WO2013124623A1

WO2013124623A1 - Containment system

Info

Publication number: WO2013124623A1
Application number: PCT/GB2013/050317
Authority: WO
Inventors: Stephanie VICTORY; James Heselden
Original assignee: Hesco Bastion Limited
Priority date: 2012-02-22
Filing date: 2013-02-12
Publication date: 2013-08-29
Also published as: GB2499622A; GB201203073D0; GB2499622B

Abstract

The present invention relates to a water containment system comprising: an elongate reinforcement member; ballast material located against at least one side of said elongate reinforcement member; an erosion inhibiting layer overlying, or at least partially embedded in, a surface of said ballast material, wherein the erosion inhibiting layer is anchored to said ballast material. The present invention also relates to a method of constructing a water containment system, and a method of re-conditioning a water containment structure.

Description

CONTAINMENT SYSTEM

This invention relates to a water containment system and methods of construction thereof and, in particular, to improvements in and relating to flood- defence systems.

There are many types of water containment systems which are suitable for preventing bodies of water from flooding adjacent areas of land. In some instances, the water containment systems may be located along a coastline to present a barrier between a sea or ocean and land along the coastline. In other instances, the water containment systems may be located inland alongside a lake or river to prevent water in the lake or river reaching adjacent areas of land.

Levees are typical water containment systems and are generally located along river banks to reinforce the natural river banks and present a barrier between the river and surrounding areas of land. These levees may be required because the areas of land lie below the level of the river, and/or because the river is prone to overflow during periods of heavy rain or storms and cause flooding of the surrounding areas of land.

Earthen levees are often used as a permanent water containment system because, for a given height of flood protection, a permanent earthen levee may be cheaper than the cost of a floodwall. These types of levees are often

ί homogeneous structures and may be constructed from materials such as, for example, sand, clay, soil, stones, rocks, concrete-rubble, cement-rubble, etc. (hereinafter "fill material" or "ballast material"). For further specificity, soil may be described and abbreviated herein according to American Society for Testing and Materials standards (herein referred to as ASTM Standards) - see ASTM D2487. Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System), pp. 1-12 - and the Unified Soil Classification System (herein referred to as the (JSCS).

A Ievee may have a sloped bank on a land-side (also referred to as the downstream slope) thereof, and an oppositely sloped bank on a water-side (also referred to as the upstream slope) thereof. A homogeneous earthen Ievee having such a configuration and which meets the United States Army Corps of Engineers (herein referred to as USACOE) and the Department of Interior Bureau of Reclamation standards (see USACOE (2000). Design and Construction of Levees, EM 11 10-2-1913, Section 6, pp. 1-2 and United States Department of Interior, Bureau of Reclamation (1987). Design of Small Dams (3f^d Edition), Table 6.5) typically requires a slope gradient between 1 :3 (or "1 in 3") and 1 :3.5 (or "1 in 3.5") for the water-side (or upstream) side-slopes when the soil fill is composed of CL, ML, CH, or MH materials (essentially clay and silt). In these cases, the land-side (or downstream) side-slopes may not be steeper than 1 :2.5 (or "1 in 2.5"). In situations where rapid drawdown may occur (meaning "drawdown rates of 6 inches or more per day after prolonged storage at high reservoir levels" - see United States Department of Interior, Bureau of Reclamation (1987). Design of Small Dams (3rd Edition), Table 6.5), the maximum water-side (upstream) slope gradient is often flattened to 1 :3.5 to 1 :4. The land-side (downstream) slope gradient is not affected.

As will be appreciated, the distance between a point at the foot of the sloped bank on the land-side and a point directly opposite at the foot of the bank on water-side may be fairly large if the banks have gradients which conform to the USACOE standards for earthen levees. It follows that a homogeneous earthen levee of this nature may have a large footprint.

There may be instances where there is insufficient space in a proposed location where a levee is to be constructed to accommodate a levee having the required footprint. In such instances, it may be necessary to increase the area of land available for construction of the levee by demolishing surrounding structures, such as buildings. Alternatively, or additionally, it may be necessary to landscape the area surrounding the proposed site of the levee to provide a suitably level surface on which the levee can be constructed. As will be appreciated, the above factors may increase construction costs and/or increase construction time, and may serve to hinder commencement of construction of the levee.

In order to meet the USACOE standards for an earthen levee, a large amount of fill or ballast material may be required. However, it may be the case that there is insufficient fill or ballast material at or near a site where an earthen levee is to be constructed. In such a case, additional fill or ballast material may need to be conveyed to the site from other locations. As will be appreciated, this may increase the time required to construct the levee and/or the cost of construction.

Earthen levees may suffer drawbacks in that burrowing animals can compromise the integrity of these earthen levees by burrowing into (and possibly through) the material forming the levee. As will be appreciated water could penetrate towards the heart of the levee through such burrows, and possibly continue through the levee to a land-side of the levee through oppositely directed burrows. Such water penetration could cause water-saturation of portions of the levee and cause widening of the burrows. Both effects may weaken the structural integrity of a levee.

Gabions are generally structures of the type which comprise side wall panels, end panels and partition panels which connect the wall panels, and all the panels are usually rectangular and may be pivotally attached or connected together so that the structure can be moved between an expanded (or deployed) condition for use and a collapsed (or folded) condition for storage and transport. In the deployed condition, the structure is elongated and the panels define a row of cavities extending in the length direction of the structure, each cavity being defined by side panels and partition panels, apart from the end cavities which are defined by side panels, partition panels and end panels. The cavities can be filled with ballast or building materials so that the structure turns into a robust wall which can be used for defences for flooding, for military equipment and personnel, and for shoring of hillsides and river banks and the like, or simply as a property or other boundary. They can be used side-by-side, end-to-end, and/or in superimposed relationship, depending upon the use to which they are to be put.

The present invention contemplates the applications of gabions in the realm of water containment systems and, in particular, flood-defence systems.

An example of a gabion structure of the type set forth above is illustrated in European Patent EP-B-1951963, and an accompanying description is also included in that Patent.

