Abstract:
An over grate filter for covering a grate and filtering storm water runoff is claimed and described. The over grate filter of the invention helps to control the flow of waterborne sediment and pollutants into the storm water grate, and it also serves to reduce the amount of sediment entering drainage systems. The invention may be fabricated from any filtration fabrics, including woven and non-woven fabrics. The selection of the specific filter fabric used in the invention depends on the anticipated storm water flow velocities, the anticipated pollutant volume and the expected maintenance schedule. The over grate filter of the invention may comprise multiple layers of filter material and a supporting inner core that enables the filter to lie flat on the storm water grate, providing improved wear resistance against foot and vehicle traffic and street sweeping activity over the prior art methods for filtering storm water.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS AND INCORPORATION BY REFERENCE 
       [0001]    This non provisional patent application claims benefit of priority to U.S. provisional patent application serial number 62/212,579, titled OVER GRATE FILTER APPARATUS AND METHOD, filed in the United States Patent and Trademark Office on Aug. 31, 2015, which is hereby incorporated in its entirety by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISK 
       [0003]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    The field of the invention relates generally to filters for storm water systems, specifically filter adaptable to fit over or work in conjunction with storm water inlet grates and the like. Such filters generally operate to keep sediment, debris and other unwanted material from entering a storm water drainage system. 
         [0006]    2. Background Art 
         [0007]    Storm water draining from construction sites or major roadways often contains suspended sediments. This may be especially true when rain encounters open soil sheet and runoff occurs. Runoff water can also carry with it debris and a variety of other pollutants such as, for example, metals, hydrocarbons, oils, trash, organic debris and the like. When water containing this unwanted material enters a storm water grate without filtering, it transfers all these pollutants into area waterways where they can disturb ecosystems and negatively affect water quality. This can result in major fines and non-compliance with federal regulations, such as the National Pollutant Discharge Elimination System (NPDES) and the Clean Water act. 
         [0008]    Traditional storm water filtering systems require removal of the grate itself to install a filter, sometimes underneath the grate as a catch basin, and sometimes as an envelope that encompasses the entire grate. Removing a grate from a storm water entry requires significantly more labor, more equipment, less safety, less convenience and less ease of use as compared to installing an over grate filter of the invention. 
         [0009]    In addition, the traditional storm water filtering systems are not designed to introduce treatments into the runoff. Their fasteners are often obtrusive, sometimes made of metal that when broken can damage vehicle tires and street sweeping equipment. Broken metal fasteners have the potential to become road hazards, damaging automobile tires and posing a slipping danger for pedestrians. 
         [0010]    What is needed in the art, therefore, is an effective storm water filtering system that does not require removal of the storm water grate, is easy to install and to remove, allows for providing treatment of water for removal of metals, hydrocarbons and the like and is safe for vehicle tires and pedestrian traffic. 
       BRIEF SUMMARY OF THE INVENTION 
       [0011]    The present over grate filter of the invention comprises an apparatus and method that have one or more of the following features and/or steps, which alone or in any combination may comprise patentable subject matter. 
         [0012]    The present invention overcomes the shortcomings of the prior art in that it provides an over-grate solution for filtering storm water that does not require removal of the storm water grate, is easy to install and to remove, and is safe for vehicle tires and pedestrian traffic. 
         [0013]    In accordance with one embodiment of the present invention, the invention comprises a low-profile filter designed to remove contaminants in storm water or other runoff before they enter a storm water grate. The invention comprises fabric that may be either a woven or non-woven filtration media made from monofilament, slit film, or fiber yarns. It is customizable in size and shape, allowing for such auxiliary mechanisms as extra-absorbent layers to be included. These special layers can serve as a point for the introduction of flocculants, coagulants, extra activated charcoal filters, heavy metal filters and hydrocarbon filters. The over grate filter of the invention may be fabricated in a variety of colors for enhanced visibility as an optional safety feature. 
