Abstract:
A stormwater control system including conveyance, filtration and discharge systems. The conveyance system includes a set of conduits and connections providing a flow path through a compacted soil embankment from an upper inlet to a lower discharge area of an underlying soil infiltration zone. The control system has configurations for transferring stormwater from pervious and impervious surfaces to the soil infiltration zone. The control system optionally includes a media filter device that may be installed within the conveyance system to intercept sediment and other contaminants prior to discharge within the underlying soil infiltration zone.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to the control and treatment of stormwater prior to discharge to localized infiltration zone soils. More particularly, the present invention relates to a system for diverting stormwater through compacted soil fill material to the infiltration zone soils. 
     2. Description of the Prior Art 
     Stormwater is rainwater that when falling on a developed environment will most often collect contaminants from the built surfaces and subsequently carry these unwanted contaminants to streams and lakes. Controlling stormwater runoff from a developed property has traditionally involved the use of systems of catch basins and pipes to catch and convey the water to centralized areas for storage and or treatment prior to discharging to either the ground or to a downstream surface water body. Although the main goals for using these traditional stormwater control systems is the prevention of flooding of downstream properties, reducing erosion of creeks and attempting to maintain water quality, the level of success in meeting these goals has been questioned. 
     Relatively recently, the idea that not focusing the stormwater to centralized storage and treatment areas, but instead treating and discharging the stormwater nearer to where it falls from the sky is gaining support. These new ideas and the associated techniques to implement these ideas are today called Low Impact Development (LID). 
     The use of porous pavement and related surfaces is one of these LID techniques that has gained acceptance as a storm control system. An alternative to catching and focusing rainwater toward centralized areas, the use of porous surfaces allows the water to soak into the existing soils approximately at the same location where the raindrop first hits the ground surface. The intent is that the water does not runoff the developed surfaces and therefore is not focused to centralized areas. The rainwater instead continues to follow the same approximate subsurface flow path after development as it did prior to development. This same idea can be achieved using traditional impermeable surfaces if multiple inlets are placed throughout the surface in a manner not generally recognized in current design technology. 
     At this time given the current technology, a significant limitation to these practices associated with the use of these porous surfaces for stormwater control purposes exists. In areas where compacted soil fill embankments are required based on existing topographic and/or other conditions, the use of porous surfaces may not be compatible. This is due to the fact that a compacted soil fill embankment that is constructed between the built porous surface and the existing ground soils essentially blocks the hydraulic connection between these surfaces and thus inhibits the water from traveling vertically downward as needed. On this basis, it is currently recognized that porous pavements sections and related surfaces should not be constructed over significant compacted soil fill embankment areas. Therefore, the current invention is needed. 
     Another recognized problem associated with the stormwater contacting the built surfaces is water quality degradation. Therefore, prior to allowing discharge of the water to native soils for infiltration or discharge to downstream water bodies it must be treated or filtered. Traditionally the use of centralized storage and treatment facilities has complicated this issue more as higher flows must be treated. In addition, filter systems presently used are centralized substantial structures. They include a plurality of individual filter assemblies in one or a very few common locations for a large developed property, for example. The failure or blockage of just a few of the assemblies, as well as regular maintenance, requires the shutdown of the centralized system, thereby exposing a substantial portion of the developed property to the generation of untreated stormwater. 
     What is needed is a stormwater control system suitable for use with pervious built surfaces or impervious built surfaces located over compacted fill material including, but not limited to, soil fill material. What is also needed is such a control system that transfers the stormwater to underlying local native infiltration zone soils. Further, what is needed is such a system that may also include a filter device that is localized rather than centralized. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a stormwater control system and related method suitable for handling stormwater on pervious built surfaces or impervious built surfaces located over compacted soil fill material. It is also an object of the present invention to provide such a control system that transfers the stormwater to underlying local native infiltration zone soils. Further, it is an object of the present invention to provide a stormwater control system that optionally includes a filter device that is localized rather than centralized. 
