Abstract:
An apparatus and method for use in conjunction with box culverts to collect and filter or otherwise treat dirty or polluted storm water runoff or other fluid is disclosed. One or more filter devices with filter media is used in connection with a box culvert. One or more internal bypass assemblies is disposed along a vertical surface in the box culvert. One or more concrete slabs is installed within the box culvert and forms a false floor below the filter devices. The false floor provides an annular space through which fluid can bypass the filter devices and be released to a drainage system.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/681,097 filed on Aug. 8, 2012, which is herein incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to apparatuses and methods for treating or filtering fluids, and more particularly to apparatuses and methods for use in conjunction with box culverts to collect and filter storm water runoff. 
       BACKGROUND OF THE INVENTION 
       [0003]    Impervious surfaces and other urban and suburban landscapes generate a variety of contaminants that can enter storm water, polluting downstream receiving waters. These contaminants can include heavy metals, oils, and greases, organic toxins, as well as trash and debris. In response to tighter guidelines imposed by environmental and regulatory agencies, the control of pollution, silt and sediment found in storm water runoff and other sources of water is receiving ever-increasing attention at all levels of federal, state, and local government. Federal and state agencies have issued mandates and developed guidelines regarding the prevention of non-point source (storm water caused) pollution that require action by governmental entities. These mandates affect the management of water runoff from sources such as storms, slopes, and construction sites. In addition, there are many other laws and regulations in place that restrict the movement or disposal of significant amounts of water. Such laws and regulations have a significant impact on, for example, the ways that states, municipalities, highway authorities and other responsible bodies can drain or otherwise dispose of storm water runoff or other water falling on or passing over highways, roadways, parking lots and the like. 
         [0004]    Typical storm water filtration systems used to reduce pollutant loading in runoff from urban developments include known filter devices housed in a vault configuration. The filter devices capture and retain sediment, oils, metals and other target constituents close the source and reduces the total discharge load. As illustrated in  FIG. 1 , the filter devices can include cylindrical filter cartridges with filter media, housed within upright walls, such as the Perk Filter™ (KriStar Enterprises, Inc.; Santa Rosa, Calif.). A filter device is also described in U.S. Pat. No. 6,241,882, which is entitled “Sump &amp; Filter Device For Drainage Inlets” and is assigned to KriStar Enterprises, Inc. 
         [0005]    Referring to  FIG. 1 , storm water can enter the filtration system via an inlet opening  101  through an outer wall  102  into a first chamber of the vault. The first chamber includes a gallery floor  103  and a floor slab  104  beneath the gallery floor. The storm water then flows through one or more bypass manifold assemblies  105 , past an internal wall  106  that is poured such that it is monolithic with the outer wall or outer walls. The bypass manifold assembly includes an inlet bypass floatable weir  107  at an upper portion that obstructs the flow of gross pollutants in the water. The bypass manifold assembly also includes an inlet bypass manifold weir  108  located at a lower portion that allows fluid to accumulate. During periods of routine flow, storm water moves through the bypass manifold assembly into an adjacent filter chamber, where it is filtered by one or more known devices, such as filter cartridges  109  containing filter media. Filtered flows then move through an outlet opening  110  along an outer wall  111 . During periods of peak flow, storm water is allowed to accumulate in the first chamber until it reaches the height of the lower bypass weir, also called an inlet bypass manifold weir. Bypass flows pass over the weir and are directed to a lower annular space, separate from the chamber with filter media, before the storm water exits the system. Angled brackets support  112  acts as a support frame for the platform on which the filter media rests. Expansion bolts  113  are used to join the angled bracket to the platform. 
         [0006]    Because the vault and the components must be separately constructed, time and effort is required to size and manufacture different vaults and components for different flow capacities. Moreover, the platform on which the filter devices rest must be sized and designed to securely fit these different vault structures. In practice, the filtration capacity is often limited by the size of an individual vault. Installation of the various components in the system may require additional effort, particularly for larger systems with a large number of filter devices and increased treatment capacities. 
