U.S. patent number RE42,695 [Application Number 12/483,633] was granted by the patent office on 2011-09-13 for reinforced silt retention sheet.
This patent grant is currently assigned to Silt-Saver, Inc.. Invention is credited to Earl R. Singleton.
United States Patent |
RE42,695 |
Singleton |
September 13, 2011 |
Reinforced silt retention sheet
Abstract
A reinforced silt retention sheet and systems for silt retention
are provided. The reinforced silt retention sheet includes a
non-woven fabric having a series of entangled polymer fibers with a
reinforcing material secured within the fabric. The resultant
reinforced silt retention sheet further can have openings of a
desired size to enable filtering of a flow of fluid passing through
the reinforced silt retention sheet.
Inventors: |
Singleton; Earl R. (Oxford,
GA) |
Assignee: |
Silt-Saver, Inc. (Conyers,
GA)
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Family
ID: |
32096047 |
Appl.
No.: |
12/483,633 |
Filed: |
June 12, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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10647758 |
Aug 25, 2003 |
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60406176 |
Aug 27, 2002 |
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Reissue of: |
11283173 |
Nov 18, 2005 |
7465129 |
Dec 16, 2008 |
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Current U.S.
Class: |
405/302.7;
442/401; 256/12.5; 428/221 |
Current CPC
Class: |
E02D
17/20 (20130101); Y10T 428/249921 (20150401); Y10T
442/681 (20150401) |
Current International
Class: |
E02D
17/20 (20060101); E01F 7/02 (20060101) |
Field of
Search: |
;405/52,74,302.6,302.7
;442/381,382,392,401,14,36 ;256/1,12.5,13 ;428/221 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Amoco Product Specification for Amoco Style 2130, issued May 21,
1999. cited by other .
Geotex, "Geotextiles for Sediment Control" Specification sheet for
"Silt Fence". cited by other.
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Primary Examiner: Mayo-Pinnock; Tara
Attorney, Agent or Firm: Womble Carlyle Sandridge & Rice
PLLC
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. patent
application Ser. No. 10/647,758, filed Aug. 25, 2003 now abandoned,
which claims priority to U.S. Provisional Application No.
60/406,176, filed Aug. 27, 2002, both of which are incorporated by
reference herein in their entirety.
Claims
What is claimed is:
1. A reinforced silt retention sheet arranged above ground, for use
in a silt management application, comprising: a flexible, water
permeable, .[.nonwoven.]. fabric comprising a plurality of
entangled polymer fibers .Iadd.and having a thickness of about 0.1
mm to about 5mm.Iaddend.; and a reinforcing material or element
extending along the .[.nonwoven.]. fabric and adapted to support
and prevent ripping or tearing of the silt retention sheet secured
.[.within.]. .Iadd.with .Iaddend.the entangled polymer fibers
without substantially being bonded thereto, the reinforcing
material or element being arranged spaced in non-overlapping
intervals in the warp and/or fill direction of the .[.nonwoven.].
fabric, wherein the silt retention sheet has a maximum apparent
opening size of less than about 0.6 millimeters as measured by ASTM
D-4751.
2. The silt retention sheet of claim 1, wherein the .[.nonwoven.].
fabric comprises a spunbond polyester having a basis weight of from
about 1 to about 8 ounces per square yard.
3. The silt retention sheet of claim 1, wherein the .[.nonwoven.].
fabric comprises a spunbond polypropylene fabric, a spunbond
polyester fabric, spunbond polyethylene terephthalate fabric, a
needle punched polyester fabric, a needlepunched polyethylene
terephthalate fabric, a needlepunched spunbond polyethylene
terephthalate fabric, or any combination thereof.
4. The silt retention sheet of claim 1, wherein the reinforcing
material comprises a fiberglass scrim having a mesh size of from
about 0.1 inches to about 0.5 inches.
5. The silt retention sheet of claim 1, having a tensile strength
of at least about 75 lbs, as measured according to ASTM D-4632.
6. The silt retention sheet of claim 1, having a standard
concentration reduction in turbidity of at least about 58% as
measured according to ASTM D-5141-96(2004).
7. The silt retention sheet of claim 1, having a double
concentration reduction in turbidity of at least about 55% as
measured according to ASTM D-5141-96(2004).
8. The silt retention sheet of claim 1, having a standard
concentration filtering efficiency of at least about 90% as
measured according to modified ASTM D-5141-96(2004).
9. The silt retention sheet of claim 1, having a double
concentration filtering efficiency of at least about 92% as
measured according to modified ASTM D-5141-96(2004).
10. The silt retention sheet of claim 1, formed by the process
comprising: (a) forming a layer of the entangled polymeric fibers;
(b) overlying the entangled polymeric fibers with the reinforcing
material; and (c) overlying the reinforcing material with
additional entangled polymeric fibers.
11. The silt retention sheet of claim 10, formed by the process
further comprising: (d) heating the sheet to form bonds between the
entangled polymeric fibers without substantially bonding the
entangled polymeric fibers to the reinforcing material.
12. The silt retention sheet of claim 10, formed by the process
further comprising: (d) selecting the polymeric fibers to have a
lower softening point than a softening point of the reinforcing
material; and (e) heating the sheet to a temperature above the
softening point of the entangled polymeric fibers but below the
softening point of the reinforcing material.
13. The silt retention sheet of claim 1, wherein the reinforcing
material comprises a plurality of strands formed from at least one
of polypropylene, polyester, nylon 6, 6, yarn, cord material,
fiberglass, aramid fibers, and combinations thereof.
14. The silt retention sheet of claim 1 and wherein the reinforcing
material .Iadd.or element .Iaddend.comprises a series of strands
aligned in proximity so as to form reinforcing elements at spaced
locations along the .[.non-woven.]. fabric.
15. The silt retention sheet of claim 1 and further comprising
ground supports attached to the reinforcing material .Iadd.or
element.Iaddend..
16. The reinforced silt retention sheet as claimed in claim 15,
further comprising an attachment means for attaching the ground
supports to the reinforcing material wherein the reinforcing
material further functions as an attachment point for the ground
supports.
17. The silt retention sheet as claimed in claim 16, wherein the
attachment means are selected from the group consisting of staples,
pins, nails, rings, clips, adhesives, hook and loop fasteners, and
combinations thereof.
18. The silt retention sheet of claim 1 and wherein the reinforcing
material comprises a polymer material entangled within the polymer
fibers of the .[.non-woven.]. fabric.
19. The silt retention sheet as claimed in claim 1, wherein the
reinforcing element is comprised of a plurality of reinforcing
strands or strips that form a band.
20. A reinforced silt retention sheet comprising a flexible, water
permeable .[.non-woven.]. fabric sheet material .Iadd.having a
thickness of about 0.1 mm to about 5 mm and .Iaddend.including a
plurality of .[.non-woven.]. polymer fibers and reinforcing
elements formed from a resilient, tear resistant material and
interspersed along said fabric sheet material to provide said
fabric sheet material with enhanced strength and resistance to
tearing, wherein the reinforced silt retention sheet has an
apparent sieve opening size of less than approximately 0.6 mm as
measured according to ASTM D-4751 to provide filtering efficiency
for sediment control applications, and has an ultimate tensile
strength ranging from about 100 lbs to 350 lbs in the warp
direction and an ultimate tensile strength ranging from about 75
lbs to 450 lbs in the fill direction.
21. The reinforced silt retention sheet of claim 20, and wherein
said fabric sheet comprises a spin bond material having a denier of
approximately 1 dpf to approximately 10 dpf.
22. The reinforced silt retention sheet of claim 20, wherein the
silt retention sheet is a silt retention fence.
23. A reinforced silt retention sheet arranged above ground, for
use in a silt management application, comprising: a flexible, water
permeable, .[.nonwoven.]. .Iadd.geotextile .Iaddend.fabric
.Iadd.filter material having a thickness of less than about 5 mm
and .Iaddend.comprising a plurality of entangled polymer fibers;
and a reinforcing material secured .[.within.]. .Iadd.to
.Iaddend.the entangled polymer fibers without being bonded thereto,
the reinforcing material being spaced in discontinuous and
non-overlapping intervals in the warp .[.and.]. .Iadd.and/or
.Iaddend.fill .[.direction.]. .Iadd.directions.Iaddend., wherein
the silt retention sheet has a maximum apparent opening size of
less than about 0.6 millimeters as measured by ASTM D-4751.
24. The reinforced silt retention sheet as claimed in claim 23,
wherein the reinforced silt retention sheet has an ultimate tensile
strength ranging from about 100 lbs to 350 lbs in the warp
direction and an ultimate tensile strength ranging from about 75
lbs to 450 lbs in the fill direction.
.Iadd.25. The silt retention sheet of claim 1, wherein the fabric
comprises a non-woven fabric..Iaddend.
.Iadd.26. The silt retention sheet of claim 1, wherein the
reinforcing elements comprise an array..Iaddend.
.Iadd.27. The reinforced silt retention sheet as claimed in claim
23, wherein the reinforcing material is secured within the
entangled polymer fibers..Iaddend.
.Iadd.28. A reinforced silt retention sheet comprising a flexible,
water permeable fabric sheet material having a thickness of about
0.1 mm to about 5 mm and including a plurality of reinforcing
elements, said reinforcing elements formed from a resilient, tear
resistant material and interspersed along said fabric sheet
material to provide said fabric sheet material with enhanced
strength and resistance to tearing, wherein said reinforced silt
retention sheet has an apparent sieve opening size of less than
approximately 0.6 mm as measured according to ASTM D-4751 to
provide filtering efficiency for sediment control applications, and
has an ultimate tensile strength ranging from about 100 lbs to 350
lbs in the warp direction and an ultimate tensile strength ranging
from about 75 lbs to 450 lbs in the fill direction..Iaddend.
