The present invention is directed to materials used in water runoff management and erosion control and, more specifically, to water runoff filtering sheet materials for sediment control and silt retention.
Sediment has been recognized as one of the most significant water quality impairments in the United States. Historically, soil erosion was primarily considered an agricultural issue, but more recently, construction sites have received increased attention as more land is being developed and there is greater awareness of water quality issues. Silt fences and erosion barriers traditionally have become commonly used for erosion and sediment control applications being used in the field to reduce soil loss from construction, residential and agricultural sites. Most silt fences generally are constructed of woven geotextile fabrics, typically supported by posts or stakes driven into the ground. Such silt fences are designed to help retard storm water runoff and to filter silt, sediment and debris from the fluid as it flows away from a development site. Often, as larger particles block the pores in the silt fence, sediment or debris is collected and builds up against the fence, which can cause the storm water runoff to pool or “pond” behind the fence, promoting sedimentation.
However, as storm water runoff collects against the silt fencing material, the silt fencing accordingly is subjected to increasing hydrostatic pressures, and as the water rises, this pressure builds against the fencing, often causing a blowout and/or collapse of the fencing. As a result, sediment, debris and other unwanted materials will be released, which can cause environmental issues and require extensive and costly clean-up operations. This can be especially problematic during times of heavy rains and/or flooding when water levels and volumes are significantly increased.
Thus, there remains a need for a sediment control product, for example, a silt retention fencing material and/or silt retention system, that features enhanced durability, strength, and the ability to accommodate increased water levels and volumes without being prone to collapse, while also effectively promoting sedimentation, thereby reducing maintenance and improving overall performance of such fencing material and/or silt retention system.
Briefly described, the present invention generally is directed to a silt retention sheet or silt screen material for use as a vertical interceptor of moving sediment and storm water, which provides varying rates of waterflows therethrough to compensate for increasing overflow storm water conditions, and is provided with reinforcements and enhanced strength along the horizontal and/or width-wise directions thereof. The resultant silt retention sheet material is thus designed to withstand increases in hydrostatic pressure and build-up of silt, dirt and other debris, and to enable varying release of water volumes/flows therethrough as needed to accommodate high water conditions, such as during flooding, without bursting, tearing, collapse or undue bulging of the silt retention sheet that would result in undesirable release of large volumes of silt and debris with such high water flows.
The silt retention sheet includes a body or web that generally will be formed of a woven filtering or geotextile material, such as a spunbond polypropylene, polyester, or similar flexible polymeric materials. Alternatively, other filtering materials, including non-woven or fibrous mat materials also can be used. The body of the silt retention sheet further is formed with designed varying porosities along its width/height so as to allow varying amounts/volumes of water to pass therethrough depending on water levels rising along the sheet, but substantially prevents silt and debris from passing therethrough. The silt retention sheet further includes one or more reinforcing elements, strips, webs, bands, and/or belts that can be integrally formed within the body of the sheet, and/or otherwise integrated into the body of the sheet at spaced intervals along or across the width of the body. Fasteners can be inserted or applied onto or through the water-permeable web of filter material at selected locations along the reinforcing strips to attach the silt retention sheet to stakes or support members.
The reinforcing elements prevent ripping and tearing of the filter material at the points where the fasteners are inserted through or attached to the filter material for supporting the engagement and hold of the fasteners to the filter material against heavy water flows or the accumulation of sediment and debris against the web. The reinforcing elements further provide enhanced horizontal strength and resistance to tearing to the body of the silt retention sheet to guard against rupture and collapse thereof as silt and debris collects thereagainst. Examples of reinforcing materials can include formation of areas or bands of thicker or denser woven sheet material, woven strips of reinforcing materials such as strands of fiberglass, wires, cables, mesh materials and/or other rugged polymeric natural and/or metallic materials woven into or otherwise integrated into the body of the silt retention sheet. The reinforcing elements alternatively also can be applied as strands, cords, arrays, strips, patches, lattice work, or lengths of material attached along the web or body of the silt retention sheet material by stitching, adhesion, felting, impregnation, heat fusion, weaving, or similar means.