         [0007]    Thus, there exists a need for practical and economical storm water filtration methods and apparatuses that can be easily manufactured and installed at a site. There is also a need for a storm water filtration system that can efficiently handle bypass flows during peak events. There is also a need for a storm water filtration system that can be configured to handle different levels of storm water flows. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides more effective methods and apparatuses for filtering and treating polluted or dirty water, such as storm water runoff, using existing box culverts. The invention relies on the support structures in the box culvert to install a “false floor” that supports the filter media and allows filtered flows to pass along the top. The false floor also creates an annular space below to allow for unfiltered bypass flows from the system. 
         [0009]    A conventional box culvert includes a rectangular-shaped drain or pipe that channels water flow under roads, parking lots, railroads, or similar obstructions. Other shapes such as arched, round, circular, or curved culverts are also available. Box culverts are generally available as precast units that can be manufactured before installation. They provide both load bearing strength and structural integrity. Because they are readily available and easily sourced for construction applications, box culverts provide a versatile, structurally strong, and cost effective structure to support storm water filtration systems. Box culverts are available in various standard sizes and known materials, such as precast concrete. Thus, one advantage of the use of a box culvert in the present invention is the ability to use existing structures that are available and manufactured according to standard industry sizes. This allows for ease of manufacture, as well as quicker and more economical installation. 
         [0010]    Another advantage of the present invention is the use of one or more false floors installed in an existing box culvert to provide a separate, alternate path for storm water flow. A false floor is set within the box culvert. It provides a platform or mounting surface on which filter devices may rest. It also creates an annular space beneath the floor through which unfiltered flows moving from the bypass assembly can move. In this way, the false floor separates filtered and unfiltered storm water flowing through the same system. 
         [0011]    Another advantage of the present invention is the flexibility to configure and use additional filter sections in box culverts, as needed for a given site or filtration capacity. Because the box culverts are modular, a plurality of box culverts may be used in different configurations, depending on the needs of a given site or construction project. The system can be expanded to accommodate multiple units. In addition, filter units can be added or removed as needed. 
         [0012]    Another advantage of the present invention is the use of one or more internal bypass assemblies disposed within one or more walls of the inlet section. The internal bypass assembly provides an alternate path for storm water during peak flow events by diverting storm water from a filter section into an annular space below the filter section. 
         [0013]    A further advantage of the present invention is the reduction of the workload required of one more particular filter unit in terms of the amount of sedimentation, silt and pollution that they are required to remove over the course of its life span. These advantages can be accomplished by installing multiple filter banks, such that at least a portion of storm water runoff or other passing fluids can be processed through multiple banks during high flow events. 
         [0014]    Another advantage of the present invention is the ability to retain gross pollutants, such as trash, debris, and coarse sediment, within a filtration system, without impeding peak flow bypass needs. The present invention allows for trash capture through the use of a bypass manifold assembly located within a box culvert. 
         [0015]    Yet another advantage of the present invention is the provision of more effective methods and apparatuses for filtering and treating polluted or dirty water, such as storm water runoff, that passes over highways, roadways, parking lots and the like, such that whatever fluid eventually makes its way into a final drainage infrastructure or destination is likely to be cleaner. This advantage is realized by providing an apparatus and method for processing water runoff or other fluid when such fluid enters a water treatment system. These and other useful objects are achieved by the improved apparatuses and methods disclosed herein. 
         [0016]    One embodiment of the present invention provides an apparatus adapted to cooperatively engage with a box culvert, comprising: an inlet section disposed within a box culvert; at least two outer walls shared with the box culvert; at least one internal bypass assembly disposed within a wall of the inlet section comprising two substantially vertical weirs; at least one filter section in fluid communication with the bypass assembly comprising at least two inner walls and filter media; at least one bottom platform disposed within the box culvert and under at least a portion of the filter section, wherein the space between a lower surface of the platform and an upper surface of the box culvert forms an annular space through which unfiltered fluid is allowed to flow; and an outlet section in fluid communication with the filter section, wherein said outlet section comprises at least two outer walls shared with a box culvert. 
         [0017]    Optionally, the apparatus may comprise an access riser along a top surface of the box culvert, wherein the access riser includes a moveable access cover. The apparatus may further comprise multiple filter sections, wherein a substantially vertical separation plate is disposed between adjacent filter sections. The apparatus may further comprise multiple bottom platforms, wherein a closure plate separates adjacent platforms. The platform of the apparatus may optionally comprise concrete. 
