Abstract:
An insert for use in a drain basin, comprising an outer wall defining a periphery of the insert and having a top edge and a bottom edge. A perforated bottom surface extends across the lower periphery of the insert. A filter, resting on the perforated bottom surface, has a peripheral edge enclosing a central portion. A flange extends inwardly from the top edge of the outer wall past the peripheral edge of the filter. The flange directs drainage water past the periphery of the filter and to its more central portion, whereupon impurities within the drainage water are extracted and filtered water exits through the perforated bottom surface into the drain basin. In a preferred embodiment of the invention, the inward-extending flanges are angled downward toward the filter. In a second embodiment, the filter, bottom surface and inward-extending flanges are arranged in a cartridge, which is removably placed inside the periphery of the outer wall.

Description:
BACKGROUND OF THE INVENTION 
     This application relates generally to drainage structures and associated hardware, and more specifically to an improved contaminant-absorbing filter insert system for use in connection with new or existing water drainage inlets to collect drainage water contaminants such as hydrocarbons and the like while permitting the undisturbed passage of the water. 
     Drainage structures such as drain inlets for sidewalks, roads and parking lots are well known and in widespread use. Such structures generally provide a path for the removal of rainwater, irrigation water, or the like that would otherwise accumulate on the ground surface. Water thus drained from the surface by these structures is usually carried to a lake, stream or other body of water. Over time, undesirable and sometimes harmful chemical materials, e.g., oil, fuel, antifreeze and the like, collect on the ground surface and can be transported by the drainage system to contaminate these bodies of water. 
     Drainage structures are also commonly used in indoor facilities, including automotive service areas, parking structures, industrial shops, restaurants, and residential basements and garages. Hydrocarbons and other chemicals are often deposited on the ground during commercial activities at, for example, automotive service and industrial facilities. To a lesser extent, contaminants accumulate on the ground in residential as well as commercial parking structures. Upon surface cleaning, these chemicals are subsequently transported along with the drainage water as with street or parking lot drains. Unless filtered out of the drainage water, contaminating material is carried with the drainage water to the ultimate drainage location. 
     Prior art filtering devices extract contaminants through the placement of an insert into a storm basin. For example, the Barella device (U.S. Pat. No. 5,720,574) is a square trough-shaped filter insert device for placement into a storm drain basin. Filtration material is placed above a perforated bottom surface of the trough. Run-off water contacts the filtration material; contaminants are filtered out and the filtered water passes through the perforated bottom surface and through to the remainder of the water-directing system. However, some of the drainage water is able to enter the device and pass down its outer wall and through the perforated bottom surface, such that it avoids substantial contact with the filter means and thereby escapes filtration. 
     Accordingly, a need exists for a greater degree of filtration of hydrocarbons and other contaminants from drainage water, preventing environmental damage while facilitating the economical and functionally efficient drainage of run-off waters. 
     SUMMARY OF THE INVENTION 
     The contaminant-absorbing catch basin filter insert system of this invention provides an improved structure for use in connection with new or existing water drainage inlets. It enables the collection of contaminants, such as hydrocarbons and the like, while permitting the passage of the drainage water. 
     The insert has an outer wall defining a periphery of the insert and having a top edge and a bottom edge. A perforated bottom surface extends across the lower periphery of the insert. A filter, resting on the perforated bottom surface, has a peripheral edge enclosing a central portion. A flange extends inwardly from the top edge of the outer wall past the peripheral edge of the filter. The flange directs drainage water past the periphery of the filter and to its more central portion, whereupon impurities within the drainage water are extracted and filtered water exits through the perforated bottom surface into the drain basin. In a preferred embodiment of the invention, the inward-extending flanges are angled downward toward the filter. In a second embodiment, the filter, bottom surface and flanges are arranged in a cartridge, which is removably placed inside the periphery of the outer wall. 
