Patent Publication Number: US-6666974-B2

Title: Subgrate drain basin filter

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not applicable 
     SEQUENCE LISTING 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a filter for use inside storm water inlet basins, beneath perforated covers such as perforated manhole receptacles and catch basins with grates. 
     2. Background-Description of Prior Art 
     Storm water collection systems are located throughout our city streets and parking lots providing flood control and drainage. The storm water needs to be as free as possible from pollutants before it enters our natural water systems such as streams. To ensure that our water sources are protected the handling of storm water is becoming more regulated. In order to meet these concerns, many inventions have been patented that provide an anti pollution support filter insert systems for catch basins and manholes. Most of these inventions are unnecessarily expensive. 
     Caldwell (U.S. Pat. No. 1,310,055) develops a storm water device to strain out large debris such as sticks and leaves and allows them to be broken up before passing down stream or be removed manually. This apparatus is ineffective in separating sand or small particulate such as cigarette filters from the storm water before flowing downstream from the opening. 
     A. Levy (U.S. Pat. No. 1,746,121) and George F. Egan (U.S. Pat. No. 2,102,310) show a receptacle for mounting below a storm water inlet. The large basket is constructed of metal. It is heavy and very complex. This would be very expensive to manufacture. They both require large equipment to install and maintain. 
     F. Lane (U.S. Pat. No. 2,615,526) shows a basket mounted entirely below a catch basin grate. It comprises a rigid metal frame for the basket, which is suspended from rods secured directly to the bottom of the grate. This would be very time consuming and awkward to install. A grate is already heavy and hard to handle. The frame when attached to the grate would be difficult to install without damaging the metal frame. Furthermore, its complexity makes it expensive to manufacture. 
     Oscar S. Arntyr et al. (U.S. Pat. No. 4,419,232) shows a double basket mounted entirely beneath a storm drain opening and grate. The device is unnecessarily complex. The initial top screen basket is unnecessary. It removes pollutants that would have been removed by the below second filter anyway. The second stage basket cannot be serviced or emptied by hand unless the whole frame is removed. The rigid frame cannot be easily adapted to the various sizes of grates or accommodate typical angular distortions. The frame with its descending circumference is unnecessarily complex and expensive to manufacture. There is no provision for a bypass to accommodate high flows or filter failure. 
     Logue, Jr. (U.S. Pat. No. 5,575,923) and John F. Harris et al. (U.S. patent application Ser. No. 09/769,212 Group Art unit 1724) show a basket essentially below the grate of a drain opening. A substantial amount of the apparatus extends above the grate. This can be a traffic hazard, and the apparatus would be vulnerable to wear and vandalism. Apparatus shown in Logue and Harris also do not provide an overflow bypass. Accordingly, during high storm water flows or filter failures these systems would cause water to back up onto the street. 
     Holly S. McDermott (U.S. Pat. No. 6,045,691) shows a receptacle entirely below a storm water inlet with a perforated cover. The receptacle, however, has limited pollutant storage capacity. McDermott discloses as system having four separate baskets, one on each corner, which would required time consuming manual cleaning as they are too small for being serviced by a typical large street vacuuming machine. Further, the fixed frame mounting does not easily adjust to the various distorted angles encountered in many rectangular storm water inlet openings. The drain basins are often out of square or of slightly different measurements than anticipated. The frame is unnecessarily expensive to manufacture. The pollutant sock is small in size and would quickly saturate, thereby becoming ineffective. 
     Accordingly, what is required is a new drain basin filter and accompanying support structure that have none of the above discussed disadvantages. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention solves the aforementioned and other problems by providing a filter with an accompanying support structure that is inexpensive to manufacture, easy to install remove, and simple to service. 
     Other features and advantages of the present invention will become apparent from a consideration of the drawings and ensuing descriptions. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is an exploded view of the components of a preferred embodiment of the invention for use in a rectangular drain basin. 
     FIG. 2 is a top view of a component of the embodiment shown in FIG.  3 . 
     FIG. 3 is an exploded view of the components of another embodiment of the invention for use in a round drain basin. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows an exploded perspective of the invention in relation to its installed position in a typical rectangle inlet basin with a perforated cover  12 . FIG. 2 shows a support structure of the invention for a round inlet basin. FIG. 3 shows an exploded perspective view of the invention and installation arrangement in a round inlet basin beneath a perforated cover. 
     In FIG. 1, a bag assembly  28  comprises a filter basket  16 , two sleeves,  24 , and a pair of drooping loops  14  located at the top peripheral portion of assembly  28 . Sleeves  24  enclose two support members  22 . Filter basket  28  is made of a porous material with hydraulic openings smaller than the pollutants intended to be filtered from the storm water. Bag assembly  28  is preferably made from a polypropylene geotextile fabric. However, this filter may be made of any type of porous materials for example, cotton, burlap, or stainless steel, fiberglass, and aluminum mesh. The filter basket is connected to the support structure by means of sleeves. 