         [0018]    In another embodiment, the present invention provides a method of processing fluid comprising the steps of selecting an inlet of a box culvert; selecting a filter device; coupling said box culvert and said filter device; installing a platform disposed within the box culvert and under the filter device, wherein the surface of the platform rests on a surface of the box culvert; and passing fluid through said box culvert and filter device. The space between a lower surface of the platform and an upper surface of the box culvert forms an alternate route for fluid flow. 
         [0019]    In some embodiments, it is contemplated that the dimensions and structural configurations of the box culvert and filter elements can vary with a range dependent on one or more design factors including but not limited to: desired water volume capacity, desired weight of each modular unit, desired load-bearing tolerance for each unit, desired amount of water flow to be managed, size and structure of overall assembly in which the system is to be used, and/or the desired access space for inspection and maintenance purposes. Other apparatuses, methods, features and advantages of the invention will be apparent to one with skill in the art upon examination of the following figures and detailed description. All such additional apparatuses, methods, features and advantages are included within this description and are encompassed within the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The included drawings are for illustrative purposes and provide examples of possible structures for the disclosed inventive storm water filtration system. These drawings in no way limit any changes in form and detail that may be made to the invention by one skilled in the art without departing from the spirit and scope of the invention. 
           [0021]      FIG. 1  illustrates a side cut-away view of a known filtration system using a vault configuration. 
           [0022]      FIGS. 2A through 2C  illustrate in top plan view, side cut-away view, and end view, respectively, a filtration system using box culverts with five treatment bays, an inlet section, and an outlet section.  FIG. 2D  illustrates in side cut-away view of an embodiment of a bypass assembly shown in  FIGS. 2A through 2C . 
           [0023]      FIG. 3  illustrates a top plan view of an exemplary filtration system with four banks 
           [0024]      FIG. 4  illustrates in side cut-away view of a bank of the filtration system described in  FIG. 3 . 
           [0025]      FIG. 5  illustrates schematically a section placement diagram showing the filter units described in  FIGS. 3 and 4 . 
           [0026]      FIGS. 6A through 6D  provide isometric views of one embodiment of a false floor of the present invention with recesses for four substantially cylindrical filter devices. 
           [0027]      FIGS. 7A through 7D  provide isometric views of another embodiment of a false floor of the present invention with recesses for eight substantially cylindrical filter devices. 
           [0028]      FIGS. 8A through 8D  provide isometric views of a further embodiment of a false floor of the present invention with recesses for sixteen substantially cylindrical filter devices. 
           [0029]      FIGS. 9A through 9D  illustrate one unit, a short end cap, made of standard concrete. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    In the following detailed description, references are made to the accompanying drawings, which form a part of the description and in which are shown, by way of illustration, specific embodiments of the present invention. Although these embodiments are described in sufficient detail to enable one skilled in the art to practice the invention, these examples are not limiting. Other embodiments may be used, and changes may be made without departing from the spirit and scope of the invention. 
         [0031]    One embodiment of the present invention includes a filtration system with multiple filter sections, each section containing filter media that forms a treatment bay for incoming storm water. The filtration system is incorporated into a precast box culvert with a standard industry design. The box culvert is shown as a large pipe structure having a rectangular cross section, but in practice, the box culvert may have any other size and shape common known in the art, such as round, elliptical, circular or curved. 
         [0032]    As shown in  FIGS. 2A through 2C , storm water may enter the system from an inlet, for example, an opening with an entrance pipe  201 , and flow through an inlet section  202 . The ordinary artisan will recognize that all or a portion of the top faces of each box culvert unit (alone or as part of a larger assembly) can be fitted with or easily adapted for fitting with a cover panel, plug, plate, grate, fitting or valve system well known in the art of water management systems. As illustrated, the inlet section includes a bolted and gasketed access cover  203  and access riser  204  with a ladder. The presence of this port allows for inspection, clean-out, monitoring, and maintenance of the inlet section. 
