MODULAR UNDERGROUND WATER MANAGEMENT SYSTEMS

FIELD OF THE INVENTION

[0001] The invention relates to modular units, component parts, and assemblies of the modular units and component parts that are useful for making and using underground water management systems.

BACKGROUND OF THE INVENTION

[0002] Nearly any new development of land must incorporate a system for managing water runoff from the developed land. Current regulatory schemes typically require developers to install underground water detention and/or retention systems that effectively maintain a flow of water into and off of the developed land that mimics the natural (i.e., pre-development) flow from the land.

[0003] Such systems typically are installed under large concrete or asphalt surfaces and often must be capable of bearing highly variable weight loads (e.g., a parking lot). Ideally, such systems should maximize water storage while occupying as small a "footprint" as possible in order to minimize land usage.

[0004] In addition, many regulatory schemes require not only controlling water run-off, but also water quality, such as levels of pollutants. Typically, developed land accumulates pollutants that can contaminate water run-off, particularly after storms. Ideally, underground water management systems should pre-treat (e.g., using filtration systems) water flow from the developed land prior to releasing it. Such pre-treatment systems should be incorporated into the underground water retention/detention system in order to minimize land usage, but also should be accessible for intermittent cleaning, repair, and/or other maintenance.

SUMMARY OF THE INVENTION

[0005] In one embodiment, the present invention provides an arched module component for use in underground water management systems comprising a half-cube structure having a substantially square top face having a circular opening and pillars that extend downward from each corner, wherein the height of the pillars is about half the length of a side of the square

top face and wherein the pillars define four arches of diameter equivalent to the circular opening. In some embodiments, the arched module comprises a solid shell, wherein said solid shell comprises a single surface that is impermeable to water. In some embodiments, the solid shell covers a hollow core. In some embodiments, the solid shell covers internal structural supports capable of providing increased load bearing strength to the arched module.

[0006] In one embodiment, the invention provides a modular unit for use in underground water management systems comprising a substantially cubic structure having six faces (i.e., corresponding to the six "sides" or faces of a cube) with a substantially circular opening in each face and a substantially spherical interior volume. In some embodiments, the modular unit comprises a solid shell that is impermeable to water. In some embodiments, the solid shell covers a hollow core. In some embodiments, the solid shell covers additional internal structural supports capable of providing increased load bearing strength to the modular unit. These internal structures may be integrated with the modular unit structure under the solid shell, or optionally provided separate pieces that fasten to (e.g., snap-in) the underside of the solid shell.

[0007] In one embodiment, the invention provides an underground water management system comprising an assembly of modular units, wherein each modular unit comprises a substantially cubic structure having a circular opening in each face and a substantially spherical interior volume, wherein at least one face of each of said modular units abuts at least one face of an adjacent modular unit such that the openings in the faces of the adjacent units substantially align, thereby forming a passage between adjacent units. In some embodiments, the assembly further comprises vertical and/or lateral couplers between the modular units. In some embodiments, the assembly is surrounded by an impermeable liner (e.g. PVC, HDPE) to function as a storage or detention system. In other embodiments, the assembly is surrounded by a woven or non-woven geotextile liner to function as a water infiltration or retention system.

[0008] In one embodiment, the invention provides an underground water management system comprising a plurality of separate zones have different water flow, retention, and/or detention characteristics, wherein said system comprises an assembly of modular units coupled vertically and/or laterally, wherein said units comprise a substantially cubic structure having a circular opening in each face, a substantially spherical interior volume, and a solid shell

impermeable to water, and wherein the water flow through at least one opening of one of said plurality of modular units is restricted. In one embodiment, the system of the present invention comprises a filtration device is located at the interface of two different zones. In one embodiment, the system comprises an inlet pipe and an outlet pipe, wherein the inlet pipe is coupled to one zone, and the outlet pipe is coupled to a different zone.

[0009] In various embodiments of the present invention, materials useful for construction of the arched module components, modular units, and assemblies constructed therefrom include but are not limited to: polypropylene, high density polyethylene, low-density polyethylene, or any other materials that can be molded or cast including but not limited to rubber, aluminum, and concrete. In some embodiments, the arched module components, modular units, and assemblies constructed therefrom comprise hollow core construction.

[0010] In some embodiments, it is contemplated that the dimensions of the modular units can vary within 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 unit is used, and/or the desired access space for inspection and maintenance purposes.

[0011] In some embodiments, the invention provides a modular unit wherein the relative size of the opening diameter dimension to the exterior dimension is selected from the group consisting of: at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, and at least about 95%.

[0012] In some embodiments, the invention provides a modular unit wherein the relative volume of the substantially spherical interior to the total volume defined by the exterior dimensions is selected from the group consisting of: at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, and at least about 65%.

[0013] In other embodiments, the invention provides a variety of component pieces useful for assembling the arched module components into modular units and the modular units into assemblies that can be used as underground water management systems. Among the various additional components are stacking couplers, lateral couplers, various solid and grated cover panels adapted for the top, bottom, and side face openings of the modular units, and various

filtration devices, including filter baskets and media filters that can be removably installed in the openings of modular units.

[0014] In one embodiment, the invention provides a stacking coupler that can be used to join vertically adjacent modular units, wherein the stacking coupler comprises a square outer frame having an outer vertical lip connected to a circular inner ring having an inner vertical lip, wherein the outer lip fits snugly around the square outer edge and the inner lip fits snugly around the inner edge of the opening at the top or bottom face of the modular unit.

[0015] In one embodiment, the invention provides an underground water management system comprising an assembly of modular units, wherein at least one modular unit comprises an optionally removable filtration system consisting of a filter basket or a media filter cartridge. In other embodiments, the system comprises a plurality of filtration devices located within the assembly.

[0016] In various embodiments it is contemplated that the dimensions and/or structural configuration of underground water management systems constructed using assemblies of modular units can vary dependent on one or more design factors including but not limited to: desired overall size of the assembly, desired load-bearing tolerance for assembly, desired amount of water flow to be managed, number and location of inlet and outlet pipes, number and location of pre-treatment zones and filtration systems, and/or the desired access space for inspection and maintenance purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Embodiments of the present invention may be described with reference to the accompanying drawings.

[0018] Figure 1 illustrates schematically upright (A) and inverted (B) views of one embodiment of the arched module component having a solid shell, hollow core construction with optional weep-holes located in the arch near the four corner pillars. Two arched modules can be assembled to prepare a modular unit as shown in Figure 2 A and 2B.

[0019] Figure 2 illustrates schematically the assembly of one embodiment of the modular unit from two arched module components. Scheme (A) depicts the two half-cube arched module components (101) of hollow core construction, one upright and one inverted, such that their

respective male and female interlocking posts are aligned; scheme (B) depicts the two half-cube arched modules with their respective male and female interlocking posts joined to form a modular unit having a substantially cubic structure with one opening in each face. Scheme (B) also depicts a base cover panel as depicted in Figure 4.

[0020] Figure 3 illustrates schematically embodiments of: (A) a stacked coupler having an outer square frame joined to an inner circular ring, wherein both the inner ring and the outer frame comprise a groove into which snugly fit the exterior and interior edges of the top (or bottom) face of a modular unit, thereby providing increased load bearing strength to the unit; (B) a stacked coupler as in (A) except that there are no apertures in the framework between the outer square and inner ring, thereby preventing the passage of water except through the inner circular ring; and (C) a lateral coupler comprising a short pipe section that fits snugly into the side face openings of two adjacent modular units thereby creating a passage between them for water flow.

[0021] Figure 4 illustrates schematically two embodiments of cover panels for the top (or bottom) openings of a modular unit. Schemes (A) and (B) depict the top and bottom views of a cover panel having inner and outer edge grooves on which fit snugly into exterior and interior edges of the top (or bottom) face of a modular unit, thereby providing increased load bearing strength to the unit. The circular center is depicted as grated allowing water flow, but can optionally be a solid layer impermeable to water. Schemes (C) and (D) depict the top and bottom views of an embodiment with the circular center removed (e.g., to provide an access port) while retaining an outer groove and inner circular edge that fit the exterior and interior edges of the top (or bottom) face of a modular unit.