Rapid deployment of a flood-defence system may be desirable during onset of flood-waters and gabions lend themselves to such situations where rapid deployment is desirable. The pivotally attached, connected multi-compartmental gabions described in EP-B-1951963 can be easily and quickly erected, and can be filled with readily available and inexpensive ballast or fill material.

WO 2008/081177 describes a gabion deployment system which may be suitable for rapid deployment of a gabion in the situation referred to above. Once flood-waters have receded, the compartments of the gabions may be opened, the fill material removed, and the gabions dismantled for removal. However, in some instances, it may be desirable to retain the deployed, filled, gabion to form part of a semi-permanent or permanent flood-defence system, and optional arrangements of the present invention may include a deployed, filled, gabion as part of a water containment system.

This invention seeks to achieve an improvement in the area of water containment systems, and to provide water containment systems without the disadvantages of the present systems.

According to an aspect of the invention, there is provided a water containment system comprising: an elongate reinforcement member; ballast material located against at least one side of said elongate reinforcement member; an erosion inhibiting layer overlying, or at least partially embedded in, a surface of said ballast material, wherein the erosion inhibiting layer is arranged in a fixed relationship with respect to said ballast material.

As noted previously, an earthen levee which meets the USACOE standards may require side-slopes having a 1 :3 (or flatter) gradient. Levees of this type may have a large footprint and may require a large amount of fill or ballast material. The water containment system of the present invention may achieve the same height and structural integrity as an earthen levee which meets the USACOE standards, but without requiring side-slopes having a 1:3 (or flatter) gradient. Therefore, such a water containment system may not require the same amount of fill material as the standard earthen levee of the same height. It follows that the footprint of such a levee comprising the water containment system of the invention may have a smaller footprint than a standard earthen levee of the same height.

Thus, a levee comprising the water containment system of the invention may meet other parameters of USACOE standards for earthen levees (such as resistance to lateral forces from, for example, static pressure of water, dynamic pressure of water, etc.), without requiring the 1:3 (or flatter) gradient for side- slopes specified in such standards or without requiring the same amount of fill or ballast material as a standard earthen levee.

The erosion inhibiting layer may serve to inhibit erosion of the side-slopes of the levee, for example, a water-facing side-slope of which at least a portion thereof may be submerged under water either temporarily at intervals or permanently. Also, the erosion inhibiting layer may inhibit erosion of parts of the levee due to processes such as, for example, toe scour or overtopping scour (which may cause lee-side erosion of the levee).

The erosion inhibiting layer may be provided with a stabilizing element arranged to bind the erosion inhibiting layer to the ballast material, and which stabilizing element may comprise at least one of, or a combination of: a vegetation layer such as grasses (for example, deep-rooted grasses), trees, bushes, flowering plants (for example, alfalfa); a cotton mulch layer; or a textile layer.

The ballast material may be located against both sides of the elongate reinforcement member and also may be located on top of the elongate reinforcement member.

The elongate reinforcement member may comprise a plurality of compartments, and a portion of the ballast material may be located in at least one of the plurality of compartments.

Optionally, the elongate reinforcement member may comprise a multi- compartmental gabion and a portion of the ballast material may be located in one or more compartments of the multi-compartmental gabion.

Optionally, individual compartments of the multi-compartmental gabion may formed from wall elements, of which adjacent ones of the wall elements of an individual compartment are connected to one another by pivotal connections, and of which adjacent wall elements of adjacent compartments are connected to one another by pivotal connections. Optionally, at least one of the pivotal connections is a releasable connection which when released allows a side wall element to open with respect to a compartment.

The wall elements of the multi-compartmental gabion may be formed from rigid mesh panels.

Provided the mesh is small enough, this may inhibit the passage of burrowing animals through the body of the water containment system.

Optionally, one or more compartments of the multi-compartmental gabion are provided with a liner material for receiving ballast material therein.

At least a portion of the ballast material is banked to form a slope of ballast material against at least one side of the elongate reinforcement member.

According to another aspect of the present invention, there is provided a method of constructing a water containment system comprising: providing an elongate reinforcement member; providing ballast material and locating the ballast material against at least one side of the reinforcement member; providing an erosion inhibiting layer to overlie, or be at least partially embedded in, a surface of the ballast material; anchoring the erosion inhibiting layer to the ballast material. The method may further comprise the step of providing the erosion inhibiting layer with a stabilizing element arranged to bind the erosion inhibiting layer to the ballast material.

The step of providing ballast material may comprise locating the ballast material against both sides of the elongate reinforcement member and also may comprise locating ballast material above the elongate reinforcement member.

The step of providing an elongate reinforcement member may comprise deploying a multi-compartmental gabion.

The step of providing ballast material further may comprise locating a portion of the ballast material in one or more compartments of the multi-compartmental gabion.

The step of providing ballast material further may comprise banking at least a portion of the ballast material to form a slope against at least one side of the elongate reinforcement member.

A water containment system may be rapidly deployed by deploying a multi- compartmental gabion, providing ballast material and locating at least a portion of the ballast material in one or more compartments of the multi-compartmental gabion. The step of providing ballast material further may comprise locating at least a portion of the ballast material against at least one side of the multi- compartmental gabion.

The step of providing ballast material further may comprise locating at least a portion of the ballast material against both sides of the multi-compartmental gabion, and also may comprise locating a portion of the ballast material above the multi-compartmental gabion.

The step of providing ballast material further may comprise banking at least a portion of the ballast material to form a slope against at least one side of the multi-compartmental gabion.