According to one aspect of the invention, the body of silt retention sheet material is formed from a woven fabric material and will include a series of flow zones including stages or areas having flow openings of differing apparent opening sizes so as to define varying porosities therealong. For example, the body can have areas of reduced or lower porosities at a lower portion thereof, defining at least one flow control region or zone including a filtering zone against which the bulk of sediment and debris is collected, and a support zone adapted to be covered by soil or other, material. The body can further include an overflow control region including one or more overflow storm water release stages having incrementally greater apparent opening sizes or porosities, increasing in size toward the upper end of the body. The release stages further can be segmented into multiple such regions of differing porosities. For example, the body can include 1-3 or more release stages having increasing flow rates at increasing elevations to release successively greater amounts of run-off water. The reinforcing elements of the body further can comprise linear support bands, strips or similar elements formed as areas of an increased denier per fiber or thickness in the woven material of the body to provide horizontal load support and connection areas for reinforced support of the attachment of fasteners connecting the body to vertical ground supports.
In another embodiment, the silt retention sheet can include a series of water-permeable webs or sheets applied in a layered or stacked fashion, with one or more reinforcing elements disposed therebetween. Alternatively, the water permeable webs can be formed with varying porosities and can be attached together in an overlapping or edge-to-edge contacting arrangement with the reinforcing elements acting to both connect and reinforce the webs, as well as provide for secure attachment points for mounting to posts or other support structures. In such embodiments, it further could be possible to connect a series of webs having desired porosities in series to build a silt fencing arrangement or system of a desired height and/or thickness and with defined, varied porosities provided to each of the connected webs or sections. The webs may be formed of woven and/or nonwoven materials and constructed to allow water to pass therethrough while helping to prevent the passage of silt and/or debris therethrough. The reinforcing element(s) also can include a plurality of reinforcing strands or strips that form a band, or can include a lattice or webbing material. A series of reinforcing bands further can be formed and applied in a manner so as to define a reinforcing structure or array extending along selected portions of the web.
These and other aspects of the present invention are described in greater detail below and shown in the accompanying drawings that are briefly described as follows.
Various features, advantages and aspects of the present invention may be set forth or apparent from consideration of the following detailed description, when taken in conjunction with the accompanying drawings. Moreover, it will be understood that the accompanying drawings, which are included to provide a further understanding of the present disclosure, are incorporated in and constitute a part of this specification, illustrate various aspects, advantages and benefits of the present disclosure, and together with the detailed description, serve to explain the principles of the present disclosure. In addition, those skilled in the art will understand that, according to common practice, various features of the drawings discussed below are not necessarily drawn to scale, and that dimensions of various features and elements of the drawings may be expanded or reduced to more clearly illustrate the embodiments of the present disclosure.
The present invention is directed generally to various erosion control materials and systems and in particular to a reinforced silt retention sheet material and/or system for use as a vertical interceptor of silt, sediment and debris in runoff water flow applications. For example, the silt retention materials may be used to retain silt suspended in storm water flowing from development sites or other erosion-prone areas. Various aspects of present invention may be illustrated further by referring to
In one aspect, as generally shown in
As used herein, the term “water-permeable” generally refers to the ability of an element or article to allow water to pass or flow therethrough. The flow rate of water through a “water-permeable” structure as used in the present invention generally will be sufficient for soil erosion control applications in which storm water runoff must be filtered and allowed to pass through the structure without substantial pooling or flooding around the silt retention sheet(s) when installed. For example, flow rates of at least 50-70 gal/min/ft2 or greater (as measured according to ASTM-D-491) can be used. However, it also will be understood that whether a particular material is sufficiently water-permeable will depend on the particular application for which the material is used, the composition of soil in the geographic location where the material is used, the particle size of the each component in the soil, and numerous other factors understood to those of skill in the art. Thus, while certain examples are provided herein, it will be understood that the performance criteria for a given application may vary, and that some materials may be suitable for some applications and not suitable for others.
