Abstract:
A modular filter system for use within a pollution removal structure. The system includes a plurality of modular filters that can be nested together forming a common passageway that passes through all of the nested filters. With normal runoff, the water passes laterally through the filters and enters the common passageway to exit the structure. In the event of a high flow of runoff, an overflow pipe conveys water directly to a downstream storm drain by-passing the filter system. The overflow is created by either: a) allowing the water to rise above the upper surface of the upper modular filter and directly into the common passageway or b) by overflow pipes which connect to a downstream pollution removal structure; or a combination of paths a) and b). By using nested filters, the number of filters nested together can be customized in accordance with the depth of the particular storm drain.

Description:
TECHNICAL FIELD 
   The present invention relates generally to a system for trapping pollution in a structure, and, more particularly, to a system having modular filters that interfit with each other to filter the water passing therethrough. 
   BACKGROUND OF THE INVENTION 
   In a pollution removal structure, there can be a filter that serves to remove pollution from the water as it passes through the storm drain. The filter thereby prevents particulate material and dissolved matter from passing further along the flow of water. At the present, there is normally a single filter that filters the water such that the water enters into and though the sides of the filter and thereafter flows by gravity downwardly through a central passageway to a discharge pipe that directs the water away from the storm drain. 
   One of the difficulties, therefore, in the construction of a pollution removal structure is that the depth of the structure may vary such that the height of the filter that is located in that structure can be uncertain and often the filter is not the proper height for the particular structure. 
   Accordingly, it would be advantageous to have a filter that could be varied in overall height to be adaptable to the depth of a particular pollution removal structure. 
   In addition, filters are typically added horizontally in a large horizontal structure making removal and replacement difficult. A vertically oriented filter would be advantageous for the removal and replacement of filter cartridges on a regular basis. 
   SUMMARY OF THE INVENTION 
   The present invention thus is a filter system that can be used in a pollution removal structure wherein a plurality of modular filters are used that can be nested together to form the overall filter for that structure. 
   Each modular filter has an upper inlet and an outlet with a passageway therebetween, with the upper inlet facing upwardly when the filter is in its as used orientation. The inlets and outlets are located such that they align when one filter is located atop of another filter, that is, the outlet of the upper filter will be automatically aligned with the inlet of the lower filter such that the individual passageways combine to form a common central passageway where water can pass through all of the filters that are stacked together to exit the structure via the discharge pipe. 
   As such, the number of modular filters can be determined and installed according to the depth of the structure so that the height of the overall nested filters will be appropriate to that particular structure. Under the normal flow of runoff water, the water will collect in the structure and pass inwardly through a lateral inlet of the filters to pass through the filter media toward the center of the filters and thereafter be drained into the common central passageway formed in the nested filters. In such manner, the undesirable materials are filtered out. In the event of a large or high flow runoff entering the structure, the water may rise to a predetermined height whereupon the water may directly enter the common central passageway and proceed to be drained through the discharge pipe without being filtered. In a variation of the design, separate overflow pipes could be added to convey the high flows. 
   Accordingly, the present filtering system can operate in its normal filtering mode to remove particulate matter from the runoff water when a normal or low flow of water is passing through the structure whereas if a large or high flow runoff is experienced, the high flow of water will bypass the filtering function and either pass directly through the common central passageway formed by the plurality of nested, modular filter, be conveyed by a separate overflow pipe, or some combination thereof. 
   These and other features of the present invention will become apparent upon review of the following detailed description of the present embodiments of the separation tank, when taken in conjunction with the drawings and the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side cross-sectional view of a storm drain having a filter system of the present invention; 
       FIG. 2  is a top view of the storm drain of  FIG. 1  with a filter system of the present invention; 
       FIG. 3  is a top perspective view of a modular filter of the present invention; and 
       FIG. 4  is a bottom perspective view of a modular filter of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to  FIGS. 1 and 2 , there is shown a side cross-sectional view and a top view respectively, of a pollution removal structure  10  for use with the present invention. As can be seen, the structure  10  is comprised of a circular concrete wall  12  that may be constructed in vertical sections and which receives the storm run-off water. While illustrated as circular, the structure  10  may be of other configurations, including rectangular, oval etc. and can be constructed of other materials such as concrete block, steel or the like. 