Where a rapidly deployed water containment system comprises a multi- compartmental gabion formed from wall elements, of which adjacent ones of said wall elements of an individual compartment, and of which adjacent wall elements of adjacent compartments, are connected to one another by releasable pivotal connections which when released allow a side wall element to open with respect to a compartment, the present invention provides a reconditioning method comprising: removing said erosion inhibiting layer; optionally removing said stabilising element prior to removing said erosion inhibiting layer; removing at least a portion of said ballast material located against at least one side of said elongate reinforcement member from at least one side of said elongate reinforcement member; opening one or more compartments in which ballast material is depleted; re-filling said one or more compartments in which ballast material is depleted with further ballast material; closing said one or more compartments which have been re-filled; returning at least a portion of said removed ballast material to said at least one side from which it was removed and/or adding new ballast material to said at least one side from which ballast material was removed; returning said removed erosion inhibiting layer to a position in which it overlies, or is at least partially embedded in, a surface of said ballast material, or locating a new erosion inhibiting layer to said position in which it overlies, or is at least partially embedded in, a surface of said ballast material; and optionally returning said stabilising element to said erosion inhibiting layer and/or providing a new stabilising element for said erosion inhibiting layer.

A water containment system rapidly deployed by way of any one of the above- described steps may be transformed from a temporary structure to at least a semi-permanent structure, by further providing an erosion inhibiting layer to overlie, or be at least partially embedded in, a surface of the ballast material, and anchoring the erosion inhibiting layer to the ballast material.

An optional further step may comprise providing the erosion inhibiting layer with a stabilizing element arranged to bind the erosion inhibiting layer to the ballast material. According to another aspect of the present invention, there is provided a method of re-conditioning a water containment structure, comprising: removing an amount of ballast material from the water containment structure to form a channel therein; locating a multi-compartmental gabion in the channel; locating at least a portion of the removed ballast material and/or new ballast material in one or more compartments of the multi-compartmental gabion; optionally, filling any gaps between the m ulti-com partmental gabion and sides of the channel with at least a portion of the removed ballast material and/or new ballast material; optionally, if required, locating at least a portion of the removed ballast material and/or new ballast material on top of said multi-compartmental gabion in the channel to fill a remainder of the channel; optionally, if required, adding at least a portion of the removed ballast material and/or new ballast material to ballast material located at least against one side of the multi-compartmental gabion; providing an erosion inhibiting layer to overlie, or be at least partially embedded in, a surface of the ballast material; anchoring the erosion inhibiting layer to the ballast material.

The method further may comprise the step of providing the erosion inhibiting layer with a stabilizing element arranged to bind the erosion inhibiting layer to the ballast material. The method further may comprise banking at least a portion of the ballast material located against at least one side of the multi-compartmental gabion to form a slope.

One or more embodiments of the invention are described further hereinafter, by way of example only, with reference to the accompanying drawings in which:

Fig. 1 shows a schematic perspective view of a water containment system according to one or more embodiments of the present invention;

Fig. 2 shows a schematic cross-sectional side view of the water containment system of Fig. 1 ;

Fig. 3 shows a schematic plan view of the water containment system of Fig.

1 ;

Fig. 4 shows a schematic view of a system for deploying an element of the water containment system of Fig. 1 ;

Fig. 5 shows a perspective view of an elongate reinforcement member comprising a multi-compartmental gabion;

Fig. 6 shows a schematic plan view of the multi-compartmental gabion of Fig. 5 in an expanded configuration and with a compartment open to allow for reconditioning of the gabion;

Figs. 7 to 10 show cross-sectional side views of water containment systems in optional arrangements; and Figs. 11 to 16 show schematic cross-sectional side views of stages of a process for restoring an old and/or damaged water containment system.

In Figs. 1 to 3, there is illustrated a water containment system 10 which comprises an earthen levee 12. The levee 12 comprises a mound or bank of ballast material 14 which has three distinct regions, namely a side-slope 16 facing a water-side of the levee 12, a crown or peak 18 (also referred to as a crest), and a side-slope 20 facing a land-side of the levee. In the illustrated arrangement, the side-slopes 16, 20 comprise angled flat surfaces and the crown or peak 18 comprises a substantially horizontal flat surface which is located between the two side-slopes 16, 18. The levee is arranged to hold back a body of water to prevent the body of water reaching land on the land-side of the levee.

Suitable material which may be used as the ballast material 14 may comprise clay soil classified by the USCS as CL (clay), CH (clay of high plasticity, e.g. "fat clay") or CL/CH. Optionally, the clay soil may be placed in approximately 15.25 cm (6") loose lifts and optionally may be compacted to at least 95% of the Standard Proctor maximum dry density.

At the heart or core of the levee 12 illustrated in Figs. 1 to 3 are provided three multi-compartmental gabions 24a, 24b, 24c which are arranged to form an elongate reinforcement member 22. The multi-compartmental gabions 24a, 24b, 24c extend longitudinally within the core of the levee 12 for at least a portion of the length of the levee 12. Optionally, the multi-compartmental gabions 24a, 24b, 24c extend longitudinally for the entire length of the levee.

Suitable multi-compartmental gabions for use in the levee 12 are illustrated in Figs. 5 and 6.

The three multi-compartmental gabions 24a, 24b, 24c are arranged with respect to one another in a lower row comprising two multi-compartmental gabions 24b, 24c arranged side-by-side, and an upper row, located on top of the lower row, the upper row comprising one multi-compartmental gabion 24a. The single multi- compartmental gabion 24a of the upper row is located on top the multi- compartmental gabion 24b of the lower row. Of course, in other optional arrangements, single multi-compartmental gabion 24a of the upper row may be located above multi-compartmental gabion 24c instead. In further optional arrangements, the single multi-compartmental gabion 24a of the upper row may be staggered with respect to the two multi-compartmental gabions 24b, 24c in the lower row. Yet further optional arrangements are illustrated in Figs. 7 to 10 and are described further below.

In arrangements where it is desirable to have the multi-compartmental gabions 24a, 24b, 24c extending for the entire length of the levee 12, it may be the case that the length of a first set of three multi-compartmental gabions 24a, 24b, 24c is insufficient to extend for the entire length of the levee 12. In that case, further sets of three multi-compartmental gabions may be located in the levee 12 in the same configuration as the first set of three multi-compartmental gabions 24a, 24b, 24c and may be placed end-to-end within the levee 12.

At least some, possibly all, of the compartments of the multi-compartmental gabions 24a, 24b, 24c are filled with ballast material. This may be the same ballast material that is used to form the body of the mound of the levee 12, and/or may be a different type of ballast material.