In a first embodiment of the invention as illustrated in
Accordingly, various water permeable materials that comply with applicable state and federal environmental regulations and performance requirements for silt retention and storm water control applications, are contemplated for use with the present invention, including woven materials, nonwoven materials, extruded, needle-punched or other sheet materials (also referred to as “webs” or “fabrics”), or any combination thereof formed from natural materials, synthetic materials, or any combination thereof. The silt retention material used in accordance with any of the various aspects of the present invention may be formed from one or more polymers or polymeric materials. As used herein the term “polymer” or “polymeric material” includes, but is not limited to, homopolymers, copolymers, such as for example, block, graft, random, and alternating copolymers, terpolymers, etc. and blends and modifications thereof. One example of a fabric that may be suitable for use with the present invention is a reinforced silt retention sheet material such as shown and described in U.S. Reissue Pat. No. RE 42,095, the disclosure of which is incorporated by reference as if fully set forth herein, and can include a needlepunched spunbond polyethylene fabric commercially available from Silt-Saver, Inc. (Conyers, Ga.) under the trade name BELTED SILT RETENION FENCE fabric. Another example of a woven polypropylene fabric that may be suitable for use with the present invention is commercially available from Amoco Fabrics and Fibers Company (Austell, Ga.) under the trade name PROPEX® 1198 geotextile.
The water permeable web material of the reinforced silt retention sheet 10 also may have any suitable basis weight as needed or desired for a particular application, for example, ranging from about 35 to about 275 grams per square meter (gsm), although greater or lesser weights also can be used depending on the particular erosion control application/environment in which the sheet 10 is to be used. The reinforced silt retention fabric sheet 10 further will have any suitable thickness as needed or desired for a particular application, and generally may be from about 0.1 to about 7 millimeters (mm), although greater or lesser thickness also can be used depending on the particular erosion control application/environment in which the sheet 10 is to be used, and an ultraviolet stability in compliance with applicable state and/or federal regulations (e.g., an ultraviolet stability of 80% of minimum tensile strength after 300 hours of weathering per ASTM D-4355). Additionally, the reinforced silt retention fabric sheet can be formed from a series of layered or stacked plies, attached or bonded together such as by stitching, thermal bonding, needle-punching, adhesives, or other attachment means, as illustrated in
In the embodiment illustrated in
In one embodiment, the flow control zones 15 can include a first flow control or filtering zone, indicated at 15A in
At least one overflow flow control zone or release stage 15B also generally will be provided, extending vertically from a sediment control level 18 defined by the upper end of the filtering zone 15A, as shown in
As a result, as the water level behind the silt retention sheet rises during use, such as due to a buildup of sediment and debris behind the silt retention sheet and/or the incidence of increased runoff water flows due to flooding or heavy rains, controlled, incrementally increasing flows of water are enabled to pass through the silt retention sheet in order to help maintain hydrostatic pressures behind the silt retention sheet at acceptable levels and help the silt retention sheet resist bursting or being washed away due to such increased water flow volumes/pressures while silt and other debris is still retained at the filtering zone. The AOS of each of the flow control zones 15A-15C further can be selected/designed to accommodate projected hydrostatic pressures that will be created as the storm water rises to/above the various release stages defined in the body 11 of the silt retention sheet. For example, if the water level is projected to increase by 15-30% at each flow control zone, the AOS of such states correspondingly can be increased/selected to accommodate for such increased volumes.
In addition, as shown in
As further illustrated in
In one preferred embodiment, such as shown in
The retention elements 25 further can be attached to or integrated within the body of the silt retention sheet by weaving or stitching additional strands, strips or other materials, such as shown at 28 in
The reinforcing elements 25 further can be applied or arranged along the body 11 of the silt retention sheet 10 at spaced locations. By way of example, as shown in
For example, for a silt retention sheet 10 having a height or width of about 36″-40″, the upper portion of the body remaining above ground typically can extend approximately 24″ with the retention section extending 8-12″ below ground and having a pocket 22 of about 4″-6″. With the construction shown in
In addition, it also will be understood by those skilled in the art that the spacing of the reinforcing elements can be varied, i.e., the reinforcing elements can be interspersed at substantially equally spaced locations extending across the width or height of the body of the silt retention material or can be provided with a closer spacing along the body 11 where areas of expected heavier pressures or force applied against the body of the silt retention sheet. Still further, as shown in
As shown in
The reinforcement elements 25 help support the web on the stakes by providing enhanced strength at the points of engagement of the fasteners with the web to resist tearing of the web as silt and dirt build up thereagainst. Alternatively, as shown in
It will be understood that the various components may be assembled in various other orders, as desired. Also, it will be understood that the fastener may be inserted through the stake or through the sheet, provided that the sheet is securely attached. If desired, the silt retention system may be pre-assembled, such that the stakes are pre-attached to the silt retention fabric using the fasteners. In such an instance, the system may be rolled up, folded, wound onto a support roll, or the like, for easy transportation and assembly. The stakes then would be inserted into the soil as desired.