.Iadd.29. The reinforced silt retention sheet as claimed in claim
28, wherein said reinforcing elements are attached to said polymer
fibers by an attachment means selected from the group consisting of
stitching, adhesion, felting, heat fusion, and
weaving..Iaddend.
.Iadd.30. The reinforced silt retention sheet as claimed in claim
29, wherein said reinforcing elements are interspersed along said
fabric sheet such that said reinforcing elements form an
array..Iaddend.
.Iadd.31. A reinforced silt retention sheet comprising: a flexible,
water permeable fabric sheet material comprising a plurality of
polymer fibers; and a plurality of reinforcing elements that
provide reinforcing points at which at least one fastener can be
attached, said reinforcing elements formed from a resilient, tear
resistant material and attached to said fabric sheet material to
provide a reinforced fabric sheet material with enhanced strength
and resistance to tearing, wherein said fabric sheet material
comprises a geotextile fabric filter material having an apparent
sieve opening size of less than approximately 0.6 mm as measured
according to ASTM D-4751 to provide filtering efficiency for
sediment control applications, and wherein said reinforced silt
retention sheet has: an ultimate tensile strength ranging from
about 100 lbs to 350 lbs in a warp direction, an ultimate tensile
strength ranging from about 75 lbs to 450 lbs in a fill direction,
a mullen burst strength ranging from about 150 to 450 pounds per
square inch, a flow rate ranging from about 35 to 160
gallons/minute/square foot, and wherein said reinforcing elements
are applied as strands, cords, arrays, strips, patches, or lengths
of material attached along the web of said flexible, water
permeable fabric sheet material..Iaddend.
.Iadd.32. The reinforced silt retention sheet of claim 31 and
further comprising ground supports attached to the reinforcing
material..Iaddend.
.Iadd.33. The reinforced silt retention sheet as claimed in claim
32, further comprising an attachment means for attaching the ground
supports to the reinforcing material wherein the reinforcing
material further functions as an attachment point for the ground
supports. .Iaddend.
.Iadd.34. The reinforced silt retention sheet as claimed in claim
33, wherein the attachment means are selected from the group
consisting of staples, pins, nails, rings, clips, adhesives, hook
and loop fasteners, and combinations thereof..Iaddend.
Description
TECHNICAL FIELD
The present invention is directed to materials used in water runoff
management and erosion control and, more specifically, to
reinforced silt retention fabric materials.
BACKGROUND
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
construction sites are receiving increased attention as more land
is being developed and there is greater awareness of water quality
issues. While numerous erosion and sediment control products and
practices are being used in the field to reduce soil loss from
construction sites, there are only few standardized tests to
evaluate the effectiveness of most of these practices, and such
tests are relatively complicated. Thus, there remains a need for a
relatively simple test procedure for evaluating sediment control
products.
As a result, silt fences have become a commonly accepted erosion
and sediment control product. Most silt fences are constructed of
woven geotextile fabrics, sometimes reinforced by wire, supported
by metal posts. Silt fences help to impound runoff and to increase
sedimentation by filtering the fluid as it flows away from the
development site. While not wishing to be bound by theory, it is
believed that the silt fence initially removes silt and sand
particles from overland flow through filtration of the large
particles, and as the larger particles block the pores in the silt
fence, runoff begins to pool or "pond" behind the fence to promote
sedimentation.
Installation and maintenance is a problem commonly reported with
silt fences. The geotextile fabric typically is attached with
fasteners to wooden or metal stakes driven into the ground to
secure the fabric in position to collect and filter dirt and debris
from runoff water flows. The fasteners typically include staples,
hooks, rings, or similar devices that are inserted through the
fabric to attach it to the stakes. However, due to their relatively
thin, porous nature, geotextile fabrics usually do not exhibit
enough tensile strength to avoid pulling and tearing at the
insertion or puncture points of the fasteners as water, direct, and
debris bear against the fabric as runoff flow passes therethrough.
When the fabric pulls and tears, it frequently fails to control
erosion effectively. Consequently, there is a need for geotextile
fabrics and sheets that resist tearing and pulling at fastener
insertion points. Additionally, undercutting and flanking of the
fence can occur due to improper installation, and overtopping can
occur when silt fences are improperly located in concentrated flow
conditions or when the flow rate through the fence is
inadequate.
Thus, there remains a need for a sediment control product, for
example, a silt retention material and/or silt retention system,
that features enhanced durability while effectively promoting
sedimentation, thereby reducing maintenance and improving overall
performance.
SUMMARY
Briefly described, the present invention generally is directed to a
silt retention sheet or silt screen material having a body or web
that generally is formed of woven or nonwoven filter material, such
as a spunbond polypropylene, polyester, or similar flexible
polymeric material that allows water to pass therethrough, but
substantially prevents silt and debris from passing therethrough.
The silt retention sheet further includes one or more reinforcing
elements, strips, or belts attached to the web at spaced intervals
along or across the width of the web. Fasteners are inserted or
applied onto or through the water-permeable web of filter material
at selected locations along the reinforcing strips to attach the
web material 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, and further provide areas 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. Some examples of the reinforcing
material include woven strips of nylon, reinforcing strands of
fiberglass and other rugged polymeric materials. The reinforcing
elements can be applied as strands, cords, arrays, strips, patches,
or lengths of material attached along the web of the silt screen
material by stitching, adhesion, felting, impregnation, heat
fusion, weaving, or similar means. For example, in one embodiment,
the reinforced silt retention sheet includes a plurality of woven
nylon strips or patches sewn onto and extending along the length of
the web of filter material, with the strips spaced across the width
of the web.
In another embodiment, the silt retention sheet includes a first
water-permeable web on which is layered a second water-permeable
web, with a reinforcing element disposed between portions of the
first and second webs. 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 can include a
plurality of reinforcing strands or strips that form a band. A
series of reinforcing bands can be formed to define a reinforcing
structure or array extending along selected portions of the
web.
According to another aspect of the invention, a silt retention
system includes various features, for example, a silt retention
material, at least one stake to attach the silt retention material
to, and at least one fastener for securing the silt retention
material to the at least one stake. The silt retention system also
may include a fastener support for further securing and stabilizing
the silt retention sheet.
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.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a side elevational view of a portion of a silt retention
sheet encompassing principles of the present invention;
FIG. 2 is a side elevational view of a portion of the silt
retention sheet of FIG. 1 fastened to support members;
FIG. 3 is a side elevational view of a portion of an additional
embodiment of a silt retention sheet encompassing principles of the
present invention;
FIG. 4 is a side elevational view of a portion of yet another
embodiment of a silt retention sheet encompassing principles of the
present invention;
FIG. 5 is a side elevational view of a portion of still another
embodiment of a silt retention sheet encompassing principles of the
present invention;
FIG. 6 is a side elevational view of a portion of another
alternative embodiment of a silt retention sheet encompassing
principles of the present invention;
FIG. 7 is a side view of a portion of a further alternative
embodiment of a silt retention sheet encompassing principles of the
present invention;
FIG. 8 is an exploded view of an another exemplary silt retention
material and system including such a material according to various
aspects of the present invention;
FIG. 9 is an exploded view of yet another exemplary silt retention
material and system including such a material according to various
aspects of the present invention;
FIG. 10 presents comparative average blank flow data for an
exemplary silt retention material according to various aspects of
the present invention and a control material;
FIG. 11 presents comparative standard concentration flow data for
an exemplary silt retention material according to various aspects
of the present invention and a control material;
FIG. 12 presents comparative double concentration flow data for an
exemplary silt retention material according to various aspects of
the present invention and a control material;
FIG. 13 presents comparative standard concentration filter
efficiency data for an exemplary silt retention material according
to various aspects of the present invention and a control
material;
FIG. 14 presents comparative double concentration filter efficiency
data for an exemplary silt retention material according to various
aspects of the present invention and a control material;
FIG. 15 presents comparative standard concentration turbidity data
for an exemplary silt retention material according to various
aspects of the present invention and a control material;
FIG. 16 presents comparative double concentration turbidity data
for an exemplary silt retention material according to various
aspects of the present invention and a control material;
FIG. 17 presents comparative flow data for an exemplary silt
retention material according to various aspects of the present
invention and a control material using a modified test method;
FIG. 18 presents comparative filter efficiency data for an
exemplary silt retention material according to various aspects of
the present invention and a control material using a modified test
method;
FIG. 19 presents comparative turbidity reduction data for an
exemplary silt retention material according to various aspects of
the present invention and a control material using a modified test
method; and
FIG. 20 depicts an exemplary test apparatus according to various
aspects of the present invention.
DETAILED DESCRIPTION
The present invention is directed generally to various erosion
control materials and systems. For example, such materials may be
used to retain silt suspended in stormwater flowing from
development sites or other erosion-prone areas. As used herein, the
term "silt" refers to soil or rock particles having a diameter of
from about 1/256 mm to about 1/16 mm (about 3.9 microns to about
62.5 microns).
In one aspect, an erosion control product or system comprises a
reinforced silt retention sheet including one or more webs or
sheets of a substantially water-permeable material to which one or
more reinforcing elements are attached and serve as points of
attachment for fasteners that are used to fasten the reinforced
silt retention sheets to support members to anchor the sheets in
position to filter silt and debris from water passing through the
sheet in soil erosion control applications. The reinforcing
elements further help to reduce the incidence of tearing, pulling,
and separation of the water-permeable web material at or around the
points of attachment for the fasteners.
