Abstract:
A stormwater receiving assembly for processing stormwater containing suspended particulate matter includes a dispensing chamber and an underlying accumulating accessory. The dispensing chamber is fabricated of thin-walled plastic contoured as a corrugated wall horizontally elongated between inlet and exit ends and having an arched cross-sectional shape with upwardly directed peak and spaced apart parallel lowermost edge extremities defining an open bottom. A circular portal is located in the peak of the chamber. The accumulating accessory has a compartment bounded by sidewall structure elongated upon a vertical axis between upper and lower extremities, and is positioned below the dispensing chamber such that the portal of the dispensing chamber is in centered vertical alignment with the lower extremity of the compartment of the accumulating accessory.

Description:
RELATED APPLICATIONS 
     This Application is a Continuation-in-Part of U.S. patent application Ser. No. 09/836,595, filed Apr. 18, 2001, now U.S. Pat. No. 6,612,777. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the management of stormwater runoff, and more particularly concerns devices which minimize and facilitate sediment maintenance, expand the storage capacity of stormwater management systems, and facilitate the infiltration of stormwater into the surrounding substrate. 
     2. Description of the Prior Art 
     Culverts, catch basins, and storm sewers are the common practices for collecting and conveying stormwater runoff. In some instances such water is discharged directly into the nearest available water body despite the potentially adverse environmental effects of such action. In some other instances, stormwater management facilities are constructed to help manage the quantity and quality of the stormwater. Wet or dry retention or detention basins/ponds represent the most common structural approach to stormwater management. Although more environmentally sound than direct discharge into an existing body of water, such stormwater management approaches preclude other uses of the land. This is of particular importance where land values are high and/or space is limited. The open ponds may also be undesirable in locations near airports because of birds attracted by the pond, or in locations where health, liability or aesthetic considerations make them undesirable. Even the use of “dry” detention basins frequently results in the same type of problems associated with wet ponds. Without proper maintenance, dry detention basins frequently transform into wet ponds. 
     Underground systems have also been developed to help manage stormwater effluent. Such systems include the use of plastic arch-shaped, open bottom stormwater chambers arranged end-to-end in rows. However, all current underground stormwater management systems are limited by the amount of area available for their installation. This is particularly relevant to the plastic stormwater chambers. The largest plastic chamber currently on the market has an arched cross-sectional area of 34 inches high by 60 inches wide and a length of eight and one half feet. The creation of larger chambers is limited by the forming capacity of molding machinery. 
     In a typical installation of plastic stormwater chambers, elongated hollow plastic chambers are emplaced in the ground to form a leaching field for receiving stormwater and dispensing the water into the surrounding earth. Such chambers have a central cavity for receiving inflow water. An open bottom, and apertures optionally located in the sides of the chambers provide the means whereby the water is allowed to exit the central cavity and disperse into the surrounding earth. The chambers are usually attached endwise to form long rows extending in side-by-side juxtaposition and seated upon a crushed rock substrate in a multi-row array that constitutes a leaching field. The stormwater is generally conducted to the array of rows by a large diameter manifolded pipe system that runs orthogonally to the rows closely adjacent one extremity thereof. 
     Examples of stormwater dispensing chambers are disclosed in U.S. Pat. Nos. 5,017,041; 5,156,488; 5,336,017; 5,401,116; 5,441,363; 5,556,231 and 6,361,248. 
     Stormwater typically carries considerable amounts of suspended particulate material, commonly referred to as Total Suspended Solids (TSS), which eventually settles out as sediment within the stormwater management system. The accumulation of such sediment adversely affects the storage capacity of stormwater management facilities, decreasing their effective life. The effective life of such facilities can be significantly extended with a maintenance program for sediment removal. Such sediment removal can generally be achieved by a vacuuming operation conducted by a suitably equipped truck. In such operation, a tube is extended from the truck through a manhole, through an associated riser pipe, and into the bottom of the chamber. The sediment in the bottom of the chamber is then removed by vacuuming. 
     Unfortunately, the maintenance of stormwater management systems is typically neglected, and typically occurs only when the system fails or sediment accumulates to a point where flooding occurs because of diminished storage capacity of the system. This problem has become so serious that some municipalities have imposed a stormwater maintenance “fee” on property owners to help pay for private-sector stormwater facility maintenance. 
     Unlike stormwater wet and dry ponds, which are readily observable and accessible, removal of sediment from underground stormwater management facilities has historically been inherently more inconvenient and costly, resulting in resistance to their use by some municipalities. Some types of underground stormwater management facilities even have to be replaced in order to remove accumulated sediment. 
     It is accordingly an object of the present invention to improve the sediment handling capacity of an underground stormwater management system. 
     It is another object of this invention to provide an accumulating accessory interactive with a plastic stormwater dispensing chamber to increase the sediment handling capacity of an underground stormwater management system comprised of said chambers. 
     It is a further object of the present invention to provide a plastic stormwater dispensing chamber combined with an accumulating accessory in a manner to facilitate removal of accumulated sediment. 