     These and other objects are achieved with the present invention, which is a total drainage system and method that facilitates the hydraulic connection between built pervious or impervious surfaces and the underlying native infiltration zone soils has been proposed. Rainwater falls onto the surface and is relatively immediately conveyed and discharged to the underlying soils in the local general area and not sent to a centralized area. Localized filters are installed if desired within standpipes of the system to remove sediment and pollutants from the water as it passes from the built surface to the soil. Given the relatively small amount of surface area delivered to any single filter, the treatment flows and requirements are simplified and the filters are more compact and easier to manage in regards to installation and maintenance. 
     It is an aspect of the present invention to provide a system apparatus and method to convey stormwater from the built surface generally downward through a compacted fill soil to the infiltration zone soils located near and below where the rainwater first contacted the ground. It is another aspect of the invention to provide a system apparatus to discretely or non-discretely discharge stormwater into infiltration zone soils in a manner similar to the natural pre-developed condition thus limiting focusing of stormwater to any single infiltration zone soil. 
     It is still another aspect of the invention to provide a system apparatus to catch stormwater flowing through a built porous surface and convey the water generally downward through a compacted fill soil embankment to the infiltration zone soils located near and below where the rainwater first contacted the ground. 
     It is a further aspect of the invention to provide a means to backflow and clean clogged built porous surfaces by hydrostatically forcing water backwards through the porous surface. 
     It is still another aspect of the invention to provide a system apparatus to catch stormwater within open inlets located on the surface of the built impervious surface or in depressed basins constructed within the built impervious surface. 
     It is a further aspect of the invention to provide an optional apparatus to filter contaminants from the stormwater prior to discharging the water to the infiltration zone soils, wherein the filter apparatus includes at least one filter device for each standpipe. The filter device may be an active device, a passive device, a device treated to attract contaminants of interest, a miniaturized version of conventional filter cartridge assemblies, other types of high surface area retention means, such as string or strand sets positionable within the fluid flow path, or any other type of filter device suitable for insertion into a standpipe and configured to remove particulate and other contaminants of a type and size of interest with minimal adverse impact on the flow of stormwater through the standpipe. 
     It is still another aspect of the invention to provide a system apparatus that allows catchment of stormwater before focusing and merging with other stormwater thus minimizing the magnitude of water quantity to be conveyed, treated and discharged. 
     In one embodiment of the invention suitable for use with a pervious surface, the stormwater control system includes a first array of porous pipes positioned below and substantially parallel with the surface, a standpipe structure coupled to the array of porous pipes and passing through material, including but not limited to, a compacted fill embankment, and a second array of porous pipes positioned between the material and the infiltration zone soil and substantially parallel with that soil. The optional filter assemblies may be included one for each standpipe structure but not limited thereto. A secondary conduit may extend from the standpipe structure to operate as a hydraulic grade line control, whether for the control system is used for a pervious surface or an impervious surface. 
     In another embodiment of the invention suitable for use with an impervious surface, the stormwater control system includes a plurality of catch basins, a standpipe structure passing through material, including but not limited to, a compacted soil fill embankment, and connected directly or indirectly through an array of conduits to the catch basins and an array of porous pipes positioned between the material and the infiltration zone soil and substantially parallel with that soil. A filter may or may not be included in one or more portions of the standpipe structure. The secondary conduit may extend from the standpipe structure to operate as a hydraulic grade line control in this embodiment of the invention. 
     In one or more embodiments, the system includes filter fabrics adjacent to the porous pipes to capture particulates that would otherwise pass into the material underlying the surface and/or the infiltration zone soil. The system may optionally include a mechanism for backflushing the system including the perforated pipes of the perforated pipe array. Further, the system including a filter in the standpipe structure may optionally include a siphon mechanism within the filter to enhance filter operation if desired. 
     The stormwater control system includes a conduit providing fluid communication between an upper inlet area through a compacted fill embankment to the lower discharge area within the underlying soil infiltration zone. That conduit is also referred to herein as a standpipe structure, which standpipe structure may also include the optional filter. The filter may be positioned so that it is accessible for maintenance, including replacement, from the built ground surface through a removable cover. The stormwater control system may be used with pervious and impervious surfaces. The upper inlet area includes an array of perforated conduits for the pervious surface stormwater control. The system may include a means to clean porous built surfaces by fluid pressurizing the perforated conduits, wherein voids below the porous built surface are then pressurized resulting in an upwards flow of water (backwash) to dislodge sediment and other materials deposited and potentially blocking the voids contained within the upper porous built surface. 