         [0033]    One or more inlet bypass assemblies  205  are located within the inlet section. The bypass assembly includes two substantially vertical weirs. A first weir is located at a lower portion of the assembly and forms a barrier to the flow of storm water entering the inlet section and against which storm water can accumulate. The second weir is behind the first weir, preferably positioned such that the top edge of the second weir is higher than the top edge of the first weir. The first weir can be located in front of the second weir to first capture gross pollutants such as trash or debris. A floatables weir, which can also take the form of a gross pollutant hood, can be optionally located at a top portion of the assembly and at least partially obstructs the passage of trash and floatables to the adjacent chambers. One or more steel plates may be used for or as part of one or more weirs. In addition, one or more pipes or flow thru tubes may be positioned through slots in the weirs to convey fluid to the filter sections. In a preferred embodiment, two flow thru tubes may be incorporated to direct flow in a given bypass assembly. One or multiple bypass assemblies can be positioned within the interior of a box culvert, downstream from the inlet opening. One or multiple bypass assemblies can be placed side by side along a wall in the inlet section. One or more filter sections  206  are placed downstream from the inlet section. An equalization port  207  is placed in the inlet section (and in the outlet section, as well). 
         [0034]    During periods of normal flow, storm water flows from the inlet section through the bypass assembly and toward downstream filtration media, where it is treated using filtration methods known in the art, including filter devices with filter cartridges or perforated sand pipes. In one embodiment, the filter devices may be cylindrical in shape and manufactured from durable polymeric components with a polymer-coated steel support screen and stainless steel hardware. Its base construction allows use with a wide variety of media chose to address site-specific pollutants of concern. Additional access covers  209  and access risers with steps  210  or ladder  211  can be included in the filter sections. The presence of these additional ports allows for inspection, clean-out, monitoring, and maintenance of the filter sections. 
         [0035]    Subsequent filter sections of the system may be built into individual box culverts or culvert segments placed side by side. To connect the segments, tongue and groove joints  212  are sealed with asphalt mastic and non shrink grout on the inside surfaces. An outlet section  208  is located at an end of the filtration system and includes an outlet  213  for storm water to exit the system. 
         [0036]    As shown in  FIG. 2C , the cross section of box culvert may be rectangular in shape. The box culvert has opposing sides and curved haunches  214  at the corners. When positioned along one or more lower corners, the haunches or shoulders of the box culvert provide a load-bearing surface to support a concrete slab that creates a false floor  215 . The false floor may be made of concrete or other suitable materials. It is placed substantially horizontally above the bottom of the box culvert and creates an annular space between the bottom of the false floor and the bottom surface of the box culvert. During periods of routine water flow, storm water moves through the three openings from the bypass assemblies to one or more filter sections for treatment. But during periods of high flow, storm water that has accumulated above the height of the second weir travels from the entrance of the inlet section into the space between the two weirs, bypasses the filter section, and exits through the outlet section or an alternative external bypass structure (such as a separate pipe). 
         [0037]    When multiple filter sections are included, as shown in  FIG. 2A and 2B , stainless steel false floor connector plates  216  can be used to connect false floors placed in adjacent filter segments. 
         [0038]    An embodiment of the bypass assembly is shown in more detail in  FIG. 2D . Under normal flow conditions, storm water from an entrance of the system flows toward the first weir  216  and second weir  217 . The storm water rises to the level of one or more flow thru tubes  218 . A floatables weir  219  is positioned in front of an upper portion of the first weir and captures gross pollutants from the incoming storm water. Storm water—i.e., “low flows”—passes through one or more of the tubes to the filter medium  220 . The floatables weir may be particularly advantageous in a system because allows the use of cartridges in the filter section without protection from floatable debris. During increased flow events, storm water passes over the first weir, into the space between the first and second weirs, and underneath the false floor. In a preferred embodiment, a perforated drain-down feed-thru tube is placed along or near one of the upwardly extending weirs. Because the lowest flow path from the inlet section to either the filter section or the bypass assembly can be above the floor, there is the potential for standing water. The perforated drain-down feed-thru tube allows that water to drain down into the filter section after the rain event has passed. 
