U.S. patent application number 11/281770 was filed with the patent office on 2006-06-22 for erosion control barrier.
Invention is credited to Douglas Paul Allard, Jonathan McDonald.
Application Number | 20060133897 11/281770 |
Document ID | / |
Family ID | 36595964 |
Filed Date | 2006-06-22 |
United States Patent
Application |
20060133897 |
Kind Code |
A1 |
Allard; Douglas Paul ; et
al. |
June 22, 2006 |
Erosion control barrier
Abstract
An erosion control roll including an elongate core member
defining an interior space, being open at both ends, and having
openings along its length, a pervious filter member open at both
ends and surrounding the elongate core member; and, an apron
disposed on the upstream side of the pervious filter member, said
apron running the length of said filter member, and extending a
predetermined distance therefrom.
Inventors: |
Allard; Douglas Paul; (Santa
Rosa, CA) ; McDonald; Jonathan; (Santa Rosa,
CA) |
Correspondence
Address: |
JOHNSON & STAINBROOK, LLP
3558 ROUND BARN BLVD., SUITE 203
SANTA ROSA
CA
95403
US
|
Family ID: |
36595964 |
Appl. No.: |
11/281770 |
Filed: |
November 16, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60628430 |
Nov 16, 2004 |
|
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Current U.S.
Class: |
405/43 ;
405/302.6; 405/302.7; 405/36 |
Current CPC
Class: |
E02D 17/20 20130101;
E02B 3/04 20130101; E02B 11/005 20130101 |
Class at
Publication: |
405/043 ;
405/302.6; 405/302.7; 405/036 |
International
Class: |
E02B 11/00 20060101
E02B011/00; E02D 17/20 20060101 E02D017/20 |
Claims
1. An erosion control roll comprising: an elongate core member
defining an interior space, being open at both ends, and having
openings along its length; a pervious filter member having an
upstream side and a downstream side, open at both said upstream and
down stream sides, and surrounding said elongate core member; and,
an apron disposed on said upstream side of said pervious filter
member, said apron running the length of said filter member, and
extending a predetermined distance therefrom.
2. The erosion control roll of claim 1 wherein said apron is
integrally formed with said pervious filter member.
3. The erosion control roll of claim 1 where the open ends of the
pervious filter member extend beyond the ends of the elongate core
member.
4. The erosion control roll of claim 1 wherein the elongate core
member is formed for from flexible corrugated pipe.
5. The erosion control roll of claim 1 wherein the elongate core
member is formed for from an open wire mesh or other open frame
material.
6. (canceled)
7. The erosion control roll of claim 4, wherein the perforations
are formed in the pipe, along a 180 degree arc, the first
perforation arcuately spaced from the bottom of the pipe so as to
define a closed-wall trough for carrying fluid to an open end of
the corrugated pipe.
8. The erosion control roll of claim 1 wherein the filter member
and apron comprise a pervious geotextile fabric.
9. The erosion control roll of claim 1 further including a silt
fence portion, said silt fence portion comprising a rectangular
section of geotextile material, extending from the base of the core
member and running longitudinally along the length of said core
member, said rectangular section having a plurality of sleeves
affixed to and extending perpendicularly from the leading edge of
said rectangular section, said sleeves sized to receive stakes for
deploying the fence and securing it in place.
10. The erosion control roll of claim 9 wherein the silt fence
portion is integrally formed from a geotextile fabric.
11. The erosion control roll of claim 10 wherein the silt fence
portion is formed of the same geotextile fabric as said apron and
filter members.
12. The erosion control roll of claim 1 further including one or
more agents interior of the core member.
13. The erosion control roll of claim 12 wherein said one or more
agents interior the core member provide a passive dosing
mechanism.
14. The erosion control roll of claim 1 wherein the openings in the
wall of the elongate core member are spaced a distance from the
base of the member, to define a walled trough for carrying fluids
entering the core member to a discharge point at an end of the
member.
15. An erosion control device including a plurality of the erosion
control rolls of claim 2, interconnected one to the other in series
by intervening couplers, thereby defining a continuous fluid path
extending from one core member to the other.
16. The erosion control device of claim 15 wherein at least one of
the intervening couplers is a tee coupler, said tee coupler
connected to a drain pipe for directing discharge of collected
fluid downstream of the roll.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of the filing
date of U.S. Provisional Patent Application Ser. No. 60/628,430,
filed Nov. 16, 2004 (Nov. 16, 2004).