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.
It 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 another aspect, a silt retention system is provided. The silt
retention system may include various features, for example, a silt
retention material, at least one stake to attach the silt retention
material to, and at least one fastener for securing the silt
retention material to the at least one stake. The silt retention
system also may include a fastener support for further securing and
stabilizing the silt retention sheet, and for reducing the
incidence of tearing at of near the points of attachment to each
stake.
Various materials are contemplated for use with the present
invention, including woven materials, nonwoven materials (also
referred to as nonwoven "webs" or "fabrics"), or any combination
thereof formed from natural materials, synthetic materials, or any
combination thereof.
As used herein, the term "woven" refers to a fabric or material
made or constructed by interlacing threads or strips of material or
other elements into a whole. Woven materials typically only stretch
in the bias directions (between the warp and weft directions)
unless the threads or other materials used to form the material are
elastic.
As used herein, the term "nonwoven" material or fabric or web
refers to a web having a structure of individual fibers or threads
which are interlaid, but not in an identifiable manner as in a
knitted fabric. Nonwoven fabrics or webs have been formed from many
processes including, but not limited to spunbonding processes,
meltblowing processes, bonded carded web processes, felting
processes, and needlepunching processes.
As used herein the term "spunbond fibers" refers to small diameter
fibers of molecularly oriented polymer formed from a spunbonding
process. Spunbond fibers are formed by extruding molten
thermoplastic material as filaments from a plurality of fine,
usually circular capillaries of a spinneret with the diameter of
the extruded filaments then being rapidly reduced.
Where the silt retention fabric is a spunbond material, the fibers
may have any suitable denier as needed or desired for a particular
application, and may generally be from about 1 to about 10 denier
per fiber (dpf) (grams per 9000 meters of fiber). In one aspect,
the denier of the reinforced silt retention fabric is from about
1.5 to about 8 dpf. In another aspect, the denier is 2 to about 7
dpf. In yet another aspect, the denier is from about 3 to about 7
dpf. In yet another aspect, the denier is from about 4 to about 5
dpf. In one particular example, the denier of the nonwoven fibers
used to form the silt retention fabric is about 4.5 dpf.
As used herein the term "meltblown fibers" refers to fine fibers of
unoriented polymer formed from a meltblowing process. Meltblown
fibers are often formed by extruding a molten thermoplastic
material through a plurality of fine, usually circular, die
capillaries as molten threads or filaments into converging high
velocity, usually hot, gas (e.g. air) streams which attenuate the
filaments of molten thermoplastic material to reduce their
diameter, which may be to microfiber diameter. Thereafter, the
meltblown fibers are carried by the high velocity gas stream and
deposited on a collecting surface to form a web of randomly
disbursed meltblown fibers. Meltblown fibers may be continuous or
discontinuous, and are generally smaller than 10 microns in average
diameter.
As used herein, "bonded carded web" refers to webs made from staple
fibers that are sent through a combing or carding unit, which
breaks apart and aligns the staple fibers in the machine direction
to form a generally machine direction-oriented fibrous nonwoven
web. Such fibers usually are purchased in bales that are placed in
a picker that separates the fibers prior to the carding unit. Once
the web is formed, it then is bonded by one or more of several
known bonding methods. One such bonding method is powder bonding,
wherein a powdered adhesive is distributed through the web and then
activated, usually by heating the web and adhesive with hot air.
Another suitable bonding method is pattern bonding, wherein heated
calendar rolls or ultrasonic bonding equipment are used to bond the
fibers together, usually in a localized bond pattern, though the
web can be bonded across its entire surface if so desired. Another
suitable and well-known bonding method, particularly when using
bicomponent staple fibers, is through-air bonding.
As used herein, a "felt" refers to a matted nonwoven material
formed from natural and/or synthetic fibers, made by a combination
of mechanical and chemical action, pressure, moisture, and
heat.
As used herein, "needlepunching" refers to a process of converting
batts of loose staple or continuous fibers, or a combination of
staple fibers and continuous fibers, into a coherent nonwoven
fabric in which barbed needles are punched through the batt,
thereby entangling the fibers.
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. Furthermore, unless otherwise
specifically limited, the term "polymer" shall include all possible
geometrical configurations of the molecule. These configurations
include, but are not limited to isotactic, syndiotactic, and random
symmetries. Typical thermoplastic polymers that may be suitable for
use with the present invention include, but are not limited to,
polyolefins, e.g. polyethylene, polypropylene, polybutylene, and
copolymers thereof; polytetrafluoroethylene; polyesters, e.g.
polyethylene terephthalate; vinyl polymers, e.g., polyvinyl
chloride, polyvinyl alcohol, polyvinylidene chloride, polyvinyl
acetate, polyvinyl chloride acetate, polyvinyl butyral; acrylic
resins, e.g. polyacrylate, polymethylacrylate, and
polymethylmethacrylate; polyamides, e.g., nylon 6,6; polystyrenes;
polyurethanes; cellulosic resins, e.g., cellulosic nitrate,
cellulosic acetate, cellulosic acetate butyrate, ethyl cellulose;
copolymers of any of the above materials; or any blend or
combination thereof.
Thus, by way of example and not by limitation, the material used in
accordance with the present invention may be a woven polypropylene
fabric, a nonwoven polypropylene fabric, for example, a spunbond
polypropylene fabric, a woven polyethylene terephthalate fabric, a
nonwoven polyethylene terephthalate fabric, for example, a spunbond
polyethylene terephthalate fabric, a needlepunched polyethylene
terephthalate fabric, a needlepunched spunbond polyethylene
terephthalate fabric, a woven nylon fabric, woven natural fiber
fabric, or any combination thereof.
One 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.RTM. 1198 geotextile. The properties of PROPEX.RTM.
1198 geotextile as provided by the manufacturer are presented in
Table 1.
TABLE-US-00001 TABLE 1 Min. Average Min. Average Property Test
Method Value (English) Value (Metric) Grab tensile ASTM-D-4632
300/200 lb 1.33/.890 kN Grab elongation ASTM-D-4632 15% 15% Mullen
burst ASTM-D-3786 450 psi 3100 kPa Puncture ASTM-D-4833 120 lb
0.530 kN Trapezoidal tear ASTM-D-4533 65 lb 0.285 kN UV resistance
ASTM-D-4355 90% at 500 hr 90% at 500 hr AOS ASTM-D-4751 40 sieve
0.425 mm Permittivity ASTM-D-4491 0.5 sec 0.5 sec Flow rate
ASTM-D-4491 50 gal/min/ft.sup.2 2035 L/min/m.sup.2
Another example of a woven polypropylene fabric that may be
suitable for use with the present invention is commercially
available from Willacoochee Industrial Fabrics (Willacoochee, Ga.)
under the trade name STYLE 2098 SILT FENCE fabric, described in
detail in the Examples.
One example of a needlepunched spunbond polyethylene terephthalate
fabric that may be suitable for use with the present invention is
commercially available from Silt-Saver, Inc. (Conyers, Ga.) under
the trade name BELTED SILT RETENTION FENCE fabric, described in
detail in the Examples.
In this and other aspects of the present invention, the silt
retention material may include one or more reinforcing elements.
The reinforcing material or element may be any suitable construct
or element (collectively "elements") that is capable of enhancing
at least one of the tensile strength, burst strength, puncture
resistance, tear strength, or the like, of the woven or nonwoven
material.
The reinforcement elements generally may be formed from any strong,
resilient, substantially tear resistant material as needed or
desired for a particular application. Examples of such materials
include, but are not limited to, woven or nonwoven polymeric
materials, such as nylon 6,6, spun or woven yarns, cord materials,
scrim, fiberglass, aramid fibers or other, similar high strength,
flexible materials, or any combination thereof. In this and other
aspects of the present invention, while various examples are
provided herein, it will be understood that any suitable material
may be used, such as those described above.
As one example of the numerous reinforcing materials and elements
described herein, the reinforcing material may comprise a scrim
formed from natural fibers, synthetic fibers, metal wire, carbon
fibers, fiberglass, other materials, or any combination thereof.
Some synthetic fibers that may be used to form a scrim include, but
are not limited to, those made from polyolefins, such as
polypropylene, polyethelene, and copolymers thereof; polyamides,
such as nylon 6,6,; polyesters, such as polyethylene terephthalate;
vinyl polymers, such as polyvinyl chloride; and any combination
thereof. Other suitable polymers described herein or contemplated
hereby also may be used.
A scrim used in accordance with the present invention may have any
suitable fiber size, denier, and weave as needed or desired for a
particular application. For example, the scrim may be from about
0.01 inch to about 1 inch mesh. In one aspect, the scrim is from
about 0.1 inch to about 0.8 inch mesh. In another aspect, the scrim
is from about 0.15 inch to about 0.5 inch mesh. In yet another
aspect, the scrim is from about 0.2 inch mesh to about 0.4 inch
mesh. In one particular example, the scrim is about 0.25 in
mesh.
The reinforcing element may be attached to or incorporated into the
silt retention material using any suitable method, process, or
technique. By way of example and not limitation, the reinforcing
element may be mechanically attached, for example, by stitches,
hook-and-loop fasteners, staples, snaps, clips, or any combination
thereof, adhesively attached, for example, by gluing, thermally
attached, for example, by fusing or ultrasonic bonding, or any
combination thereof.
