U.S. patent application number 10/115088 was filed with the patent office on 2002-10-17 for reactive geocomposite for remediating contaminated sediments.
Invention is credited to Alshawabkeh, Akram N., Henry, Karen Sue, Sheahan, Thomas Clair.
Application Number | 20020151241 10/115088 |
Document ID | / |
Family ID | 26812820 |
Filed Date | 2002-10-17 |
United States Patent
Application |
20020151241 |
Kind Code |
A1 |
Sheahan, Thomas Clair ; et
al. |
October 17, 2002 |
Reactive geocomposite for remediating contaminated sediments
Abstract
In one application for remediating sediments, employing a
geocomposite sheet eliminates the need for a thick cap or removal
and subsequent ex situ treatment of the sediment. A geocomposite
with at least one layer of reactive material is placed over the
area to be remediated. A layer of available surcharge materials
such as sand, gravel, or riprap covers the geocomposite. The weight
of the surcharge materials causes pore water to flow from the
sediment through the reactive layer or layers of the geocomposite.
Contaminants may be trapped in this reactive layer or layers. A top
or bottom layer, or both a top and bottom layer, may be provided to
inhibit incursion from outside the sediment layer, while permitting
appropriate flow direction of pore water into the reactive layer or
layers.
Inventors: |
Sheahan, Thomas Clair;
(Wellesley, MA) ; Alshawabkeh, Akram N.;
(Franklin, MA) ; Henry, Karen Sue; (Lyme,
NH) |
Correspondence
Address: |
HUMPHREYS ENGINEER CENTER SUPPORT ACTIVITY
ATTN: CEHEC-OC
7701 TELEGRAPH ROAD
ALEXANDRIA
VA
22315-3860
US
|
Family ID: |
26812820 |
Appl. No.: |
10/115088 |
Filed: |
April 4, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60283291 |
Apr 11, 2001 |
|
|
|
Current U.S.
Class: |
442/327 ;
442/181; 442/268; 442/321; 442/354; 442/380 |
Current CPC
Class: |
B32B 2262/106 20130101;
Y10T 442/60 20150401; Y10T 442/658 20150401; Y10T 442/3707
20150401; Y10T 442/51 20150401; B32B 5/26 20130101; Y10T 442/63
20150401; Y10T 442/30 20150401 |
Class at
Publication: |
442/327 ;
442/181; 442/268; 442/321; 442/354; 442/380 |
International
Class: |
D03D 025/00; D03D
015/00; B32B 005/26; D04H 001/08; D04H 001/00; D04H 003/00; D04H
005/00; D04H 013/00; B32B 015/02 |
Goverment Interests
[0002] The invention described herein may be manufactured and used
by or for the Government of the United States of America for
governmental purposes without the payment of any royalties thereon
or therefor.
Claims
We claim:
1. A geocomposite comprising: at least one first layer of
geosynthetic material; at least one second layer of geosynthetic
material; and at least one third layer composed of at least some
reactive material, said at least one third layer affixed between
said first and second layers, wherein said geocomposite may be
employed to remediate sediments.
2. The geocomposite of claim 1 in which said geosynthetic material
is commercially available.
3. The geocomposite of claim 2 in which said commercially available
geosynthetic material is selected from the group consisting of
woven, non-woven, and combinations of woven and non-woven
geosynthetic material.
4. The geocomposite of claim 1 in which said reactive material is
commercially available.
5. The geocomposite of claim 4 in which said commercially available
reactive material is selected from the group consisting of
activated carbon, zeolites, particulate polymers, granular forms of
commercially available chemical adsorption materials, activated
carbon fabric commercially available in sheets, geosynthetic
drainage net incorporating pores for holding granular reactive
material, and combinations thereof.
6. A remediation configuration comprising: a geocomposite
comprising: at least one first layer of geosynthetic material; at
least one second layer of geosynthetic material; and at least one
third layer composed of at least some reactive material, said at
least one third layer affixed between said first and second layers,
and a layer of surcharge materials placed above said geocomposite,
wherein said remediation configuration may be employed to remediate
sediments.
7. The remediation configuration of claim 6 in which said
geosynthetic material is commercially available.
8. The remediation configuration of claim 7 in which said
commercially available geosynthetic material is selected from the
group consisting of woven, non-woven, and combinations of woven and
non-woven geosynthetic material.
9. The remediation configuration of claim 6 in which said reactive
material is commercially available.