     The stormwater control system and related method of the present invention enable removal of water and entrained particulates from pervious and impervious surfaces and transfers the water to the local infiltration soil zone, including local infiltration zones underlying compacted fill, such as compacted fill soils, but not limited thereto. These and other advantages of the invention will become more apparent upon reviewing the following detailed description, the accompanying drawings and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a section elevation view of a first embodiment of the system of the present invention located under a built pervious surface. 
         FIG. 2  is a section elevation view of the first embodiment of the system including an optional filter cartridge assembly installed within the standpipe. 
         FIG. 3  is a wider section elevation view of the first embodiment of the system including the optional filter cartridge assembly. 
         FIG. 4A  is a plan view of the wider section of a first arrangement of the first embodiment of the invention showing portions of the system, and  FIG. 4B  is a plan view of the wider section of a second arrangement of the first embodiment of the invention showing portions of the system. 
         FIG. 5  is a section elevation view of a second embodiment of the system of the present invention located under a built impervious surface with a crowned sloped surface section and including an optional filter cartridge assembly installed within the standpipe. 
         FIG. 6  is a section elevation view of an alternative version of the second embodiment of the system located under a built impervious surface with a cross sloped surface section including the optional filter cartridge assembly and showing an optional cartridge insertion and retrieval attachment. 
         FIG. 7  is a wider section elevation view of the version of the second embodiment of the system of the present invention shown in  FIG. 7 . 
         FIG. 8A  is a plan view of the wider section version of a second arrangement of the second embodiment of the invention showing portions of the system, and  FIG. 8B  is a plan view of the wider section version of a second arrangement of the second embodiment of the invention showing portions of the system. 
         FIG. 9  is a partial cutaway perspective view of an embodiment of a standpipe with filter cartridge assembly installed. 
         FIG. 10  is a section elevation view of the embodiment of the standpipe with filter cartridge assembly shown in  FIG. 9 . 
         FIG. 11  is a partial cutaway perspective view of an embodiment of a filter cartridge assembly showing the handle and support shaft. 
         FIG. 12  is a section elevation view of an embodiment of a standpipe with added appendage piping for a filter cartridge assembly installed with alternative outlet assembly including siphon. 
         FIG. 13  is a section elevation view of the system of the present invention including a mechanism for back-flushing the system. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A first embodiment of the present invention is stormwater control system  10  shown in  FIGS. 1-4B . The stormwater control system  10  is used to transfer liquid from pervious surface  12  to infiltration zone soil  14  located under the pervious surface  12  for the situation in which relatively non-absorbing material, such as compacted fill embankment material  16 , such as compacted soil fill but not limited thereto, is located between the surface  12  and infiltration zone soil  14 . The stormwater control system  10  is configured to ensure that liquid on the surface  12  is managed locally in the vicinity of where it exists rather being transfer to a remote liquid handling system, such as a municipal conveyance or treatment facility. It is to be understood that the infiltration zone soil  14  is configured in a manner known to those of skill in the art to handle anticipated stormwater runoff conditions. For purposes of describing the present invention, compacted fill embankment  16  refers to any change made to the elevation of a built surface relative to the existing grade where the compacted material is anything other than undisturbed native soil. 
     The control system  10  includes a first grid  20  of stormwater receiving pipes, one or more standpipes  22  and a second grid of stormwater delivery pipes  24 . The receiving pipes of first grid  20  and the delivery pipes of second grid  24  may be of the same type. The pipes are arranged to enable fluid to enter and/or exit along their lengths through perforations  21  rather than solely at their ends. Perforated pipes have been determined to be suitable for that purpose. The first grid  20  and the second grid  24  may be aligned approximately in parallel with one another but not limited thereto. The first grid  20  and the second grid  24  may be aligned approximately in parallel with either or both of the surface  12  and the soil  14  but not limited thereto. The pipes of the second grid  24  include one or more receiving ports  25  coupled to the standpipes  22  for the purpose of receiving stormwater therefrom. 