[0022] Figure 5 illustrates schematically two embodiments of cover panels for the side face openings of a modular unit. Schemes (A) and (B) depict the top and bottom views of a grated side cover panel having an circular edge of outer diameter which fit snugly into the inner diameter of a side face opening of a modular unit, thereby allowing restricted water flow out of the side face opening of the modular units while preventing passage of large floatables. Schemes (C) and (D) depict the top and bottom views of a solid side cover panel (impermeable to water) having an circular edge of outer diameter which fit snugly into the inner diameter of a side face opening of a modular unit, thereby preventing the passage of water out of the side face opening of the modular unit.

[0023] Figure 6 illustrates schematically a water management system comprising a stack of three modular units.

[0024] Figure 7 illustrates schematically a water management system comprising a 3x3x3 assembly of modular units.

[0025] Figure 8 illustrates schematically an embodiment of a water management system comprising an assembly of modular units that includes inlet bay module with a filter basket module for pre-filtration of coarse sediment, trash and debris.

[0026] Figure 9 illustrates schematically an embodiment of a filter basket incorporated into an assembly of modular units where a top "row" of four modular units opposite the inlet pipe are left open so as to create an extended inlet bay.

[0027] Figure 10 illustrates schematically an embodiment of a filter basket incorporated into an assembly of modular units where a top "row" of four units are used to create a high flow bypass outlet.

[0028] Figure 11 illustrates schematically two embodiments of media filter cartridges. Figure HA depicts an embodiment of a radial media filter cartridge design. Figure HB depicts an embodiment of a vertical media filter cartridge.

[0029] Figure 12 illustrates schematically one embodiment of a water management system comprising an assembly of modular units with a vertical media filter cartridge for pre-treatment of the water before retention/detention in the rest of the system.

[0030] Figure 13 illustrates schematically a blow-out side-view of the embodiment of Figure 12 that further depicts an access cover on top of a riser module and an optional inlet pipe clean-out access.

[0031] Figure 14 illustrates schematically one embodiment of a water management system comprising an assembly of modular units with an inlet bay comprising a pair of radial media filter cartridge for pre-treatment of the water.

[0032] Figure 15 illustrates schematically the embodiment of Figure 14 modified to include an additional inlet "sump" module beneath the inlet pipe.

[0033] Figure 16 illustrates schematically a side view of one embodiment of a water management system comprising a sand filter.

[0034] Figure 17 illustrates schematically an overhead plan view of one embodiment of a water management system comprising an assembly of modular units with a plurality of inlets and filter module assemblies.

[0035] Figure 18 illustrates schematically a blow-out overhead view of one embodiment of a water management system that includes an "inlet bay" for water pre-treatment that includes "walls" with stacks of modular units that with removable vertical media filter cartridges, (e.g., similar to Figures 12 and 13).

[0036] Figure 19 illustrates schematically a blow-out side view of the assembly of Figure 18 and further depicts the access ports provided above the top modular units having the vertical media filters.

[0037] Figure 20 illustrates schematically an isolated flow embodiment of a water management system comprising a 3x3x3 assembly of modular units with a perforated outlet flow control pipe.

[0038] Figure 21 illustrates schematically two stacked modular units. The top modular unit consists of two half-cube arched module components (101) of hollow core construction, one upright and one inverted, such that their respective male and female interlocking posts are aligned. The notches are located on the outer surface of the arch, to receive cover panels snaps that secure the cover panel in place. The external ribs are located on the external solid shell of the module components (101), near the four corners. In the bottom modular unit, the external ribs are located on the external solid shell, near the corners.

DETAILED DESCRIPTION OF THE INVENTION

[0039] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive or and not to an exclusive or. For example, a

condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

[0040] Also, use of the "a" or "an" are employed to describe elements and components of the invention. This is done merely for convenience and to give a general sense of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described herein. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

[0042] In the following description, numerous specific details are provided, such as the identification of various system components, to provide an understanding of embodiments of the invention. One skilled in the art will recognize, however, that embodiments of the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In still other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of various embodiments of the invention.

[0043] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

I. Overview

[0044] The present invention provides a modular underground system for water management applications. A wide range of underground water management applications may be addressed using the systems described herein. These include but are not limited to all water retention/detention applications typically addressed with underground caverns, chambers, cisterns, etc. typically made using simple piping, pre-cast concrete, and/or plastic "milk crate" type assemblies. Particular applications include underground storm water retention and/or detention, rainwater harvesting, and other water run-off related issues.

[0045] The water management systems of the present invention have a structure comprising an assembly of modular units. The modular unit is a substantially cubic structure with an arched opening in each of six faces, such that passages for water flow extend through the center of the structure to each opposing face. As described herein, each modular unit has at least one top face opening, a bottom face opening, and four side face openings, that define at least three distinct passages (i.e., virtual pipes) through the center of the structure. The width of the passages expands up to a widest point at the center of the structure such that each modular unit comprises a substantially spherical hollow interior volume that is capable of water storage. The modular unit can be assembled from a pair of arched module components described in greater detail herein.

[0046] In some embodiments, the modular unit comprises a substantially cubic structure with a substantially spherical hollow interior volume and comprises an exterior solid shell (i.e., exterior layer or "skin") that is impermeable to water. In some embodiments, the modular unit comprises a solid shell covering a hollow core structure (i.e., a substantially empty volume under the shell). In some embodiments, the core of the modular unit under the shell can include additional internal structural supports (e.g., supporting panels, framework pieces, or beams), which provide increased load bearing strength to the modular unit. In one embodiment, the ribs are added on the interior surface, over the top of the arch, spanning from corner to corner. In another embodiment, ribs are added on the interior surface around the weep holes to prevent cracking around the weep holes. These internal structures may be integral to the modular unit structure, or optionally separate pieces that fasten to (e.g., snap-in) the underside of the solid shell.

[0047] In other embodiments, vertical ribs are located in the corner areas on the external and internal side of the modular unit. These vertical ribs enhance the structural strength and also

assist with stacking or nesting of the un-assembled arched module component. In another embodiment, ribs are added on the outer surface of the device, running along the under or inner side of the modular unit.

[0048] The invention also provides a stacked coupler that can be integral to the top or bottom face of the modular unit, or optionally a separate piece attachable to the top or bottom face. The stacked coupler provides additional load-bearing structural integrity to a modular unit and facilitates stacking the unit above or below other modular units, thereby allowing formation of assemblies for water management.

[0049] The invention also provides a lateral coupler that fits snugly into the side face openings of two adjacent modular units creating a passage between them for water flow and providing structural support to assemblies of modular units.

[0050]Additionally, the invention provides optional solid, perforated, or grated cover panels (i.e., "plugs") for the openings on the modular unit, thereby allowing each modular unit to be separately modified for a particular water retention/detention function.

[0051] The substantially cubic structure of the modular units greatly facilitates fabrication of underground systems (e.g., via stacking). Both simple (e.g., a 3x3x3 cube assembly) and highly complex systems (e.g., with outlet flow control, water filtration systems, etc.) can be built using the same modular units. The hollow structure of the modular units further facilitates assembly by minimizing weight (e.g., particularly with the molded polypropylene hollow core structure) while maximizing water flow and storage volume. Additionally, the arched openings of the modular unit and optional stacking and lateral couplers provide sufficient loading bearing strength and structural integrity for a wide range of underground water management applications.

[0052] The substantially cubic structure of the modular unit with openings in each face, a substantially spherical interior volume, passages between adjacent units, and the capability of isolation for flow control, provides enhanced access for inspection and maintenance of underground assemblies, e.g., for clean-out of debris following a storm. Further, the modular unit of the present invention can be customized in its water flow characteristics with the use of the standard set of coverings that fit over the openings.

II. The Modular Unit

A. Arched module component

[0053] Figure 1 illustrates schematically a disassembled view of one embodiment of the substantially cubic modular unit. In this embodiment, the unit comprises a pair of arched module components 101, each of which provides half of the substantially cubic structure. The two-piece half-cube design using the arched module greatly simplifies fabrication and assembly of the modular units which can be used in the assembly of water management systems as described herein.

[0054] As shown by the "table-like" structure depicted in Figure IA, each arched module 101 defines a half-cube with four arches and four corner "pillars" 102. The substantially square face at the top of the arched module also includes an opening 103. The opening 103 in the square top face is substantially circular and of the same diameter as the semi-circular openings defined by the four arches. Thus, the arched module component comprises a half-cube structure having a substantially square top face having a circular opening and pillars that extend downward from each corner. The height of the corner pillars is about half the length of an exterior edge of the square top face and wherein the pillars define four arches of diameter equivalent to the circular opening.

