Abstract:
A stormwater runoff treatment system that offers an economical means of achieving highly efficient, effective, and compact means of treating runoff through a unique method of flow restrictions, diversions, elevation differences and strategically located components to achieve a combination of treatment advantages.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to provisional application 61/769,994 filed on Feb. 27, 2013. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Stormwater runoff from impervious surfaces is a serious environmental problem due to the pollutants contained in the water and the additional volume of runoff that is created because the impervious surface no longer allows water to enter the ground. While the field is replete with technologies that clean or filter the water and some that attenuate or slow down the water, there are few that combine all of the above. 
         [0003]    The present invention is a unique method of treating and routing stormwater runoff that enables a highly efficient, effective, and compact means of treating the runoff. 
         [0004]    Stormwater runoff has a significant variation in intensity: from a light drizzle with virtually no measureable runoff to an extreme intensity localized thunderstorm with flash flooding runoff levels. To remove the level of pollutants required to meet today&#39;s regulations, filtration is most often required. 
         [0005]    With a filter having a limited flow rate, it takes a substantial filtration area to treat peak flows. The filtration area can be reduced by storing the water prior to filtration and filtering it over time. For example, storage and filtering over a 24 hour period. This storage and delayed release reduces the impacts of peak intensity storms and at the same time reduces the risk of downstream flooding 
         [0006]    In addition, with the focus on reduction of runoff through ground water replenishment or infiltration, water can be recharged through placing it in a stone pit or equivalent to allow it to percolate into the ground. However this also takes time. A very important element to the longevity of the recharge is that only clean water is recharged because the pollutants will quickly occlude the surface soils in the recharge area and diminish its effectiveness. 
       SUMMARY OF THE INVENTION 
       [0007]    The current invention offers an economical means of achieving all of the above through a unique method of flow restrictions, diversions, elevation differences and strategically located components to achieve a combination of treatment advantages. 
         [0008]    The stormwater treatment system performs as follows: Water enters the Flow Diversion (FD); initial flows are diverted to the Filtration Chamber/Filter Vault (FV). When the Filter Vault is full, the water level increases in height and enters the Extended Detention System (EDS). When the EDS is full, the water level increases to a higher elevation where it flows into a bypass outfall. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a top view of the treatment system as described herein. 
           [0010]      FIG. 2  is a side cross sectional view along line A-A of the treatment system of  FIG. 1 . 
           [0011]      FIG. 3  is a side cross sectional view along line B-B of the treatment system of  FIG. 1 . 
           [0012]      FIG. 4  is a side cross-sectional view along line C-C of the treatment system of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    As shown in  FIG. 1 , the stormwater treatment system  10  performs as follows: Water enters Flow Diversion Structure (FDS)  11 ; initial flows are diverted to the Filter Vault (FV)  12 . When the Filter Vault  12  is full, water increases in height and enters the Extended Detention System (EDS)  13 . When the Extended Detention System is full, the water level increases in height and is then diverted to a bypass outfall. 
         [0014]    As water enters the Filter Vault  12  it passes through the filtration device(s)  14  where the filter effluent can pass through have two outflow locations; a high flow  15  and low/restricted flow outflow  16 . The high flow outlet  15  is connected to an underdrain system  17  of the EDS  13  which has perforated pipe  18  or other open chambered collection system and a gravel or sand bottom. This becomes the recharge or infiltration location for the water to enter the ground. This is ideally located in an area where water will most likely percolate into the soils. 
         [0015]    The low flow outflow  16  has a flow restriction  19  in it which is sized to release the entire system capacity over a predetermined maximum period of time, for example 24 hours. The filter is able to flow because of head differential, so with the top of the storage in the infiltration stone at or below the maximum height of water in the filter vault the entire infiltration will be filled up with preferential flow as it is unrestricted. During this time a limited amount of water will be released through the flow restriction  19 . Optionally, there is a check valve  20  preventing the water from flowing back into the Filter Vault  12  and out the flow restriction. In some situations the check valve will not be necessary or desirable as the check valve will maximize the amount of water that infiltrates by preventing it from flowing back through the orifice. 
         [0016]    The connection between the Filter Vault  12  and the EDS  13  has a check valve  20   b  in it to prevent water that has entered the infiltration stone from flowing back out the orifice. As the water is filtered over time in the Filter Vault  12 , and the water level lowers, flap valve  20   a  will only open as the water level in the Filter Vault  12  becomes lower than the EDS  13 , at which time the water will flow into the Filter Vault  12  and be filtered. 
         [0017]      FIG. 2  shows a side cross sectional view along line A-A of the treatment system. On the right side of this figure, the Flow Diversion Structure  11  is shown. On the left side of this figure, the Extended Detention System  13  is shown. As shown, water enters the system through the FDS inlet, and initial flows are diverted to the FV. 
         [0018]      FIG. 3  shows a side cross sectional view along line B-B of the treatment system. As shown here, the line B-B makes a right angle turn to accommodate the schematic shown. However, it is understood that alternative embodiments and configurations may also be used advantageously with this invention. 
         [0019]      FIG. 4  shows a side cross sectional view along line C-C of the treatment system. A preferred embodiment of the underdrain system described herein is shown here. Persons with knowledge in the area of the invention would understand that other underdrain systems are also adaptable for use in this invention. 
         [0020]    By controlling the flow of stormwater runoff as shown and described—through the use of a series of check valves, orifices, and strategically located components—all water that is not bypassed is either filtered and recharged, or attenuated, filtered, and released. 
         [0021]    This configuration provides several substantial advantages over the prior art. For example, less storage is required, more volumes are filtered, more volumes are recharged, and the recharge occurs over a greater surface area. Furthermore, by incorporating the recharge under and/or around the EDS, the system is more economical to construct.