     It is yet another object of this invention to provide a combined stormwater dispensing chamber and accumulating accessory of the aforesaid nature of durable, simple construction amenable to low cost fabrication and installation. 
     These objects and other objects and advantages of the invention will be apparent from the following description. 
     SUMMARY OF THE INVENTION 
     The above and other beneficial objects and advantages are accomplished in accordance with the present invention by a stormwater receiving assembly comprised of an accumulating accessory interactive with a stormwater dispensing chamber comprised of a plastic wall elongated between inlet and exit ends and having an arched cross-sectional shape with upwardly directed peak and spaced apart parallel lowermost edge extremities defining an open bottom, said wall having clean out portal means in said peak. 
     The accumulating accessory is comprised of a compartment bounded by sidewall structure elongated upon a vertical axis between upper and lower extremities, said upper extremity being open and having a perimeter disposed in a plane orthogonal to said axis. 
     The accumulating accessory is operatively positioned below said dispensing chamber in a manner such that the clean out portal means of the chamber is in centered vertical alignment with the lower extremity of said compartment. 
     In preferred embodiments, the sidewall structure of the compartment of the accumulating accessory is downwardly convergent toward its lower extremity which is closed by way of a bottom panel. The sidewall structure may be fabricated of four flat panels joined in an inverted pyramidal configuration having a rectangular upper extremity, and said panels may have apertures to permit water drainage. The size and configuration of said upper extremity is preferably such as to support the edge extremities of the overlying chamber. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing forming a part of this specification and in which similar numerals of reference indicate corresponding parts in all the figures of the drawing: 
     FIG. 1 is a top and side perspective view of an embodiment of the accumulating accessory useful in the stormwater receiving assembly of the present invention. 
     FIG. 2 is a top and side perspective view of an embodiment of the stormwater receiving assembly of this invention. 
     FIG. 3 is a schematic top and side perspective view of the embodiment of FIG. 2 shown in functional association with a suction tube that removes accumulated sediment. 
     FIG. 4 is a top view of the assembly of FIG. 2 with the chamber component shown in phantom outline so as to reveal underlying features. 
     FIG. 5 is a side view of the assembly of FIG. 2 shown in schematic functional association with components of a stormwater leaching field. 
     FIG. 6 is a plan view of a stormwater leaching field incorporating the stormwater receiving assembly of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 2, an embodiment of the stormwater receiving assembly of this invention is shown comprised of receiving chamber  22  and an accumulating accessory  10  positioned below said chamber. The accumulating accessory exemplified in FIG. 2, as best illustrated in FIG. 1, is shown as a monolithic structure fabricated of polyethylene, polypropylene or equivalent thermoplastic polymer and having a uniform thickness throughout of between 2 and 8 mm. The accumulating accessory is comprised of a compartment  11  having an open upper extremity  12  and closed lower extremity  13 . Said compartment is further defined by sidewall structure  14  which is downwardly convergent upon center vertical axis  15 . The degree of convergence is such that the cross-sectional area of the lower extremity, taken in a plane orthogonal to said axis is 10% to 40% of the cross-sectional area of said open upper extremity. The height of the accumulating accessory, measured between said upper and lower extremities is preferably between 20 and 72 inches. In alternative embodiments, the sidewall structure may be of non-convergent configuration, having a cylindrical or rectangular shape. 
     In the exemplified embodiment, said sidewall structure is comprised of four flat panels  17  disposed in an inverted pyramidal configuration, causing upper extremity  12  to have a rectangular perimeter  19  defined by straight edges  16 . 
     Flat apron panels  18 , emergent from opposed straight edges  16 , are directed outwardly from said compartment within the plane of perimeter  19 . Alignment means in the form of paired retaining lips  20  are emergent from said apron panels and directed upwardly from said compartment. Said retaining lips engage the interior surface of the associated chamber  22  adjacent its lowermost edge  25 , thereby stabilizing the interaction of the chamber with the underlying accumulating accessory and further serving to achieve lateral alignment of said accessory with associated chamber  22 . Additional alignment means, which may be in the form of indicia  66  on apron panels  18  and chamber  22 , facilitate axial alignment of chamber  22  with respect to accessory  10 . Sidewall structure  14  may be provided with a multitude of apertures  21  which facilitate drainage of water from said compartment. The diameter of the apertures may range from ⅛″ to 1″. The total area of said apertures preferably occupies between 1% and 10% of the total area of sidewall structure  14 . 
     FIGS. 2-5 illustrate the manner in which the accumulating accessory  10  is combined with a stormwater dispensing chamber  22  for the purpose of increasing the amount of sediment that the chamber can hold, and also for facilitating the removal of such sediment from the chambers. Chamber  22  is comprised of a wall  23  extending upon a longitudinal axis between inlet and exit ends,  31  and  32 , respectively, and having an arch shape cross-section with an upwardly directed peak  24 , and opposed lowermost spaced apart parallel edges  25  which define an open bottom  26 . Wall  23  has a multiplicity of corrugations  27  disposed in planes orthogonal to edges  25 , thereby causing said wall to have increased compressive strength. Chambers useful in the practice of the present invention are fabricated preferably of polypropylene or high density polyethylene by way of thermal vacuum forming or gas assisted injection molding techniques, generally in accord with the technology described in U.S. Pat. Nos. 5,401,459; 5,087,151; 4,247,515; 4,234,642; 4,136,220 and 4,101,617. During molding, the plastic is configured to form a chamber having outwardly directed hollow ribs or corrugations  27 . The disclosures of the foregoing patents are hereby incorporated by reference. 
