  18 . 
     A bypass weir  102  is located above trap  12  to permit continued flow in the event that net  17  of the trap  12  is filled to capacity with debris or otherwise clogged, or in the event that the flow into the inlet  13  becomes greater than can pass through the trap  12 . The weir  102  is a metal screen with large openings therein to allow water that rises to a level above the top of the traps to flow through. The weir  102  is hinged at its upper end  103  to the vault  11   a  so that it can pivot in the downstream direction, illustrated by the arrow  104  in FIG.  2 B. Normally, however, under most overflow conditions, the weir remains in the position shown in FIG. 2A, locked in this position by a shear ring or other shear device  105  at its bottom edge to structure fixed to rails  19  that are provided to hold the traps  12  to the vault  11   a.    
     Under extreme flow conditions, high flow rates of water and large pieces of debris that do not pass through the grate of the weir  102  cause pressure to increase on the weir  102 . The shear ring  105  is designed to provide only limited movement of the weir  102  until forces on the weir  102  exceed a predetermined design threshold, whereupon the shear ring is designed to break, allowing the weir grate  102  to swing open to the position shown in FIG.  2 B. The shear ring  105  is corrosive resistant material consistent with the tensile strength and temperature ranges of operation of the particular installation. 
     Another aspect of the present invention is embodied in the system  200  illustrated in FIGS. 3A and 3B. The system  200  is also similar to debris removal systems  10  of FIG. 1, particularly to version  10   a  thereof illustrated in FIG. 1A, but the features of the invention are adaptable to other versions of the system  10 . As illustrated in FIGS. 3A and 3B, system  200  includes in-line trap  12  within the subterranean vault  11   a.  The vault  11   a  includes inlet  13  and outlet  14  each respectively connected to conduits  15  and  16  of a storm drain or sewer conduit. The trap  12  includes a mesh net  17  that is attached to frame structure  18 . The frame  18  has hooks or eyebolts  210  on the top thereof to facilitate loading and removing of the trap  12  from the vault  11   a  by cables  211  through the doors  22   a  on the top of the vault  11   a.    
     The frame  18  of the trap  12  has on each side thereof one or more rollers or large pins  212 . The pins  212  hold the trap  12  in position in the vault  11   a  and facilitates the guiding of the trap  12  into and out of position in the vault  11   a  by locating the front of the frame  18  in openings in a pair of guide rails  219  that are fixed to the vault  11   a.  Guide rails may also be fixed to the vault  11   a  on opposite sides of the trap  12  to guide the downstream end of the trap  12  into position as it is loaded into the vault  11   a.  These are illustrated as plates  220  integrally formed on the face of the access ladder  221  that is fixed to the vault  11   a  and extends from the bottom thereof to the access doors  22   a.    
     Another aspect of the present invention is embodied in the system  300  illustrated in FIGS. 4A,  4 B and  4 C. The system  300  is similar to debris removal systems  10  of FIG. 1, particularly to version  10   a  thereof illustrated in FIG. 1A, but the features of the invention are adaptable to other versions of the system  10 . As illustrated in FIG. 4A, system  300  includes in-line trap  12  within the subterranean vault  11   a.  The vault  11   a  includes inlet  13  connected to conduit  15  of a storm drain or sewer conduit. Flow through the system  300  is in the direction indicated by the arrow  301 . The trap  12  includes a mesh net  17  that is attached to frame structure  18 . A bypass weir  302  is located above trap  12  to permit continued flow in the event that net  17 of the trap  12  is filled to capacity with debris or otherwise clogged, or in the event that the flow into the inlet  13  becomes greater than can pass through the trap  12 . 
     Under certain conditions, flow through the inlet  13  exerts nonuniform pressure on the trap  12 . This can be due to flow turbulence in the inlet conduit  15  or to flow concentrated at the center of the trap  12 , which can particularly occur when the diameter of the inlet  13  is small. The system  300  is provided with a flow dissipating member  310  attached to the vault  11   a  at the upstream side of the trap  12  inside of the inlet  13 . The flow dissipating member  310  may be fixed to the vault wall or, as illustrated, has a pivotal connection  311  to the vault  11   a  above the top of the inlet  13 , so that, for example, its lower end  312  normally rests on the bottom of the vault  11   a,  as illustrated in FIG.  4 A. Adjacent the lower end  312  of the member  310  is a plow-shaped blade  313  having two flared surfaces  314  that curve outwardly and extend in the downstream direction, as illustrated in FIG.  4 C. The surfaces  314  of the blade  313  deflect the flow of water from the center of the inlet  13 , indicated by the arrow  315 , and spread the flow outwardly and more widely over the area of the inlet of the trap  12 , as illustrated by the arrows  316 . This deflection by the blade  313  enables the member  310  to absorb and dissipate energy in the flow and reduce the velocity of the flow entering the trap  12 . The blade  313  also introduces turbulence in the flow, which absorbs additional energy in the flow. The blade  313  is provided with weights  320  in the downstream face thereof so that the pivoting of the member  310  results in lifting of the blade  313  from the bottom of the vault  11   a  in an amount that is proportional to the energy or velocity of water flowing into the inlet  13 . The weights  320  can be changed, added or removed to calibrate the system  300  at each site to achieve the desired degree of velocity dissipation. 
     The force required to pivot the member  310  and lift the blade  313  is determined by the design shape of the blade  313  plow and the weights  320  on the downstream face of the blade  313 , and is related to the flow velocity and height of the water in the chamber of the vault  11   a.  The design is preferably selected so that the force required to lift the blade  313  increases as the flow velocity and depth of the water increases. This provides a self adjusting characteristic and results in increasing velocity dissipation with increasing height and velocity of flow to achieve a desired downstream velocity level over a range of flow velocities. Additionally, because of the shape of the plow-shaped velocity dissipation element and the way it hangs from the pivot point above the main flow of the water and moves up and down with changed in the velocity, it is self cleaning in that floatables or trash does not stick to become caught on the surface of the plow. 
     A further aspect of the present invention is embodied in the system  400  illustrated in FIG.  5 . The system  400  is also shown in an embodiment similar to debris removal systems  10  of FIG.  1  and particularly to version  10   a  thereof illustrated in FIG.  1 A. As illustrated in FIG. 5, system  400  includes in-line traps  12  within the subterranean vault  11   a  having an inlet  13  and outlet  14  each respectively connected to conduits  15  and  16 . Flow through the system  400  is in the direction indicated by the arrow  401 . The traps  12  each include a mesh net  17  that is attached to frame structure  18 . 
     The system  400  is provided with structure for collecting small settling suspended solids from flowing water both before and after the passing through the traps  12 . This structure includes deep bottom pits  415  and  416  respectively upstream and downstream of the traps  12 . These pits are sized and shaped to generate low flow velocity in water passing over them, allowing suspended solids that are smaller than those collected by the traps to settle in them. The pits  415  and  416  provide this function while adding a minimum of parts to the system  400  and can be easily cleaned. 
     Other applications of the invention can be made. Those skilled in the art will appreciate that the application 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.