Alternatively or additionally, the reinforcing element may be
integrally formed with the silt retention material, for example, by
weaving or by incorporating the element into the nonwoven material
during manufacture. Thus, the silt retention sheet may comprise a
nonwoven fabric having a reinforcing element embedded within the
entangled nonwoven fibers. The silt retention sheet may be formed,
for example, by depositing one or more layers of nonwoven fibers on
a moving wire, depositing the reinforcing material and/or
element(s) thereon, and depositing one or more layers of additional
fibers over the reinforcing material such that the fibers overlie
and substantially encompass the with the reinforcing material and
or element(s).
If desired, the resulting structure may be subject to one or more
additional processes as is known to those in the art. For example,
the resulting structure may be subject to a mechanical entanglement
process to enmesh the various layers of fiber and the reinforcing
material. As a result, the reinforcing material is secured within
the fibers by mechanical entrapment in the absence of thermal or
adhesive bonding or fusing to or with the nonwoven fibers. One
example of a system that includes such a material is commercially
available from Silt-Saver, Inc. (Conyers, Ga.) under the trade name
BELTED SILT RETENTION FENCE, described in detail in the
Examples.
Alternatively, the reinforcing element may be secured within the
fibers by mechanical entrapment with only minimal bonding or fusing
to the nonwoven fibers. Such materials may be formed according to
numerous processes. For example, where the reinforcing element is
formed from a polymer or other material capable of softening in
response to heat, the polymer used to form the nonwoven fibers may
be selected such that the nonwoven fibers have a lower softening
point than the reinforcing element. The structure then can be
through air bonded or point bonded at a temperature above the
softening point of the entangled polymeric fibers but below the
softening point of the reinforcing element. By doing so, the
softened polymer fibers fuse primarily to other softened polymer
fibers, but also may bond somewhat to the reinforcing element.
Thus, the reinforcing element may be secured within the fibers by
mechanical entrapment in the absence of substantial bonding or
fusing to the nonwoven fibers.
As another example, the reinforcing material may be secured within
the fibers by mechanical entrapment and also is thermally,
adhesively, and/or mechanically bonded or otherwise attached to the
nonwoven fibers. Such materials may be formed by numerous
processes. For example, the reinforcing material and the polymer
used to form the reinforcing element may be selected to have a
particular softening point, and the resulting structure may be
point bonded or through air bonded at a temperature above the
softening point of each to fuse the polymeric fibers and the
reinforcing material and increase the integrity of the resulting
nonwoven fabric.
Various aspects of present invention may be illustrated further by
referring to the figures. For purposes of simplicity, like numerals
may be used to describe like features. It will be understood that
where a plurality of similar features are depicted, not all of such
features are necessarily labeled on each figure. While various
examples are shown and described in detail herein, it also will be
understood that any reinforcing material may be used with any silt
retention material described herein or contemplated hereby.
In FIG. 1, a reinforced silt retention sheet 10 generally includes
a sheet, blanket, or web 12 comprising a geotextile fabric or
other, similar water-permeable filter material to which
reinforcement elements or belts 20 are attached in spaced series.
In this and other aspects of the present invention, the
water-permeable web of filter material 12 can be formed any
suitable from woven or nonwoven, natural or synthetic material. In
this example, the reinforcement elements 20 are applied to the
water-permeable web 12 such as with lines of stitching 24. However,
as discussed above, the reinforcement elements 20 may be attached
to the water-permeable web 12 by any other appropriate means, such
as adhesives, hook-and-loop fasteners, staples, etc., or any
combination thereof. The reinforcement belts support and provide
reinforcement points at which fasteners can be attached to the web
12 for securing the web to stakes or other supports.
As shown in FIG. 1, the exemplary reinforced silt retention sheet
10 also includes a reinforcement border 22 attached to the edge of
the water-permeable web 12. The reinforcement border 22 further
helps to strengthen the water-permeable web 12 and provide an
additional area for attaching fasteners thereto.
FIG. 2 shows the reinforced silt retention sheet 10 of FIG. 1
fastened to ground supports, such as stakes 50, by fasteners 60.
The stakes 50 typically are wooden or metal, but can be formed from
of any other resilient, durable material capable of supporting the
web. In this and other aspects of the invention, the fasteners 60
may include staples, pins, nails, rings, clips, or any other
suitable fastener for securing the web to the stakes, depending on
the type of stakes used. The fasteners 60 are fastened to the
stakes 50 and inserted through the reinforcement elements 20 and
the reinforcement border 22 to retain the sheet 10 in place. In
this manner, the sheet 10 may be securely positioned at desired
locations for filtering runoff waterflows passing through the
water-permeable web 12 while preventing the passage of silt or
debris therethrough. The reinforcement elements help support the
web on the stakes 50 by providing enhanced strength at the points
of engagement of the fasteners 60 with the web to resist tearing of
the web as silt and dirt build up thereagainst.
FIG. 3 shows an alternative embodiment of a reinforced silt
retention sheet 110 according to the present invention. In this
embodiment, the reinforcement elements 120 generally comprise
patches or strips distributed or applied at selected locations
across the sheet of the water-permeable material or web 112. The
reinforcement elements 120 may be attached to the water-permeable
web 112 as discussed above with regard to attachment of the
reinforcement elements 20 to web 12. As discussed above, the
water-permeable web 112 of the present invention may be any
suitable material used to retain silt and debris while allowing
passage of water therethrough. The reinforcement elements 120 may
be distributed along the sheet 110 in any appropriate or desired
number or pattern to provide multiple spaced areas of reinforcement
and/or attachment. The web is attached via fasteners applied
through the reinforcement elements to attach the web to supports
such as stakes and prevent or resist tearing or pulling of the web
away from the supports as water passes therethrough.
FIG. 4 illustrates another example of a reinforced silt retention
sheet according to the present invention. In this embodiment, the
silt retention sheet 210 is formed of a nonwoven, water-permeable
web 212 composed of a suitable polymeric material. Reinforcing
elements 220 are attached at spaced locations across the width of
the web 212 by appropriate means, such as stitching, adhesion,
felting, stapling, riveting, etc. The reinforcing elements 220 in
this embodiment generally are bands that extend longitudinally
along portions of the web 212 to provide points of attachment of
fasteners to the sheet 210. The bands may be formed of various
materials, such as woven polymeric belts, plastic strips, twisted
or spun yarns, cord, ropes, spun fibers such as fiberglass, or
other suitable structures. The reinforcing bands 220 enable
attachment of the web 212 to ground supports with various desired
spacing between the supports as needed.
FIG. 5 shows yet another embodiment of a reinforced silt retention
sheet 310. As with the silt retention sheet 210 shown in FIG. 4,
the silt retention sheet 310 generally includes a water-permeable,
woven, or nonwoven filtering material body or web 312 to which a
series of reinforcing elements 320 are attached. The reinforcing
elements 320 generally are composed of a plurality of reinforcing
strips or strands 322 that are aligned in proximity with each other
to form bands extending along the web 312. The reinforcing strands
322 may be formed from various materials including, but not limited
to, polymeric filaments, such as polypropylene, polyester, or nylon
6,6, spun or woven yarns, cord materials, scrim, fiberglass, aramid
fibers or other, high strength, flexible materials, or any
combination thereof.
As shown in FIG. 5, the reinforcing strands 322 are aligned in
proximity to each other but do not intertwine or overlap. The
reinforcing strands 322 can be attached by a variety of means to
the web 312, including threading or weaving the strands through the
web, felting, heat fusion or simply can be disposed within the web
312 during manufacture of the web.
The proximity of the reinforcing strands 322 to each other to form
the reinforcing elements 320 tends to increase the strength of the
sheet 310 in and around the reinforcing elements 320, even though
the reinforcing strands do not intertwine or overlap. Nonetheless,
the reinforcing strands 320 impart sufficient strength to the silt
retention sheet 310 to reduce the incidents of tearing, separation,
and pulling of the web 312 when the sheet 310 is fastened to
support members by fasteners attached to the sheet 310 at the
reinforcing elements 320, as discussed above with reference to the
sheet 10 of FIGS. 1 and 2.
FIG. 6 shows a further alternative silt retention sheet 410 of the
present invention in which an array 424 of reinforcing strands 422
is provided. As shown in FIG. 6, the reinforcing strands of the
array 424 intersect and overlap each other across at least a
portion of the silt retention sheet 410. The array 424 further
typically can include one or more bands 421 of reinforcing
materials that make up the reinforcing elements 420. The bands 421
generally are composed of two or more reinforcing strands 422 that
are aligned adjacent to each other in closer proximity than the
other strands within the array 424. The reinforcing strands of the
bands 421 generally are aligned parallel to each other and may
contact or overlap each other to form the bands 421. In this
embodiment, the reinforcing elements 420 constitute areas along the
sheet 410 that have higher concentrations of reinforcing strands
422 than the average concentration of strands on the sheet 410. The
array 424 of reinforcing strands generally strengthens the web 412
to which it is attached. In the example shown in FIG. 6, the web
412 is composed of a nonwoven material, such as a spunbond
polypropylene or polyester, or any of the other materials described
herein or contemplated hereby. The reinforcing strands of the
reinforcing elements 420 and the array 424 may be attached to the
web 412 by various means, such as adhesion, heat fusion,
impregnation, weaving, stitching, felting, etc.