     The chamber preferably has opposed axially elongated base panels  29  integral with said edges  25  of wall  23 . Said base panels support the chamber, discouraging its descent into the underlying substrate. 
     The terminal or first rib or corrugation  30  adjacent inlet end  31  may be slightly larger than the multitude of ribs, and terminal rib  33  adjacent exit end  32  is slightly smaller than the multitude of ribs. Such configuration of the terminal ribs facilitates end-to-end joinder of successive chambers wherein vertical lowering of a chamber automatically causes the larger rib of one chamber to embrace the smaller rib of the next successive chamber. 
     Typical chambers of this invention may have a length of 6-12 feet measured between inlet and exit ends and a height up to 50 inches. The width of the chamber, measured between said opposed base panel  29 , may range to 80 inches, including the width of said base panels. 
     Side inlet portal means  38  may be disposed in wall  23  for the purpose of accommodating horizontally disposed conduits that deliver stormwater to the chamber. Top portal means  39  is disposed in the peak of wall  23  adjacent exit end  32 . Said top portal means is either a circular aperture or an indented portion of the wall which facilitates the cutting of a circular aperture. This permits visual observation of sediment level and removal thereof by vacuum equipment. The expression “adjacent exit end  32 ” is intended to denote a site along the horizontal length of the chamber which is within 20%, and preferably within 10% of the distance going from said exit end toward the opposed inlet end. The diameter of said portal means is preferably less than the diameter of the closed lower extremity  13  of said compartment. 
     The exit end  32  of the chamber may be provided with flow impeding means in the form of transverse panel  42 , as best shown in FIG. 2, having a lower impervious portion  43  and an apertured upper portion  44 . Said transverse panel functions to reduce the velocity of water flow, thereby causing sediment to accumulate in the area of exit end  32  of the chamber, and directly below top portal means  39 . 
     Accumulating accessory  10  is functionally associated with a stormwater dispensing chamber as shown in FIGS. 2-5, wherein said chamber is positioned atop the accumulating accessory in a manner whereby base panels  29  of the chamber are caused to rest upon apron panels  18  of said accessory, and the paired retaining lips  20  of the accessory are disposed within said chamber in close adjacency to said base panels. It is to be further noted that the accessory is positioned such that its vertical axis  15  intersects the center of top portal means  39 . The primary purpose of apron panels  18  is to provide support to the chamber by abutment with base panels  29 . Such support is desirable because of the deformational stress caused by the loss of ground support because of the excavation  59  required to accommodate the accumulating accessory. 
     As shown in FIGS. 3 and 5, the combined chamber and accumulating accessory of this invention is installed in an excavation upon a porous subterranean substrate such as crushed rock  45  that extends to the top of the chamber. A filter fabric  46  may be disposed atop the crushed rock substrate. A zone of compacted clean fill, gravel or crushed stone  47  extends from filter fabric  46  to an overlying layer such as pavement  48 . A manhole  49  may be disposed in a concrete pad  50  centered above top portal means  39 . A riser conduit  51  communicates between said manhole and top portal means. Accumulated sediment is removed from the chamber by causing a suction tube  52  to pass through conduit  51  to the bottom of the accumulating accessory. A vacuuming operation then transports the sediment upwardly into a servicing truck. 
     In a typical installation, as shown in a leaching field in FIG. 6, a multitude of the stormwater dispensing chambers are joined endwise to form long rows  54 . A number of such rows are in side-by-side juxtaposition immersed within crushed rock substrate. Feeder conduits  55  deliver the water to the drainage field, conveying the water directly to side portals  38  in the sides of the chambers of outermost row  57 . Water is then conveyed to other rows by way of interconnecting conduits  58  communicating between side portals of contiguous chambers. 
     Within each row  54 , the first chamber  64  has an upstream or inlet extremity which is closed by an end wall. The successive chambers in the row, subsequent to the first chamber may have completely open inlet and exit ends. The exit end  32  of the last chamber  63  in a row has a completely closed end wall. This causes sediment to accumulate in the area of said exit end, and directly below top portal  32 . Accordingly, within the leaching field, as shown in FIG. 6, the accumulating accessory is preferably employed with the last chambers  63  of the rows, which represent the downstream extremity of the overall flow pattern through a leaching field. 
     While particular examples of the present invention have been shown and described, it is apparent that changes and modifications may be made therein without departing from the invention in its broadest aspects. The aim of the appended claims, therefore, is to cover all such changes and modifications as fall within the true spirit and scope of the invention.