Abstract:
A water permeable dewatering bag for removing suspended solids from water, the bag having an open end that is sealed during the filtering operation but may be opened to remove collected solids after the filtering operation for reuse of the bag. The open is temporarily sealed using a clamping assembly such that the size of the bag may be adjusted as desired.

Description:
[0001]     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/600565, filed on Aug. 11, 2004. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     This invention relates generally to devices known as dewatering bags, gravity bag filters or sediment filter bags, all of which are devices used to remove gravel, dirt, sediment, sand and other suspended solids from water prior to the water being discharged into the environment.  
         [0003]     It is often necessary to remove accumulated water, such as groundwater, water from cofferdams, diverted water or water used in construction activities from construction sites or the like. This is usually accomplished by pumping, conveying and discharging the accumulated water into a drainage system or a stormwater system, or by removing the water in transport vehicles, or by piping the water to a chosen location such as a retention pond. In order to prevent the transfer of any suspended solid pollutants contained in the accumulated water, the water should be filtered prior to discharge to entrap the suspended solids, which may then be properly disposed of separately from the now filtered water.  
         [0004]     Devices to accomplish this task comprise bags or envelopes formed of a filter material, such as a non-woven geotextile fabric, with mesh, aperture or interstitial spacing of a size capable of preventing passage of the suspended solids while allowing water to flow through the material. The bags typically have a tubular inlet opening adapted to be connected to the pump discharge hose such that all flow from the hose is directed into the interior of the bag. The bag is generally square or rectangular with a relatively large surface area in comparison to the inlet opening, such that water can spread through the bag and the flow rate from the pump discharge hose is not impeded. The filtered water passes though the bag walls and the suspended solids having a size greater than the filter apertures remain trapped within the bag. Once the build-up of trapped solids excessively interferes with the water flow rate, i.e., the filter becomes clogged, the bag is detached from the pump discharge hose and disposed of.  
         [0005]     A problem with known dewatering bags is that they are produced in multiple sizes to account for differing applications. Typical sizes include bags of 3 feet by 3 feet, 3 feet by 5 feet, 5 feet by 7 feet, 6 feet by 6 feet, 10 feet by 15 feet, 15 feet by 15 feet, 15 feet by 20 feet, and 15 feet by 25 feet. Thus, the user must correctly ascertain the proper dewatering bag sizes that may be needed at a particular site, or must maintain a ready supply of all available sizes. Because maintaining a full supply of sizes is costly, most often the user will have only one or several sizes on hand. This often results in the use of a dewatering bag that is either too big for a particular application, when the use of a less costly smaller size would have been sufficient, or that is too small, such that the bag clogs prior to full pump out of the accumulated water, meaning that multiple bags must be used. Another problem with known dewatering bags is that they are designed for single use. Once the filtering capacity of a bag is reached, the bag is discarded. This produces excessive landfill waste and increased expense to the users, especially in circumstances where the captured sediment is not environmentally harmful.  
         [0006]     In order to address this problem, it is an object of this invention to provide a dewatering bag that is size adjustable, whereby the filtering surface area can be increased or decreased as required to achieve the desired filter flow rate. It is a further object to provide a dewatering bag that is releasably sealed, such that trapped solids may be removed from the interior of the bag for proper disposal, thereby allowing the bag to be reused after it has been cleaned.  
       SUMMARY OF THE INVENTION  
       [0007]     The invention comprises in general a dewatering bag, also know as a gravity bag filter or sediment filter bag, used to filter large quantities of water to entrap suspended solids such as gravel, dirt, sand and other particulate debris, such that the filtered water released through the walls of the bag is environmentally safe. The invention comprises a bag or envelope, typically square or rectangular, with an inlet neck of smaller dimension being provided for temporary attachment of the device to the discharge hose of a water pump, such that water from the pump is directed into the interior of the bag. Water exits the bag through the wall material, such that any suspended particulate matter of a size greater than the size of the mesh, apertures or interstitial spacing of the wall material is trapped within the bag.  
         [0008]     The bag further comprises size adjustment means whereby the usable filter surface area of the bag may be altered. In the preferred embodiment, the size adjustment means comprises a removable clamping assembly that allows one end or side of the bag to be folded or rolled and then secured in the folded or rolled position such that water is essentially precluded from passing through the folded or rolled portion of the bag.  
         [0009]     The dewatering bag is most preferably provided with an open end or side that is not permanently sealed, but instead is provided with removable, releasable or temporary closure means. The closure means most preferably also serves as the size adjustment means. Upon completion of the filtering operation, the closure means is removed or released such that the bag may be opened to allow removal of the entrapped solids. Upon cleaning and resealing of the bag, the bag may then be reused.  
         [0010]     The size adjustment means and the closure means may comprise a pair of interconnecting rod members that are joined to enclose the folded or rolled portion of the bag. Segmented anchoring members may be attached to the open end or side of the bag that cooperate with the rod members to ensure that the bag remains folded or rolled during use.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a top view of the dewatering bag.  
         [0012]      FIG. 2  is a view of the dewatering bag of  FIG. 1  shown prior to the sheet material being folded and joined.  
         [0013]      FIG. 3  is an exploded view of the rod members forming the clamping assembly.  
         [0014]      FIG. 4  is a side view of the clamping assembly showing the rod members in the assembled configuration.  