A suitable construction process for building levee 12 may comprise an initial step of locating the multi-compartmental gabions 24a, 24b, 24c as required. The multi- compartmental gabions 24a, 24b, 24c are filled with ballast material and then further ballast material is banked to the sides of the multi-compartmental gabions 24a, 24b, 24c. The banked ballast material forms the side-slopes 16, 20 of the levee 12. Further ballast material may be placed over the multi-compartmental gabions 24a, 24b, 24c to form the crown 18 of the levee 12. The ballast material then may be compacted and/or landscaped as required.

Once the construction of the mound of the levee 12 is completed, a suitable erosion inhibiting layer 26 (see Figs. 1 and 2) is laid over the levee 12. This erosion inhibiting layer 26 is fixed to the ballast material 14 of the levee 12 by a plurality of discrete anchoring elements 28 which are spaced at regular intervals in an array over the erosion inhibiting layer 26. The spacing between adjacent discrete anchoring elements 28 and/or whether they are arranged in an array or otherwise may be determined depending upon the requirements for the levee 12.

The discrete anchoring elements 28 penetrate the erosion inhibiting layer 26 and extend to a suitable depth in the ballast material 14 and serve to fix the erosion inhibiting layer 26 to the ballast material 14 to prevent slippage of the erosion inhibiting layer 26 relative to the ballast material 14.

In the specific arrangement illustrated, the erosion inhibiting layer 26 comprises a high performance turf reinforcement mat (such as ArmorMax™ manufactured by Propex) and the discrete anchoring elements 28 comprise type 2 earth percussion anchors. In optional arrangements, other materials may be used as the erosion inhibiting layer 26 and/or other types of method may be used to anchor or bind the erosion inhibiting layer 26 to the ballast material 14. For instance, the erosion inhibiting layer 26 may be at least partially embedded in the surface of the ballast material 14 and a vegetation layer may be incorporated to bind the erosion inhibiting layer 26 to the ballast layer 14. The choice of seed and/or vegetation may be determined based on the geographical location of the levee 12.

Other suitable materials for the erosion inhibiting layer may comprise a cotton mulch layer or a textile layer. The erosion inhibiting layer may serve to inhibit erosion of the side-slopes of the levee, for example, a water-facing side-slope of which at least a portion thereof may be submerged under water either temporarily at intervals or permanently. Also, the erosion inhibiting layer may inhibit erosion of parts of the levee due to processes such as, for example, toe scour or overtopping scour (which may cause lee-side erosion of the levee).

The illustrated levee 12 of Figs. 1 to 3 also includes an arrangement for allowing drainage of water from the core of the levee 12.

The ballast material 14 may be such that water (e.g. from rainfall) can seep into the ballast material 14. This occurrence may prove undesirable in certain instances because the presence of water in the ballast material 14 may affect the structural integrity of the levee. A drainage arrangement may mitigate the effects of the presence of water in the ballast material 14 because it can allow the water to drain from the ballast material to a more appropriate location.

The drainage arrangement of the illustrated levee 12 comprises a drainage conduit 30 which is located within the ballast material 14 and runs alongside one of the multi-compartmental gabions 24c. In the illustrated arrangement, the drainage conduit 30 comprises a PVC header collection Schedule 40 pipe (i.e. wall thickness of 7.1 12 mm (0.280") of nominal diameter 150 mm (6"). The pipe is perforated to allow water in the ballast material 14 to drain into the pipe. Of course, other suitable types of conduit may be incorporated in optional arrangements.

A drainage conduit outlet section 32 is connected to, and extends from the drainage conduit 30. The drainage conduit outlet section 32 is in fluid communication with the drainage conduit 30 and extends from the drainage conduit 30 through the side-slope 20 facing a land-side of the levee and protrudes from the side-slope 20. Optionally, both the drainage conduit 30 and drainage conduit outlet section 32 may be arranged so that water entering the drainage conduit 30 at the core of the levee 12 can drain from the levee 12 via the drainage conduit 30 and drainage conduit outlet section 32 under the influence of gravity alone.

The drainage arrangement is located within a protective cage 34 (Fig. 1 only) which serves to protect the drainage arrangement, and which may further serve to assist flow of water to the drainage arrangement. The protective cage 34 comprises a first multi-compartmental gabion unit in which the drainage conduit 30 is located and through which the drainage conduit 30 extends longitudinally. The drainage conduit outlet section 32 is located in a similar manner within a second multi-compartmental gabion unit which extends transversely from the first multi-compartmental gabion unit. The first and second multi-compartmental gabion units are filled with sand which may present less resistance to the flow of water therethrough than the ballast material and thereby serves to assist flow of water to the drainage arrangement.

The drainage arrangement may be a primary source of water drainage from the levee. Water entering into the core of the levee will likely be transmitted into the drainage arrangement and out of the levee system. However, if the drainage arrangement becomes blocked (for example, by an animal entering the drainage arrangement or during freezing conditions, etc.), the sand-filled units (i.e., protective cages) will allow water to exit the system before the water pressure builds up and damages the land-side (or downstream) toe of the levee.

In the illustrated arrangement of Fig. 1 , the first and second multi-compartmental gabion units of the protective cage 34 are smaller than the three multi- compartmental gabions 24a, 24b, 24c of the elongate reinforcement member 22. However, this need not be the case in optional arrangements.

In other optional arrangements, the protective cage 34 may not be required. In yet further optional arrangements, the drainage arrangement may not be required, or may be substituted with a different drainage arrangement to the one illustrated and as described above.

Although in the levee 12 illustrated in Figs. 1 to 3, the multi-compartmental gabions 24a, 24b, 24c are located at the centre of the levee, this need not be the case and, if required, they may be located off-centre. Also, although the illustrated levee 12 is symmetrical in cross-section, this need not be the case and may comprise a levee in which the highest point is skewed (i.e. is not equidistant between the foot of the levee on the land-side and the foot of the levee on the water-side).