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
[0003] Not applicable.
TECHNICAL FIELD
[0004] The present invention relates generally to soils erosion
control barriers, and more particularly to an erosion control
barrier in which water runoff is diverted via the barrier to a
remote point of discharge.
BACKGROUND INFORMATION AND DISCUSSION OF RELATED ART
[0005] Controlling soil erosion, such as erosion on slopes at
construction sites, and particularly control of the sedimentation
and debris carried in fluid flow on slopes is a continuing problem.
Fiber rolls (also known as wattles) are the current industry
standard for use in controlling erosion. Fiber rolls are typically
made of fibrous materials such as straw or excelsior (shredded
wood) made into rolls that are held together with netting. During
construction, the rolls are placed across the face of a slope to
curtail soil erosion and to direct and/or filter fluid flow as the
fluid flows down the slope. Silt fences, generally black porous
cloth strung vertically on wooden stakes across a slope, are an
alternative means of controlling erosion. However, most regulatory
agencies now discourage the use of silt fences alone due to the
propensity for silt fences to collapse from high fluid flows and
high winds.
[0006] Fiber rolls have been found to be more capable of performing
the erosion control function than silt fences. However, fiber rolls
are deficient in their ability to direct fluid flow in a controlled
manner. Moreover, numerous fiber rolls are generally required due
to their inherent deficiencies in directing fluid flow as the flow
proceeds down a slope.
[0007] An improved fiber roll is disclosed in commonly owned U.S.
Pat. No. 6,527,477, to Allard. The '477 patent discloses a fiber
roll wattle with a core member defining an interior space. One or
more openings in the wall of the core member communicates with the
interior space and allows fluids reaching the fiber rolls to enter
the core member through said openings. The core member may comprise
a flexible plastic pipe, such as high density polyethylene pipe
having a plurality of perforations. By providing such an interior
space, the erosion control roll not only serves as a barrier to
erosion, but redirects hillside runoff to a point of discharge
remote from the point of collection, such as when a multiplicity of
rolls are linked one to the other by couplers to provide a
continuous flow path to, for example, drain pipes associated with
the connectors, or to the far terminal ends of the linked rolls. In
the embodiment illustrated in the patent, outlet pipes are
connected to the tee/elbow connectors used to connect the rolls
longitudinally, the outlet pipes directing the fluid flow received
by the core members to desired downstream locations.
[0008] Yet another improved erosion control wattle is described in
commonly owned U.S. Pat. No. 6,641,335, to Allard, naming the first
named inventor of the present invention. The '335 patent shows a
walled elongated core member having a first open end, a second end,
an interior space and one or more openings in the wall
communicating the interior space with the exterior of the core
member. A fiber roll outer filter member surrounds the core member,
which can be coupled with to one or two complimentary core members
comprising tee connectors or elbow connectors. One advantage of the
present invention is the ability to connect outlet pipes to tee or
elbow connectors for directing fluid flow received by the core
members to desired locations downstream of the core members.
[0009] The foregoing commonly owned patents reflect the state of
the art devices of which the present inventors are aware. Reference
to, and discussion of, these patents is intended to aid in
discharging Applicant's acknowledged duty of candor in disclosing
information that may be relevant to the examination of claims to
the present invention. However, it is respectfully submitted that
none of the above-indicated patents disclose, teach, suggest, show,
or otherwise render obvious, either singly or when considered in
combination, the invention described and claimed herein.
Specifically, although each of the patents show improved barriers
to intercept and divert water away from the barrier, there remains
a problem with soil erosion in the area adjacent and around,
underneath and downstream of the erosion rolls caused by water
flowing to, over and underneath the rolls.
BRIEF SUMMARY OF THE INVENTION
[0010] The erosion control barrier of the present invention
represents yet another significant advance over the fiber roll
wattles in the prior art. The present invention includes a walled
elongate core member having a first open end, a second open end, an
interior space, with one or more openings in the wall communicating
the interior space with the exterior of the core member, and
further including an outer, pervious filter member which surrounds
the core member. In one embodiment, the outer filter member
includes an apron which is affixed to the filter member along its
length, and extends outwardly away from the core member. The apron
is of a predetermined width, and includes means to secure the apron
upstream of the elongate core member, so as to cover the ground
adjacent said member, and direct fluid runoff and sediments to the
elongate core member. Fluids passing through the pervious outer
filter and through the openings in the wall of the elongate core
member are carried by the core member to discharge points at the
end of the core member.