         [0015]      FIG. 5  is a view of the dewatering bag in use, showing connection to a pump discharge hose and with a portion of the bag rolled onto the clamping assembly.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     With reference to the drawings, the invention will now be described in detail with regard for the best mode and preferred embodiments. The invention generally comprises a dewatering bag, gravity bag filter or sediment filter bag  10  composed of a water permeable filter material capable of precluding suspended solids greater than a certain size from passing through the material. Suitable filtering material in sheet-form includes for example non-woven, synthetic, geotextile material such as sold under the brand names AMOCO PROPEX, MIRAFI, and TERRATEX. Such materials are durable, resistant to tear or puncture, and resistant to environmental and UV degradation. Suitable water flow rates for example may range between 70 to 110 gpm/ft 2  and suitable Apparent Opening Sizes for the mesh, apertures or interstitial openings in the material may range for example from U.S. Sieve No. 80 to 100, however, the invention is not to be limited to these ranges.  
         [0017]     The dewatering bag  10  as shown in  FIGS. 1, 2  and  5  comprises a main body  11  formed by a permanently sealed or joined end  14 , a pair of opposing sealed or joined sides  16 , and an unsealed or open end  15 . The sealed end  14  and sealed sides  16  may be formed by stitching  17  or other equivalent means such as adhesive bonding, melt bonding, mechanical fastening or the like, in a manner whereby the end  14  and sides  16  will remain connected during use under pressure. One of the sides  16  may be created by folding the sheet material forming the main body  11  prior to stitching, as illustrated in  FIG. 2 . Extending from the sealed end  14  is an open, generally tubular, inlet neck  12  to receive the end of a discharge hose or pipe  99 , such as coming from a pump, which is typically from about 2 to 4 inches in diameter. Neck connection means, shown herein to comprise a strap member  13  having hook-and-pile fastening elements, are provided to cinch the inlet neck  12  securely around the pump discharge hose  99  such that no water may escape from the connection. In this manner all water discharged from the pump passes through the neck inlet  12  and into the interior of the main body  11 . The main body  11  may be provided with reinforcement stitching or straps  18  as well as with lifting strap members  19  to assist in moving the bag  10 .  
         [0018]     The main body  11  is preferably provided with a releasably sealable open end  15 , preferably disposed opposite to the inlet neck  12 , which may be closed and opened as desired utilizing sealing or closure means. Alternatively, it is to be understood that one of the sides  16  may be provided as an open side with end  15  permanently sealed, or both side  16  and end  15  may both be open and resealable, or portions of end  15  and side  16  may be open and resealable. The open end  15  is preferably provided with anchor members  20  in order to increase the rigidity of the open end  15  and to provide members to interact with the closure means to better seal the device during use. As shown, the anchor members  20  may comprise relatively short segments of PVC pipe, cylinders or similar material that are disposed within an elongated pocket flap  21 . The anchor members  20  are alternately positioned such that when the sheet material is folded, the anchor members  20  will be disposed in a generally linear alignment along the open end  15 , with one set of anchor members  20  being positioned in the top side of open end  15  and the other set of anchor members being positioned in the bottom side of open end  15 .  
         [0019]     The dewatering bag  10  is preferably provided with size adjusting means as well as releasable closure means, which preferably comprise the same structural elements, whereby the surface area and overall size or dimensions of the main body  11  can be reduced or adjusted to accommodate varying water flow rates or sediment concentration. As shown, the size adjusting means and releasable closure means comprise a clamping assembly  30  that cooperates with the anchor members  20  such that the open end  15  is securely sealed when desired. The clamping assembly  30 , as shown in  FIGS. 3 and 4 , may comprise a first elongated member  31  and a second elongated member  32 , which may be formed as sleeve members  33   a  and  33   b  and insertion members  34   a  and  34   b  in order to allow the length of the clamping assembly  30  to be adjusted as desired to fit dewatering bags  10  of differing width. The first and second elongated members  31  and  32  may be formed of aluminum tubes or similar material. As shown, the first elongated member  31  is provided with tab flanges  35  on each end and the second elongated member  32  is provided with slotted flanges  36  on each end, the slots being sized to receive the tab flanges  35  therethrough.  
         [0020]     To utilize the dewatering bag  10 , the bag  10  is laid onto a relatively flat surface. The first elongated member  31  is placed abutting the pocket flap  21  retaining the anchor members  20  on the open end  15  of the bag  10 . The open end  15  is then rolled or folded with first elongated member  31  acting as a spindle or shaft. One or both sides  16  may also be folded inward to further reduce the surface area of the main body  11 . When the desired dimensions for the bag  10  are reached, the second elongated member  32  is connected to the first elongated member  31  by placing the slotted flanges  36  onto the tab flanges  35  to create in combination the clamping assembly  30 . In this manner the open end  15  is sealed and the main body  11  is precluded from unrolling or unfolding under the pressure of the incoming water. The inlet neck  12  is connected to the pump discharge hose  99  and secured using strap  13 . Water is then introduced into the dewatering bag  10 . After the suspended particulates have been trapped and the water has been filtered and released through the walls of main body  11 , the suspended solids trapped within the bag  10  may be accessed for removal by disassembling the clamping assembly  30 , unrolling or unfolding the main body  11  and opening the open end  15 . Upon removal of the solids and sufficient cleaning of the main body  11 , the dewatering bag  10  may be reused by resealing the open end  15  as described above.  
         [0021]     It is understood that equivalents and substitutions to certain elements set forth above may be obvious to those skilled in the art, and therefore the true scope and definition of the invention is to be as set forth in the following claims.