   The wall  12  basically encloses and creates a chamber  14  for the run-off water where that water may accumulate over time and be filtered prior to being discharged to a groundwater conveyance system or downstream storm drain. Thus as can be seen, the structure  10  includes a base  16 , which can also be a concrete material and which has an upper surface  18  and a cover  20  that seals the upper opening or upper inlet of the chamber  14 . A discharge pipe  22  passes through the base  16  and carries water from the structure  10  to be discharged into the surrounding ground, leaching field, or downstream storm drain. Although discharge pipe  22  is shown within the base  16 , it is obvious that the filter system can be raised such that discharge pipe  22  sits on the base  16  of the structure  10 . 
   There is also an outlet pipe  24  that communicates with the chamber  14  and which can be used to carry overflow water from chamber  14  to another storm drain. The outlet pipe  24  is preferable located in the vertically upper area of the structure  10 . Additionally, there can be an inlet pipe  26  that can be used to receive water from a storm drain or separator such that the filter can be used either as an inlet to the structure or online anywhere within the storm drain system. The inlet pipe  26  is preferably located in the vertically upper area of the storm drain  10 . An upstream sedimentation system that can be used to feed water to the inlet pipe  26  can be that shown and described in my U.S. Pat. No. 6,951,619, issued Oct. 4, 2005 and the disclosure of that patent is hereby incorporated herein in its entirety. As can be seen in  FIG. 2 , the inlet pipe  26  preferably has a ninety degree bend  28  so that the water entering the chamber  14  will tend to swirl around within that chamber  14 . 
   Another outlet pipe  30  can be provided in communication with the chamber  14  and which is used to divert water from the chamber  14  to another filter system constructed in accordance with the present invention to obtain more recharge volume. As can be seen, the outlet pipe  30  is located intermediate the base  16  and the cover  20  and is preferably in the lower half of the structure  10  but above the base  18  of the structure  10  such that the pipe  30  does not become clogged with sediment. 
   The cover  20  can comprise a frame  36  having a removable grate  34  aligned over the opening  37  in the raised cover  20  if the structure  10  is used as an inlet. If the structure  10  is to be used online with an inlet pipe  26 , the cover  20  can comprise a frame  36  having a removable solid cover  34  aligned over the opening  37  in the cover  20 . The frame and cover/grate can be vertically adjusted using bricks or concrete rings  32  as required to meet the ground surface. 
   Within the interior of chamber, there is a plurality of modular filters including an upper modular filter  38 , a lower modular filter  40  and intermediate modular filters  42 . Each of the modular filters has an upper inlet  44  and an outlet  46  and a passageway  48  extending between the upper inlet  44  and the outlet  46 , (for convenience in  FIG. 1  only the upper inlet  44  of the upper modular filter  38  and the outlet  46  of the lower modular filter  40  and the passageways  48  of those modular filters is identified), it being understood that each of the modular filters  38 ,  40 ,  42  are similarly shaped and the upper inlet and outlet of each is located in a predetermined position such that, when the modular filters  38 ,  40  and  42  are stacked together as shown in  FIG. 1 , the outlet of one modular filter interfits with the upper inlet of the modular filter next below so as to form a common passageway made up of the aggregate of all of the individual passageways  48  of the modular filters  38 ,  40  and  42 . 
   Turning now to  FIGS. 3 and 4 , there is shown top and bottom perspective views of a typical modular filter, such as, for example, the upper modular filter  38 . As can be seen in the exemplary embodiment, the upper modular filter  38  is comprised of a cylindrical body  50  and has an upper surface  52  and a lower surface  54  with the passageway  48  extending between and communicating with the centrally located inlet  44  and outlet  46 . The outlet  46  itself is formed as a cylindrical projection  56  extending outwardly from the cylindrical body  50  and has a reduced diameter with respect to the outer diameter of the cylindrical body  50 . 