         [0014]    The invention comprises fasteners that hold the over grate filter firmly to the grate, and these fasteners differ from conventional fasteners in that they are made of soft plastic, nylon, rubber, foam and other materials that are safe for vehicle tire and foot traffic. They are unobtrusive and can be installed securely from above the grate with no special tooling. The fasteners of the invention are designed to receive plastic locking mechanisms to hold the top and bottom pieces together. The filter units extend past the edge of the receiving grate to ensure no bypass of material between the grate and supporting grate structure. 
         [0015]    The present method and device of the invention further overcome the shortcomings of the prior art by performing well when vehicles drive over it. The stabilizing mesh incorporated into the design helps it maintain its shape and integrity and reduces the chances of distortion. This also maintains the filter profile and minimizes fabric stretching, preventing the filter from becoming a trip hazard or getting caught on maintenance equipment. 
         [0016]    In an embodiment, the over grate filter of the invention is a fabric filter designed to cover a grate that receives water runoff. The over grate filter of the invention helps to control the flow of waterborne sediment and pollutants into the storm water grate, and it also serves to reduce the amount of sediment entering drainage systems. The invention may be fabricated from any filtration fabrics, including woven and non-woven fabrics. The selection of the specific filter fabric used in the invention depends on the anticipated storm water flow velocities, the anticipated pollutant volume and the expected maintenance schedule. The over grate filter of the invention may comprise multiple layers of filter material and a support inner core that enables the filter to lie flat on the storm water grate, providing improved wear resistance against foot and vehicle traffic and street sweeping activity over the prior art methods for filtering storm water. Previously available filters tend to tear and to wear quickly due to the action of the stiff polypropylene sweeper bristles that are used in sweeping operations. 
         [0017]    The over grate filter of the invention filters out particulate matter which may be silts, sand, and mid-sized debris such as grass clippings, leaves or trash. The over grate filter of the invention comprises a sediment ridge perimeter extending above a hard surface (i.e., asphalt, concrete roadway) that helps reduce water velocity in order to encourage settling of solids suspended in the water. Solids that are easily conveyed by water flow are then filtered by the layers of filter fabric and metallic mesh. 
         [0018]    The over grate filter of the invention may optionally contain activated carbon, chitosan, flocculants, coagulants, polymers, adsorbents and absorbent media to help reduce pollutants entering the drainage system. Low-profile fasteners and retaining plates secure the filter with a lower retaining plate that drops through the grate from the top (without the need for lifting the grate), and an upper retaining plate on top, attached by plastic locking mechanisms to keep the filter of the invention in place. These easy-to-install fasteners reduce time and labor to install over the systems of the prior art while providing stable, inexpensive and effective holding of the over grate filter of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one or more embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating the preferred embodiments of the invention and are not to be construed as limiting the invention. In the drawings: 
           [0020]      FIG. 1  depicts a cross-sectional view of an embodiment of a storm water grated entry with an over grate filter of the invention installed. 
           [0021]      FIG. 2  depicts a partial perspective view of a storm water grated entry, showing the retaining hardware that holds the over grate filter to an upper surface of the grate. 
           [0022]      FIG. 3  is a top view of a typical storm water grate upon which the over grate filter of the invention is typically installed. 
           [0023]      FIG. 4  is a top view showing a typical arrangement of retaining hardware holding the over grate filter to an upper surface of a storm water grate. 
           [0024]      FIG. 5  is a schematic view of the retaining hardware for holding the over grate filter to an upper surface of the grate. 
           [0025]      FIG. 6  is a photograph of a lower retaining plate, or bottom retainer, of the invention. 
           [0026]      FIG. 7  is a photograph of an upper retaining plate, or top retainer, of the invention. 
           [0027]      FIG. 8  is a photograph of a fastener of the invention being inserted into one of the retaining plates of the invention. 
           [0028]      FIG. 9  is a photograph of a fastener of the invention inserted into one of the lower retaining plates of the invention. 
           [0029]      FIG. 10  is a photograph of a filter of the invention, showing a hole through which a fastener may pass in order to retain the filter to the retaining hardware. 
           [0030]      FIG. 11  is a photograph of a filter of the invention, showing a hole through which a fastener may pass in order to retain the filter to the retaining hardware, and showing a fastener of the invention inserted into one of the lower retaining plates of the invention. 