FIG. 7 shows a further alternative embodiment of the reinforced
silt retention sheet 510, which includes a first water-permeable
nonwoven web 512a on which is layered on a second water-permeable
nonwoven web 512b. As used herein, the term "layered on" refers to
the orientation of one article or element relative to another and
generally means that at least a portion of one element is applied
to another element in an overlapping and parallel relationship. An
array 524 of reinforcing strands is disposed between the first and
second webs 512a and 512b and includes one or more bands 521 formed
of reinforcing strands that constitute reinforcing elements 520 of
the sheet 510. Although the webs 512a and 512b shown in FIG. 7
generally are nonwoven, the silt retention sheets may be formed
from woven webs, as discussed above. For example, the reinforced
silt retention sheet of the present invention may include one or
more nonwoven water permeable webs layered on one or more woven
water-permeable webs that tend to prevent the passage of silt and
debris therethrough. The webs may be layered upon and secured to
each other using various means, such as adhesion, interweaving,
stitching, felting, heat fusion, etc. Although FIG. 7 depicts an
array 524 of reinforced strands that form in part the reinforcing
elements 520 of the sheet 510, it is to be understood that, in this
and other aspects of the invention, other reinforcing elements and
combinations thereof shown in the various embodiments may be
incorporated into a sheet in which two or more webs are layered on
each other.
The reinforced silt retention fabric may be designed to have
various properties, as needed or desired for a particular
application. It 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.
By way of example, and not by limitation, the minimum requirements
for the state of Georgia for various applications are presented in
Tables 1 and 2 (Manual for Erosion and Sediment Control in Georgia,
2000).
TABLE-US-00002 TABLE 1 Application Type Description A This 36-inch
wide filter fabric shall be used on developments where the life of
the project is greater than or equal to six months. B Though only
22-inches wide, this filter fabric allows the same flow rate as
Type A silt fence. Type B silt fence shall be limited to use on
minor projects, such as residential home sites or small commercial
developments where permanent stabilization will be achieved in less
than six months. C Type C fence is 36-inches wide with wire
reinforcement. The wire reinforcement is necessary because this
fabric allows almost three times the flow rate as Type A silt
fence. Type C silt fence shall be used where runoff flows or
velocities are particularly high or where slopes exceed a vertical
height of 10 feet. Provide a riprap splash pad or other outlet
protection device for any point where flow may top the sediment
fence. Ensure that the maximum height of the fence at a protected,
reinforced outlet does not exceed 1 ft. and that support post
spacing does not exceed 4 ft.
TABLE-US-00003 TABLE 2 Property Type A Type B Type C Minimum
tensile strength (lb) Warp - 120 Warp - 120 Warp - 260 (ASTM
D-4632) Fill - 100 Fill - 100 Fill - 180 (min. roll average of 5
specimens) Maximum elongation (%) 40 40 40 (ASTM D-4632) AOS -
Apparent opening size #30 #30 #30 (max. sieve size) (0.595 mm)
(0.595 mm) (0.595 mm) (ASTM D-4751) Flow Rate (gal/min/sq.ft.) 25
25 70 (GDT-87) Ultraviolet stability (% of 80 80 80 required
initial minimum tensile strength) (ASTM D-4632 after 300 hours
weathering per ASTM D-4355) Bursting strength (psi) 175 175 175
(ASTM D-3786) Minimum fabric width (in.) 36 22 36
The reinforced silt retention fabric may have any suitable basis
weight as needed or desired for a particular application, and
generally may be from about 35 to about 275 grams per square meter
(gsm). In one aspect, the basis weight of the reinforced silt
retention fabric is from about 50 to about 200 gsm. In another
aspect, the basis weight is about 75 to about 150 gsm. In yet
another aspect, the basis weight is from about 100 to about 130
gsm. In one particular example, the basis weight of the reinforced
silt retention fabric is about 120 gsm.
The reinforced silt retention fabric may have any suitable
thickness as needed or desired for a particular application, and
generally may be from about 0.1 to about 5 millimeters (mm). In one
aspect, the thickness is from about 0.15 to about 3 mm. In another
aspect, the thickness is from about 0.2 to about 2 mm. In yet
another aspect, the thickness is from about 0.25 to about 1 mm. In
another aspect, the thickness is from about 0.3 to about 0.7 mm. In
one particular example, the thickness of the reinforced silt
retention sheet is about 0.4 mm.
The reinforced silt retention fabric generally may have a maximum
apparent opening size (AOS) of 0.595 mm (30 mesh) or less, as
measured according to ASTM D-4751. In one aspect, the maximum AOS
is 0.595 mm. In another aspect, the maximum AOS is 0.500 mm (35
mesh). In another aspect, the maximum AOS is 0.420 mm (40 mesh). In
still another aspect, the maximum AOS is 0.354 mm (45 mesh). In yet
another aspect, the maximum AOS is 0.297 mm (50 mesh). In another
aspect, the maximum AOS is 0.250 mm (60 mesh). In yet another
aspect, the maximum AOS is 0.210 mm (70 mesh). In still another
aspect, the maximum AOS is 0.177 (80 mesh).
In another aspect, the maximum AOS is less than 0.595 mm. In yet
another aspect, the maximum AOS is less than 0.500 mm. In another
aspect, the maximum AOS is less than 0.420 mm. In still another
aspect the maximum AOS is less than 0.354 mm. In yet another
aspect, the maximum AOS is less than 0.297 mm. In another aspect,
the maximum AOS is less than 0.250 mm. In yet another aspect, the
maximum AOS is less than 0.210 mm.
The reinforced silt retention fabric may have any suitable flow
rate therethrough as measured according to ASTM D-4491, and may
generally be from about 35 to about 160 gallons/minute/square foot
(gal/min/sqft). In one aspect, the flow rate is from about 50 to
about 140 gal/min/sqft. In another aspect, the flow rate is from
about 70 to about 125 gal/min/sqft. In yet another aspect, the flow
rate is from about 80 to about 100 gal/min/sqft. In another aspect,
the flow rate is at least about 50 gal/min/sqft. In still another
aspect, the flow rate is at least about 70 gal/min/sqft. In a
further aspect, the flow rate is at least about 90 gal/min/sqft. In
another aspect, the flow rate is greater than 50 gal/min/sqft. In
one particular example, the water flow rate through the reinforced
silt retention fabric is about 95 gal/min/sqft.
The reinforced silt retention fabric generally may have a tensile
strength of at least about 100 lb in the warp (machine) direction
("warp tensile strength"), as measured according to ASTM D-4632. In
one aspect, the warp tensile strength is at least about 125 lb. In
another aspect, the warp tensile strength is at least about 150 lb.
In yet another aspect, the warp tensile strength is at least about
175 lb. In another aspect, the warp tensile strength is at least
about 200 lb. In still another aspect, the warp tensile strength is
from about 100 to about 150 lb. In another aspect, the warp tensile
strength is from about 200 to about 300 lb. In another aspect, the
warp tensile strength is from about 100 to about 350 lb. In one
particular example, the warp tensile strength of the reinforced
silt retention fabric is about 124 lb.
The reinforced silt retention fabric generally may have a tensile
strength of at least about 75 lb in the fill (cross machine)
direction ("fill tensile strength"), as measured according to ASTM
D-4632. In one aspect, the fill tensile strength is at least about
100 lb. In another aspect, the fill tensile strength is at least
about 125 lb. In yet another aspect, the fill tensile strength is
at least about 150 lb. In another aspect, the fill tensile strength
is at least about 175 lb. In still another aspect, the fill tensile
strength is from about 75 to about 100 lb. In another aspect, the
fill tensile strength is from about 75 to about 150 lb. In yet
another aspect, the fill tensile strength is from about 150 to
about 250 lb. In another aspect, the fill tensile strength is from
about 75 to about 450 lb. In one particular example, the fill
tensile strength of the reinforced silt retention fabric is about
88 lb.
The reinforced silt retention fabric generally may have a
trapezoidal tear strength in the warp direction ("warp trapezoidal
tear strength") of at least about 10 decaNewtons (dN), as measured
according to ASTM D-4533. In one aspect, the warp trapezoidal tear
strength is at least about 15 dN. In another aspect, the warp
trapezoidal tear strength is at least about 20 dN. In still another
aspect, the warp trapezoidal tear strength is from about 15 to
about 60 dN. In another aspect, the warp trapezoidal tear strength
is from about 17 to about 40 dN. In yet another aspect, the warp
trapezoidal tear strength is from about 20 to about 30 dN. In one
particular example, the warp trapezoidal tear strength of the
reinforced silt retention fabric is about 22 dN.
The reinforced silt retention fabric generally may a trapezoidal
tear strength in the fill direction ("fill trapezoidal tear
strength") of at least about 10 dN, as measured according to ASTM
D-4533. In one aspect, the fill trapezoidal tear strength is at
least about 15 dN. In another aspect, the fill trapezoidal tear
strength is at least about 18 dN. In still another aspect, the fill
trapezoidal tear strength is from about 12 to about 50 dN. In
another aspect, the fill trapezoidal tear strength is from about 15
to about 40 dN. In yet another aspect, the fill trapezoidal tear
strength is from about 18 to about 30 dN. In one particular
example, the fill trapezoidal tear strength of the reinforced silt
retention fabric is about 20 dN.
The reinforced silt retention fabric generally may have puncture
strength of at least about 12 dN, as measured according to ASTM
D-4533. In one aspect, the puncture strength is at least about 18
dN. In another aspect, the puncture strength is at least about 20
dN. In still another aspect, the puncture strength is from about 12
to about 75 dN. In another aspect, the puncture strength is from
about 15 to about 50 dN. In yet another aspect, the puncture
strength is from about 18 to about 30 dN. In one particular
example, the puncture strength of the reinforced silt retention
fabric is about 24 dN.