[0055] The Figure 1 embodiment of the arched module component 101 provides a substantially circular opening in each face 103, the diameter of which is at least about 75% the length of the exterior dimensions of the substantially square top face (e.g., 18 inch diameter opening for 24 inch length top face exterior dimension). This relative dimension of the opening provides optimal structural integrity when a pair of components is combined to fabricate a modular unit (as described further herein) while also allowing a large volume for water storage and passage. In other embodiments, standard design options may be selected that allow for a decrease or increase in the relative dimension of the opening diameter to the length of the sides. Thus, in some embodiments the relative dimensions of the opening diameter to the length of the exterior dimension of the substantially square top face can be at least about 50%, about 60%, about 70%, about 80%, about 90%, or about 95%, or more.

[0056] In the embodiment depicted in Figure 1, the arched module component 101 has only

one opening in the top face of the structure. When pairs of arched modules are combined to form modular units, a total of six opening are created (one for each face) thereby defining three distinct passages for water flow in a single modular unit. The use of a minimal number of openings in the arched module component (e.g., one opening in the top face of at least 75% relative diameter) provides the advantage of mim ^' mizing surfaces that debris flowing through the modular unit can become snagged or otherwise caught resulting in obstructions.

[0057] The ordinary artisan also will recognize that the absolute dimension of the opening can be selected to accept industry standard pipe connections/fittings (e.g., rubber boots).

[0058] The four corner pillars 102 comprise connecting means at their base for joining to four pillars of a second arched module (in the inverted position depicted in Figure IB), thereby forming a modular unit. The connecting means, in one embodiment, includes fabricating the base of each pillar in a shape capable of forming an interlocking connection with a pillar having a complementary shape. Any of a multitude of complementary shapes capable of forming interlocking connections and well know to the ordinary artisan could be used.

[0059] As shown in the embodiment of Figure IB, two of the corner pillars 102 are shaped so as to form a female socket 104 and the other two corner pillars are shaped so as to form a complementary male plug 105 that forms a snug interlocking connection with the complementary female socket.

[0060] In some embodiments, the connecting means are integrated into the structure of the corner pillar. In other embodiments, the connecting means may comprise separate connector pieces (e.g., fasteners, pins, rods, clips, etc.) that are introduced, for example, during assembly of the modular unit.

[0061] Optionally, one or more corner pillars of the arched module can include a central hole. When joined to a pillar with a central hole in a complementary arched module to form a modular unit, the alignment of the two holes provides a passage. In one embodiment, this passage can be left unobstructed allowing water and/or air to flow through (i.e., function as a "weep-hole"). In another embodiment, a fastening means can be inserted in this passage at the junction of two pillars to facilitate coupling of the pair of arched modules. In those embodiments where stacks of modular units are assembled (see description herein), a single

rod can be inserted through the corner pillar passages defined of the stacked modular units, thereby providing further lateral stability to the stack.

[0062] As shown in Figure 1, in one embodiment the arched module component structure comprises a shell and a hollow core. In some embodiments, the shell comprises a single, solid layer impermeable to water. Typically, the shell and hollow core construction is of a polymeric material (e.g., injection molded polypropylene). In some embodiments, the hollow core of the arched module can include internal structures providing additional structural strength. For example, a vertical panel extending from the inside of each corner to the internal side of the opening. Such vertical panel would be integrated into the hollow core structure and add structural integrity by linking the outer square wall to the inner openings in the top and bottom faces of the arched module.

[0063] As depicted in Figure 1, in some embodiments, the single, solid layer includes optional "weep-holes" 106 therethrough that allow water and/or air to pass. The weep-holes are optionally plugged (with e.g., rubber plugs) to prevent water and/or air flow. Alternatively, the weep-holes can be optionally screened to prevent large particle or sediment passage.

B. Assembly of modular unit from arched module components

[0064] Figure 2 illustrates schematically one embodiment of a modular unit 201 assembled using the arched module components of Figure 1.

[0065] Figure 2A depicts a pair half-cube arched modules 101 of hollow core construction, one upright and one inverted, such that their respective male and female interlocking corner pillars 102 are aligned. The pair of arched modules 101 is connected by inverting one module and inserting its male plugs 105 into the complementary female sockets 104 on the top of the other arched module's corner pillars. As shown, the corner pillars with female connecting means 104 on the inverted module align with, and fit snugly over the opposing corner pillars with male connecting means 105 on the lower arched module, thereby forming an interlocking connection of all four pillars to yield a substantially cubic modular unit.

[0066] Figure 2B depicts the two half-cube arched modules with their respective male and female interlocking pillars joined, thereby forming a substantially cubic modular unit with a

substantially spherical interior volume, and six circular openings, one for each face of the structure.

[0067] In the modular unit embodiment depicted in Figure 2, the two arched module components 101 used are identical. It is contemplated however, that in some embodiments a pair of arched module components can be used which are not identical. For example, there can be embodiments where the bottom and top arched modules differ in the connecting means, the top module having all female connecting posts, and the bottom module have all male connecting posts.

[0068] Although the two-piece construction based on the arched module components is depicted in Figure 2, it also contemplated that the modular unit structure (e.g., embodiment depicted in Figure 2B) also can be fabricated as a single piece that requires no further assembly, e.g., made by injection molding of polymer or concrete. This single-piece modular unit simplifies construction of larger assemblies of modular units, but is more difficult to store (due to large volume) and may increase modular unit manufacturing costs.

C. Materials used for modular unit construction

[0069] The ordinary artisan can recognize that other materials commonly used in applications involving underground retention/detention of water can be employed with in the present invention. Generally any material that can be molded or cast can be used to fabricate an arched module component, including but not limited to polypropylene, high density polyethylene (HDPE), low-density polyethylene (LDPE), rubber, aluminum, and concrete.

[0070] For example, in an alternative embodiment, pre-cast concrete can be used to construct an arch module useful for making modular units of the present invention. In such an embodiment, the arched module is typically of solid-body construction due to the greater ease of pre-casting such a structure. While greatly adding to the weight of each modular unit, assemblies of pre-cast concrete units may be desired where the use of underground systems made of polymer are precluded by regulation and/or environmental conditions.

[0071] Figures 1 and 2 depict embodiments of hollow core construction. Hollow core construction greatly reduces weight thereby facilitating storage, transport and assembly of the arched modules. In one embodiment, the material used for the hollow core arched-module

is injection-molded polymer. In one embodiment, the polymer selected is a polypropylene, including but not limited to recycled polypropylene. The ordinary artisan will recognize that any polymer capable of injection molding could be used to construct an arched module of the present invention. Similarly, the ordinary artisan will recognize that a variety of design selections can be made for the polymer material used to construct an arched module of the general structure depicted in Figure 1.

D. Modular unit structure

[0072] The modular unit has a substantially cubic structure with an arched opening in each of the six faces. Because of its substantially cubic structure, the relative lengths of the three exterior dimensions (i.e., length, width, and height) of the structure are substantially equal (i.e., the same within about 10%). This substantially cubic embodiment with substantially equal exterior dimensions, as depicted in Figure 2, provides optimal structural integrity and water storage volume, along with ease of design, manufacture and assembly.

[0073] It is contemplated that in some embodiments variations in relative length of the exterior dimensions of the modular unit may be implemented due to various design options available to the ordinary artisan. Generally, the dimensions of the modular units can vary within 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 unit is used, and/or the desired access space for inspection and maintenance purposes.

[0074] In one embodiment, a design option is contemplated wherein some increase or decrease (e.g., less than about 10%, about 5%, or less) of the relative height and/or width of the three exterior dimensions may be implemented when more suitable for a particular system, without departing from the substantially cubic structure. For example, a shortened height about 10% less than the other dimensions may be used in the design of the modular unit.

[0075] The Figure 2 embodiment of the modular unit 201 provides a substantially circular opening in each face 202, the diameter 203 of which is at least about 75% the length of the sides of the structure (e.g., 18 inch diameter opening for 24 inch length exterior edge dimension 204). This relative dimension of the opening 202 provides optimal structural

integrity to the modular unit while also allowing a large volume for water storage and passage. In other embodiments, standard design options (e.g., the use of structurally stronger or weaker materials) may be selected that allow for a decrease or increase in the relative dimension of the opening diameter to the length of the sides. Thus, in some embodiments the relative dimensions of the opening diameter to the length of the exterior side can be at least about 50%, about 60%, about 70%, about 80%, about 90%, or about 95%, or more.