           [0031]      FIG. 12  is a photograph of a filter of the invention, showing a hole through which a fastener is being passed in order to retain the filter to the retaining hardware, and showing a fastener of the invention inserted into one of the lower retaining plates of the invention. 
           [0032]      FIG. 13  is a photograph of a filter of the invention, showing a hole through which a fastener is being passed in order to retain the filter to the retaining hardware, and showing a fastener of the invention inserted into one of the lower retaining plates of the invention, and showing an upper retaining plate with the fastener protruding therethrough and an upper locking mechanism installed on the fastener. 
           [0033]      FIG. 14  is a photograph of a filter of the invention, showing the fastener of the invention protruding through the filter. 
           [0034]      FIG. 15  is a photograph of a filter of the invention, showing a hole through which a fastener is being passed in order to retain the filter to the retaining hardware, and showing a fastener of the invention inserted into one of the lower retaining plates of the invention, and showing an upper retaining plate with the fastener protruding therethrough and an upper locking mechanism installed on the fastener. 
           [0035]      FIG. 16  is a photograph of a filter of the invention being installed on a storm water grate before the lower retaining plate is inserted into a grate. 
           [0036]      FIG. 17  is a photograph of a filter of the invention being installed on a storm water grate after the lower retaining plate is inserted into a grate. 
           [0037]      FIG. 18  is a photograph of a filter of the invention being installed on a storm water grate after the lower retaining plate is inserted into a grate. 
           [0038]      FIG. 19  is a photograph of a filter of the invention being installed on a storm water grate, after the lower retaining plate is inserted into a grate, and after the fastener and locking mechanism have been tightened and the locking mechanism has been trimmed 
           [0039]      FIG. 20  is a photograph of a filter of the invention being installed on a storm water grate, showing a final, installed condition. 
           [0040]      FIG. 21  depicts a data sheet showing material characteristics of Beltech 4×6 permeable filter fabric material. 
           [0041]      FIG. 22  depicts a data sheet showing material characteristics of LM 2199 permeable filter fabric material. 
           [0042]      FIG. 23  depicts a data sheet showing material characteristics of LM 2404 permeable filter fabric material. 
           [0043]      FIG. 24  depicts a data sheet showing material characteristics of 160N permeable filter fabric material. 
           [0044]      FIG. 25  depicts a data sheet showing material characteristics of FW 300 permeable filter fabric material. 
           [0045]      FIG. 26  depicts a data sheet showing material characteristics of FW 403 permeable filter fabric material. 
           [0046]      FIG. 27  depicts a data sheet showing material characteristics of 140 NL permeable filter fabric material. 
           [0047]      FIG. 28  depicts a data sheet showing material characteristics of 180 N permeable filter fabric material. 
           [0048]      FIG. 29  depicts a data sheet showing material characteristics of FW500 permeable filter fabric material. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0049]    The following documentation provides a detailed description of the invention. 
         [0050]    As referred to herein, “permeable filter fabric” means any water permeable fabric, such as, for example, a non-woven geotextile. As referred to herein, a non-woven geotextile allows water flow there through, including planar water flow. They are commonly known as filter fabrics, although woven monofilament geotextiles can also be referred to as filter fabrics. Typical applications for non-woven geotextiles include aggregate drains, asphalt pavement overlays and erosion control. As an example, such water permeable fabrics may be comprised of 4, 8, 10, or 12 oz. per square yard non-woven geotextile material, Belton 4×6 geotextile, 140NLO geotextile, 160NO geotextile, 180NO geotextile, Filter Mat OC geotextile, FW404 geotextile, FW500 geotextile, FW300 geotextile, FW403 geotextile, LM 2199 geotextile or LM 2404 geotextile polypropylene yarn fabrics, in any combination. Data sheets for these exemplary materials are attached as  FIGS. 21-28 . While these materials are set forth herein as comprising the permeable filter fabric of the invention, it is within the scope of the claimed invention that any fabric may comprise the invention, and any permeable filter fabric may comprise the invention. Thus the scope of the invention is not limited to only those fabrics specifically set forth in  FIGS. 21-29 . Also, the over grate filter of the invention may comprise any one or more different permeable filter fabric materials in any combination; it is therefore not necessary that the entire over grate filter be comprised of a single type of permeable filter fabric material. 