The reinforced silt retention fabric generally may have a mullen
burst strength at least about 150 psi, as measured according to
ASTM D-3786. In one aspect, the mullen burst strength is at least
about 200 psi. In another aspect, the mullen burst strength is at
least about 250 psi. In yet another aspect, the mullen burst
strength is at least about 300 psi. In another aspect, the mullen
burst strength is at least about 350 psi. In still another aspect,
the mullen burst strength is at least about 400 psi. In another
aspect, the mullen burst strength is t least about 500 psi. In
still another aspect, the mullen burst strength is from about 150
to about 450 psi. In yet another aspect, the mullen burst strength
is from about 175 to about 300 psi. In one particular example, the
mullen burst strength of the reinforced silt retention fabric is
about 206 psi.
The reinforced silt retention fabric generally may have a standard
concentration filtering efficiency of at least about 85%, as
measured according to ASTM D-5141-96(2004). In one aspect, the
standard concentration filtering efficiency is at least about 90%.
In another aspect, the standard concentration filtering efficiency
is at least about 92%. In another aspect, the standard
concentration filtering efficiency is at least about 94%. In yet
another aspect, the standard concentration filtering efficiency is
at least about 96%. In still another aspect, the standard
concentration filtering efficiency of the reinforced silt retention
fabric is at least about 98%. In still another aspect, the standard
concentration filtering efficiency is greater than 97% for sand. In
still another aspect, the standard concentration filtering
efficiency is greater than 87% for silt. In yet another aspect, the
standard concentration filtering efficiency is greater than 90% for
clay.
The reinforced silt retention fabric generally may have a standard
concentration reduction in turbidity of at least about 20%, as
measured according to ASTM D-5141-96(2004). In one aspect, the
standard concentration reduction in turbidity is at least about
35%. In another aspect, the standard concentration reduction in
turbidity is at least about 50%. In yet another aspect, the
standard concentration reduction in turbidity is at least about
65%. In still another aspect, the standard concentration reduction
in turbidity of the reinforced silt retention fabric is at least
about 80%.
In another aspect, the standard concentration reduction in
turbidity is greater than 25% for sand. In yet another aspect, the
standard concentration reduction in turbidity is greater than 30%
for sand. In another aspect, the standard concentration reduction
in turbidity is greater than 35% for sand. In still another aspect,
the standard concentration reduction in turbidity is greater than
40% for sand. In another aspect, the standard concentration
reduction in turbidity is greater than 45% for sand. In yet another
aspect, the standard concentration reduction in turbidity is
greater than 40% for sand. In another aspect, the standard
concentration reduction in turbidity is greater than 45% for sand.
In a further aspect, the standard concentration reduction in
turbidity is greater than 50% for sand. In another aspect, the
standard concentration reduction in turbidity is greater than 55%
for sand.
In yet another aspect, the standard concentration reduction in
turbidity is greater than 58% for silt. In another aspect, the
standard concentration reduction in turbidity is greater than 60%
for silt. In still another aspect, the standard concentration
reduction in turbidity is greater than 65% for silt. In yet another
aspect, the standard concentration reduction in turbidity is
greater than 70% for silt. In another aspect, the standard
concentration reduction in turbidity is greater than 75% for silt.
In yet another aspect, the standard concentration reduction in
turbidity is greater than 80% for silt.
In another aspect, the standard concentration reduction in
turbidity is greater than 51% for clay. In yet another aspect, the
standard concentration reduction in turbidity is greater than 55%
for clay. In still another aspect, the standard concentration
reduction in turbidity is greater than 60% for clay. In another
aspect, the standard concentration reduction in turbidity is
greater than 65% for clay. In yet another aspect, the standard
concentration reduction in turbidity is greater than 70% for clay.
In another aspect, the standard concentration reduction in
turbidity is greater than 75% for clay. In still another aspect,
the standard concentration reduction in turbidity is greater than
80% for clay.
The reinforced silt retention fabric generally may have a double
concentration filtering efficiency of at least about 90%, as
measured according to ASTM D-5141-96(2004). In one aspect, the
double concentration filtering efficiency is at least about 92%. In
another aspect, the double concentration filtering efficiency is at
least about 94%. In yet another aspect, the double concentration
filtering efficiency is at least about 96%. In still another
aspect, the double concentration filtering efficiency of the
reinforced silt retention fabric is at least about 98%.
In another aspect, the double concentration filtering efficiency is
greater than 97% for sand. In yet another aspect, the double
concentration filtering efficiency is greater than 98% for
sand.
In still another aspect, the double concentration filtering
efficiency is greater than 90% for silt. In another aspect, the
double concentration filtering efficiency is greater than 92% for
silt. In yet another aspect, the double concentration filtering
efficiency is greater than 94% for silt. In still another aspect,
the double concentration filtering efficiency is greater than 96%
for silt.
In yet another aspect, the double concentration filtering
efficiency of the reinforced silt retention fabric is greater than
91% for clay. In another aspect, the double concentration filtering
efficiency of the reinforced silt retention fabric is greater than
93% for clay. In yet another aspect, the double concentration
filtering efficiency of the reinforced silt retention fabric is
greater than 95% for clay. In still another aspect, the double
concentration filtering efficiency of the reinforced silt retention
fabric is greater than 97% for clay.
The reinforced silt retention fabric generally may have a double
concentration reduction in turbidity of at least about 20%, as
measured according to ASTM D-5141-96(2004). In one aspect, the
double concentration reduction in turbidity is at least about 35%.
In another aspect, the double concentration reduction in turbidity
is at least about 50%. In yet another aspect, the double
concentration reduction in turbidity is at least about 65%. In
still another aspect, the double concentration reduction in
turbidity of the reinforced silt retention fabric is at least about
80%.
In another aspect, the double concentration reduction in turbidity
is greater than 31% for sand. In yet another aspect, the double
concentration reduction in turbidity is greater than 35% for sand.
In another aspect, the double concentration reduction in turbidity
is greater than 40% for sand. In still another aspect, the double
concentration reduction in turbidity is greater than 45% for sand.
In another aspect, the double concentration reduction in turbidity
is greater than 50% for sand.
In another aspect, the double concentration reduction in turbidity
is greater than 58% for silt. In yet another aspect, the double
concentration reduction in turbidity is greater than 60% for silt.
In still another aspect, the double concentration reduction in
turbidity is greater than 65% for silt. In yet another aspect, the
double concentration reduction in turbidity is greater than 70% for
silt. In another aspect, the double concentration reduction in
turbidity is greater than 75% for silt. In yet another aspect, the
double concentration reduction in turbidity is greater than 80% for
silt. In a further aspect, the double concentration reduction in
turbidity is greater than 85% for silt.
In another aspect, the double concentration reduction in turbidity
is greater than 45% for clay. In yet another aspect, the double
concentration reduction in turbidity is greater than 50% for clay.
In another aspect, the double concentration reduction in turbidity
is greater than 55% for clay. In still another aspect, the double
concentration reduction in turbidity is greater than 60% for clay.
In another aspect, the double concentration reduction in turbidity
is greater than 65% for clay. In a further aspect, the double
concentration reduction in turbidity is greater than 70% for clay.
In another aspect, the double concentration reduction in turbidity
is greater than 75% for clay. In yet another aspect, the double
concentration reduction in turbidity is greater than 80% for
clay.
The reinforced silt retention fabric generally may have a standard
concentration filtering efficiency greater than about 80% for silt
as measured according to modified ASTM D-5141-96(2004), described
in Example 2. In one aspect, the standard concentration filtering
efficiency is greater than 84% for silt. In another aspect, the
standard concentration filtering efficiency is greater than 86% for
silt. In yet another aspect, the standard concentration filtering
efficiency is greater than 86% for silt.
The reinforced silt retention fabric generally may have a standard
concentration reduction in turbidity of greater than about 40% for
silt, as measured according to modified ASTM D-5141-96(2004). In
one aspect, the standard concentration reduction in turbidity is
greater than 46% for silt. In another aspect, the standard
concentration reduction in turbidity is greater than 50% for silt.
In yet another aspect, the standard concentration reduction in
turbidity is greater than 55% for silt. In still another aspect,
the standard concentration reduction in turbidity is greater than
60% for silt.
The reinforced silt retention fabric generally may have a double
concentration filtering efficiency greater than about 80% for silt
as measured according to modified ASTM D-5141-96(2004). In one
aspect, the double concentration filtering efficiency is greater
than 85% for silt. In another aspect, the double concentration
filtering efficiency is greater than 87% for silt. In another
aspect, the double concentration filtering efficiency is greater
than 89% for silt. In another aspect, the double concentration
filtering efficiency is greater than 90% for silt.
The reinforced silt retention fabric generally may have a double
concentration reduction in turbidity of greater than about 50% for
silt, as measured according to modified ASTM D-5141-96(2004). In
one aspect, the double concentration reduction in turbidity is
greater than 53% for silt. In one aspect, the double concentration
reduction in turbidity is greater than 55% for silt. In another
aspect, the double concentration reduction in turbidity is greater
than 60% for silt. In yet another aspect, the double concentration
reduction in turbidity is greater than 65% for silt. In another
aspect, the double concentration reduction in turbidity is greater
than 70% for silt.
The reinforced silt retention sheet typically has a width of about
1 to about 4 feet, though greater or lesser widths can be used
depending upon the application or use, and generally will be
unrolled or fed out and cut to a desired length. In one aspect, the
silt retention sheet has a width of from about 18 to about 26
inches, for example, about 22 inches. In another aspect, the silt
retention sheet has a width of from about 32 to about 40 inches,
for example, about 36 inches. In yet another aspect, the silt
retention sheet has a width that is at least about 15 inches, for
example, at least about 20 inches.