[0076] In the embodiment depicted in Figure 2, the modular unit 201 has only one opening per face of the substantially cubic structure, for a total of six openings 202. In assemblies of these modular units, each opening aligns with the opening in the opposite face, thereby creating a passage (i.e., a "virtual pipe") for water flow defined by the two openings. In such an embodiment, the six opening define three distinct passages for water flow in a single modular unit. This use of a minimal number of larger openings (e.g., one per face of at least 75% relative diameter) provides the advantage of minimizing surfaces that debris flowing through the modular unit can become snagged or otherwise caught resulting in obstructions.

[0077] The ordinary artisan also will recognize that the absolute dimensions of the openings can be selected to accept industry standard pipe connections/fittings (e.g., rubber boots). Such fittings can offer flexible and watertight connections between modular units and piping for controlling water flow into and out of an assembly of modular units.

[0078] The embodiments of the arched module components and modular units depicted in Figures 1 and 2 also include one or more "weep-holes" 106 not in the faces of the substantially cubic structure but through the structure along an axis parallel to the corner pillars 102. The weep-holes 106 allow for some water flow through the modular unit and assemblies of vertically stacked modular units constructed therefrom. Additionally, the weep-holes allow for the release of air which can become trapped particularly in hollow core embodiments of the modular unit. In one embodiment, two weep-holes 106 are located in the inner volume of the unit, near the top (or base if inverted) of each corner pillar 102.

E. Solid shell construction

[0079] In one embodiment, the modular unit comprises a solid shell surface that is impermeable to water. With this solid shell surface the water flow through the unit is limited

to the openings in each face of the substantially cubic structure (and any optional weep-holes 106 that are left unplugged). For example, in the embodiment shown in Figure 2, assuming the solid shell surface is impermeable to water, flow into or out of the substantially spherical interior volume of the modular unit is restricted to one of the six openings 202 (assuming the weep-holes are plugged). By fitting cover panels, grates, or plug embodiments (e.g., as shown in Figures 3-5) over any of these six openings, water flow can be further restricted and/or directed as described

[0080] Because the solid shell surface limits water flow to those passages created by the openings in each face of the substantially cubic structure, it is possible to customize the water flow characteristics of an individual modular unit or a group of units that are part of a larger assembly. For example, a row of four modular units in a larger assembly can be isolated (e.g., by plugging the top, bottom, and two side face openings, thereby providing a passage (i.e., a "virtual pipe") for directed water flow horizontally down the row (e.g., as shown in Figure 10 and described herein).

[0081] Similarly, the solid shell construction facilitates isolating a group of modular units inside a water management system made up of a larger assembly of units. For example, to create a separate zone to pre-treat water before it enters a retention/detention zone of the assembly a group of modular units can be isolated and fitted with filtration systems that filter the water passing through them (see e.g., Figures 8-20 as described herein).

[0082] The ability of the solid shell construction to allow customization of the water flow characteristics of one or a group of modular units also allows for isolated flow control zones in a larger assembly. For example, the outlet water flow rate from an isolated group of modular units can be controlled by fitting the openings of the units with grated or perforated cover panels (as shown in Figures 3-5 described herein).

[0083] Alternatively, an isolated outlet flow control zone can be created by sleeving a perforated outlet pipe through the openings of a row of laterally coupled modular units (as shown in Figure 20 described herein). The perforated outlet pipe provides a controlled rate of water drainage from the adjacent separate retention zone of the assembly.

JP. Water permeable surfaces

[0084] It is also contemplated that in some embodiments the modular unit can be constructed of materials having a surface with multiple small holes or pores. For example, the hollow core structure embodiment of Figure 2 with a substantially solid surface (except for the weep-holes) could be modified by drilling numerous small holes through surface exterior into the interior hollows.

[0085] It is also contemplated that in applications where the ability to isolate and internally channel water is not necessary and/or coarse debris obstructions are not of concern, a modular unit structure may be used with more than one opening in each face. Thus, in one embodiment it is contemplated that modular units in an assembly are constructed of materials having a web-like or lattice structure. For example, a substantially cubic structure having one opening in each face, but of a web-like structure (rather than a solid shell), wherein the relative area of the opening to the length of the outside edge of the cube is at least about 50%, about 60%, about 70%, about 80%, about 90%, or about 95%, or more, depending largely on the structural strength required.

[0086] In an alternative embodiment, it is contemplated that modular units having solid shell construction impermeable to water are combined in a single assembly with modular units (or other water retention/detention structures) having web-like or lattice type structure that allow water flow in all directions.

H. Modular unit inner volume and water retention/detention capacity

[0087] Two arched modules when combined form a modular unit having a relatively small yet strong substantially cubic structure with a hollow interior volume that allows significant water storage. In one embodiment, the interior volume of the modular unit is substantially spherical. The radius defining the spherical volume extends from the center of the modular unit to the center of the plane defined by a face of the cube (i.e., at the center of an opening in a face).

[0088] The interior volume of the modular unit can be defined in relation to the total volume defined by the outer dimensions of the substantially cubic modular unit. Thus, in various embodiments of the present invention, the substantially spherical interior volume can be at least about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, or even a larger percentage of the total volume defined by the outer dimensions of the substantially cubic

modular unit. The ability to utilize higher relative percentage interior volumes will depend on other design option selections, for example the use of a material capable of maintaining sufficient structural integrity despite a lower relative volume.

[0089] In addition to the substantially spherical volume, the hollow core embodiment of the modular unit provides volume for the storage of water throughout the hollow body spaces in the structure. The total available volume will depend on the hollow core structure design selected. To the extent sufficient structure integrity can be provided by certain materials and structure design choices, even higher hollow-space volumes may be provided in the modular unit. Thus, in some embodiments, the available volume for water storage in the hollow core embodiment is at least about 75%, about 80%, about 85%, about 90%, about 95%, or even a larger percentage of the total volume defined by the outer dimensions of the substantially cubic modular unit.

[0090] The design of the modular unit embodiment depicted in Figure 2 is scalable. The ordinary artisan will recognize that the absolute dimensions can be varied based on the range of design options available, e.g., materials, water management application, excavation site, etc. For example, smaller modular unit dimensions (e.g., exterior dimensions of about 12 inches x 12 inches x 12 inches) may be selected for residential water management applications where less underground water retention/detention volume is needed or available. Alternatively, larger modular unit dimensions (e.g., exterior dimensions of about 48 inches x 48 inches x 48 inches) may be desired for larger industrial application, particularly where solid body construction modular units are used (e.g., pre-cast concrete embodiments). Such solid body units require larger exterior dimensions in order to create a sufficient interior volume for water storage.

[0091] In one embodiment, the modular unit is a substantially cubic hollow core structure (as depicted in Figure 2) constructed of polypropylene with outside dimensions of about 24 inches x 24 inches x 24 inches and openings of diameter about 18 inches. The hollow interior volume of the modular unit is defined by a substantially spherical volume of about 50

3 cubic inches (equivalent to about 4.19 ft or 31.3 gallons). Thus, in this structural embodiment of the modular unit, the interior spherical volume is at least about 50% of the total volume defined by the outer dimensions.

[0092] In the hollow core structure embodiment, water also may fill the voids throughout the hollow core of the substantially cubic structure. Consequently, the total volume available for water storage is just slightly less than the total volume defined by the outside dimensions

3 of about 24 inches x 24 inches x 24 inches (equivalent to 8 ft or about 59.8 gallons). It is believed that these dimensions for a hollow core, molded polypropylene modular unit provide an optimal compromise of structural integrity, light weight for ease of assembly, large interior volume for water storage, and large openings for ease of maintenance access.

/. Coupling of stacked modular units

[0093] In some embodiments, separate couplers are provided that facilitate joining of multiple modular units in larger assemblies. Figures 3 A and 3B illustrate schematically two embodiments of a "stacking coupler" 301 and 310 for joining modular units vertically - e.g., in a 3 unit stack. As depicted in Figure 3A, the stacking coupler 301 comprises a structure with an outer square frame 302 with a vertical edge (or lip), designed to fit around the outer and/or square edge of the bottom (or top) of a modular unit, connected to a circular inner ring 303, designed with a vertical edge (or lip) that fits around the inner and/or outer edge of the arched opening in the bottom (or top) face of the modular unit 201. The inner circular ring 303 of the stacking coupler 301 provides a hole that aligns with the opening 103 in the bottom or top face of the modular unit 201. Because the single piece coupler fits to and secures to both the outer square edge and inner opening edge of the modular unit, the coupler provides enhanced structural integrity to the modular unit.

