Abstract:
A silt fence system employs silt fencing that is supported along the fence length with stakes. The stakes have a polymer or plastic outer casing, and either a flexible core or a core segment of rigid material such as cement. The outer casing provides resistance to the elements and the flexible material provides the give to handle hydraulic forces with breaking of the stake, as is the case when wooden stakes are used. The system employs the rigid core stakes in situations where hydraulic forces are large enough that the combination of the plastic outer casing and flexible core is insufficient to maintain stake position.

Description:
[0001]    This application claims priority from provisional patent applications 60/330,934 filed on Nov. 2, 2001, No. 60/294,573 filed on Jun. 1, 2001, and No. 60/290,650 filed on May 15, 2002. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention is directed to a silt fence system, and in particular, to a system that employs flexible yet long-lasting fence stakes.  
         BACKGROUND ART  
         [0003]    In the prior art, it is mandatory in most jurisdictions to use erosion control measures at construction sites. In many instances, hay bales, filters over drain openings, or the like are used to control erosion. Another popular technique is the erection of silt fences around a perimeter of a particular site. These fences include a fabric material that is water permeable, but resistant to the passage of fine dirt or soils, sediment, and the like. The principal use of these types of fences is to control the erosion of the land under construction, and prevent soil from entering the public drainage system.  
           [0004]    One significant problem with silt fences is the inability of these structures to handle excessive forces created by the combination of soil and water accumulating at the fence line. The fence material is usually stapled to wooden stakes that are pounded in the ground. In many instances, the wooden stakes are not strong enough or are too rigid to withstand the large hydraulic forces created by the soil and/or water. Thus, the stakes often times break, thus compromising the integrity of the silt fencing.  
           [0005]    Another problem with these prior art fence systems is a lack of longevity for the wooden stakes. In many fence installations, the stakes rot due to the moist conditions well before the construction job is completed. This is particularly burdensome in construction sites that may be in existence for more than one or two years. With the degradation of the wooden stakes, the silt fence system must be continually repaired, and such repair increases the cost of the construction both in terms of manpower costs to repair the fence, material costs for the stakes themselves, and lost time towards completing the construction. In addition, builders can be subjected to fines or other penalties from the localities for local erosion control ordinance violations, and these types of penalties can be particularly onerous to the builder.  
           [0006]    As such, a need has developed to provide improved silt fencing for erosion control. In response to this need, the present invention provides a silt fence system that employs flexible fence stakes that are capable of withstanding heavy loads without breaking. In addition, the fence stakes have increased service lives so that replacement of the stakes is minimal during the construction period.  
         SUMMARY OF THE INVENTION  
         [0007]    It is a first object of the present invention to provide an improved silt fence system.  
           [0008]    Another object of the invention is to provide a silt fence system that employs stakes that have a rubber or rubber material core for flexibility, and an outer casing or coating of a plastic or polymeric material for both rigidity or strength and longevity.  
           [0009]    Still another object of the invention is a method of installing the improved silt fence system in place of systems employing wooden stakes.  
           [0010]    Other objects and advantages of the present invention will become apparent as a description thereof proceeds.  
           [0011]    The invention is an improvement in silt fence systems that employ a fabric material and a plurality of stakes, wherein the fabric material is secured to the stakes to define an erosion control barrier at a construction site. The improvement comprises in one embodiment that each stake have a core of a flexible material and an outer casing of a plastic or polymeric material.  
           [0012]    The invention also entails a method of installing a silt fence at a construction site by providing a silt fence fabric material, and a plurality of fence stakes, wherein each fence stake further comprising a core of a flexible material and an outer casing of a plastic or polymeric material. At least a portion of each stake is inserted into the ground, and the stakes are in spaced apart intervals defining an erosion barrier line; the silt fence fabric material to attached to the stakes.  
           [0013]    The system and method can include means for attaching the fence to the stakes, said means including (1) fasteners sized to fit within openings in the stakes, (2) staples, and (3) snaps molded to the stakes to fit within openings in the stakes.  
           [0014]    The stakes can be square in cross section and the fence can have a reinforcing band running along its length. The fence can have a flap at a bottom edge thereof, with the flap adapted to rest on a ground surface. The flap can have a plurality of openings to attach the flap to the ground surface using stakes, pins or other fasteners. The stake outer casing can be molded or extruded onto the flexible core and the flexible material can be a rubber material. The polymeric material can be PVC piping.  