     The standpipes  22  are generally configured to provide conduits to pass stormwater from the first grid  20  to the second grid  24 . The standpipes  22  are aligned approximately orthogonally with respect to the orientation of the surface  12  but not limited thereto. The standpipes  22  may be accessed from the surface  12  by way of one or more access ports  26  that may simply be holes with cleanout covers  28  or they may be incorporated into one or more catch basins. The cleanout covers  28  are sealable with traffic bearing capacity. The system  10  may further optionally include a first array of filter material, such as first filter fabric  30 , positioned below and adjacent to the first grid  20  of pipes with respect to the surface  12  to trap any fine particulates that may pass through the pipes to the compacted soil fill material  16 , and a second array of filter material, such as second filter fabric  32 , positioned above and adjacent to the second grid  24  of pipes with respect to the surface  12  to limit the introduction of fine particulates into the second grid  24  from the compacted soil fill material  16 . 
     In operation, the system  10  functions as follows. Stormwater permeating through the surface  12  enters the first grid  20  of pipes and flows into the standpipes  22 . It is then conveyed through the compacted fill material  16  by way of the standpipes  22  to the second grid  24  of pipes and then discharges into the infiltration zone soils  14 . 
     Optionally, the system  10  may include for each of the standpipes  22  at least one filter device, such as a filter cartridge assembly  34 , as shown in  FIGS. 3 and 4 . The filter cartridge assembly  34  is configured to intercept and retain contaminants, such as sediments and chemicals, mixing with the stormwater as it flows on the surface  12 . A miniaturized version of stormwater filter cartridge assemblies have been determined to be suitable for that purpose. The inclusion of the filter cartridge assembly  34  in each of the standpipes  22  localized the filter function, making it easier to complete installation and maintenance functions with minimal impact on the operation of other standpipes  22 . The filter cartridge assembly  34  may be of any design suitable for the indicated purpose and arranged to fit within the dimensions of the standpipes  22  as determined by the particular stormwater control application. 
     It can be seen in  FIGS. 4A and 4B , that either or both of the first grid  20  and the second grid  24  may be arranged in any one or more of orthogonal, parallel and diagonal orientations. Further, the standpipes  22  may be interconnected, including in parallel, orthogonally and/or diagonally. 
     A second embodiment of the present invention is stormwater control system  100  is shown in  FIGS. 5-8B , with  FIGS. 6 and 7  showing a second version of the second embodiment. The stormwater control system  100  is used to transfer liquid from impervious crowned sloped surface  102  with roadside curbs  103  to the infiltration zone soil  14  located under the impervious surface  102  for the situation in which the relatively non-absorbing material, such as compacted fill embankment material  16 , is located between the surface  102  and the infiltration zone soil  14 . The stormwater control system  100  is configured to ensure that liquid on the surface  102  is managed locally in the vicinity of where it exists rather being transfer to a remote liquid handling system, such as a municipal treatment facility. It is to be understood that the infiltration zone soil  14  is configured in a manner known to those of skill in the art to handle anticipated stormwater runoff conditions. 
     The control system  100  includes an array of catch basins  104 , an array of catch basin conduits  106 , one or more standpipes  108  and a grid of stormwater delivery pipes  110 . The catch basins  104  are configured to receive stormwater that flows across the impervious surface  102  and may be configured in a manner known to those of skill in the art as similar to smaller versions of the types of catch basins used in typical stormwater control systems forming part of larger municipal stormwater control systems. They may include typical oil-water separators. The catch basins  104  are connected to the conduits  106 , which are arranged to receive the stormwater from the catch basins  104  and transfer it to the one or more standpipes  108 . The standpipes  108  are arranged to transfer the stormwater to the delivery pipes  110 . The delivery pipes  110  include one or more receiving ports  112  coupled to the standpipes  108  for the purpose of receiving stormwater therefrom. The delivery pipes  110  are arranged to enable fluid to exit along their lengths rather than solely at their ends. Perforated pipes have been determined to be suitable for that purpose. The basin conduits  106  and the grid of delivery pipes  110  may be aligned approximately in parallel with one another but not limited thereto. The basin conduits  106  and the delivery pipes  110  may be aligned approximately in parallel with either or both of the surface  102  and the soil  14  but not limited thereto. 