[0011] The inventive apparatus (variously referred to herein as the
inventive "erosion control roll" or the inventive "erosion control
barrier") may used in conjunction with a silt fence deployed in
abutting relationship to the control roll. The stakes used in the
deployment of the silt fence serve the secondary purpose of
providing additional stabilization for the control roll. The silt
fence can be formed integral to the control roll, in which event
the silt fence extends from the downstream side of the filter
member, in the opposite direction of the apron, and is provided
with holes sized to receive securing ground stakes. In another
embodiment the upstream apron may be covered with earth, to provide
additional ballast for system fixation and stabilization.
[0012] As with the erosion control rolls of the above-indicated
commonly owned patents, two or more core members may be connected
together. Accordingly, one or both of the open ends can be fitted
to couplers or connectors for connecting one core member to
another. The couplers can comprise tee connectors or elbow
connectors, which allows for the connection of outlet pipes to the
tee or elbow connectors for re-directing fluid flow received by the
core members to desired locations downstream of the core
members.
[0013] It is therefore an object of the present invention to
provide a new and improved erosion control barrier roll that
provides runoff water diversion and filtering.
[0014] It is another object of the present invention to provide a
new and improved erosion control roll that reduces soil erosion
around, underneath and downstream of the erosion control roll
caused by water flowing to, over and underneath the roll.
[0015] A further object or feature of the present invention is a
new and improved erosion control barrier that filters water
differentially, depending on the materials suspended in the water,
the amount of sedimentary deposit around the roll, and the water
depth adjacent the roll.
[0016] There has thus been broadly outlined the more important
features of the invention in order that the detailed description
thereof that follows may be better understood, and in order that
the present contribution to the art may be better appreciated.
There are, of course, additional features of the invention that
will be described hereinafter and which will form additional
subject matter of the claims appended hereto. Those skilled in the
art will appreciate that the conception upon which this disclosure
is based readily may be utilized as a basis for the designing of
other structures, methods and systems for carrying out the several
purposes of the present invention. It is important, therefore, that
the claims be regarded as including such equivalent constructions
insofar as they do not depart from the spirit and scope of the
present invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0017] The invention will be better understood and objects other
than those set forth above will become apparent when consideration
is given to the following detailed description thereof. Such
description makes reference to the annexed drawings wherein:
[0018] FIG. 1 is a perspective view of a section of the erosion
control barrier of the present invention;
[0019] FIG. 2 is a perspective view of the roll of FIG. 1, further
including a fabric section deployed to form a silt fence;
[0020] FIG. 3 is a side view in elevation of the embodiment of FIG.
2 shown deployed on a sloping surface;
[0021] FIG. 4A is a front view of an exemplary corrugated member
suitable for use with the erosion control barrier of the present
invention;
[0022] FIG. 4B a sectioned view illustrating a distribution of
openings in the core member of FIG. 4A according to an embodiment
of the invention;
[0023] FIG. 5 is a perspective view of the erosion control barrier
of FIG. 1, but having additional features; and
[0024] FIG. 6 is a side view in elevation of an alternative
embodiment of the erosion control barrier of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Referring to FIGS. 1 through 6, wherein like reference
numerals refer to like components in the various views, there is
illustrated therein a new and improved erosion control barrier. The
erosion control barrier of the present invention is adapted for use
in controlling sedimentation and debris flow, especially in
connection with construction site and hillside runoff. In its most
essential aspect, the apparatus includes a hollow core member
covered with an outer filter member incorporating a longitudinal
apron which serves several purposes: It provides means to secure
the hollow core member to the ground; it directs fluid flow to the
core member; and it covers the ground adjacent the core member to
prevent soil erosion around and beneath the core member. The
present invention is particularly useful in controlling erosion
resulting from sedimentation and debris flow on slopes at
construction sites and other areas where soil erosion poses
environmental issues.
[0026] Referring now to FIG. 1, a first embodiment of the present
invention is shown to include an elongate walled core member 10,
such as a perforated pipe, covered by a filter member or sleeve 12.
The core member 10 is open at each end. As illustrated, core member
10 may extend beyond the edges of filter member 12 with which it is
covered. However, in another embodiment filter member 12 may be
fabricated to overlap and extend beyond the end or ends of core
member 10. Preferably the filter member and the accompanying apron
14, as later described, extend a sufficient distance beyond each
end of the core member so as to cover over any connectors (likewise
later described) which may be used, and therefore to provide a
continuous sleeve/apron combination extending the length any number
of roll segments connected in series.