         [0051]    Referring now to  FIGS. 1-5 , an embodiment of the over grate filter of the invention is depicted in various views. Referring specifically to  FIG. 1 , a cross-sectional view of an over grate filter  100  of the invention installed on a great is depicted. Filter  101  is disposed on an upper surface of grate  002  and may be attached and held in place by a retaining assembly comprising lower retaining plate  107 , upper retaining plate  104 , fastener  102 , fastener stop  105  and locking mechanism  103 . Grate  002  may be a typical storm grate as is typically used to cover storm water entrances and the like but may be any similar structure for which it is desired to filter out debris, sediment, particulate matter, and other unwanted matter from a stream of water. Fastener  102  extends from below lower retaining plate  107 , and passes up through the storm water grate  002 , through a hole disposed in the filter  101 , and through upper retaining plate  104 , where it is retained by a locking mechanism  103 . In this manner, filter  101  is attached to an upper surface of storm water grate  002 . As depicted in the figure, there may be a plurality of lower retaining plates  107  in a retaining assembly, and likewise there may be a plurality of upper retaining plates  104  in a retaining assembly. A retaining assembly may comprise any number of upper and lower retaining plates  104  and  107 , respectively. The invention may comprise one or more retaining assemblies for retaining filter  101  to an upper surface of grate  002 . Storm water containing particulate matter, sediments, or other undesired materials may move towards the filter in the direction of arrow A. As storm or other runoff water enters filter  101 , the undesired materials such as particular matter, sediments, debris, or other matter are substantially filtered out of the water by operation of filter  101 , allowing filtered water to pass through the filter, continue through storm water grate  002 , and into the storm water drainage system in the direction of arrow B. In this manner, storm water containing undesired particular matter and the like is filtered by the over grate filter system of the invention  100 . 
         [0052]    Still referring to  FIGS. 1-5 , fastener stop  105  operates to prevent fastener  102  from pulling through lower retaining plate  107 . Lower retaining plate  107  prizes and opening for accepting fastener  102  and allowing it to pass there through. Fastener stop  105  may be for example in a mechanical device attached to a lower end of fastener  102  that prevents fastener  102  from pulling completely through the opening in lower retaining plate  107 . Fastener  102  is any fastener known in the art. Fastener  102  may, in a preferred embodiment, be a heavy duty zip tie. A zip tie is typically fabricated of nylon or some other plastic material, and has a flexible tape section with teeth that engage with a pawl in the head to form a ratchet so that as the free end of the tape section is pulled the tie-wrap tightens. In the embodiments of the invention in which fastener  102  is a zip tie, fastener stop  105  may be the head of fastener  102 , and locking mechanism  103  may be the head of another zip tie that has been trimmed, with the head installed on the upper end of fastener  102 . This embodiment of the retaining assembly of the invention is depicted in  FIGS. 9 through 19 . 
         [0053]    Still referring to  FIGS. 1-5 , filter  101  may comprise any type of fabric, and any combination of layers of fabric, in any number, as may be desired by a user to establish a particular filtration effect. Factors to be considered in the selection of permeable filter fabrics to be used, and the number of layers to be used to comprise filter  101 , include the velocity of the expected storm water containing particulate matter and the anticipated level of sediment, debris, or other unwanted material to be filtered. Typically, filter  101  may be comprised of at least one layer of permeable filter fabric. Other types of fabric, including both woven and non-woven fabrics, in any number of layers or combinations of layers, may comprise filter  101 . Furthermore, filter  101  may comprise a structural support member which may be, for example, a mesh material contained between the fabric layers of the filter. The mesh material may be fabricated from metal, plastic or any other material suitable for the anticipated application. 