     The foregoing and other objects, features and advantages of the invention will become more readily apparent from the following detailed description of a preferred embodiment of the invention that proceeds with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows an exploded perspective view of the drain basin filter insert system constructed according to the invention installed within a typical storm drain. 
     FIG. 2 shows an exploded perspective view of the drain basin filter insert system constructed according to the invention installed within a typical floor drain. 
     FIG. 3 shows a sectional view of a side elevation of the drain basin filter insert of FIG.  1 . 
     FIG. 4 shows a sectional view of an alternative embodiment of the invention, in which the inner flanges are angled downward toward the filter means and the bottom perforated surface is concave. 
     FIG. 5 shows an exploded perspective view of a second embodiment of the present invention of FIG. 2, in which the drain basin filter insert system includes an outer frame and a filter cartridge. 
     FIG. 6 shows a sectional view of side elevation of an alternative cartridge embodiment of the filter insert system of FIG. 5, in which the filter cartridge inner flanges have been angled inward toward the filter means. 
    
    
     DETAILED DESCRIPTION 
     The filter insert system  100  according to the present invention is shown generally in exploded view in FIG.  1 . The invention is designed to be placed into a storm drain or floor drain basin. A typical storm drain is comprised of a drain basin  102  having a mouth  104  and an exit aperture  106  communicating with the remainder of the water drainage system (not shown). A grate  108  covers the basin mouth  104  and is commonly maintained at substantially ground surface level  110 . The grate or screen  108  is supported within the basin by a recessed peripheral ledge  112 . In most cases, the grate  108  covers the mouth  104  of the drain to prevent debris from entering and being carried through or clogging the drain basin or exit aperture  106 . A floor drain (see, e.g., FIG.  2 ), commonly circular or rectangular, possesses a similar structure but is generally constructed for lower-demand use conditions. The inventive filter insert system can be manufactured to fit the various sizes and shapes of rectangular and circular water drainage inlets but is not limited thereto. 
     The filter insert  100  includes an outer wall portion  114  and preferably includes a peripheral support means for positioning the device below surface level in a drain basin. The means may include, as illustrated, a set of perpendicular support flanges or lips  116  (“support flanges”) attached to and projecting outward from the top edge  302  (FIG. 3) of at least two of the outer walls  114 . When installed in a storm drain basin  102 , the support flanges  116  rest on the basin&#39;s recessed ledge  112 . A ground-level grate  108  would, in most applications, rest on the support flanges  116 . Alternatively, the system can be implemented without support flanges, for use in drain inlets that do not have grate-bearing surfaces  112 . In these installations, the outer walls  114  of the filter system can be directly secured to the inside walls  118  of the inlet structure using clips, bolts, or an equivalent fastening method. Alternatively, the filter system can be positioned in such inlets by using a mechanical support placed below the inserted system in the basin. 
     FIG. 2 shows an embodiment of the present invention as used in a circular drain of the type commonly found in indoor installations, such as in residential basement or commercial automotive service area floors. Typically, the basin mouth  104  and exit aperture  106  are smaller than the corresponding elements of a storm or other street drain basin. The embodiment as depicted has a circular outer wall  114  and peripheral support means in the form of support flanges  116 . The support flanges  116 , when employed as the peripheral support means, rest on the grate-bearing surfaces  112  of the drain basin  102  and under the surface-level grate  108 . 
     FIG. 3 shows in greater detail the structural elements of the present invention. A bottom surface  304 , of mesh or other perforate construction, is positioned substantially in a plane defined by the lower edges  306  of the outer walls  114 . The bottom surface  304  may be directly attached to the to the outer wall  114 . Alternatively, tabs  305  or other support flanges may be employed to position the bottom surface  304 . Together, the outer walls and perforated bottom surface define a chamber  308  into which a filter means  310  is removably placed. The filter means  310  may be a quantity of loose filter material or a filter medium-filled fluid-permeable “sock” or “pillow”. Loose filter media material may be covered with a media restrainer such as a screen or bracket (not shown), which would be placed above the filter means  310 . Such media restrainers are known to and used by those skilled in the art. 