The water containment system 10 further comprises anchor trenches 35 located on both the land and water-facing sides of the levee 12. Ends of the erosion inhibiting layer 26 extend into the anchor trenches 35 and fill material is added to the trenches around the ends of the erosion inhibiting layer 26. The anchor trenches 35 serve to fix the ends of the erosion inhibiting layer 26 into the land surrounding the levee 12 and anchor the ends of the erosion inhibiting layer 26 into the ground.

The anchor trenches 35 comprise a trench approximately 60cm wide and 60 cm deep (approx. 2 feet deep and 2 feet wide) into which the ends of the erosion inhibiting layer 26 extend. Other depths and/or widths of trench may be used in optional arrangements.

The ends of the erosion inhibiting layer 26 may effectively be "wrapped-around" within the anchor trenches 35 (e.g. the ends of the erosion inhibiting layer 26 may extend over a first side, a bottom, and a second side of each anchor trench). In optional arrangements, the ends of the erosion inhibiting layer 26 may simply terminate in the anchor trenches 35 without "wrapping-around" within the trenches.

Although in the illustrations of Figs. 1 to 3 the anchor trenches 35 are located at a toe region of both the land and water-facing side slopes 16, 20, in an optional arrangement, one or both of the anchor trenches 35 may be located in the ground at a location spaced from the toe region of one or both of the land and water-facing side slopes 16, 20.

In another optional arrangement, the water containment system 10 may be constructed without one or both of the anchor trenches 35, and other suitable anchoring devices may be used to fix the ends of the erosion inhibiting layer 26.

Fig. 4 shows a schematic view of a system for deploying an element of the water containment system. In the illustrated arrangement, the element of the water containment system is a multi-compartmental gabion 24, and the multi- compartmental gabion 24 is located in a container 38 on a truck 46. When located in the container 38, the gabion 24 is in a folded condition (as illustrated). Partition walls between adjacent compartments of the folded multi- compartmental gabion are denoted by reference numeral 36.

The container 38 has a roof 40. From opposite ends of the underside of the roof 40 depend eyelets 42 to which a retaining means in the form of a retaining cable 48 is attached or connected by way of snap hooks 44. Partition walls 36 of the gabion 24 are attached or connected to the retaining cable 48 by way of suitable frangible couplings 50 which allow the gabion 24 to become detached from the retaining cable 48 when a predetermined load is applied to such couplings 50.

When the gabion 24 is to be deployed to form part of a water containment system, the door of the container 38 is opened and a first partition wall 36' of the gabion 24 is pulled in the direction indicated by Arrow A. A coupling is configured to disconnect 50' under the weight of a part of the gabion or to disconnect when an additional force B is applied thereto. Thus, the gabion 24 can be deployed unit-by-unit by a user (not shown) by first pulling a desired number of units out A and relying upon the weight of the deployed units to disconnect the units from the retaining cable. Optionally, the user may also pull down B to disconnect units from the retaining cable. If couplings 50 are configured to disconnect under just the weight of the gabion 24, then the user need only pull the first unit out A and the rest will follow if the truck 46 is advanced C.

WO 2008/081 177 describes a gabion deployment system which may be suitable for rapid deployment of a gabion in the manner described above.

Fig. 5 illustrates a multi-compartmental gabion 24 comprising opposed side walls 52, 54 connected together at spaced intervals along the length of gabion 24 by a plurality of partition walls 36 defining, together with side walls 52, 54, individual compartments 56, 58, 60 of multi-compartmental gabion 24. Individual compartment 58 (and other similar individual compartments) of multi- compartmental gabion 24 are bounded by opposed side wall sections 62, 64 of the respective opposed side walls 52, 54. Partition walls 36 (and similar partition walls) are pivotal ly connected to side walls 52, 54 at hinge points 66, 68, 70, 72.

In the illustrated arrangement of Fig. 5, each side wall section 62, 64 of multi- compartmental gabion 24 comprises two side wall elements 74, 76, 78, 80 with openable pivotal connections being provided between neighbouring side wall elements 74, 76, and between neighbouring side wall elements 78, 80. The pivotal connections between partition walls 36 (and other partition walls in the multi-compartmental gabion) and side walls 52, 54, and the openable pivotal connections between neighbouring side wall elements 74, 76, 78, 80 allow multi- compartmental gabion 24 to fold concertina-wise for flat-packing in transportation and storage (i.e. a gabion of this type may be suitable for storage in the container of the system described above and for deployment from such a system).

In the illustrated arrangement of Fig. 5, the concertina-wise folding optionally operates so that the openable pivotal connections between neighbouring side wall elements 74, 76, 78, 80 move inwardly with respect to the longitudinal axis of multi-compartmental gabion 24 so that the width of the flat-packed gabion is at least approximately corresponding to the width of partition walls 36. Referring to Fig. 6 there is shown in schematic plan view the multi- compartmental gabion in which the pivotal connections between neighbouring compartments are indicated by multiple reference numerals 82, whilst the openable pivotal connections between neighbouring side wall elements are indicated by multiple reference numerals 84. Locking pins 86 may also be seen in Fig. 6.

This figure also shows a compartment which has been opened to allow for reconditioning, i.e. to allow re-filling of depleted fill or ballast material in a compartment of the multi-compartmental gabion. As can be seen, the side wall elements may be moved pivotal ly in directions indicated by arrows D and E to open the compartment of the gabion. This may allow for the compartment to be re-filled with fill material more conveniently.

Therefore, on occasions when a water containment system must be rapidly deployed (e.g. during onset of flooding), the deployment system of Fig. 4 may be used to deploy a multi-compartmental gabion, such as that illustrated in Figs. 5 and 6, to form part of the water containment system.

Once the multi-compartmental gabion has been deployed as required, one or more compartments of the gabion can be filled with fill material. Optionally, a lining material may be provided in one or more compartments of the multi- compartmental gabion to prevent fill material being washed away during periods of flooding.

A water containment system which has been rapidly deployed in this manner may be required merely as a temporary measure to offer an element of protection against flooding. However, it may be desirable to maintain the deployed water containment system as a more permanent feature. In this instance, further steps may be required in order to improve the longevity and/or effectiveness of the water containment system.