         [0039]    The design of the filtration system of the present invention is scalable. Because the box culverts are modular and can be added as needed, the filtration system can be assembled in various configurations to accommodate relatively high fluid flow along a space.  FIG. 3  illustrates one embodiment of the present invention that uses three hundred and sixty-eight (368) filter cartridges, each standing about 18 inches tall. The system includes box culverts with an internal space in the shape of cubes that houses the inlet and filter sections. The box culverts are configured to form four substantially rectangular filter banks,  301 ,  302 ,  303 , and  304 , each receiving storm water from inlet  305 . As a non-limiting example, each bank can be about 55 feet (660 inches) long and 9.33 feet (112 inches) wide. The footprint of the system can be about 55 feet long (660 inches) and 37.33 feet (448 inches) wide. 
         [0040]    Storm water enters through an inlet section  306 . One or more inlet bypass assemblies  307  are located downstream from the entrance of each bank. In a preferred embodiment, three bypass assembles are placed in each of the four banks, providing for a total of twelve bypass assemblies. The inlet sections include equalizing boot couplers,  308  and  309 . During periods of routine flow, storm water moves from the inlet section through the bypass assembly, after which it is filtered by filter cartridges  310  placed in the filter sections  311 . The filtered flows are directed to one or more outlet sections  312 , which also include one or more equalizing boot couplers  313 , and exit the system through an outlet  314  located on one side. False floors disposed within the box culverts under the filter cartridges provide a secondary route for unfiltered bypass flows during period of high storm water flow. Stainless steel connecting plates  315  join false floors from adjacent filter sections. By way of example, a filtration system configured in this way may be designed to handle a treatment flow rate of about 6,624 gallons per minute (14.76 cubic feet per second) and a bypass flow rate of about 15.9 cubic feet per second. 
         [0041]    In this embodiment, storm water enters through a single inlet; filtered and unfiltered exits through a single outlet. However, the system can be configured to accept flow from additional inlets and additional outlets, such as external pipes or other structures. For example, unfiltered bypass flow can be directed to a separate pipe or manifold, from which it would then exit the system. 
         [0042]    Notably, the system of the present invention allows for flexibility in the event that additional capacity is needed after installation. Although the filter banks are shown in the figures to be populated, in practice, some of the filter banks may be left vacant. Plugs, such as stainless steel separation plates or other dividers, can be provided to isolate those unused banks during operation. As the filtration needs of a particular site increases, filter devices with additional media may be added in the previously unused banks, and the plugs can be removed to increase the filtration capacity of a given system. 
         [0043]      FIG. 4  shows an assembled side cut-away view of an installed system, as described in  FIG. 3 . The system is placed on bedding  401  that conforms to American Public Works Association (“APWA”) Standard Specification, Section  306 -1.121, except that the minimum bedding depth shall be 12-inches or greater. Backfill added around the side and top  402 , conforms to APWA Standard Specification, Section  306 -1.121, except that the minimum side backfill width shall be as required to allow sufficient room for compaction but no less than 6-inches and the minimum final backfill depth should be 12-inches. Compacted soil  403  may be placed above the filtration system. 
         [0044]    For cleanout and maintenance, bolted and gasketed access covers  404  may be integrated using field poured concrete collar. The access covers may be lifted to allow for maintenance, clean-out, or monitoring of a filter section. In this way, the filtration system will not be clogged. Additional access risers with steps  405  or a ladder  406  can also be included to facilitate access into and out of a particular unit. 
         [0045]    Between individual filter sections, tongue and groove joints  407  are sealed with asphalt mastic and non-shrink grout on one or more inside surfaces. It is contemplated that in some embodiments, further connecting means or fastening means may be provided for securing the box culverts. For example, wires, plastic ties, fasteners (e.g., screws, rivets, nails, snap-clips, and the like) or adhesive means (e.g., tape, glue, and the like) may be used to secure box culverts.  FIG. 5  is a diagram showing the section placement of the units in each filter bank. 
         [0046]    The present invention uses the haunch or shoulder of the box culvert as a load-bearing surface, to support a false floor. This assembly provides for a more economical design, as available standard precast concrete box culverts may be used. It can also eliminate the need for separate piping and the accompanying hydraulic issues that may arise, as bypass flows can be directly to the annular space under the false floor. 