     A third set of flanges  312  (“inner flanges”) project inward above and over the periphery  314  of the filter means  310 . At least part of each inner flange  312  rests in essentially the same plane as that defined by the top edge  302  of the outer wall portion  114 . The inner flanges  312  direct draining water directly onto and toward the center (shown by the bracketed more central portion  316 ) of the filter means  310 . This improvement over the prior art results in a greater percentage of the water flowing over flange  112  as along the arrow  317  and contacting the filter means  310  and increases the efficacy of the contaminant filtration. 
     FIG. 4 shows an alternative embodiment of the present invention in which the inner flanges  312  are slanted downward out of the plane of ground level and toward the filter means. The sloping inner flanges  312  improve the guidance of drainage water into the drain insert  100  and, more specifically, into direct contact with the filter means  310 . The enhancement in drain water guidance results in more optimal filtration and increased efficiency of the device over the prior art. For example, in the Barella &#39;574 device as practiced with a filter medium-filled “sock”, water can flow into the device and directly along its outer walls to the perforated bottom surface, bypassing the filter means. By contrast, the inward-projecting flanges  312  of the present invention direct drainage water medial of the outer walls  114  as along path  317  so that it falls onto the more central portion  316  of the filter means  310  in the chamber  308  of the inventive apparatus. This inward water guidance reduces bypass of the filtering means and improves the degree of drainage water filtration over the previous art. It has been found that angling the inner flanges  312  downward maximizes this water-guiding effect. The effect of this angling is realized with flange deflections of as little as about 5 degrees. As the inner flanges  312  approach vertical, the guidance of water onto the central portion of the filter means  310  diminishes. The maximum downward angle which provides useful inward water guidance is about 60 degrees. By directing water onto the centralmost portion  316  of the filter means  310  and preventing water from avoiding the filter means  310 , the present invention maximizes the percentage of water filtered and decreases the amount of contaminating materials delivered by the drainage water to downstream drainage locations. 
     The perforated bottom surface  304  is, in this alternative embodiment according to the present invention, of a concave shape. Concavity of the bottom surface  304  increases the volume of filtering media  310  which can be placed in the insert device. Enlarging the volume of filter media  310  improves the filtration of drainage water and increases the time period between filter means replacements. Further, a concave bottom perforated surface results in the filter media having a greater depth in the central portion  316  than at its periphery  314 . Water directed by the inner flanges toward the central portion of the filter media must pass through this thicker portion of filter media, thereby enhancing filtration. 
     By overhanging the periphery of the filter means  310 , drainage water is guided, as indicated by the black arrows  317 , onto the more central portion  316  of the filter means  310  rather than its periphery  314 . The beneficial action of the inner flanges  312  is to prevent drainage water from running down the outer walls  114 , passing through the insert  100  and drain basin  102  while avoiding the filter means  310 . Enhanced downward and central guidance of drainage water is represented in FIG. 4, in which the inner flanges  312  are shown angled downward toward the filter means  310  at approximately 45 degrees. This slope permits better collection of drainage water down and into the basin insert. At the same time, the sloped inner flanges  312  still guide the water toward the center portion  316  and away from the periphery  314  of the filter means  310 , preventing water from following the outer walls  114  and failing to contact the filter means  310 . 
     The filter insert system is installed into a drain basin by removing the inlet grate and lacing the filter system inside of the basin, with the support flange resting on the bearing surfaces or grate seat that typically exist along the top edge of the basin. The support flanges, if present, are sized to the proper width of the grate seat but may be modified if necessary for the installation. As noted previously, the insert may alternative be supported within the basin using fastening means. The filter insert system is installed on the inside surface of a drainage structure so that drainage water that would normally flow directly through the drainage structure is caused instead to flow through the filtration element. Undesirable and toxic materials, that may otherwise be carried in the water, are removed while permitting the water itself to pass through to the ultimate drainage location. 