[0027] As will be appreciated, the perforations in the perforated
pipe of the core member may have perforations circumferentially
spaced openings at points along its length. However, any
configuration or scheme adapted for selectively filtering fluids
containing sediments and large pieces of debris may be
employed.
[0028] The perforated pipe may be constructed of generally flexible
material to facilitate the lay out of the erosion control barrier
in a manner that closely follows the contours of the slope to be
stabilized. It may also be corrugated, as illustrated in the
figures. Accordingly, the core member may be made of any suitable
stable, non-toxic and lightweight material, such as flexible high
density polyethylene, polypropylene, polyvinyl chloride, polyester,
or nylon pipe. Hollow core member may be comprised of perforated
polymeric pipe element or semi-rigid netting. Perforation size may
vary widely with application and material.
[0029] The filter member 12 covering core member 10 may be made
from any pervious (i.e. porous/permeable) filter fabric, such as a
woven or non-woven geotextile fabric, or a permeable polymeric
matrix. Materials include polypropylene, polyethylene, polyester,
natural cotton or other similar geotextiles and polyethylene fiber
mat. Densities generally range, but may not be restricted to, 3-16
oz/sf. Geotextile materials may be woven, nonwoven, needle-punched
or knit, while fiber mat may be woven, stitched or spun-bonded.
Geotextile fabrics are typically made from polyester or
polypropylene fibers. An exemplary woven geotextile fabric useable
with the rolls of this invention is FILTERWEAVE.RTM. available from
TC Mirafi Company, Pendergrass, Ga. Such geotextile fabrics
generally have a porosity AOS (Apparent Opening Size) factor of not
less than 180 .mu.m, to permit the flow of water therethrough,
while at the same time filtering out larger sediments, fines and
other debris. The porosity of such fabrics is generally not less
than 70 gpm/sq ft.
[0030] The filter sleeve and apron can be integrally formed from
separate pieces or the same piece of geo textile fabric, or from
different geo textile fabrics. By way of illustration, with
reference to FIG. 1, apron 14 can be formed from the same geo
textile fabric as filter member 12, by folding over a section of a
selected rectangular fabric piece, the folded-over section equal to
predetermined width 16 of apron 14, with seam 18 stitched at the
leading edge 20 of the apron, and seam 22 stitched at the trailing
edge of the apron and overlapping the other end of the geo textile
fabric piece. It is to be appreciated that the total width of the
fabric piece to be used to form the filter sleeve/apron should be
such that the tubular pocket formed in the fabric piece by seam 22
is suitably sized to easily and securely receive the perforated
pipe. It should be appreciated that the apron may alternatively be
formed from a separate section of fabric and sewn to the filter
sleeve. In such a case, the apron material may, but need not be the
same as the material used to form the filter sleeve.
[0031] If desired, the leading edge of the apron can be provided
with a reinforced edge. The reinforcement can be provided by sewing
in or otherwise securing a rigid member proximate the leading edge.
For instance, a steel rod or geogrid can be sewn into the leading
edge, in a manner well known in the art. Such reinforcement helps
to maintain contact of the apron with the uphill ground surface,
from the apron's leading edge to the midpoint of the filter
member.
[0032] The apron can also be provided with a plurality of holes 26
fitted with protective grommets so as to allow for the insertion of
metal pins or nails 27 to secure the apron to the ground.
Alternatively, the apron can be secured to the ground surface on
which the assembly is placed with U shaped staples or stakes.
[0033] With reference to FIG. 2, a second preferred embodiment of
the erosion control barrier of FIG. 1 shows that the core member
and apron can be used in conjunction with a silt fence 28 deployed
in an abutting relationship to the core member and apron. The silt
fence may be formed of the same geotextile fabric as the filter
sleeve, but more likely will be formed from less pervious or non
pervious material. The silt fence 28 can be integrated with the
filter sleeve member by being sewn to the member. Alternatively,
when the same geotextile material is used for the filter member,
the apron, and the silt fence, the geotextile fabric piece selected
to fabricate the assembly will be sized so as to allow for the
formation of the silt fence, the filter member, and the apron from
a single piece of fabric. Silt fences are typically about 36''
high. Thus to form the combined silt fence/filter member/apron
assembly, a longitudinal seam is provided at a point about 36''
from one edge of the fabric piece, to define the fence portion and
a suitably sized pocket seamed to received the perforated pipe. A
multiplicity of sleeves 30 are provided, stitched to the textile
fabric piece 28 and arranged perpendicular to its lengthwise edge
to receive stakes 32, which in turn are used to secure the system
to the ground.