[0094] Typically, the two-sides of the stacking coupler 301 are identical. Thus, a single coupler can fit to and secure the bottom edges (outer square and inner opening) of one modular unit and the top edges of a second modular unit, thereby joining the two modular units in a stack. The stacking couplers provide lateral (inward and outward) wall support to stacked assemblies of modular units. Additional units may be added above and below using couplers to join them. Generally, stacks of any number of modular units may be easily assembled using the stacking coupler, with the only limitation being the structural stability due to the weight of the stack itself.

[0095] In the embodiments depicted in Figure 3A and 3B, the stacking couplers 301 and 310 comprise a pair of inner and outer vertical edges (or lips) that define a groove on one or both

of the outer square 302 (or 311) and inner circular frame 303 (or 312) of the coupler. In the hollow core embodiment of the modular unit, the substantially square outer edge of the bottom (or top) of the modular unit 201 and/or the edge of the arched opening, fit snugly into the groove(s). Particularly in embodiments of modular units comprising hollow core construction in recycled propylene, the snug fit of the edges into outer and inner grooves of the frame of the coupler enhances the structural integrity of the substantially cubic structure. For example, "flowering" of the edges of the arched opening 103 due to heavy loads is eliminated or greatly diminished by the lateral stabilization provided by the lips of the coupler grooves.

[0096] In addition to added lateral support, the grooved embodiment of the stacking coupler also provides a stronger vertical connection that permits larger stacks of modular units to be lifted as a single unit without detaching. This single stack lifting ability greatly facilitates assembly and installation of underground water management systems based on assemblies of modular units.

[0097] In one embodiment, the inner circular opening edge and the outer square edges of the top (or bottom) of the modular unit fit snugly against the coupled circular and square vertical edges of the stacking coupling, and no further fastening is required.

[0098] It is contemplated that in some embodiments of assemblies of modular units, further connecting means or fastening means may be provided for securing stacks of modular units in addition to stacking couplers. For example, wire, plastic ties, fasteners (e.g., screws, rivets, nails, snap-clips, etc.) or adhesive means (e.g., tape, glue, etc.), may be used to further secure stacks of modules for easy lifting as a single unit. In one embodiment, one or more self-tapping screws through the outer square edge (or pair of edges defining a groove) of the stacking coupler and the overlapping edge of the modular unit is used to join them. In such an embodiment, the vertical outer square edge (or pair of edges defining a groove) of the stacking coupler is at least about 0.5 to about 1.5 inches in height.

[0099] As depicted in Figure 3 A and 3 B, the stacking coupler 301 can be a web-like structure with the square outer frame 302 and the inner ring 303 connected by four integral support beams from the corners 304 and optionally four additional support beams from the midpoint of the square outer edge 305. The space between the support beams is open, leaving apertures

for water flow 306. This support-beam structure can be designed to provide minimal solid volume while allowing maximal volume water flow-through from weep-holes in the modular unit structure. Additionally, the inner ring of the stacking coupler can include a short horizontal flange 307 extending inward capable of supporting an optional filtration system (e.g., a filter basket or media filter cartridge).

[0100] In the embodiment of the stacking coupler 310 depicted in Figure 3B, the outer square frame and inner ring of the stacking coupler are connected by the integral support beams but a solid single-layer 313 of material extends between the beams so that there are no apertures between the outer square frame 311 and the inner circular ring 312. Optionally, a solid single layer of material also can extend across the opening defined by the inner circular ring. In such embodiments, the stacking coupler serves only to join and stabilize the vertical stack of two modular units without allowing the passage of water between the two units. This solid stacking coupler may be used to prevent vertical water flow and thereby create horizontal water flow channels in an assembly of modular units.

[0101] In another embodiment, a stacking coupler with a solid layer 310 as in Figure 3B can be fabricated with a removable piece covering the center circular opening. This piece can be removable e.g., by cutting or by a twist-lock connection. Such a solid layer stacking coupler with a removable cover could be used optionally to set up a vertical flow passage (i.e., by removing the center solid layer) or to set up a horizontal flow passage by keeping the central solid layer in place.

[0102] In another embodiment, a solid layer stacking coupler may include "weep-holes" in the solid layer between the square outer edge and the inner ring. These weep-holes would allow air and some water flow through the hollow core of the modular unit structure while maintaining a closed vertical passage.

/. Cover panels, grates, and risers for openings

[0103] The ordinary artisan will recognize that the top, bottom, and/or side face openings of each modular unit (alone or as part of a larger assembly) can be fitted with (or easily adapted for fitting with) any cover panel, plug, plate, grate, fitting, or valve system, well-known in the art of water management systems. Figures 4 and 5 illustrate schematically embodiments of various such cover panels, plugs and grates that can be used with the modular units.

[0104] Generally, cover panels for a top or bottom face opening of a modular unit (or assembly) are of square shape, as illustrated by embodiments in Figure 4. As depicted in Figure 4A, in some embodiments, the cover panel for the top or bottom face opening of a modular unit comprises a structure similar to a stacking coupler (see above) with an outer square groove and inner circular groove that snugly fits the outer and inner edges of the modular unit. These cover panels incorporate the lateral support mechanism of the stacking coupler and thereby provide increased load-bearing strength to the underlying (or overlying) stack of modular units. In some embodiments, the top/bottom cover panels include a circular center (defined by the inner groove as depicted in Figure 4A) that is grated allowing restricted water flow and preventing flow-through by large solids. In another embodiment, the top/bottom cover panels can be a solid layer that is impermeable to water.

[0105] In one embodiment, the top/bottom cover panels comprise a removable center piece thereby providing an access port, as depicted in Figures 4C and 4D. For example, the top cover panel can include a circular center opening with a flange capable of supporting a removable cover (e.g., a man-hole type port). As depicted in Figures 4C and 4D in one embodiment, the cover panel retains an outer groove and inner circular edge that fit the exterior and interior edges of the top (or bottom) face of a modular unit, even when the central cover piece is removed. Typically, the access opening will be of the same diameter as the top face opening of the modular unit underlying it and will thereby allow access to the assembly of modular units for cleaning and maintenance.

[0106] In one embodiment, a solid top/bottom cover panel is fabricated with one or more guide lines on the outer surface (see e.g., Figure 4A) in order to guide field cuts when necessary to create an opening. Such top panel openings can be used for providing access to the assembly or fitting pipes into the installation.

[0107] When used on the top (or bottom) opening of a modular unit in a stack (or larger assembly), the cover panel can simply be a solid plate of sufficient strength to bear the loads expected at the particular site. Top cover panels can be designed also to act as a weight to stabilize the stack of modular units below. Thus, top cover panels may include steel panels or grates.

[0108] Typically, impermeable solid panels would be selected for top cover panels where it is

desired to allow water in-flow via underground pipe connections into side face openings on the exterior of an assembly. Grated top cover panels would be selected where percolation of water through the whole top surface of a modular unit assembly is desired.

[0109] In some embodiments, a riser module that fits the outer square edge of the top modular unit can be used as an adapter to adjust the height of the cover panel. As shown in Figure 6, such a riser module 602 comprises a square frame-like structure, adapted to fit a stacking coupler on the top modular unit of a stack.

[0110] Generally, bottom cover panels can include any of the designs used for top cover panels and vice-versa. In some embodiments, the bottom cover panel will be a grated panel that allows surface infiltration and/or percolation of water through the floor of the modular unit assembly.

[0111] Generally, cover panels for the side face openings have a circular edge that fits snugly in the inside diameter of the opening. Figure 5 illustrates schematically two embodiments of cover panels for the side face openings of a modular unit.

[0112] In some embodiments, grated cover panels that allow water flow, but with some restriction depending on size of grate, may be used to cover some or all of the side face openings of a modular unit. Figure 5 A and 5B depict the top and bottom views of a grated side cover panel having a circular edge of outer diameter which fit snugly into the inner diameter of a side face opening of a modular unit, thereby allowing restricted water flow out of the side face opening of the modular units while preventing passage of large floatables.