According to another aspect of the present invention, a silt
retention system is provided. In one variation of this aspect shown
in FIG. 8, the system includes a silt retention sheet 610, at least
one stake 612, and at least one fastener 614. To assemble the silt
retention system into a silt retention fence 600, a stake 612 is
inserted into the soil (not shown), the silt retention sheet 610 is
aligned with the stake 612, and the fastener 614 is inserted
through the sheet 610 into the stake 612. This process is repeated
until the desired silt retention fence or system is attained.
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.
Any silt retention fabric 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 a
scrim-reinforced nonwoven silt retention fabric, where the
reinforcing material is embedded with the fibers and secured by
mechanical entrapment, without substantially bonding or fusing the
scrim reinforcing element to or with the nonwoven 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 with the fibers and is secured
further by adhesive and/or thermal bonding.
The stake can be wood, metal, plastic, or other suitable material,
as needed or desired for a particular application. Likewise, any
suitable fastener may be used, for example, a staple, pin, clip,
hook, hook and loop, snap, band, screw, nail, or any other
implement capable of penetrating the fabric and securing it to the
stake.
Thus, in one particular example, the system may include at least
one wood stake, at least one fastener, for example, a staple, and a
needlepunched spunbond polyester nonwoven fabric having a
fiberglass scrim 616 entrapped and entangled with the fibers 618
without additional adhesive or mechanical bonding.
In another variation of this aspect shown in FIG. 9, the system
includes a silt retention sheet 710, at least one stake 712, at
least one fastener 714, and at least one fastener support 716. To
assemble the silt retention into a fence 700 according to this
aspect, a stake 712 is inserted into the soil (not shown), the silt
retention sheet 710 is aligned with the stake 712, the fastener
support 716 is positioned over the sheet distal, but in at least
partial alignment with, the stake 712, and the fastener 714 is
inserted through the fastener support 716, through the sheet 710,
and into the stake 712. This process is repeated until the desired
silt retention fence or system is attained.
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
fastener support, provided that the sheet is securely attached.
As with above, 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 and fastener supports. 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.
In use, the fastener support minimizes tearing of the fabric at or
proximate the attachment points along the stake, thereby reducing
the rate of failure of the silt retention fence. Furthermore,
depending on the particular application, use of a fastener support
also may improve sedimentation by providing a more stable fence
that is capable of retaining more solids, even during heavy
flow.
Numerous fastener supports are contemplated by the present
invention. If desired, any of the various numerous strips, bands,
belts, patches, and other reinforcing elements described herein or
contemplated hereby also may be used as a fastener support. In one
aspect, the fastener support is a strip, band, piece, disk, or any
other shaped piece of wood, plastic, metal, composite material, or
any other suitable material through which the desired fastener can
penetrate.
The fastener support may be dimensioned to have any desired width,
for example, from about 0.125 to about 0.75 inches. As another
example, the width of the fastener support may be from about 0.25
to about 0.5 inches. If desired, the width of the fastener support
may be selected to be approximately equal to that of the stake for
easy alignment thereof. However, it will be understood that the
width of the support may be greater or less than that of the
stake.
The fastener support may have any thickness as needed or desired,
provided that fastener is capable of sufficiently penetrating the
support, the fabric, and the stake to provide a secure attachment
of the fabric thereto. It will be understood that if a particular
support is desired to be used, an alternate fastener may be
selected to achieve a secure attachment of the fabric to the
stake.
Likewise, the fastener support may have any length as desired. The
support generally may have a length that is less than the length of
the stake (or the height of the resulting fence). In one example,
the fastener support has a length that is approximately equal to
that of the intended exposed area of the stake (that which is not
underground). In one aspect, the support has a length of from about
2 to about 24 inches, for example, about 18 inches. In another
aspect, the support has a length of from about 32 to about 40
inches, for example, about 30 inches. In yet another aspect, the
support has a length that is at least about 15 inches, for example,
at least about 18 inches. Other examples of lengths that may be
suitable include 2 inches, 5 inches, and 12 inches. However,
numerous other lengths are contemplated hereby.
Any silt retention sheet 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 a
scrim-reinforced nonwoven silt retention sheet, where the
reinforcing element is embedded with the fibers and secured by
mechanical entrapment, without bonding or fusing the reinforcing
element to or with the nonwoven fibers. In another exemplary system
according to this aspect, the system includes a scrim-reinforced
nonwoven silt retention sheet, where the reinforcing element is
embedded with the fibers and is secured further by adhesive and/or
thermal bonding.
As with the various other systems provided herein or contemplated
hereby. The stake can be wood, metal, plastic, or other suitable
material, as needed or desired for a particular application.
Likewise, any suitable fastener may be used, for example, a staple,
pin, clip, hook, hook and loop, snap, band, screw, nail, or any
other implement capable of penetrating the fastener support and the
fabric, and securing it to the stake.
Thus, by way of example and not by limitation, one example of a
system according to this aspect may include a fabric comprising a
wood stake, a wood lattice strip fastener support, a fastener, for
example, a staple, and a needlepunched spunbond polyester nonwoven
material having a fiberglass scrim 718 entrapped and entangled with
the fibers 720 without any additional adhesive or mechanical
bonding. Various aspects of the present invention may be understood
further by way of the following examples, which are not to be
construed as limiting in any manner.
EXAMPLES
The properties and performance of an exemplary silt retention
system (S) according to the present invention were evaluated to
determine its sediment restraining properties and flow through
rates relative to a commercially available Type C silt fence (W)
control. Dimensional analysis also was conducted to determine the
maximum loads that would be expected with typical sediment barrier
applications. The physical characteristics of the systems are
provided in Table 3.
TABLE-US-00004 TABLE 3 Sample W Sample S General description Woven
polypropylene, style Fiberglass scrim (0.25 in. mesh) 2098, 28 EPI
.times. 19 PPI reinforced spunbond polyester (about 4-5 dpf)
attached to stake using wood lattice fastener support strip Source
Willacoochee Industrial Fabrics Silt-Saver, Inc. (Willacoochee, GA)
(Conyers, GA) Basis weight (osy) 6.2 3.0 Thickness (mm) Not tested
0.4 mm Grab tensile (lb) Warp (machine direction) - 300 Warp
(machine direction) - 124 (ASTM D-4632) Fill (cross direction) -
200 Fill (cross direction) - 88 Grab elongation (%) 30 Warp
(machine direction) - 81 (ASTM D-4632) Fill (cross direction) - 102
AOS - Apparent # 40 # 70 opening size (max. (0.420 mm) (0.210 mm)
sieve size) (ASTM D-4751) Flow rate 50 95 (gal/min/sq. ft.) (2035
L/min/m.sup.2) (ASTM D-4491) Permittivity (per sec) Not tested 1.27
(ASTM D-4491) Permeability Not tested 0.226 (cm/sec) (ASTM D-4491)
Ultraviolet stability 90% Not tested after 300 hours (after 500
hours) (ASTM D-4355) Burst strength, PSI 450 206 (ASTM D-3786)
Minimum fabric unknown 42 width (in.) Puncture (lb) 120 24 dN
Trapezoid tear 65 lb Warp - 22 dN Fill - 20 dN
Example 1
Testing was conducted according to ASTM D-5141-96(2004) titled
"Standard Test Method for Determining Filtering Efficiency and Flow
Rate of a Geotextile for Silt Fence Application Using Site-Specific
Soil". A watertight flume was constructed using aluminum and
pressure treated plywood using specifications from FIG. 1 of ASTM
D-5141. The flume was supported at an 8% grade. The test material
was fastened securely along the entire length of 3 sides of the
flume opening to ensure that the material had no wrinkles or loose
sections across the entire cross section.
Three soil types were selected for use in preparing slurry
mixtures. The soils were chosen to represent the variety of
textural properties commonly found in Georgia and to test the
materials effectiveness at containing sediment derived from various
parent materials (Table 4). To represent the diversity found in
many soils, for example, in Georgia, a Cecil (sandy clay loam to
clay), Tifton (sand to sandy loam), and Fannin (loam to silt loam)
series were prepared.
TABLE-US-00005 TABLE 4 Soil Texture % Sand % Silt % Clay Sand 88 8
4 Silt loam 22 64 8 Clay loam 30 40 30
Test soils were collected in the field from the upper 10 cm of the
soil profile and air dried and sieved through a 2 mm sieve prior to
testing. Three concentrations were used for the testing: 0 ppm
(clear), the concentration set forth in the standard, 2890 ppm
(standard), and double the standard concentration, 5780 ppm
(double).
The three concentrations of sediment laden water were mixed in a 50
L holding container on top of the flume. Next, 150 and 300 g of dry
test soil were added to 50 L of tap water within the top holding
container to mix the standard and double concentrations,
respectively. The temperature of the solution was recorded so that
the viscosity of the water could be standardized. The solution was
thoroughly mixed using a mechanical stirring device (paint stirrer
on a 4 amp drill) for one minute to ensure a uniform mix. While
continuously mixing the solution, a 150 ml depth integrated sample
was taken to measure the initial turbidity of the sediment laden
water. After one minute of mixing, the sediment solution was
released from the container into the upper end of the flume. The
timer was started upon release of the water. The holding container
then was rinsed using 2 L of water allowing the rinse water to
enter into the upper end of the flume.
The flow of water through the material was timed and recorded until
no water remained behind the material or 25 minutes had elapsed. In
the cases where 25 minutes elapsed and water remained behind the
material, the distance from the material to the edge of the water
up the flume was measured. The filtrate that passed through the
flume was collected in a 100 L plastic container. The collected
filtrate was then agitated with a stirrer for one minute. After one
minute of stirring, a 500 ml depth integrated sample was taken to
measure the suspended solids and turbidity of the leachate.