     Where the invention has thus far been described as comprising a unitary insert with a removable filter means, an alternative embodiment  500  implements an insert device of two pieces, an insert frame and a filter cartridge. FIG. 5 shows an exploded perspective view of this embodiment according to the invention. The outer wall portion  114  and peripheral support means  116  (here, support flanges) are arranged in a basin insert frame  501 . The second piece of the embodiment is a removable filter cartridge  502  comprising a perforated bottom surface  304  (FIG.  6 ), inner flanges  312 , and filter means  310  (FIG.  6 ), as described previously. A second peripheral wall  514  and perforated upper surface  504  combine with the perforated bottom surface  304  to form the interior of the cartridge chamber  608  (FIG.  6 ). A filter means  310  is housed within the cartridge chamber. The filter cartridge  502  is sized to fit closely into the basin insert frame  501 . The insert frame  501  provides tabs or flanges  605  to position and support the filter cartridge  502 . 
     FIG. 6 shows the same cartridge embodiment, further utilizing the angled inner flange feature. The perforated upper surface  504  is shown in the plane of the medial edge  602  of the inner flange  312 ; the upper surface  504  could alternatively be placed higher than this plane without affecting the function of the filter insert device  100 . 
     The cartridge in FIG. 5 is illustrated with a particular orientation; as a substitute, the filter cartridge  502  can be arranged with inner flanges  312  on both its faces (FIG.  6 ). If so constructed, the filter cartridge  502  may be placed in the basin insert frame  501  with either surface acting as the upper surface. Inner flanges  312  would be arranged and function as described in the embodiments of FIGS. 3 and 4. An improvement of this embodiment is that employment of a cartridge provides filter means replaceability without the need to directly handle the filter means. Constructing the cartridge with inner flanges on both upper and bottom surfaces obviates its orientation in the basin insert frame and simplifies the installation of the present invention. 
     The filter insert system of the present invention can be made of many suitable materials, such as sheet metal. Alternatively, portions of the filter insert system (such as the cartridge of the embodiment described in FIGS. 5 and 6) can be constructed of polyethylene or similar high density synthetic materials. Such materials are currently known to and used by those skilled in the art. Selection of different materials allows for adaptation of the system to specific uses based on criteria such as strength, cost, suitability in various disposability schemes, and exposure and resistance to specific chemicals. 
     The filtration element material is preferably an approved collecting agent but can alternatively be any other filter medium which retains contaminants—i.e., oil, antifreeze, fuel, solvents or the like—while allowing water to flow through more or less directly. Specific filter media compositions are well-known to persons skilled in that art. For example, polypropylene strips, an inert inorganic blend of amorphous siliceous material containing sodium, potassium and aluminum silicates, in variable composition, and particulate perlite (U.S. Pat. No. 5,632,889) have been shown to be effective. The filter media is placed in the bottom of the trough, above the perforations in the trough, and can be retained there if necessary with clips or other retaining mechanisms to keep the filter from floating or otherwise moving. The filter media may be replaced on a periodic or otherwise as needed. 
     The filtration element is placed in the bottom of the insert, above the perforated bottom surface and can be immobilized if necessary with an upper perforated surface, by clips or using equivalent retaining mechanisms. The filter means may be replaced as necessary, to regenerate maximum filtration using the original insert device structure. 
     A person skilled in the art will be able to practice the present invention in view of the present description, where numerous details have been set forth in order to provide a more thorough understanding of the invention. In other instances, well-known features have not been described in detail in order not to obscure unnecessarily the invention. 
     Having described and illustrated the principles of the invention in a preferred embodiment thereof, it should be apparent that the invention can be modified in arrangement and detail without departing from such principles. We claim all modifications and variations coming within the spirit and scope of the following claims.