It may be the case that, during an initial period of flooding, fill material in one or more compartments of the multi-compartmental gabion may have become depleted, e.g. because fill material has been washed away by flood waters. In this case, it may be desirable that the fill material in one or more compartments of the multi-compartmental gabion will need to be replenished. The one or more compartments can be opened as illustrated in Fig. 6 to accomplish this.

Further fill or ballast material may be provided against one or both side walls of the multi-compartmental gabion. In a particular arrangement, the ballast material provided against one or both side walls of the multi-compartmental gabion may be banked to provide a side slope on one or both sides of the multi- compartmental gabion. In such an arrangement, the multi-compartmental gabion forms an elongate reinforcing core or spine of the water containment system. Yet further fill or ballast material may be provided on top of the multi- compartmental gabion.

Once the ballast material has been located as required, an erosion inhibiting layer is provided. The erosion inhibiting layer is positioned to overlie a surface of the ballast material. However, in an optional arrangement, the erosion inhibiting layer may be at least partially embedded in the surface of the ballast material.

As in the arrangement illustrated in Figs. 1 to 3, and as described above, the erosion inhibiting layer may comprise high performance turf reinforcement mat (such as ArmorMax™ manufactured by Propex).

The erosion inhibiting layer is fixed relative to the ballast material (e.g. bound or anchored to the ballast material). This may be achieved by providing the erosion inhibiting layer with a suitable stabilizing element arranged to bind the erosion inhibiting layer to the ballast material and/or using discrete anchoring devices to anchor the erosion inhibiting layer to the ballast material.

In a particular optional arrangement, the stabilizing element is a vegetation layer such as, for example, grass. However, other suitable materials such as, for example, a cotton mulch layer or a textile layer, etc. may be used in other optional arrangements. Thus, the longevity, structural integrity, and/or effectiveness of the original, temporary, rapidly-deployed water containment system may be improved by adding ballast banks around the originally deployed multi-compartmental gabion, an erosion inhibiting layer (to inhibit erosion of the banks), and a stabilizing element to bind the erosion inhibiting layer to the ballast banks (to further improve inhibition of erosion of the banks). The completed water containment system constructed from the temporary flood-defence system using the above- described steps may be the same as that illustrated in Figs. 1 to 3.

Figs. 7 to 10 show schematic views of water containment systems 10 in optional arrangements of the present invention. These figures illustrate cross-sections of a water containment system 10, such as an earthen levee 12, in which a plurality of multi-compartmental gabions 24 form an elongate reinforcement member 22 of the water containment system 10. Although the profile of the levee 12 in the illustrated arrangements comprises a curve (similar to a Gaussian distribution curve), other profiles are envisaged. Indeed, the profile may be similar to that illustrated in Fig. 2, i.e. the side slopes of the levee may be angled flat surfaces and the crown or peak may be a substantially horizontal flat surface.

The illustrated levees of Figs. 7 to 10 comprise mounds or banks of ballast material 14 and which have three distinct regions, namely a side-slope 16 facing a water-side of the levee 12, a crown or peak 18, and a side-slope 20 facing a land-side of the levee. The levees are arranged to hold back a body of water 90 to prevent the body of water 90 reaching land on the land-side 91 of the levee 12.

At the heart or core of each of the levees 12 illustrated in Figs. 7 to 10 is provided a plurality of multi-compartmental gabions 24 arranged with respect to one another in various configurations. In an optional configuration illustrated in Fig. 7, multi-compartmental gabions 24 forming an elongate reinforcement member 22 are arranged in an upper row and a lower row. There is provided a central column formed from two multi-compartmental gabions 24 in which a first multi- compartmental gabion 24 of the upper row is stacked upon a second multi- compartmental gabion 24 of the lower row. The lower row is further configured such that a third multi-compartmental gabion 24 is located against a land-side of the second multi-compartmental gabion 24 and at substantially the same level as the second multi-compartmental gabion 24. A fourth multi-compartmental gabion 24 is located against a water-side of the second multi-compartmental gabion 24 and at substantially the same level as the second multi-compartmental gabion 24. The three multi-compartmental gabions 24 of the lower row are arranged side-by-side.

Fig. 8 illustrates an optional configuration in which a first multi-compartmental gabion 24 in an upper row is staggered with respect to multi-compartmental gabions 24 located side-by-side in a lower row, i.e. rather than being located directly above one multi-compartmental gabion 24 to form a column, the first multi-compartmental gabion 24 is located so as to be supported by two multi- compartmental gabions 24 located below it. Thus the elongate reinforcement member 22 comprises a first multi-compartmental gabion 24 in an upper row and second and third multi-compartmental gabions 24 in a lower row.

If water containment systems 10 of greater height are required, then further rows of multi-compartmental gabions 24 can be provided as appropriate. For example, Fig. 9 illustrates an optional configuration comprising three rows, i.e. the height of the elongate reinforcement member 22 is that of three stacked multi- compartmental gabions 24. Fig. 10 illustrates a similar arrangement to that of Fig. 9 but in which the same height of levee 12 is required with a smaller levee footprint. The configuration of Fig. 10 again makes use of the staggered arrangement of multi-compartmental gabions 24 in adjacent rows.

The arrangements of multi-compartmental gabions 24 illustrated in Figs. 7 to 10 to form elongate reinforcement members 22 are intended merely as examples only. Other arrangements of the multi-compartmental gabions 24 with respect to one another can be provided according to the requirements of the water containment system. Indeed, although in Figs. 7 to 10, the one or more multi- compartmental gabions 24 are located in a symmetrical arrangement at the centre of the levee, this need not be the case and, if required, may be located off- centre and/or in an asymmetric arrangement (e.g. an L-shape). Also, although the illustrated levees are symmetrical in cross-section, this need not be the case and may comprise levees in which the highest point is skewed (i.e. is not equidistant between the foot of the levee on the land-side and the foot of the levee on the water-side).

Figs. 11 to 16 illustrate schematic views of stages of a process for restoring an old and/or damaged water containment system. These figures illustrate a cross- section of a water containment system, such as an earthen levee, prior to, or during a restoration process.