   In a similar manner, the inlet  44  is a cylindrical indentation  58  having a diameter that is about the same as the diameter of the outlet  46 , with the outlet  46  being just slightly smaller in order to provide a generally watertight fit when the outlet  46  of one modular filter in interfitted into the inlet  44  of another modular filter. In the embodiment where the modular filters are cylindrical, the inlet and outlet are both preferably formed along the longitudinal axis of the modular filter. 
   As can be seen, while the exemplary embodiment illustrates an embodiment where the inlet has a cylindrical indentation and the outlet has a cylindrical projection, the projection and indentation may be reversed or other configuration of inlets and outlets can be employed, it only being of significance that the outlet of a modular filter that is vertically orientated above another modular filter be in alignment with the inlet of the lower oriented modular filter. 
   The modular filters are constructed of a material that filters the water that can pass laterally inwardly via a lateral inlet through the filter media of the cylindrical body  50  to reach the passageway  48  and that material may be plastic, or other comparable material. As a convenience, there may also be a handle  60  provided at the top of the modular filters to facilitate the handling and installation of the modular filters. Gaskets may be employed on either or both of the surfaces  52  or  54  to further ensure water tightness where the modular filters, connect. 
   Accordingly, the operation of the overall water filter system can now be described. The runoff water from a storm enters structure  10 , grate  34  and opening  37 , and or inlet pipe  26 , to enter the chamber  14 . Under normal runoff, the water will accumulate to some level within the chamber  14  depending upon the flow of the runoff water and that water will proceed laterally inwardly through a lateral inlet in one or more of the modular filters beginning at the lower modular filter  40  and working upwardly to the intermediate modular filters  42 , again, depending upon the level of that water in chamber  14 . The water is thus filtered by the modular filters and passes into the passageway  48  where it proceeds downwardly by gravity to be discharged through the discharge pipe  22 . 
   As can be seen, since all of the passageways  48  of the individual modular filters are aligned to form a common central passageway, the water will proceed to the discharge pipe along the same passageway no matter how many modular filters it passes through. 
   In the event of a large flow runoff, the water can rise to a level such that the water can pass into the inlet  44  of the upper modular filter  38  and that excess water then passes directly through the common central passageway to the discharge pipe  22  thereby bypassing the filtering function. If the passageway  48  is not large enough to convey the required peak flows, an additional standpipe(s) located in chamber  14  can be connected directly to pipe  22  to convey flows to the downstream storm drain system. The height of the vertical standpipe(s) would be below the top filter module  38 . If pipe  22  is connected to a groundwater discharge system, the overflow can be conveyed by pipe  24  to the downstream storm drain system to prevent the discharge of untreated water to groundwater through passageway  48 . 
   By the use of the individual modular filters, the number of filters can vary from storm drain to storm drain, that is, the desired number of modular filters can be installed in the storm drain depending upon the particular depth D of a storm drain. Thus, there may be 2, 3, 4, 5 or a greater number of modular filters that can be stacked together as is appropriate to the depth of the storm drain so that a custom made filter is not needed for each different depth of storm drain. In each instance, no matter how many modular filters are used, they all stack and interfit together such that the outlet of a modular filter communicates directly with the inlet of the next lower modular filter to create a common central passageway to carry the water as described. 
   As such the installation of a water filter system in a storm drain can be readily accomplished by positioning the lower modular filter  40  against the bottom  16  of the structure  10 . As shown in  FIG. 1 , that installation can be accomplished by interfitting the outlet  46  of the lower modular filter  40  into an opening  62  in the bottom  16 . Thereafter, the intermediate modular filters  42  can be nested to the next lower modular filter to build up the filter system to locate the upper modular filter  38  at the desired elevation for the particular storm drain. 
   Those skilled in the art will readily recognize numerous adaptations and modifications which can be made to the water separation tank of the present invention which will result in an improved storm drain filter system, yet all of which will fall within the scope and spirit of the present invention as defined in the following claims. Accordingly, the invention is to be limited only by the following claims and their equivalents.