10. The remediation configuration of claim 9 in which said
commercially available reactive material is selected from the group
consisting of activated carbon, zeolites, particulate polymers,
granular forms of commercially available chemical adsorption
materials, activated carbon fabric commercially available in
sheets, geosynthetic drainage net incorporating pores for holding
granular reactive material, and combinations thereof.
11. The remediation configuration of claim 6 in which said
surcharge materials are selected from the group consisting of
riprap, gravel, sand, and combinations thereof.
12. A method for remediating sediments, comprising: deploying a
geocomposite in a plane, said geocomposite having at least a
topmost edge when deployed approximately vertically and comprising:
at least one layer of geosynthetic material, wherein at least one
said at least one layer is composed of at least some reactive
material, and covering said geocomposite with a layer of surcharge
materials, wherein if more than one layer is used in said
geocomposite, each of said layers is arranged approximately
parallel to each other in said plane, and wherein said method
facilitates remediating sediments.
13. The method of claim 12 in which said layer of surcharge
materials is deployed over said geocomposite along said plane.
14. The method of claim 13 in which said plane is approximately
horizontal.
15. The method of claim 13 in which said plane is approximately
vertical, wherein said layer of surcharge materials is deployed
above said topmost edge and over the surface horizontally adjacent
to said topmost edge for the length of said topmost edge.
16. The method of claim 12 in which said geosynthetic material is
commercially available.
17. The method of claim 16 in which said commercially available
geosynthetic material is selected from the group consisting of
woven, non-woven, and combinations of woven and non-woven
geosynthetic material.
18. The method of claim 12 in which said reactive material is
commercially available.
19. The method of claim 18 in which said commercially available
reactive material is selected from the group consisting of
activated carbon, zeolites, particulate polymers, granular forms of
commercially available chemical adsorption materials, activated
carbon fabric commercially available in sheets, geosynthetic
drainage net incorporating pores for holding granular reactive
material, and combinations thereof.
20. The method of claim 12 in which said surcharge materials are
selected from the group consisting of riprap, gravel, sand, and
combinations thereof.
21. A geocomposite for remediating sediments comprising: at least
one layer of geosynthetic material, wherein at least one of said at
least one layers is composed of at least some reactive
material.
22. The geocomposite of claim 21 in which said geosynthetic
material is commercially available.
23. The geocomposite of claim 22 in which said commercially
available geosynthetic material is selected from the group
consisting of woven, non-woven, and combinations of woven and
non-woven geosynthetic material.
24. The geocomposite of claim 21 in which said reactive material is
commercially available.
25. The geocomposite of claim 24 in which said commercially
available reactive material is selected from the group consisting
of activated carbon, zeolites, particulate polymers, granular forms
of commercially available chemical adsorption materials, activated
carbon fabric commercially available in sheets, geosynthetic
drainage net incorporating pores for holding granular reactive
material, and combinations thereof.
26. A remediation configuration for remediating sediments
comprising: a geocomposite comprising: at least one layer of
geosynthetic material, wherein at least one of said at least one
layers is composed of at least some reactive material; and a layer
of surcharge materials placed above said geocomposite.
27. The remediation configuration of claim 26 in which said
geosynthetic material is commercially available.
28. The remediation configuration of claim 27 in which said
commercially available geosynthetic material is selected from the
group consisting of woven, non-woven, and combinations of woven and
non-woven geosynthetic material.
29. The remediation configuration of claim 26 in which said
reactive material is commercially available.
30. The remediation configuration of claim 29 in which said
commercially available reactive material is selected from the group
consisting of activated carbon, zeolites, particulate polymers,
granular forms of commercially available chemical adsorption
materials, activated carbon fabric commercially available in
sheets, geosynthetic drainage net incorporating pores for holding
granular reactive material, and combinations thereof.
31. The remediation configuration of claim 26 in which said
surcharge materials are selected from the group consisting of
riprap, gravel, sand, and combinations thereof.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of prior co-pending U.S.
Provisional Patent Application Serial No. 60/283,291, "Reactive
Geocomposite For Remediating Contaminated Sediments," by Sheahan et
al., filed Apr. 11, 2001.
FIELD OF THE INVENTION
[0003] The field of the invention is remediation of contaminants,
in particular the use of reactive geocomposites for remediating
contaminated sediments.
BACKGROUND
[0004] Conventional isolation or treatment of contaminated soils
and sediments is by either "capping" or removal. Capping may use
natural materials such as soils or gravel, or geosynthetic layers,
or a combination of any of these.