The ASTM standard provides equations for calculating suspended
solids, filtering efficiency, and flow rate. The equations for
suspended solids and filtering efficiency were given as:
.times. ##EQU00001## where: S.sub.s=Suspended solids, ppm; A=weight
of filter plus residue (g); B=weight of filter (g); and C=sample
size, ml.
.times. ##EQU00002## where: F.sub.E=Filtering efficiency; and 2890
represents the sediment placed behind the material, and is replaced
with 5780 for the double concentration runs.
However, the equations for the flow rate that were given in the
ASTM standard were determined to be incorrect. Through consultation
with the standard developers, the following equations were derived
to calculate flow rate (F.sub.T) through the specimen in
m.sup.3/m.sup.2/min:
For complete drainage in less than 25 minutes: F.sub.T=0.606/t (3)
or for incomplete drainage:
.times..times. ##EQU00003## where: t=time for flow, min.; and
X=distance from the material to the edge of the water behind the
geotextile, mm.
Since there was very little temperature variation in the room over
the testing period (temperature ranged from 21.7.+-.0.4.degree.
C.), a correction for the viscosity of water was made using the
average temperature rather than the individual runs as outlined in
equation 5 of the standard.
Each test consisted of a clear, single, and double concentration
run on a single section of material. The test was run in triplicate
for each soil type on both materials for a total of 18 tests. After
each test was completed, the test material was removed from the
flume, dried, and saved. The top holding tank, the flume, gutter,
and collector then were cleaned using tap water to remove any
remaining sediment. A new section of material was then fastened
securely along the entire length of 3 sides of the flume for the
next test. The results are presented in Table 5 and FIGS.
10-12.
TABLE-US-00006 TABLE 5 Flow Rate (m.sup.3/m.sup.2/min) Sample Clear
Single Double Sand S 0.6753 0.0470 0.0015 W 0.4560 0.1072 0.0098
Silt S 0.4544 0.0014 0.0005 W 0.4265 0.0022 0.0015 Clay S 0.4163
0.0016 0.0005 W 0.3881 0.0023 0.0021
Captured samples from each of the tests were analyzed for total
suspended solids and turbidity. Total suspended solids were
analyzed using the standard method set forth in Methods for the
Examination of Waster and Wastewater (Greenberg at al., 1998).
Whatman 934-AH glass micro fiber filters were used for the
procedure. The sample volume was 100 ml.
Turbidity was run on a HF scientific DRT 100B. The instrument was
zeroed using deionized (DI) water. Samples bottles were shaken
vigorously for 10 seconds. A small subsample was poured into the
instrument cuvette and capped. The subsample was again shaken
vigorously for 10 seconds and placed in the instrument. A 10 second
average was taken for the reading. The subsample was then discarded
and the cuvette was rinsed thoroughly with DI water. This process
was repeated for each sample. SAS analysis of variance (ANOVA) was
used for statistical analysis to determine differences between the
treatments. The results are presented in Table 6, in FIGS. 13 and
14 (filtration efficiency), and in FIGS. 15 and 16 (turbidity).
TABLE-US-00007 TABLE 6 Suspended Turbidity F.sub.E % Reduction Type
solids (ppm) (NTU) (%) in turbidity Standard concentration Sand S
46.0 25.5 98 58 W 92.3 43.3 97 25 Silt S 161.3 77.7 94 81 W 365.7
167.0 87 58 Clay S 76.7 83.2 97 82 W 300.7 220.7 90 51 Double
Concentration Sand S 73.3 43.3 99 55 W 163.0 77.0 97 31 Silt S
166.7 92.7 97 90 W 608.7 359.3 90 58 Clay S 139.3 138.3 98 84 W
509.3 452.7 91 45
Example 2
The flume was raised to about 58% to produce more hydraulic head
and simulate a 60% slope (referred to herein as "modified ASTM
D-5141-96(2004))". Testing at the higher slope was only conducted
for the silt loam soil. Each test included a clear, single, and
double concentration run per material. The test was run in
triplicate for each fence for a total six tests.
The same apparatus was used for the 60% slope as for the 8% slope
(Example 1), except as follows: the brace that secured the holding
tank was modified to level the tank; the gutter that channeled the
leachate into the 100 L plastic container was removed and replaced
with flashing, which allowed the leachate to freefall into a new
plastic container that was wider than the flume; and the new
receptacle was calibrated so the volume of leachate collected could
be calculated by the depth of leachate in the container.
The same timing and sampling procedure was used for the 60% slope
as for the 8% slope (Example 1), except that the total volume of
slurry passing the fence was measured and recorded instead of
measuring the distance of pooled water behind the fence after 25
minutes. The following equations were derived and used to calculate
the flow rate:
for complete drainage in less than 25 minutes: F.sub.T=0.2252/t
(5); or for incomplete drainage:
##EQU00004## where: t=time for flow in minutes, Vnet=total flow
that passed through the fence barrier in cubic meters, and
0.222=the area of fence material exposed to flow.
The results are presented in Table 7 and FIGS. 17-19.
TABLE-US-00008 TABLE 7 Flow % Rate Suspended Reduction Fence
(m.sup.3/m.sup.2/ solids Turbidity F.sub.e in type Run min) (ppm)
(NTU) (%) turbidity S Clear 0.4054 Standard 0.0149 290 130 90 61
Double 0.0084 447 197 92 74 W Clear 0.3747 Standard 0.0084 474 171
84 46 Double 0.0068 860 322 85 53
Example 3
In addition to flume testing, an additional structure and test
method were constructed to determine if simplified method would
produce similar results. Using the apparatus shown in FIG. 20,
additional evaluations were conducted using the silt loam soil.
These runs were only conducted at the standard concentration.
PVC piping was used to construct an apparatus consisting of a 7 L
holding tank placed on top of a valve. Attached below the valve was
a 14 in. section of 4 in. PVC pipe which ran perpendicular to the
ground. A 45.degree. elbow with a 4 in. diameter was attached to
the bottom of the pipe. A 7 inch diameter section of geotextile was
tightly fastened to the open end of the elbow with a ring clamp. A
plastic container was placed below the opening to collect the
leachate.
For this test, 21 g of soil was added to 7 L of tap water in order
to make the standard concentration, 2890 ppm. The temperature of
the water was recorded and the soil laden water was mixed with a
small paint stirrer for 1 minute. While still mixing, a depth
integrated sample was taken to measure the initial turbidity of the
water. At this point the valve was opened and the timer started. An
additional 100 ml of water was used to rinse any remaining sediment
from the holding container.
The flow of slurry was timed until the leachate began to drip into
the plastic container or 25 minutes had elapsed. If 25 minutes
elapsed the total volume of leachate collected was measured and
recorded. The leachate was then agitated for 1 minute with a small
paint stirrer and a depth integrated 500 ml sample was taken to
measure the suspended solids and turbidity of the leachate. Clear
and standard concentrations were run for each geotextile material
using the silt loam soil. The fence was replaced after each test.
Each test was done in triplicate for each geotextile.
Flow rates were calculated by dividing the volume of flow collected
(m.sup.3) by the area (m.sup.2) and the time required to collect
the flow (maximum of 25 minutes). The results are presented in
Table 8.
TABLE-US-00009 TABLE 8 Flow rate Suspended Reduction Fence
(m.sup.3/ solids Turbidity F.sub.e in turbidity type Run
m.sup.2/min) (ppm) (NTU) (%) (%) S Clear 2.5493 Standard 0.0314 148
61 95 82 W Clear 2.7337 Standard 0.0266 350 130 88 60
Comparison of Test Methods
A general comparison of the results obtained using each of the
various test methods is provided in Tables 9 and 10. Table 9
provides a comparison of average flow rates (m.sup.3/m.sup.2/min)
for each method using the silt loam soil. Table 10 provides a
comparison of average filtering efficiency and percent reduction in
turbidity for each method using the silt loam soil at the standard
sediment concentration. Each value represents the average of the
three replicates.
TABLE-US-00010 TABLE 9 Fence Run Flume at 8% Flume at 58% Proposed
Test S Clear 0.4544 0.4054 2.5493 Standard 0.0014 0.0149 0.0314 W
Clear 0.4265 0.3747 2.7337 Standard 0.0022 0.0084 0.0266
TABLE-US-00011 TABLE 10 Filtering Efficiency % Reduction in
Turbidity Flume Flume Flume Flume Fence at 8% at 58% New test at 8%
at 58% New test S 94.4 90.0 94.9 81 61 82 W 87.3 83.6 87.9 58 46
60
The filter efficiencies and turbidity reductions for both the S and
W systems were nearly the same as those measured using the ASTM
test method. Since this testing apparatus is much easier to
construct and the tests are easier to conduct, this procedure may
offer advantages over the standard test method.
Although certain embodiments of this invention have been described
above with a certain degree of particularity, those skilled in the
art could make numerous alterations to the disclosed embodiments
without departing from the spirit or scope of this invention. All
directional references (e.g., upper, lower, upward, downward, left,
right, leftward, rightward, top, bottom, above, below, vertical,
horizontal, clockwise, and counterclockwise) are used only for
identification purposes to aid the reader's understanding of the
various embodiments of the present invention, and do not create
limitations, particularly as to the position, orientation, or use
of the invention unless specifically set forth in the claims.
Joinder references (e.g., joined, attached, coupled, connected, and
the like) are to be construed broadly and may include intermediate
members between a connection of elements and relative movement
between elements. As such, joinder references do not necessarily
imply that two elements are connected directly and in fixed
relation to each other.
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.
* * * * *