     The standpipes  108  are generally configured to provide means to pass stormwater from the basin conduits  106  to the delivery pipes  110 . The standpipes  108  are aligned approximately orthogonally with respect to the orientation of the surface  102  but not limited thereto. The standpipes  108  may be accessed from the surface  102  by way of one or more access ports  114  that may simply be holes with cleanout covers  28  or they may be incorporated into one or more catch basins similar to the catch basins  102 . The cleanout covers  28  are sealable with traffic bearing capacity. The system  10  may further optionally include an array of filter material  116 , such as a filter fabric, positioned above and adjacent to the delivery pipes  110  with respect to the surface  102  to limit the introduction of fine particulates into the delivery pipes  110  from the compacted material  16 . 
     In operation, the system  100  functions as follows. Stormwater running across the surface  102  enters the catch basins  104  and flows to the basin conduits  106  for transfer to the standpipes  108 . It is then conveyed through the compacted fill embankment  16  by way of the standpipes  108  to the delivery pipes  110  from where it discharges into the infiltration zone soils  14 . 
     Optionally, the system  100  may include for each of the standpipes  108  at least one filter cartridge assembly  34 . As indicated with regard to the control system  10  of the present invention, the filter cartridge assembly  34  is configured to intercept and retain contaminants, such as sediments and chemicals, mixing with the stormwater as it flows on the surface  102 . The filter cartridge assembly  34  may be of any design suitable for the indicated purpose and arranged to fit within the dimensions of the standpipes  108  as determined by the particular stormwater control application. 
     The control system  100  may further include one or more hydraulic grade line conduits  118  coupled to the standpipe  108  and configured to control hydraulic head within the system  100 . When the control system  100  is located on a slope, the hydraulic buildup in the drainage rock zone could create an undesired slide potential in an adjacent area. The use of the grade line conduits  118  ensures that when the hydraulic pressure within the system  100  reaches a certain level, the stormwater within the standpipe  108  will divert through the conduits  118  to another location. In one example, a plurality of conduits  118  may be linked together to ensure that the hydraulic pressure does not exceed a selectable level for a relatively wide area. It is to be noted that the conduits  118  may also be employed with the system  10  used in association with the pervious surface. Additionally, for system  100 , one or more of the catch basins  104  may include a basin overflow conduit  120  for the purpose of enabling direct stormwater discharge to a larger control system as needed under certain limited conditions of rare storm events. 
     As indicated,  FIGS. 6 and 7  show a second version of the system  100 ′ configured for a cross sloped surface  102 ′. The system  100 ′ includes the standpipe  108  directly joined to the catch basin  104  so that there is no need for the basin conduit  106  interface that forms part of system  100  of  FIGS. 5 and 6 . As also shown in  FIG. 7 , the filter cartridge assembly  34  includes an inverted elbow  35  used as an oil-water separator device. That is, the inverted elbow  35  acts to block oil and other coarse lighter-than-water contaminants resting on the surface of the stormwater from entering the standpipe  108 . The inverted elbow is also optionally fabricated with sufficient structural integrity to act as a grab bar to allow ease of access to the filter cartridge assembly  34  for maintenance thereof when recessed within the standpipe  108 . The inverted elbow  35  may be metallic or nonmetallic and is shown represented as a curved bar but is not limited thereto. The inverted elbow  35  is fabricated with sufficient strength to support the filter cartridge assembly  34  and to withstand the environment within the catch basin  104 . The inverted elbow  35  may be employed with any cartridge filter assembly  34  described in all embodiments of the system of the present invention. 
     It can be seen in  FIGS. 8A and 8B  that one or more of the basin conduits  106 , delivery pipes  110  and conduits  118  may be arranged in any one or more of orthogonal, parallel and diagonal orientations. Further, the standpipes  108  and associated catch basins  104  may be interconnected, including in parallel, orthogonally and/or diagonally. 