[0005] Capping systems comprised of soil or gravel layers are
relatively thick and prone to erosion and disturbance. This may
cause mixing with the adjacent contaminated soil or sediment. In
sub-aqueous applications, such as harbors or shipping channels,
thick caps may present obstructions to ships. The cap may be
damaged by the turbulence caused by ship traffic as well as by
direct contact. Additionally, these thick caps are not designed to
interact with any contaminant chemicals that may be in the pore
fluid.
[0006] Soil may be removed for ex situ treatment, simple off-site
storage, or both.
[0007] However, sub-aqueous sediment removal is expensive and can
result in significant contaminant re-suspension in the overlying
water column during removal of the sediment.
[0008] Embodiments of the present invention address the above
deficiencies in a cost-effective manner.
SUMMARY
[0009] A preferred embodiment of this invention incorporates at
least one chemically reactive layer in a geocomposite that may
itself comprise multiple additional layers. The reactive layer or
layers constitutes an active "clean-up" element that concentrates
contaminants in a very thin zone, neutralizes contaminants, or does
both. Simultaneously, contaminated sediment is isolated from
overlying water or the atmosphere by a geocomposite structure
comprising the geocomposite itself and a cover or surcharge layer.
This inhibits erosion from either moisture or air, while also
inhibiting resuspension of contaminants. Because the geocomposite
structure is thin compared to conventional "caps," it is suited for
use in sub-aqueous applications such as shipping channels and
harbors. Further, a preferred embodiment of this invention may be
removed or "rejuvenated" to achieve further interaction with pore
fluids containing dissolved contaminants or chemicals sorbed onto
small particles.
[0010] Provided in a preferred embodiment of the present invention
is a geocomposite structure or system (hereafter referred to as
geocomposite structure) for remediating contaminated sediments that
includes a geocomposite incorporating a top layer of geosynthetic
material, one or more middle layers of reactive material, and a
bottom layer of geosynthetic material. Depending on site
conditions, the top or bottom layer, or both the top and bottom
layers, may be omitted and achieve the same functionality. The
geosynthetic material used for the geocomposite may be selected
from that commercially available and may be woven or non-woven.
Likewise, the reactive material used in the geocomposite may be
chosen from that commercially available including: activated
carbon, zeolites, particulate polymers, granular forms of
commercially available chemical adsorption materials, activated
carbon fabric commercially available in sheets, and geosynthetic
drainage net incorporating pores for holding granular reactive
material, and combinations of these.
[0011] Further, a method is provided for remediating contaminated
sediments. When the geocomposite is employed in a remediation
configuration it may have a layer of surcharge materials overlaid
to facilitate the flow of pore water from the sediment through the
geocomposite structure. The geocomposite structure may be employed
horizontally, such as laying a sheet over sediments in a harbor or
ship channel or vertically such as pressing it into soft soil to
capture horizontally flowing pore water.
[0012] Advantages of embodiments of the present invention
include:
[0013] uses conventional geosynthetic materials for ease in
fabrication of the structure;
[0014] reduces encroachment on shipping lanes as compared to
conventional caps;
[0015] resists erosion or other deterioration because of its
enhanced stability and tensile strength;
[0016] captures solid contaminants and chemicals sorbed onto small
particles that are pulled from the sediments via the consolidation
induced by the surcharge layer as opposed to simple isolation of
conventional capping;
[0017] renders some chemicals less toxic or insoluble depending on
specific reactions occurring in the reactive layer;
[0018] provides an alternative site remediation tool in soft soils
that may be inherently difficult to remediate;
[0019] reduces expense when compared to conventional methods of
removal and treatment;
[0020] facilitates reuse via removing from service and
re-constituting the reactive layer;
[0021] is accepted readily by regulatory bodies and the public;
and
[0022] minimizes disturbance of the environment as compared to
conventional methods.
BRIEF DESCRIPTION OF DRAWINGS
[0023] Like numbers depict like elements in all figures.
[0024] FIG. 1 depicts a side view of layers of a preferred
embodiment of the present invention as used in a single plane that
may be horizontal.
[0025] FIG. 2 depicts a cross-section view of a preferred
embodiment of the present invention as used in a vertical
configuration for lateral fluid flow collection.
DETAILED DESCRIPTION
[0026] Refer to FIGS. 1 and 2. A preferred embodiment of this
invention inhibits dispersal of harmful environmentally mobile
chemicals in areas likely to hold them, such as sediments 104.