[0113] In the embodiment of the grated side cover panel depicted in Figure 5 A and 5B, the grated cover panel is a flat circular piece with one side bearing a circular vertical flange of outside diameter that fits snugly into the inside diameter of the side face opening, but which also includes a series of opening through the panel, e.g., a spoke-like structure extending from the center of the panel with circular support "ribs" connecting the spokes. In one embodiment, the circular support ribs are set at distances from the center allowing them to act as guides for field or factory installation of standard size pipe openings.

[0114] In some embodiments, a grated cover panel may be used for outer side face openings of an assembly of modular units in order to allow for percolation of water into the

surrounding soil. Typically, a filter fabric may also be installed between the grated side face opening and the soil.

[0115] In some embodiments, solid cover panels impermeable to water flow (i.e., plugs) may be used to cover some or all of the side face openings of a modular unit. For example, solid cover panel/plug may be used on the outer side face openings of an assembly of modular units in order to create a closed system — e.g., for water detention or in filtration applications. In one embodiment, the solid cover panel is a flat circular piece with one side bearing a circular vertical flange of outside diameter that fits snugly into the inside diameter of the side face opening.

[0116] Figure 5 C and 5D depict the top and bottom views of a solid side cover panel (impermeable to water) having an circular edge of outer diameter which fit snugly into the inner diameter of a side face opening of a modular unit, thereby preventing the passage of water out of the side face opening of the modular unit.

[0117] In some embodiments, solid cover panels for side face openings may include one or more guide lines on the outer surface in order to guide field cuts when necessary to create an opening (see e.g., side face opening of bottom unit of stack depicted Figure 6). Such side panel openings can be used for providing access to the assembly or fitting pipes into the installation.

G. Lateral coupling of modular units

[0118] In one embodiment, adjacent modular units and stacks of units can be joined using a lateral coupler which comprises a short section of pipe of an outside diameter that fits snugly in the aligned side face openings of two adjacent modular units, thereby acting as a connector providing a smooth channel between the two units. Typically, the lateral coupler is just long enough to bridge the gap between the two adjacent modular units while providing adequate friction contact with the inside diameter of the two openings to secure the units. Additionally, the lateral coupler can act as an adapter for connecting a pipe to an opening of a modular unit.

[0119] In one embodiment of a lateral coupler 320 (shown in Figure 3C) the outer circumference of the lateral coupler comprises an outer flange 321 (i.e., an outer ridge)

equidistant between its two ends that is of greater diameter than the opening. This flange acts a guide during assembly that stops the insertion of the ring at the proper distance in the opening.

[0120] The outer flange of the lateral coupler structure can be shaped to fill any space between the adjacent modular units in an assembly, thereby providing better transfer of load between the units in an assembly. For example, the outer flange optionally is shaped to fit (i.e., conform) to any slope present in the sides of the adjacent modular units.

[0121] In one embodiment illustrating the lateral coupler, the inside diameter of the modular unit opening is 18 inches and the outside diameter of the lateral coupler is 18 inches with a linear dimension (i.e., the short cylinder length) of about 6 inches. A lateral coupler (e.g., 320) will slide 3 inches into the 18 inch diameter openings of two adjacent modular units, thereby providing a smooth passage between them that joins and provides lateral shear support. Alternatively, this coupling could be used to connect the modular unit opening to an 18 inch inside diameter pipe - e.g., for inlet or outlet flow from the cube.

[0122] In some embodiments, the opening of the lateral coupler inside the ring may be partially obstructed. For example, the circular aperture may be spanned by a partial wall or weir that extends only about halfway up the coupling. This partial wall can be a grate or web-like structure that catches and/or redirect coarse debris. In another embodiment, the partial wall can be impermeable to water (e.g., a plate or plug) and thereby redirect water in low flow situations while allowing flow when the water rises above the height of the wall.

III. Assemblies of Modular Units

A. Three-cube stack

[0123] Figure 6 illustrates schematically an assembly comprising a three modular unit stack. Each modular unit comprises two half-cube arched module components. Each modular unit is joined to the abutting modular unit above and/or below via a stacking coupler. The inner circular frame of the stacking coupler includes a horizontal flange/ledge capable of supporting an optional filtration device. The ends of the top and bottom modular units are covered with grated cover panel. The top modular unit further includes an optional riser module between the top coupler and the top cover grated cover panel. The riser module

provides additional vertical extension of the stack where necessary. The bottom modular unit includes an optional cover panel on one of the side face openings. The three-cube stack can be easily joined to up to four adjacent 3 cube stacks using lateral couplers in the side face openings.

B. 3x3x3 Cube assembly

[0124] Figure 7 illustrates schematically one embodiment of a water management system comprising a 3x3x3 assembly of substantially cubic modular units. The 3x3x3 assembly depicted comprises a total of 27 substantially cubic modular units that form four 3x3 "walls," "ceiling" and a "floor."

[0125] A top porthole above the center of the 3x3 "ceiling" allows access to the center of the assembly which can be used for entry and/or maintenance (e.g., using a pressure washing system). In typical embodiments, the top porthole would be covered with removable solid cover panel and optional riser module.

[0126] In one embodiment, two modular units can be omitted from the assembly directly beneath the top porthole thereby providing a central "room" inside the assembly that allows better access to the interior volumes of the modular units making up the cube. In such an embodiment, the top porthole will be supported over the access "room" by the adjacent modular unit "walls" or other suspension means available to the ordinary artisan.

[0127] A side porthole also is depicted in the embodiment of Figure 7. Such a side porthole may be connected to exterior piping and used e.g., for outflow in high volume storm water conditions. The ordinary artisan, however, will recognize that the use of the modular units provides up to 9 available exterior openings in each wall for inlet or outlet piping. Thus, as described further below, any side of the 3x3x3 cube assembly is available for water inlet or outlet piping.

[0128] Typically, when installed underground, the 3x3x3 cube assembly will be surrounded by a liner. In some embodiments, the liner will be impermeable to water (e.g., PVC plastic), and inflow and outflow from the assembly will be only through inlet and outlet pipes.

[0129] In other embodiments, the surrounding liner will be semi-permeable, allowing water to seep out of the assembly but keeping out coarse dirt. In some embodiments, the bottom

face openings of the modular units in the "floor" of the 3x3x3 cube will include grated cover panels that allow water to percolate into the underlying ground.

III. Filtration Systems

[0130] As described above, the modular unit of the present invention facilitates the incorporation of a range of filtration devices into underground water management systems made using assemblies of the units. The ordinary artisan will recognize that the top, bottom, or side face openings of the substantially cubic modular units which align to provide passages for the flow of water through underground assemblies can also be adapted to accept standard filtration devices known in the art. The use of solid shell construction permits the isolation of individual and/or groups of modular units thereby permitting water flow to be directed through filtration systems installed in one or more units. Furthermore, the modular unit is well-adapted to facilitate access to and maintenance of incorporated filtration devices due to its relatively large substantially spherical interior volume and the availability of openings in each face of the structure. The ability to maintain and/or replace filtration devices in an underground water management system with relative ease provides a great advantage in the use of such systems.

[0131] Additionally, when installed in a modular unit (e.g., as part of the water inlet module), the incorporated filtration system provides filtration capacity within the modular underground water management system. Consequently, there is no need for a separate pre-filtration system located outside the system. Thus, the ability to incorporate filtration systems can reduce space demands, reduce construction costs, and simplify maintenance procedures.

A. Filter baskets

[0132] A "filter basket" (also referred to herein as a "basket filter") is a filter that captures coarse debris and gross pollutants, e.g., coarse sediment, trash, oils. In one embodiment, the

® filter basket is a drop-in style filter that is removable, such as the FloGard+PLUS multipurpose catch basin insert designed to capture sediment, debris, trash & oils/grease from low (first flush) flows (Kristar Enterprises, Inc.; Santa Rosa, CA).

[0133] Typically, a filter basket for coarse debris is installed in an assembly of modular units under the water flow inlet to the system. Figure 8 illustrates schematically one embodiment

of a water management system comprising an assembly of modular units with a filter basket installed in a single module at the inlet for pre-filtration of coarse sediment, trash and debris. Water flows into the top modular unit of the three unit stack via an inlet pipe fit to a side face opening on the exterior of the assembly. The removable filter basket is fit in the bottom face opening of the top modular unit to which the inlet pipe is connected. The three other side face openings are fitted of this top modular unit are fitted with grated (or perforated) cover panel, thereby channeling the flow through the basket filter. All other modular units inside the assembly have their internal facing side face openings fully open. This inlet modular unit of the assembly thereby forms an "inlet bay" for the whole retention/detention system.