[0034] While in the above embodiment the silt fence/pocket/apron is
formed from a single piece of fabric, it is not required, and in
fact such will not be the case where it is preferred that the silt
fence and/or the apron be formed from geotextile materials
different from that used to form the filter sleeve. In these
circumstances, both the silt fence and apron portions of the
erosion control roll can be formed of separate pieces and stitched
together. The dimensions for the patterning of the various fabric
pieces, seams and pockets will be obvious to those of ordinary
skill in the art, and as such, the exact dimensional
characteristics of the apparatus does not constitute a part of this
invention.
[0035] An installation of the erosion control roll of the invention
incorporating the use of both an apron and silt fence is
illustrated in FIG. 3. In this illustration, the perforated pipe is
shown positioned on a hillside, the apron secured to ground
upstream of the filter sleeve using nails 27 (or staples, if
desired). The silt fence is erected using stakes 32, which
typically are made from wood. In this arrangement, silt and water
will flow over apron 14, where water will pass through filter
member 12 to enter the interior of pipe 10. Silt and other debris
will be retained by filter sleeve 12, and behind silt fence 28,
such sediment and debris eventually building up behind the fence
and overtop the perforated pipe. If desired, in order to provide
further stability to the installed assembly, upon installation, the
apron can be covered with a limited amount of dirt, which helps
hold the roll in place. When the rolls are employed in combination
with and abutted by a stand alone silt fence, the stakes securing
the fence add further stability to the erosion control roll
installation.
[0036] In either of the above embodiments, one or both of the open
ends of the core members can include couplers or connectors for
connecting one core member to one or two complimentary core
members. A multiplicity of core members may be connected together
to create any desired length of roll/silt fence. The connectors can
be standard industry connectors or couplers for coupling piping,
such that each of the connected pipes is in fluid communication
with each other pipe. In addition, the couplings can comprise tee
connectors, or elbow connectors. In turn, the tee or elbow
connectors can be connected to outlet pipes to direct fluid flow
received by the core members to desired locations downstream of the
core members. In cases where erosion control rolls are placed at
the toe of a slope, water may be directed down a single row of core
members (deployed perpendicular to the slope) to a single outlet
point. Connectors fitted with outlet pipes are preferably used
where it is desirable to have water redirected so as to continue
downhill (parallel to the slope) following filtration.
[0037] The flexible pipe may comprise a corrugated pipe, with ribs
extending along at least a portion of the exterior surface of the
core member. With reference to FIGS. 4A and 4B, in one embodiment,
ribs 36 and valleys 37 extend along the periphery (i.e.
perpendicular to the longitudinal axis of the member) of the
exterior of core member 35. One or more openings 38 can be situated
in one or more of the ribs. Preferably the openings are elongated
slots located across the top of the rib.
[0038] In one embodiment a plurality of the openings are located in
the ribs at spaced intervals along the periphery of the core
member. For example, illustrated in FIG. 4B, the openings can be
spaced from a first opening along the periphery of the member
within a 180 degree arc as measured from the longitudinal axis of
the core member. A particularly preferred pattern is to space four
openings from a first opening at positions of approximately 22.5
degrees, 45 degrees, 90 degrees and 112.5 degrees from the first
opening as measured along an arc from the longitudinal axis of the
core member. In practice, the first opening is situated in the rib
near the top of the core member (as it will be positioned in the
particular erosion control barrier) such that the additional
openings will be situated towards the upstream side of the fluid
flow path.
[0039] In providing such an arrangement of openings, a non-porous
or closed-wall trough or channel is provided at the base of the
elongate core member, below the lowest positioned opening 38. Water
entering through the openings will be collected in and carried by
this channel to one or both ends of the roll, depending upon the
elevation of the first and second open ends. In one embodiment, as
previously noted, where the roll is connected to a second roll via
a tee connector, the collected water may be discharged through a
pipe fitted to the connector to a point downstream of the roll. In
another embodiment, the connector may direct the received water to
the next downstream roll, connected in series to the first roll,
for discharge at the free end of the second roll. Alternatively, an
elbow connector can be provided at the free end of the second
segment, and a drain pipe connected to the elbow connector to
redirect the received runoff to a discharge point downstream of the
erosion control roll.