While doing this, it may also chemically neutralize or physically
immobilize one or more of these chemicals.
[0027] A preferred embodiment of this invention envisions a
reactive geocomposite "sandwich" structure 100 incorporating a
geocomposite with at least one reaction layer 103 that may be an
inner, or middle, layer. In one embodiment, the geocomposite also
comprises two sheets of geotextile fibers, one being a top layer
101, and the other being a bottom layer 102. Conventional
geotextile materials may be employed. These generally are
fabricated as synthetic sheets of material that may be woven or
non-woven. The reactive layer 103 may comprise: activated carbon,
zeolites, particulate polymers, and granular forms of available
chemical adsorption materials. Commercially available products that
may facilitate fabrication include activated carbon fabric
available in sheets and geosynthetic drainage net incorporating
pores for holding granular reactive material.
[0028] In one application, the structure 100 separates contaminated
sediments 104 from adjacent uncontaminated material 107. Pore fluid
106 and some small solid particles (not separately shown) contained
therein are induced to flow through the geocomposite structure 100.
One method of inducing flow of the pore fluid is by applying an
overlying surcharge layer 105 to the employed geocomposite. The
combination of the surcharge layer 105 and the geocomposite
comprises the geocomposite structure 100. The weight of the
surcharge materials facilitates consolidation within the targeted
sediment 104. Employed in a horizontal configuration as depicted in
FIG. 1, the bottom layer 102 retards passage of at least some
suspended particles so that pore fluid 106 and dissolved chemicals
enter the geocomposite structure's reactive layer (or layers) 103.
Depending on the makeup of this bottom layer 102, very fine solid
particles may pass to the reactive layer 103. The reactive layer
103 interacts with chemicals in the contaminated sediment 104 that
pass through the bottom layer, the pore fluid 106 itself within the
geocomposite structure 100, or both. The top layer 101 prevents
overlying particles (not separately shown) from engaging the middle
or reactive layer 103, while allowing the pore fluid 106 to pass
completely through the geocomposite structure 100 into the
overlying surcharge layer 105.
[0029] Referring again to FIG. 1, in one embodiment, the
geocomposite used in the geocomposite structure 100 may be
fabricated in large sheets, e.g., rolls of 30 m (100 ft) in length
or more by 34.6 m (10-15 ft) in width. These sheets may be deployed
on the surface of a sediment deposit 104. The deposit 104 may be
saturated or near saturated, sub-aqueous or terrestrial. After
emplacement of the geocomposite, a layer 105 of surcharge
materials, such as riprap, gravel, or sand, is placed on the
geocomposite to facilitate consolidation of the sediment 104.
[0030] Subsequent consolidation of the sediment 104 expulses pore
fluid 106 that contains targeted harmful chemicals or small
particles upon which the chemicals may be sorbed. As the pore fluid
106 flows through the geocomposite structure 100, the reactive
material in the reactive layer or layers 103, interacts with the
chemicals in the fluid 106. For example, the reactive material may
simply adsorb them. Alternatively, it may also chemically
"neutralize" them. This both isolates and concentrates the targeted
chemicals within the reactive layer 103, or layers. In addition,
this reactive layer 103, or layers, may retain fine particles on
which chemicals may have sorbed.
[0031] Refer to FIG. 2. An embodiment of the present invention may
also be employed as a geocomposite structure in a vertical
orientation, having an outer layer 201, or layers, and at least one
middle reactive layer 103. This embodiment may be emplaced
vertically by pressing it into the ground. A surcharge layer 105 of
material such as gravel, sand, or riprap may be emplaced above the
soil adjacent to the vertically oriented geocomposite and the
consolidation of the sediment 104 may occur both horizontally and
vertically, due to the weight of the surcharge layer 105. In an
embodiment installed vertically, the geocomposite structure 104 may
employ a sleeve 201 surrounding the reactive layer 103, thus
forming a continuous outer layer for the geocomposite, much like a
sack used to protect a mattress when moving. One or more layers 103
of reactive material may be emplaced inside the sleeve 201 (i.e.,
the continuous outer layer or layers).
[0032] Although specific types of geocomposite structures are
discussed, other similar geocomposite structures, including those
that may have only some of the constituents used in the above
described examples, may be suitable for remediation using a
structure or method that falls within the ambit of a preferred
embodiment of the present invention as provided in the claims
herein.
* * * * *