           [0015]    In another embodiment, each stake has a core segment of at least a cement or cement-like material and an outer casing of a plastic or polymeric material. The method for installing this stake parallels the method described above for the stake with a flexible core. The core can include a granular material, and more preferably, a granular material that is disposed between segments of the cement or the cement-like material. The invention also relates to the stakes of the silt fence system as well. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    Reference is now made to the drawings of the invention wherein:  
         [0017]    [0017]FIG. 1 is a perspective view of one embodiment of a stake of the invention;  
         [0018]    [0018]FIG. 2 is a cross-sectional view along the line II-II of FIG. 1;  
         [0019]    [0019]FIG. 3 is a cross-sectional view of an alternative stake configuration; and  
         [0020]    [0020]FIG. 4 is a perspective view of one embodiment of the silt fence system of the invention;  
         [0021]    [0021]FIG. 5 is a sectional view of one mode of attachment of the fence to the stake of FIG. 4;  
         [0022]    [0022]FIGS. 6 and 7 are sectional views of alternative modes of attachments; and  
         [0023]    FIGS.  8 - 12  show various views of another embodiment of the inventive stake.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]    The present invention offers significant advantages in the field of erosion control, particularly erosion control through the use of silt fences. The invention involves a silt fence system wherein the fence stakes have a flexible core made from a rubber or rubber-like material, and an outer casing or core made from a plastic or polymeric material. The flexible core allows the stakes to flex when subjected to heavy loads from soil and water against the fence fabric material. The plastic outer core provides strength to support the loads, and longevity in resisting the affects of the elements, e.g., humidity, sunlight, abrasion, etc., over time.  
         [0025]    Referring now to FIGS.  1 - 7 , one embodiment of the silt fence system of the invention is designated by reference numeral  10  (FIG. 4), and includes a silt fence  1 , and a pair of fence stakes  3 . While only a pair of stakes  3  are shown, it should be understood that the system could involve a number of stakes.  
         [0026]    In FIG. 1, each stake  3  is depicted with a square cross section, but as explained below, other surface configurations can be employed. The stake  3  has a striking end  5  and a pointed opposite end  7 . The stake  3  also includes an inner core  9  and an outer casing or layer  11  (FIG. 2). The core  9  is made of a flexible material such as a rubber material or the like. The outer casing is shown with openings  12  to facilitate attachment of the silt fence as discussed below. As also explained below, other types of attachments can be utilized.  
         [0027]    The dimensions of the stake, either in terms of a side dimension, or a diameter, can vary depending on the intended application. For example, in areas where high loads are anticipated, e.g., at the bottom of a slope or the like, the stakes can have a heavier duty construction such that the dimensions would be larger. In lighter duty applications, the dimensions can be smaller since the forces from soil/water would be less. The casing thickness could vary as well depending on the particular application. A thicker casing could be used where more strength is needed, and a thinner casing could be employed in applications where less forces may be present. Similarly, the dimension of the core could change depending on the application, a larger core could be employed where more flexibility is needed.  
         [0028]    A preferred dimensional range for a square stake would be between about one-half inch square to 2.5 inches square, with a more preferred size of about 2 inches square. The casing dimensions could vary using thin dimensions, e.g., up to {fraction (1/4)} inch, to up to an inch or more in thicker uses.  
         [0029]    [0029]FIG. 3 shows an alternative stake construction wherein the core  9 ′ is circular with an annular outer casing  11 ′.  
         [0030]    [0030]FIG. 4 shows the system  10  with a portion of a silt fence  13 . The fence  13  has a flap  15 , preferably about 6 inches in width, designed to rest on the ground surface  17  when installed on the stakes  3 . The flap  15  can have openings  19 , e.g., grommets or the like, to allow the flap to be pinned or staked to the ground with pins  21  for additional resistance against loads applied to the fence and stakes. Of course, openings other than grommets can be employed to assist in keeping the flap down. Further yet, the flap  15  could be made without openings if desired.  
         [0031]    The silt fence  13  can also have a band  23  of reinforcement running along its length, such as nylon or the like. The band can be sewn onto the fence fabric to provide the reinforcement, or be made an integral part thereof. Preferably as shown in FIG. 4, the band is at or near the bottom of the fence to provide maximum resistance against forces from soil and/or water.  
         [0032]    The silt fence material itself is well known in the art of erosion control, and a further explanation is not necessary for understanding of the invention. Examples of silt fences are disclosed in U.S. Pat. No. 5,108,224, herein incorporated by reference.  
         [0033]    The core of the stake can be any number of flexible materials such as rubber or rubber-like material. Similarly, the outer casing can be any number of plastic or polymeric materials, such as polyethylene, polyvinyl chloride, polypropylene, or the like. A preferred material for the core is an EDPM rubber material for flexibility, with the outer core/casing being made of polyvinyl chloride for both strength and resistance to the environment.  
         [0034]    The stakes can vary in height, e.g., 1 to 5 feet, and also vary in cross sectional shape or configuration. For example, besides the stakes depicted with square cross sections, stakes could employ oval, circular, octagonal, or just about any polygonal shape. Further, the outer surface of the outer casing could have one configuration with the cross sectional shape of the inner core having another shape. For example, the outer surface could be square in cross section with the inner core being circular in cross section.  