     For those versions and embodiments of the present invention including the optional filter device such as filter cartridge assembly  34 , an example of a suitable form of the assembly  34  is shown in  FIGS. 9-11 . The assembly  34  is preferably gasketed to ensure that all water flowing into the standpipes  22 / 108  must pass through filter media  36  of the filter cartridge before transfer to the grid of delivery pipes below the compacted material. The assembly  34  includes the filter media  36  positionable within the standpipe  22 / 108 , an adjustable discharge cylinder  38 , a support base  40  and an adjustable handle  42 . While the assembly  34  is shown in the drawings as positioned under a cleanout cover  28 , it may also be used in a catch basin  104 . In operation, stormwater entering the standpipe  22 / 108  contacts the filter media  36  at upper standpipe region  44 . It passes through the filter media  36 , which collects particulates, and the filtered stormwater passes to inner drainage space  46  through inner drainage ports  48  of internal conduit  50 . It then moves from the inner drainage space  46  to lower standpipe region  52 . The filter media  36  is retained on support base  40  and if the stormwater level in the assembly  34  exceeds capacity, overflow not passing through the filter media  36  may pass into the internal conduit  50  through filter overflow port  54 . The filter device preferably substantially fills the standpipe  22 / 108  and further, optionally is sealed to the internal walls of the standpipe  22 / 108 . 
     An upper section of the adjustable handle  42  includes a grab ring  58  for ease of insertion and removal for maintenance. The handle  42  is adjustable to enable the user to position it within the standpipe  22 / 108  where desired. The handle  42  also includes a perimeter flange  60  that is arranged to sit on filter stop frame  62  associated with the standpipe  22 / 108 . 
     A modified design of a standpipe  200  of the type that includes a filter cartridge assembly  34  is shown in  FIG. 12 . The standpipe  200  includes upper region  202  of primary conduit  204  and lower region  206  of primary conduit  204  above and below, respectively, the filter cartridge assembly  34 . Additionally, the standpipe  200  includes a discharge overflow conduit  208  and a siphon tube  210 . The siphon tube  210  includes backup section  212  positionable within internal conduit  50  or combined as conduit  50  of the filter cartridge assembly  34 . The backup section  212  is arranged to receive water through port  214  that has entered internal conduit  50  after passing through filter media  36 . It is in fluid communication with siphon return section  216  that is, in turn, in fluid communication with backup section  212  by way of filter support section  218  that is fixed in place with respect to the filter cartridge assembly  34  by siphon tube alignment key  220 , which is preferably gasketed. The siphon tube  210  is arranged to siphon water from the internal conduit  50  in the standpipe  200  and deliver it to the lower region  206 . Weep holes  222  allow water to drain from the filter cartridge assembly  34 , causing the siphon to subsequently break. 
     As illustrated in  FIG. 13 , the embodiment of the system  10  to be used with the pervious surface  12  may include a back-flush system  300  to be used to maintain the system  10  and, in particular, to flush out voids of the surface  12 . The back-flush system  300  includes a standpipe plug  302  and a flush conduit  304 , which may be coupled to a water source, for each standpipe of the first grid  20 . The plug  302  is used for the purpose of preventing water flow from water source into the standpipes  22 . The plug may be fabricated of any material and shape suitable for substantially sealing the standpipes  22  and resisting dislodgement when subjected to sufficient back-flushing water pressure. When the water source is turned on, the water flows through the flush conduit  304  and is diverted into the receiving pipes of first grid  20 . The water is then forces outwardly through the perforations  21  and moves through gravel, crushed rock, etc. between the first grid  20  and the surface  12  before contacting the surface  12  and dislodging matter trapped in the voids of the pervious surface  12 . The back-flushing system  300  may also minimize blockage of the perforations  21  of the receiving pipes of the first grid  20  and thereby reduce maintenance obligations. 
     The present invention has been described with respect to specific embodiments and variations. Nevertheless, it is to be understood that various modifications may be made without departing from the spirit and scope of the invention. All equivalents are deemed to fall within the scope of this description of the invention as set out in the following claims.