Fig. 1 1 illustrates an old and/or damaged earthen levee 88 prior to a restoration process. Again, the illustrated levee 88 comprises a mound or bank of ballast material 14 and has three distinct regions, namely a side-slope 16 facing a waterside of the levee, a crown or peak 18, and a side-slope 20 facing a land-side of the levee 88. The levee 88 is arranged to hold back a body of water 90 to prevent the body of water reaching land on the land-side 91 of the levee.

In a first stage of a restoration process, as illustrated in Fig. 12, a trench or channel 92 is cut into the heart of the levee to a required depth. Ballast material removed from the levee to form the channel 92 may be set aside for use in a later stage of the restoration process.

Suitable retaining walls 94a, 94b may be placed against sidewalls of the channel to hold back ballast material 14 of the levee 88 and prevent such ballast material 14 from falling into the channel 92. In an optional arrangement, the retaining walls 94a, 94b may be sheet piles.

Although in the illustration of Fig. 12 the channel 92 is formed at the centre of the levee, this need not be the case and, if required, may be formed off-centre.

If required, a suitable temporary structure may be erected adjacent the side- slope 16 facing a water-side of the levee 88 to hold back the body of water 90 from construction works on the levee 88 during the restoration process. The temporary structure may be, for example, a cofferdam constructed around the portion of the levee where restoration works are to be carried out.

In a next stage of a restoration process, as illustrated in Fig. 13, an elongate reinforcement member 22 is located in the channel 92. In the particular arrangement illustrated in Fig. 13, the elongate reinforcement member 22 comprises one or more multi-compartmental gabions 24. Two such multi- compartmental gabions 24 are located in the channel 92 in the arrangement illustrated in Fig. 13. A first multi-compartmental gabion 24a is located upon a bed 96 of the channel 92, and a second multi-compartmental gabion 24b is located upon the first multi-compartmental gabion 24a.

Both of the multi-compartmental gabions 24a, 24b are filled with suitable ballast material, e.g. the ballast material which was removed to form the channel 92 and/or new ballast material. In the particular arrangement illustrated, the first multi-compartmental gabion 24a is filled with ballast material prior to location of the second multi-compartmental gabion 24b on top of the first multi- compartmental gabion 24a and filling of the second multi-compartmental gabion 24b.

For the avoidance of doubt, the term "new", when used above and hereinafter, can refer to both brand-new elements or materials, and also elements or materials other than those which have been removed.

In the illustrated restoration process, the width of the channel between retaining walls 94a, 94b is substantially the same as the width of the multi-compartmental gabion 24 when deployed. However, in an optional arrangement, the width of the channel 92 may be greater than that of the multi-compartmental gabions 24 and, if required, additional ballast material may be provided in gaps between sidewalls of the multi-compartmental gabions 24 and the retaining walls 94a, 94b.

In an optional arrangement, a grout-type material may also be provided in gaps between sidewalls of the multi-compartmental gabions 24 and the retaining walls 94a, 94b. This may inhibit the formation of voids between the reinforcement member and the existing fill soil which could be problematic as such voids could provide a seepage path. In a further optional arrangement, any suitable type of void-filling material (e.g. an expandable material) may be used in place of the grout-type material referred to above.

As will be appreciated, the channel 92 may be formed to a depth to accommodate as many multi-compartmental gabions 24 in a stacked arrangement (or otherwise) as required. Of course, there may be instances where only a single multi-compartmental gabion is required.

Similarly, the channel 92 may be formed to have a width to accommodate multi- compartmental gabions 24 side-by-side. In the figures, there is a single column of stacked multi-compartmental gabions 24a, 24b, but in other arrangements, there may be two or more columns of stacked multi-compartmental gabions. In further optional configurations, the stacked multi-compartmental gabions may be staggered or there may be more than one multi-compartmental gabion in a row, e.g. such as the optional configurations illustrated in Figs. 7 to 10.

In a next stage of the restoration process, as illustrated in Fig. 14, the retaining walls 94a, 94b are removed from the channel 92 and a capping layer 98 of ballast material is added to the channel 92 on top of the uppermost multi- compartmental gabion 24b located in the channel. This capping layer 98 of ballast material may serve to restore the crown or peak 18 of the levee. The ballast material used in the capping layer 98 may be ballast material removed to form the channel and/or new ballast material.

In an optional arrangement, the retaining walls may remain in the levee to form part of the completed levee.

An erosion inhibiting layer 26 is provided in a next stage of the restoration process (see Fig. 15). In the illustrated configuration, the erosion inhibiting layer 26 overlies the surface of the ballast material 14 forming the side-slopes 16, 20 and crown 18 of the levee. However, in other configurations, this need not be the case, and the erosion inhibiting layer may overlie only portions of the levee, e.g. side-slopes of the levee.

The erosion inhibiting layer 26 may comprise high performance turf reinforcement mat (such as ArmorMax™ manufactured by Propex). In optional arrangements, other materials may be used as the erosion inhibiting layer 26.

In an optional configuration, the erosion inhibiting layer 26 may be at least partially embedded in the surface of the ballast material 14.

The erosion inhibiting layer 26 may be anchored to the ballast material 14 by any means which is suitable to maintain the erosion inhibiting layer 26 in a substantially fixed position relative to the ballast material 14, e.g. to prevent slippage of the erosion inhibiting layer 26 with respect to the ballast material 14. The means may comprise discrete anchoring means which penetrate the erosion inhibiting layer 26 and extend to an appropriate depth in the ballast material 14. In other optional configurations, the means may comprise a stabilising element arranged to bind the erosion inhibiting layer to said ballast material. Suitable materials for the stabilising element may comprise, for example, one or more of a vegetation layer (such as grass), a cotton mulch layer or a textile layer.

Fig. 16 illustrates schematically the restored levee after provision of a layer of grass to the erosion inhibiting layer 26, with the layer of grass serving to bind the erosion inhibiting layer 26 to the ballast material 14.