         [0054]    Still referring to  FIGS. 1-5 , a method for assembling an over grate filter of the invention  100  and assembling it onto an upper surface of a storm water grate may be described as follows. First, fastener  102  is inserted through at least one lower retaining plate  107  until it is prevented from pulling further through lower retaining plate  107  by operation of fastener stop  105 . This step is repeated for each of the retaining assemblies to be utilized in the installation. Next, lower retaining plate  107  for each retaining assembly is canted at an angle and inserted through opening  003  in grate  002  at the desired locations where it is intended for retaining assemblies to be disposed. A typical pattern for location of retaining assemblies is depicted in  FIG. 4  which, as an example only, depicts an installation comprising eight retaining plate assemblies. The retaining plate assemblies of the invention may be of any number and at any location is desired by user, based upon the anticipated volume and velocity of anticipated storm water runoff. Next, after lower retaining plates  107  are inserted through opening  003  in grate  002 , fasteners  102  are motivated through openings in filter  101 , and are continued to be motivated through at least one upper retaining plate  102  as depicted in  FIG. 1  and  FIG. 5 . Finally, locking mechanisms  103  are installed on the upper end of fastener  102  for all retaining plate assemblies, and locking mechanisms  103  are snugged down onto an upper surface of upper retaining plate  104 . The over grate filter of the invention  100  is then ready for use and will be retained in place by at least one, but preferably a plurality, of retaining plate assemblies as depicted in the figures. 
         [0055]    Referring now to  FIGS. 9-20 , the assembly process hereinbefore described is depicted in photographs in a typical but not limiting installation.  FIG. 8  is a photograph of a fastener of the invention being inserted into one of the retaining plates of the invention.  FIG. 9  is a photograph of a fastener of the invention inserted into one of the lower retaining plates of the invention.  FIG. 10  is a photograph of a filter of the invention, showing a hole through which a fastener may pass in order to retain the filter to the retaining hardware.  FIG. 11  is a photograph of a filter of the invention, showing a hole through which a fastener may pass in order to retain the filter to the retaining hardware, and showing a fastener of the invention inserted into one of the lower retaining plates of the invention.  FIG. 12  is a photograph of a filter of the invention, showing a hole through which a fastener is being passed in order to retain the filter to the retaining hardware, and showing a fastener of the invention inserted into one of the lower retaining plates of the invention.  FIG. 13  is a photograph of a filter of the invention, showing a hole through which a fastener is being passed in order to retain the filter to the retaining hardware, and showing a fastener of the invention inserted into one of the lower retaining plates of the invention, and showing an upper retaining plate with the fastener protruding therethrough and an upper locking mechanism installed on the fastener.  FIG. 14  is a photograph of a filter of the invention, showing the fastener of the invention protruding through the filter.  FIG. 15  is a photograph of a filter of the invention, showing a hole through which a fastener is being passed in order to retain the filter to the retaining hardware, and showing a fastener of the invention inserted into one of the lower retaining plates of the invention, and showing an upper retaining plate with the fastener protruding therethrough and an upper locking mechanism installed on the fastener.  FIG. 16  is a photograph of a filter of the invention being installed on a storm water grate before the lower retaining plate is inserted into a grate.  FIG. 17  is a photograph of a filter of the invention being installed on a storm water grate after the lower retaining plate is inserted into a grate.  FIG. 18  is a photograph of a filter of the invention being installed on a storm water grate after the lower retaining plate is inserted into a grate.  FIG. 19  is a photograph of a filter of the invention being installed on a storm water grate, after the lower retaining plate is inserted into a grate, and after the fastener and locking mechanism have been tightened and the locking mechanism has been trimmed 
         [0056]      FIGS. 21-29  depict data sheets describing various characteristics of permeable filter fabrics that may comprise filter  101  of the invention. The scope of the invention is not limited to the specific permeable filter fabrics depicted in the figures; rather, the physical characteristics of the filter fabrics depicted in the figures are exemplary parameters for filter fabrics that may comprise filter  101 . Filter  101  may comprise fabric layers other than permeable filter fabrics as described in the figures. Furthermore, filter  101  may comprise any number of permeable filter fabric layers, or other layers of fabric, as may be desired by the user. 
         [0057]    Although a detailed description as provided in the attachments contains many specifics for the purposes of illustration, anyone of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the following preferred embodiments of the invention are set forth without any loss of generality to, and without imposing limitations upon, the claimed invention. Thus the scope of the invention should be determined by the appended claims and their legal equivalents, and not merely by the preferred examples or embodiments given.