     The support structure comprises support members  22  and bridge  18 . The sleeves  24  receive the support members  22 . The members stretch the sleeves across a portion of the inlet cover support  26 . In most drain basins, the cover support commonly comprises a ledge as shown in the figures. However, other structures have been used as cover supports such as short steels rods or angle irons. The bag assembly&#39;s loops  14  droop lower than the level of the support members, thereby forming overflow bypasses. See FIG.  1 . If overflow bypasses are not required, the remaining basin sides may be equipped with additional support members  22  inserted into additional sleeves  24 . When assembled together, the two support members rest directly on the cover support ledges  26  with the distal ends of support members  22  resting generally in the corners of the basin support ledge  26 . Support ledges  26  are typically about two inches wide. Support members  22  may be comprised of fourteen gage galvanized sheet metal two inches wide and about one inch shorter than the length of ledge  26  on which it rests. The support members  22  are intended to be placed between the cover support ledges  26  and perforated cover  12 . In certain rectangular basins with only a single pair of opposing cover support ledges  26 , a pair of support members  22  lay at a 90-degree angle relative to ledges  26 . The ends of each bar extends onto each of the ledges. If additional strength is required, the support members may be of one-inch galvanized angle iron. The angle iron is notched out back about one and one-half inch on each end so as to rest flat on the two parallel ledges. The ends are then placed on the ledges and in a comer of the basin. Bridges  18  span across the remaining sides of the basin. Bridges  18  may be composed of 18 gage 50-52 aluminum sheet metal. Bridge  18  alternatively could comprise any other suitable metal or fabric. For example, bridge  18  can be made of the same material as filter basket  16 . Bridge  18  could also be attached directly to the basket. In the embodiment shown in FIG. 1, bridge  18  comprises a pair of support flanges  20  and an incline ramp  21 . Bridge  18  may be manufactured by bending a substantially rectangular piece of sheet metal in half, thereby forming a upper half and a lower half, the lower half is notched at each end about 1½ inch to form a pair of support flanges  20 . Support flanges  20 , rest on the top of sleeves  24 , which enclosed support members  22 , in the basin&#39;s corners. The remaining lower half  21  hangs between the two support members  22 and extend into the cavity of filter basket  16 . 
     In the embodiment shown in FIG.  2  and FIG. 3, support members and the bridge have been combined into a unified support structure  200  comprising a bridge portion  218  with incline ramp  240  and support arms  220 . Support structure  200  may be made of of one piece of 14 gage 50-52 aluminum sheet metal. The perimeter of support structure  200  is circular and sized to fit within the inlet opening and rest to on cover support ledge  326 . Support arms  220  separate at  230 . Bag assembly  328  has a substantially circular top opening with a single sleeve  324  having two open ends. Sleeve  324  is mounted on to support structure  200  by inserting support arms  220  into sleeves  324 . Like the embodiment shown in FIG. 1, the filter basket has a loop (not shown) between the two support arms underneath bridge incline ramp  240  to form a bypass channel. Incline ramp  240  is inclined downward covering the loop and extends into the center of the support structure. 
     The invention removes and retains storm water pollutants within a storm water inlet basin. Storm water flows from the street through the perforated cover. Then it flows either across the sleeve, in which the support member is inserted into, or across the bridge. The storm water then flows into the filter basket. The basket&#39;s filter material permits storm water to flow through the filter basket and into the basin chamber while retaining pollutants within the basket&#39;s cavity. 
     The invention is convenient to install. For example in the embodiment of FIG. 1, remove the perforated cover  12  insert two support members  22  into sleeves  24  of bag assembly  28 , lay each sleeve  24  on cover support ledges  26  and replace cover  12 . Where there are only two parallel cover support ledges, instead of one continuous ledge, place the sleeves with support bars inserted therein perpendicular to the two ledges resting the ends of the bars on the ledges in the basin corners. Place the bridges on the two remaining sides of the catch basin by laying bridge support flanges  20  on top of the bars in the basin corners. Incline ramp  21  should extend between the two bars and into the filter basket. Replace cover  12 . The invention is removed in reverse order. 
     Installing the embodiment shown in FIG.  2  and FIG. 3 is also convenient. With incline ramp  240  extending downward, insert one arm  220  into one end of bag sleeve  324  and slide sleeve  324  around and up against the side of bridge  218 . Insert the remaining arm  220  into the other opening of sleeve  324  and move that sleeve around to the other side of the bridge. Lay the assembled apparatus directly on top of support ledge  326 . Replace the cover  312 . 
     Servicing the filters is convenient. They can be either vacuumed or pulled out by hand and emptied. 
     Accordingly, this invention can remove pollutants from storm water within an inlet basin before the water is released down stream from the basin. It is economical to manufacture, install and service. In addition, as mentioned above a variety of filtering media can be used with this invention. 
     The description above should not be construed as limiting the scope of the invention but to merely provide examples of some of the embodiments of this invention. The scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.