         [0047]    As shown in more detail in  FIG. 6 , a false floor can be made of one or more slabs of suitable material, such as concrete. The pre-existing structure of the box culvert provides a supporting surface that can be used to support a false floor. At the two ends, the false floor includes top and bottom chamfers located along the shorter top and bottom sides  601  and  602 . Each chamfer is set at about a 45-degree angle to the adjacent face. The angles of the chamfers match those of the corresponding haunches in the box culvert. During installation, the chamfers are aligned with the haunches of the box culvert to slide the false floor so that it rests in within the box culvert. Epoxy can be used to fill in the annular space between the false floor and box culvert to create a seal and prevent leakage. When a system includes multiple false floors, closure plates can be used to fill in the gaps between adjacent false floors. 
         [0048]    The false floor includes one or more cartridge impression forms  603  that create recesses, on which filter cartridges can rest. Threaded insert forms  604  are also included to be used with threaded inserts. Because of it relatively compact size, this false floor with four filter recesses may be placed at an outlet section, next to an outlet pipe. 
         [0049]    Another embodiment of the false floor of the present invention is shown in  FIGS. 7A through 7D . The false floor is made of standard concrete. Chamfers  701  and  702  located at the ends of the false floor can be designed to align with the haunches of a box culvert (not shown). Cartridge impression forms  703  located on the upper surface of the false floor create eight circular indentations on which eight circular filter cartridges can securely rest. Insert forms  704  are located along a side for threaded inserts. A through hole  705  can be placed at the center of the slab to secure the bypass assembly. Four standard lift eyes  706  can be placed along a wall to facilitate transport. This false floor, which includes eight filter recesses, may be placed next to one or more bypass assemblies in an inlet section of a filtration system. 
         [0050]    Yet another embodiment of the false floor with additional filter cartridges is shown in  FIGS. 8A through 8D . Chamfers  801  and  802  located at the ends can be designed to align with the haunches of a box culvert (not shown). Cartridge impression forms  803  located on the surface of false floor create sixteen circular indentations on which sixteen circular filter cartridges can securely rest. Threaded insert forms  804  and  805  are located along two sides for threaded inserts. Through holes  806  and  807  can be placed at the center of the slab to secure one or more bypass assemblies. Four standard lift eyes  808  can be placed alone a wall to facilitate transport. This false floor may span the length, or at least the partial length, of a filter section. 
         [0051]      FIGS. 9A through 9D  shows an embodiment of a short end cap unit that can be installed in a box culvert, for use in the filtration system of the present invention. Installation of this unit can involve a series of concrete pours to secure components of the system. In the first pour, the walls and end slabs  901  are secured. In the second pour, the internal wall  902  is set in place. In the third pour, a gallery wall along the bottom (not shown) can be set. Heavy-duty lift eyes  903  are placed along the side walls to facilitate transport of the systems. The walls surrounding the aperture along a side, which can be offset to form a “stepped can,” may include two layers resulting in outside  904  and inside  905  walls. 
         [0052]    The components of the present filtration system, including the bypass assemblies, false floor, filter sections, and banks can be placed in different positions and configurations to address storm water management needs along different surfaces and around different surface structures. For example, the false floor can be installed along side walls or underneath vertical walls. Different filter media known in the art may be used. In addition, the filtration system may be used alone or in connection with other storm water management devices to increase the capacity and improve processing of storm water. The box culverts may be attached to a retention or detention system for water storage. As a further embodiment, a method of telemetric monitoring can be incorporated into the systems to better manage water flows. 
         [0053]    Although the foregoing invention has been described in detail by way of illustration and example for purposes of clarity and understanding, it will be recognized that the above described invention may be embodied in numerous other specific variations and embodiments without departing from the spirit or essential characteristics of the invention. Certain changes and modifications may be practiced, and it is understood that the invention is not to be limited by the forgoing details, but rather is to be defined by the scope of the appended claims. Various modifications, alternative constructions, design options, changes and equivalents will readily occur to those skilled in the art and may be employed, as suitable, without departing from the true spirit and scope of the invention. Such changes might involve alternative materials, components, structural arrangements, sizes, shapes, forms, functions, operational features or the like.