[0040] In one embodiment, as illustrated in FIG. 5, at least one
cable or string 34, as a tag line, may be attached to the outer
filter member 12 to allow an installer to grip and tow the filter
member over a separate core member to facilitate integration of the
filter sleeve and core member in the field. In another variation,
where the core member is to be pulled through the filter sleeve (as
opposed to the sleeve being pulled over the core member) for on
site installation, at the time of fabrication of the sleeve when
the pocket is sewn, a loose string or tag line is laid inside the
pocket along the length of the sleeve. The string may be free at
one end or include a grip or handle, and contain a clasping means
or noose at its other end for attachment to the end of a core
member. For assembly, the one end of the line containing the
clasping means is affixed to the leading end of a core member to be
inserted into the sleeve. An installer then, grasping the other end
of the tag line, can pull the member into the sleeve.
[0041] In another embodiment, a pipe with openings around its
circumference may be used in combination with a less pervious
backing member 33 (FIG. 5) affixed to the filter member. This
backing member may be a solid sheet or a sheet of less pervious,
finer mesh fabric, placed around the back side (downhill side) of
the core member to decrease or block flow from passing transversely
through the core member. By use of such a backing member, a trough
for directing fluid flow is defined, whereby fluid received and
retained within the core member can be redirected to one or both of
its open ends for discharge. In this alternative, it should be
appreciated that the corrugated pipe may be replaced by an open
wire mesh or other similar frame, which defines an interior space
when covered by the filter sleeve.
[0042] Defined holes are added along the apron edges both adjacent
to and furthest from the main body to allow for staking. These
holes may be set out in any of a number of suitable configurations
to allow for more secure attachment of the apron to the ground
surface.
[0043] Expendable (i.e. dissolvable) agents used to assist in the
sediment removal function of the device, such as coagulants and
flocculants, may be added to the inside of the elongate core member
to provide a passive dosing mechanism. These agents 35, as
illustrated in FIG. 3, may be in solid form, comprising their own
structure, or contained in a filter bag element, or may be in
liquid form contained in a smaller dosing structure.
[0044] If desired, for certain other applications, such as the
formation of break waters, the erosion control roll can be capped
at either end to close off the pipe. In one embodiment, the filter
sleeve can be cinched closed to affect this closing off. This can
be accomplished by constructing the sleeve so that it extends a
significant distanced beyond the end of the core member at each
end, and includes means at its ends to provide for closure. Such
means can include a series of holes provided around the periphery
of the ends of the sleeve, through which a cord can be threaded and
then cinched to affect the closing.
[0045] Referring now to FIG. 6, in yet another embodiment of the
present invention, a bypass strip 13 comprises a portion of the
filter member sleeve 12 surrounding the core member 10. The opening
size of the bypass strip is generally at least 16 mesh and not
greater than 1/4''. The material comprising the downstream half of
the filter member may be less permeable (or impermeable) than that
comprising the upstream half when the device is intended to reduce
free runoff by intercepting and redirecting some portion of flow
entering perpendicular to it. The downstream half of the pervious
filter member is generally at least as permeable as the upstream
half when the device is employed as a check dam to slow runoff and
increase sedimentation. In providing a strip of material having a
different porosity than the remainder of the material in the filter
member, it is possible to govern the functions of the erosion
control roll depending on the conditions immediately surrounding
the roll when in use. For instance, if it is desired to strongly
filter runoff for sediment and toxin, a fine mesh material may be
provided in the lower portion of the filter member. But if water
buildup becomes so extensive that the potential for damage from
erosion is imminent, then material having a significantly greater
porosity can be provided in the upper portions of the filter
member. Thus, when water builds up to an undesirable height
alongside the erosion roll, it is allowed to more readily pass
through the filter member for diversion by the core member.
Alternatively, when water diversion is a primary concern for rapid
runoff, some predetermined length of erosion rolls, typically
connected end to end, may be provided with a filter member having
substantially impermeable lower portion, thus directing water
downhill before allowing it to pass through the filter member and
into the core member.
[0046] Having fully described several embodiments of the present
invention, many other equivalents and alternative embodiments will
be apparent to those skilled in the art. These and other
equivalents and alternatives are intended to be included within the
scope of the present invention. Therefore, the above description
and illustrations should not be construed as limiting the scope of
the invention, which is defined by the appended claims.
* * * * *