         [0035]    In one mode, the outer casing can be formed on the inner core, e.g., by extrusion, by dipping, by spraying, by molding, by extrusion, or the like. In another mode, the outer casing could be a pre-formed article, e.g., a sleeve that is snugly fit over the inner flexible core. Preferably, the casing is molded to the core.  
         [0036]    The method of use entails first inserting each stake into the ground in spaced apart intervals. Insertion can be done using a hammer or the like and directing the pointed edge of the stake towards the ground. The silt fence is then attached to the stakes, with the flap folded toward the side intended to catch the soil. The flap can then be secured to the ground surface using the pins  21 .  
         [0037]    To attach the fence to the stakes in one mode, as shown in FIG. 5, a tack  31  could be employed to fit within a complementary sized opening  33  in the outer casing  11 . Tacks  31  would be pressed through the fence material  13  and into the openings  33  to secure the fence in place. Alternatively, the fence material  13  could be stapled using staples  35  as shown in FIG. 6.  
         [0038]    [0038]FIG. 7 shows an embodiment wherein plastic snaps  37  could be molded into the outer casing  11  and used to secure the fence  13 . In this mode, the stakes would be end stakes to allow for attachment of the end edge  39  of the fence  13  to the stake, as opposed to stakes used in the middle of the fence as shown in FIG. 4. It should be understood that the mode of attachment can vary from that disclosed and other attachments can be utilized to secure the fence to the stakes, e.g., other type fasteners or snaps and the like. Another example would be an elongated member having a number of protrusions, each protrusion aligned to fit within the spaced apart openings  12  in the stake, see FIG. 4.  
         [0039]    Although not shown, the stake end  5  could have a reinforced layer to better withstand the impact from driving the stake into the ground. Examples of reinforced layers include a fiber-reinforced plastic to resist impact, a plastic which is more flexible or forgiving than the outer casing  11  to better absorb impact, or even a flexible material such as the core material or like materials.  
         [0040]    While the stake is preferably used as a support for silt fence systems, it can be used in other applications such as supporting landscape items such as trees, bushes and the like, or other items or articles such as signs, or the like. The stakes could also be used with twine, rope, etc., to surround areas to limit access thereto.  
         [0041]    Another aspect of the invention involves a stake that is made of polymer piping and a core of a rigid material such as a cement. Referring to FIG. 8, the piping is designated by reference numeral  41 , and it is preferably PVC piping. The piping has an inside passageway  43 . Referring to FIG. 9, the passageway is filled with a cement  45 , preferably a quick-setting cement, thus forming the stake  40 . Since the cement is exothermic, the setting action helps form a bond between the inner wall of the PVC piping and the cement.  
         [0042]    The cement can occupy the entire passageway length, or a portion thereof. In a preferred mode as shown in FIG. 10, sand  47  can be situated between two segments of cement  45 . In this way, the piping flexibility is enhanced over its length, and its overall weight is reduced. In yet another mode as shown in FIG. 11, the cement  45  could occupy a lower portion of the piping with the sand  47  occupying an upper portion. The one end of the piping with the sand  47  could have a cap  49  to contain the sand  47  occupying the one end of the piping  41 .  
         [0043]    In yet another mode as shown in FIG. 12, one end  51  of the piping  41 ′ can be tapered to facilitate driving the piping into the ground.  
         [0044]    It should be understood that the embodiments of FIGS.  8 - 12  could be substituted for the other stakes with the silt fencing, methods of attachment, and methods of use as described above for FIGS.  1 - 7 .  
         [0045]    In summary, silt fence stake system embodiment comprises a plurality of silt fence stakes and a length of slit fence, the stakes attached to the length of silt fence at intervals to create a silt barrier. Each stake further comprises a length of polymer piping, preferably PVC piping, wherein at least a portion of an inner passageway of the piping has a rigid material such as a cement therein. Preferably, the rigid material is inserted into the passageway, and then the stake is installed with the fence. The inner passageway can be filled entirely with the cement or a mixture of cement and another material that provides flexibility such as a sand or the like.  
         [0046]    The piping can be attached to the silt fence and can be driven into the ground in any conventional manner. While PVC and quick-setting cement are exemplified, other polymers could be used for the piping, and other materials could be used as the rigid material insert other than cements, e.g. other setting compositions that would add rigidity to the piping. The polymer piping affords protection against the elements with the cement providing rigidity against hydraulic forces.  
         [0047]    A preferred way of attachment of the silt fence to the stakes is through the use of hook and loop fasteners.  
         [0048]    As such, an invention has been disclosed in terms of preferred embodiments thereof which fulfills each and every one of the objects of the present invention as set forth above and provides new and improved silt fence system and method of use.  
         [0049]    Of course, various changes, modifications and alterations from the teachings of the present invention may be contemplated by those skilled in the art without departing from the intended spirit and scope thereof. It is intended that the present invention only be limited by the terms of the appended claims.