The body of each of the plies 102A and 102B forming the body 101 of the silt retention sheet 100 generally will be provided with a series of flow control zones 105 along the width or height thereof, including a filtering zone 105A, overflow release stages 105B-C and a retention stage or zone 105D having a J-shaped portion or pocket 122 at the end thereof, and as discussed above. A series of lateral reinforcing elements 110 generally can be arranged, formed or integrated in the body of each ply at spaced locations along and/or across the plies forming the body of the silt retention sheet, defining linear supports for the body. In addition, in the embodiment shown in
In addition, as shown in
As further illustrated in
A second section or region 205 can be provided, defining an intermediate flow control zone that can overlap with or start at and extends upwardly from the sediment flow control zone 202. This intermediate section or area of the silt retention sheet generally will have a series of pores or openings 206 that can vary in terms of their porosity, i.e., increasing in porosity from the bottom edge 207 to the top edge 208 thereof. For example, the pores 206 can be of about 25 AOS and can further increase to about 20 AOS. A third section or portion 210 defining a third or upper overflow control zone 211 can be applied and secured over the upper end 208 of the intermediate section 205. This upper section 210 generally will include pores 212 of a larger apparent opening size to enable still further increased water flow volumes therethrough.
The overlapping edges of each of the sections 201, 205 and 210 of the silt retention sheet 200 of the embodiment shown in
The attachment of the reinforcing elements connecting the sections of the reinforced silt retention sheet 200 further can be releasable and removable (i.e., via removable fasteners) so as to enable repair and replacement of sections of the silt retention sheet as needed, without having to substantially replace the entire silt retention fence or sheet. In addition, the modular nature of the silt retention sheet 200 of this embodiment further enables additional sections of a water permeable web material having pores with varying apparent opening sizes or porosities to be added to the silt retention sheet 200 as needed or desired. For example, as silt and sediment build up behind the silt retention sheet once installed, effectively raising the ground level therebehind, the intermediate and/or upper, overflow sections of the silt retention sheet can be replaced, for example, by adding additional sections of a lower or smaller porosity, and/or additional overflow sections can be added on top of the existing overflow sections to reconfigure the silt retention sheet as needed.
The reinforced silt retention fabric may be designed to have various properties, as needed or desired for a particular application. Thus, as it will be understood, any fabric filtering material may be used, including but not limited to, those described herein or contemplated hereby. In one exemplary system according to this aspect, the system includes an integrally reinforced woven silt retention fabric, where the reinforcing elements are embedded with the fibers and/or integrally formed within the body by increasing the denier per fiber or thickness of the weave at selected areas to provide a unitary, flexible filtering structure with enhanced strength for connection of fasteners and resistance to horizontal loading, without having substantially bonding or fusing the scrim reinforcing element to or with the fibers. In another exemplary system according to this aspect, the system includes a scrim-reinforced nonwoven silt retention fabric, where the reinforcing material is embedded integrated into the body and is secured further by mechanical entrapment adhesive and/or thermal bonding.
It further will be understood by those of skill in the art that depending on the particular application and the particular jurisdiction in which the silt retention material is used, various minimum physical property and performance requirements may apply. As also noted, the release stages, and the transitions therebetween can be of a high visibility color (with each stage being the same or a different color) to provide a visual delineation of the over flow release and filtering stages and to increase visibility of the silt retention fence for workers.
While the present invention is described herein in detail in relation to specific aspects, it is to be understood that this detailed description is only illustrative and exemplary of the present invention and is made merely for purposes of providing a full and enabling disclosure of the present invention. It will be recognized by those skilled in the art, that various elements discussed with reference to the various embodiments may be interchanged to create entirely new embodiments coming within the scope of the present invention. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the spirit of the invention as defined in the appended claims. The detailed description set forth herein is not intended nor is to be construed to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications, and equivalent arrangements of the present invention.
Accordingly, it will be readily understood by those persons skilled in the art that, in view of the above detailed description of the invention, the present invention is susceptible of broad utility and application. Many adaptations of the present invention other than those herein described, as well as many variations, modifications, and equivalent arrangements will be apparent from or reasonably suggested by the present invention and the above detailed description thereof, without departing from the substance or scope of the present invention.
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