[0134] In the embodiment of Figure 8, the exterior facing side face opening is not shown but would typically have solid cover panels, or grated cover panels if it is desired to allow water to percolate back into the soil. Also, not shown, the exterior of the assembly may be wrapped in a geotextile during excavation (described herein).

[0135] As depicted in Figure 8, in some embodiments, the filter basket is removable and includes a circular rim is supported by a flange that extends into the opening between the top two modular units. The flange can be provided by a stacking coupler joining the two units (see e.g., Figure 3), or can be integral to the module opening. In one alternative embodiment, a modular unit may be provided with an integral (i.e., built-in) filter basket in the bottom face opening.

[0136] In one embodiment, the modular units used to hold the filter baskets (or other filters) are fabricated out of a brightly colored material that allows them to be easily identified during assembly of the water management system.

[0137] Although not depicted in Figure 8, the top face opening of the top modular unit may be provided with a top cover panel comprising an access port (see e.g., Figure 4C and D) in order access to maintain and/or replace the filter basket as necessary.

[0138] In alternative embodiments, a filter basket may be fit in lower modules of an assembly, for example, just before an outlet pipe.

[0139] Figure 9 illustrates another embodiment of a filter basket incorporated into an

assembly of modular units. In this embodiment, a top "row" of four modular units opposite the inlet pipe are left open so as to create an extended inlet bay able to accommodate higher in flow rates. In one embodiment, it is contemplated that all four modular units in the row would have removable filter baskets installed in their lower openings.

[0140] Figure 10 illustrates another embodiment of a filter basket incorporated into an assembly of modular units. As in the embodiment of Figure 9, a top "row" of four units are left open to the inlet pipe, but have solid cover panels over their side and bottom face openings, except for the last modular unit in the row, to which a high flow bypass outlet pipe is connected. This configuration provides coarse debris filtration in normal flow situation with a bypass for high-flow storm situations. Thus, a separate zone with different water flow characteristics has been defined by the use of cover panels on the top row of the assembly.

[0141] In other embodiments of the water management system, multiple filter baskets may be installed in an assembly of modular units. For example, one may install a series of two or more filter baskets with increasingly fine levels of filtration. Thus, coarse debris and trash would be captured by the first filter basket (e.g., a chain or metal screen type filter) and finer sediment and/or oil would be captured by the second filter basket (e.g., a geotextile liner material filter and/or optional media pouches). Clip-in filter pouches containing

TM hydrocarbon capturing media, e.g., Fossil Rock media pouches (Kristar Enterprises, Inc.; Santa Rosa, CA) can also be included in the filter basket.

B. Media filters

[0142] A "media filter" contains filtering media designed to capture very fine sediments (typically less than about 100 μm), nutrients, metals, oils and grease, organics and bacteria. The media used in the media filter can be customized to target specific pollutants and/or meet site specific pollutant removal criteria. The ordinary artisan will recognize that a wide range of media are available and can be used in the media filter applications of the present invention.

[0143] Figure 11 illustrates schematically two embodiments of media filter cartridges. Figure 11A depicts a typical "radial media filter cartridge design." The cartridge is substantially cylindrical in shape and water flow enters the filtering media through the

radially positioned inlet screen. The treated water exits at the center of the bottom through an outlet port. There is a bypass port at the top of the cartridge to accommodate high flow situations.

[0144] Figure HB illustrates schematically one embodiment of a vertical media filter cartridge. The vertical media filter is a removable cartridge that includes an optional angled (or domed) pre-filter screen inlet on the cartridge's bottom that acts as a pre-filter for large debris that can foul or plug the media filter cartridge. The water flows in an upward direction through the media cartridge and out the top.

[0145] Figure 12 illustrates schematically one embodiment of a water management system comprising an assembly of modular units with a vertical media filter cartridge for pre-treatment of the water for specific pollutants, very fine sediment, and/or whatever the media is selected to filter, prior to entering the larger water retention/detention system. In this embodiment, water flows into the bottom modular unit of the three unit stack via an inlet pipe fit to a side face opening of the bottom unit. The vertical media filter is fit in the bottom face opening of the top modular unit, and as shown in the Figure 12, spans the middle unit of the stack so that its prefilter screen extends through the top face opening of the bottom modular unit.

[0146] In order to allow the upward flow through the media filter, the side face openings in the lower two modular units are plugged with solid cover panels. There is also a high-flow bypass on the pipe directly into the side face opening of the top modular unit, and all three interior side face openings of the top unit are fully open to the rest of the assembly.

[0147] In normal flow situations, water flow is directed upward through the vertical media filter into the top modular unit and out one or more of the side face openings of the top unit, and into the rest of the water retention/detention system. In high flow situations a port into a side face opening of the top unit allows the water flow to bypass the media filter and flow directly through the top modular unit.

[0148] In some embodiments, an impermeable liner may also be wrapped around the three unit inlet stack to provide additional protection against unfϊltered water leakage into the rest of the assembly resulting in contamination.

[0149] Figure 13 illustrates schematically a blow-out side-view of the embodiment of Figure 12 that shows that the top face opening of the top modular unit includes an access cover on top of a riser module that provides a port for accessing and maintaining the vertical media filter cartridge. There is also an optional inlet pipe clean-out access provided.

[0150] In one embodiment, a modular unit may be designed with the pre-filter inlet screen for a vertical media filter cartridge integrally attached to the top face opening of the unit. This integral pre-filter screen would also act as the housing for a removable vertical media filter cartridge, which would fit and lock into the integral pre-filter screen. In one embodiment, the vertical media-filter adapted modular unit would be fabricated in a different brightly colored material in order to facilitate its identification and proper placement in an assembly of modular units.

[0151] Figure 14 illustrates schematically one embodiment of a water management system comprising an assembly of modular units with an inlet bay comprising a pair of radial media filter cartridge for pre-treatment of the water. The inlet bay comprises the inlet pipe modular unit and two adjacent modular units on either side, each having a radial media filter installed in its bottom face opening. For all three units of the inlet bay, the side face openings facing the interior of the assembly are closed with solid cover panels, thereby isolating the inlet water so that it must pass through the filters. Thus, the inlet bay defines a separate zone with different water flow and filtration characteristics than the interior of the rest of the assembly in which all of the units are left open.

[0152] Additionally, the middle unit without the filter has perforated cover panels on its side face openings facing the filter modules thereby limiting the flow and acting as a pre-filter for coarse debris and floatables. As shown in Figure 15, the embodiment can be modified to create an additional inlet "sump" module beneath the inlet pipe to better capture coarse debris and sediment and prevent clogging of the radial media filters.

[0153] Unlike the vertical media filter systems which require upward flow of water, water flows from the inlet pipe into the middle modular unit, through the perforated panels and then must pass through the radial media filters before entering the rest of the retention/detention system. In high flow situations, the bypass inlet at the top of the radial media cartridges allows flow into the system without filtration.

[0154] Although not shown in Figures 14 and 15, it is contemplated that access ports would be provided through the top face opening of the three inlet bay modular units thereby facilitating maintenance of the filter cartridges and/or the sump modules.

C. Sand filter

[0155] Figure 16 illustrates schematically one embodiment of a water management system comprising a sand filter. In this embodiment, water drains into a grated cover on the top face opening of the top modular unit in a two unit stack. The top unit is filled with approximately 18" of filter sand held above the bottom face opening by a removable mesh screen. Additionally, a pipe with an opening above the surface of the sand filter bed provides a high flow bypass out of a side face opening of the top modular unit. An optional PVC riser module above the top face opening of the top modular unit can provide further access space if desired (e.g., an additional 18" of height).

[0156] Water flowing through the grated access cover (e.g., from a downspout) flows into the sand filter. After passing through the sand filter the water enters the bottom modular unit. The bottom unit typically has a single outflow pipe through a side face opening. The side and bottom face openings of the bottom unit can be closed or optionally opened. In the embodiment shown in Figure 16, the bottom face opening of the two unit stack is grated and placed above a base of drain rock surrounded by filter fabric. The system thereby provides sand filtering of drain water with some retention and some percolation into the underlying soil.