Although a levee having a particular cross-section is illustrated in Figs. 1 1 to 16, the above described restoration process may be applied to levees having different cross-sections.

The restored levee which is restored using the above-described steps may be the same as that illustrated in Figs. 1 to 3.

Claims

1. A water containment system comprising: an elongate reinforcement member; ballast material located against at least one side of said elongate reinforcement member; an erosion inhibiting layer overlying, or at least partially embedded in, a surface of said ballast material, wherein the erosion inhibiting layer is arranged in a fixed relationship with respect to said ballast material.

2. A system according to claim 1 , wherein said erosion inhibiting layer is provided with a stabilising element arranged to bind said erosion inhibiting layer to said ballast material.

3. A system according to Claim 2, wherein said stabilising element comprises at least one of, or a combination of: a vegetation layer; a cotton mulch layer; a textile layer.

4. A system according to Claim 3, wherein said vegetation layer comprises grass.

5. A system according to any one of the preceding claims, wherein said ballast material is located against both sides of said elongate reinforcement member.

6. A system according to any one of the preceding claims, wherein a portion of said ballast material is located on top of said elongate reinforcement member.

7. A system according to any one of the preceding claims, wherein the elongate reinforcement member comprises a plurality of compartments, and further wherein a portion of said ballast material is located in at least one of said plurality of compartments.

8. A system according to any one of the preceding claims, wherein at least a portion of said ballast material is banked to form a slope of ballast material against at least one side of said elongate reinforcement member.

9. A system according to any one of the preceding claims, wherein the elongate reinforcement member comprises a multi-compartmental gabion and further wherein a portion of said ballast material is located in one or more compartments of said multi-compartmental gabion.

10. A system according to Claim 9, wherein individual compartments of said multi-compartmental gabion are formed from wall elements, of which adjacent ones of said wall elements of an individual compartment are connected to one another by pivotal connections, and of which adjacent wall elements of adjacent compartments are connected to one another by pivotal connections.

11. A system according to Claim 9 or 10, wherein wall elements of said multi-compartmental gabion are formed from rigid mesh panels.

12. A system according to Claim 1 1 , wherein one or more compartments of said multi-compartmental gabion are provided with a liner material for receiving ballast material therein.

13. A system according to any one of Claims 10 to 12, wherein at least one of the pivotal connections is a releasable connection which when released allows a side wall element to open with respect to a compartment.

14. A method of constructing a water containment system comprising: providing an elongate reinforcement member; providing ballast material and locating said ballast material against at least one side of said reinforcement member; providing an erosion inhibiting layer to overlie, or be at least partially embedded in, a surface of said ballast material; anchoring the erosion inhibiting layer to said ballast material.

15. A method according to Claim 14, further comprising the step of providing the erosion inhibiting layer with a stabilizing element arranged to bind said erosion inhibiting layer to said ballast material.

16. A method according to Claim 14 or Claim 15, wherein said step of providing ballast material comprises locating said ballast material against both sides of said elongate reinforcement member.

17. A method according to any one of Claims 14 to 16, wherein said step of providing ballast material further comprises banking at least a portion of said ballast material to form a slope against at least one side of said elongate reinforcement member.

18. A method according to any one of Claims 14 to 17, wherein said step of providing an elongate reinforcement member comprises deploying a multi-compartmental gabion.

19. A method according to Claim 18, wherein said step of providing ballast material further comprises locating a portion of said ballast material in one or more compartments of said multi-compartmental gabion.

20. A method of reconditioning a water containment system as claimed in Claim 13, the method comprising: removing said erosion inhibiting layer; optionally removing said stabilising element prior to removing said erosion inhibiting layer; removing at least a portion of said ballast material located against at least one side of said elongate reinforcement member from at least one side of said elongate reinforcement member; opening one or more compartments in which ballast material is depleted; re-filling said one or more compartments in which ballast material is depleted with further ballast material; closing said one or more compartments which have been re-filled; returning at least a portion of said removed ballast material to said at least one side from which it was removed and/or adding new ballast material to said at least one side from which ballast material was removed; returning said removed erosion inhibiting layer to a position in which it overlies, or is at least partially embedded in, a surface of said ballast material, or locating a new erosion inhibiting layer in a position in which it overlies, or is at least partially embedded in, a surface of said ballast material; and optionally returning said stabilising element to said erosion inhibiting layer and/or providing a new stabilising element for said erosion inhibiting layer.

A method of re-conditioning a water containment structure, comprising: removing an amount of ballast material from said water containment structure to form a channel therein; locating a multi-compartmental gabion in said channel; locating at least a portion of said removed ballast material and/or new ballast material in one or more compartments of said multi-compartmental gabion; providing an erosion inhibiting layer to overlie, or be at least partially embedded in, a surface of said ballast material; anchoring the erosion inhibiting layer to said ballast material.

22. A method according to Claim 21 , further comprising filling gaps between said multi-compartmental gabion and sides of said channel with at least a portion of said removed ballast material and/or new ballast material.

23. A method according to Claims 21 or 22, further comprising, prior to said erosion inhibiting layer providing step, locating at least a portion of said removed ballast material and/or new ballast material on top of said multi- compartmental gabion in said channel to fill a remainder of said channel.

24. A method according to any one of Claims 21 to 23, further comprising, prior to said erosion inhibiting layer providing step, adding at least a portion of said removed ballast material and/or new ballast material to ballast material located against at least one side of the multi- compartmental gabion.

25. A method according to any one of Claims 21 to 24, further comprising the step of providing the erosion inhibiting layer with a stabilising element arranged to bind said erosion inhibiting layer to said ballast material.

26. A method according to any one of Claims 21 to 25, further comprising banking at least a portion of said ballast material located against at least one side of the multi-compartmental gabion to form a slope. A water containment system substantially as hereinbefore described with reference to and as illustrated in, any one or more of Figs. 1 to 3, 7 to 10 or 16 of the accompanying drawings.

A method of re-conditioning a water containment structure formed of ballast material substantially as hereinbefore described with reference to and as illustrated in, any one or more of Figs. 11 to 16 of the accompanying drawings.