IV. Underground Water Management Systems

A. Excavation and installation

[0157] Typical underground water management applications begin by creating an excavation to a desired dimension, e.g., based on the water storage requirements for the project and/or the available "footprint" on the site. The modular nature of the present invention provides a variety of design options for systems. Generally, it is contemplated that the dimensions and/or structural configuration underground water management systems constructed using assemblies of modular units can vary dependent on one or more design factors including but not limited to: desired overall size of the assembly, desired load-bearing tolerance for

assembly, desired amount of water flow to be managed, number and location of inlet and outlet pipes, number and location of pre-treatment zones and filtration systems, and/or the desired access space for inspection and maintenance purposes.

[0158] For example, a single layer of connected modular units may be installed where a wider surface area is available but depth of excavation is limited. Alternatively, stacks of 3 or 4 modular units may be joined (e.g., as a 3x3x3 cube) to provide a greater volume where a larger surface footprint is not possible but a deeper excavation is. Further, due to their higher interior volume, the assemblies of connected modular unit stacks can be designed with surface ports (e.g., manholes) that provide access for maintenance and/or cleaning (e.g., changing filters).

[0159] In some embodiments, the modular units are assembled into customized shapes combining single layers, with stacks, and other multi-modular unit assemblies as necessary to fit the available excavation site.

[0160] Similarly, the relatively lightweight modular nature of the systems provides different options for installation methods. A system comprising an assembly of modular units may be constructed above-ground then inserted as a whole unit into the excavation. Alternatively, the system may be completely or partially assembled in the excavation.

[0161] Depending on the water management application (e.g., stormwater retention or detention), either a filter cloth or plastic (e.g., PVC) liner is placed beneath and around the assembly of modular units, thereby forming a semi-permeable or completely water impermeable envelope around the entire system. Typically, prior to sealing an assembly in a liner, side plugs (solid or grated), may be placed in the modular unit openings where desired around the assembly.

[0162] As described above, appropriate inlet and/or outlet pipe may be fit to the top, bottom, or side face openings on the exterior of the modular units. Because openings are available everywhere on the assembly of the modular units, piping into and out is not limited to any specific side of the assembly. In one embodiment, cuts are made in the liner to allow the pipes access.

[0163] After installation of the modular unit assembly and appropriate piping in an

excavation backfill material can be placed around and over the system. To enhance the load carrying capacity of the installed system, geo-grid or other suitable solid stabilization material may be installed on the top or bottom sides of the system.

B. Water retention/detention system with multiple inlet ports

[0164] Underground water management systems based on assemblies of modular units of the present invention provide the ability to accept water flow for filtration, retention/and or detention into a single assembly from a plurality of different sources (and directions). Generally, the filtration systems (e.g., filter basket or media filter) may be located in any modular unit around the exterior sides (i.e., the "walls") of the assembly. This ability to locate the filtration system(s) in close proximity to each of several inlet pipes eliminates the need to construct multiple (or one central) pre-treatment device outside the boundaries of the assembly. This greatly reduces the cost and difficulties of piping and construction.

[0165] Figure 17 illustrates schematically an overhead plan view of one embodiment of a water management system comprising an assembly of modular units with a plurality of inlets and filter module assemblies. The overall assembly comprises an 8x8 assembly of modular units in 2, 3, or 4 unit stacks. Inlet pipes are fitted to the side face openings of four modular units on the top outer edge of the assembly. Each of these inlet modular units includes an access opening and a filtration system. Any of the filtration system embodiments described above (and depicted in Figures 8-15 can be adapted to this assembly configuration.

[0166] Thus, water from four different inlet pipes can be pre-filtered for coarse debris (e.g., using a filter basket) or for specific pollutants (e.g., using a media filter) before being detained in the interior volumes of the 8x8 assembly.

[0167] In some embodiments, the 8x8 assembly is surrounded by an impermeable liner and the pre-filtered water is detained and then released only through the outlet pipe. In other embodiments, the liner may be semi-permeable so that the water can percolate into the surrounding soil.

C. System with separate inlet bay zone for media filtration

[0168] The ability to create separate zones and control the water flow characteristics within an assembly of modular units provides a distinct advantage over underground water

management systems wherein water flow inside the system is unrestricted. Such systems typically comprise a lattice or web-like structure (e.g., "stacked milk-crate-like" assemblies) through which water flows freely in all directions and generally can only function as retention/detention reservoirs or chambers. It may be possible to install plastic liners to act as boundaries within such systems, but generally, internal installation of such a plastic liner is cumbersome, can interfere with the structural connections (thereby weakening the structure) and overall very limited in the types of customized internal zones it can be used to make.

[0169] Alternatively, an impermeable plastic liner can be used to isolate groups of modular units in an assembly thereby allowing the creation of different water treatment zones within a single assembly. For example, vertical media filtration systems (as shown above in e.g., Figure 13) that are part of a larger assembly can be wrapped in a plastic liner, with appropriate holes cut, and fitted with an appropriate outlet pipe into an adjacent volume of the assembly.

[0170] In some embodiments, a plastic liner can be inserted at the interfaces between adjacent modular units to create isolated zones. The insertion of material at an interface, however, can interfere with the use of vertical or lateral couplers, possibly resulting in decreased overall load bearing strength of the assembly.

[0171] Figure 18 illustrates schematically a blow-out overhead view of one embodiment of a water management system comprising a plurality of water treatment zones. The first zone is an inlet bay that comprises a water flow inlet into a detention area surrounded by "walls" comprising stacks of modular units. Three of the walls of the inlet comprise stacks of modular units that include a removable vertical media filter cartridge, e.g., in an up-flow configuration similar to that shown in Figures 12 and 13. The three walls of the inlet bay with vertical media filters abut an outlet zone comprising a larger assembly of modular units. In this embodiment, the water flows through the inlet pipe into the inlet bay where it is detained until it passes through the media filters in the three walls and into the outlet zone. The modular units in the walls of the inlet bay have solid cover panels over all of their exterior facing openings in order to prevent leakage of unfiltered water out of the assembly. Additionally, the modules in the inlet bay zone can be surrounded by a water impermeable material (e.g., PVC plastic liner).

[0172] The outlet zone includes an outlet pipe, typically adapted to a lower unit side face opening. Typically, the outlet zone typically would be surrounded by an impermeable material to prevent dirt and sediment from entering the filter treated water. However, in some embodiments, only a semi-permeable geotextile may be surrounding the outlet zone and the filter treated water is allowed to percolate back into the surrounding soil.

[0173] Figure 19 illustrates schematically a blow-out side view of the assembly of Figure 18 and further depicts the access ports provided above the top modular units having the vertical media filters.

D. Outlet flow control

[0174] Figure 20 illustrates schematically one embodiment of an outlet flow control system integrated into an assembly of modular units with a filter basket at the inlet similar to the embodiments described above and depicted in Figures 8-10. The assembly is installed in an excavation with an impermeable liner around the exterior and/or with all exterior facing openings plugged (e.g., with solid cover panels). Water flow out of the system is provided by a single outlet pipe at the base of the assembly. The outlet pipe is of an outside diameter that fits within the openings of the modular unit and is "sleeved" into through the side face openings of a row of four modular units along the base of the cube assembly. The end of the outlet pipe inside the assembly is capped. Additionally, the end of the outlet pipe is snugly fit where it extends outside the assembly to prevent leakage. The portion of the pipe inside the assembly includes perforations along its length that allow water in the assembly to leak into it. By varying the number of perforations accordingly, the water retained in the assembly (e.g., after a storm flow) is allowed to leak into the pipe at a metered rate and thereby is released out of the assembly at that rate.

[0175] In a further modification of the embodiment depicted in Figure 20, a riser pipe may be coupled to the outlet pipe inside the assembly and sleeved vertically through 1, 2, or 3 modular unit openings. The open top end of the riser pipe thereby provides an internal high flow bypass to the outlet pipe.

[0176] The above disclosure is sufficient to enable one of ordinary skill in the art to practice the invention, and provides the best mode of practicing the invention presently contemplated by the inventor. While there is provided herein a full and complete disclosure of specific

embodiments of this invention, it is not desired to limit the invention to the exact construction, dimensional relationships, and operation shown and described. 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.