GB2508628A - Flood management bag - Google Patents

Abstract

The invention relates to a sandbag 10 figure 2 for use in flood management and comprises a bag or sealed bag of substantially rectangular dimensions and constructed from non-woven polyethylene or polypropylene, with welded seams 20. If the bag is a sealed bag then the bag is also sealed 22 by welding to seal the contents in the bag. The bag may have a plurality of attachment points 30 for the attachment of one bag to another by the use of hook and loop fastenings which strengthen any structure built using the bags. The bags may have inner and outer skins, contain water absorbent materials, and plant seeds. The bags may be used in the long term for the removal of heavy oils by adding microbes to polymers within the bag to break down the heavy oils.

Description

Flood Management System and Aiciaratus The present invention relates to a flood management system and apparatus and specifically one suitable for rapid deployment to provide a water flood control and storage systems.

Flood management and the control of excess water is an on going problem and many devices, apparatus and system have been developed to facilitate flood management and controL It is, however, notable that the most commonly used device in flood control, particularly in emergency situations, is the traditional sandbag. The sandbag is typically a hessian sack which is filled with sand or soil, sealed and then placed horizontally, typically along with many similar such bags to form an ad hoc wall or barrier structure. This has been proved to provide a relatively fast, and largely affected interim solution to flood management and control of excess water particularly in emergency situations.

One disadvantage with the traditional sandbag is that it is necessary to either pre-fill with sand and hence transport a heavy and bulky item or it is necessary to fill with sand on location. Sand may not be readily available on location and the likely alternative, soil, is most likely to be present as mud in a flooded area, which is difficult to handle effectively.

One approach to overcoming this disadvantage is the use of a bag filled with a water adsorbent material. DE9944402458 discloses a conventional sandbag supplemented by a water adsorbent material so that the sack increases in volume on contact with water.

Another approach to overcome the requirement for using soil is provided in ON 2396098 which discloses the use of a traditional hessian sack or a woven chemical fibre bag filled with a water adsorbent material capable of an adsorbent water to many times its own weight such as to increase the weight of the bag, inflate the bag and otherwise produce an in-situ bulky item suitable for creating a barrier as an alternative to a traditional sandbag. A development of this is disclosed in ON 2883484 in which a sack-in-sack configuration is provided. An inner cotton bag or sack, to stop leakage of the water adsorbent material, is filled with that water absorbent material and an outer sack of conventional type is provided to give physical integrity to the inner bag or bag. A similar disclosure is provided in KR20050000694.The use of a water adsorbent material is avoided completely in the disclosure of JP2001073337 in which a flexible bottle is used to contain water and thus form a sandbag.

Whilst the use of sandbags of a form where the weight and volume of the bag are created in situ by use of a water adsorbent material, such as a polymer, are known these devices have not found widespread use. One reason is that the density of such bags is similar to that of water. The bag is therefore lacking the weight necessary to maintain their position in a wall of such bags and are theiefore not necessarily particularly effective as water level rises.

There is therefore the need for an improved form of in-situ generated sandbag.

A further issue arises with flood control. Flood contiol is often undertaken as an emeigency procedure and as such a significant subsequent issue is in a damage limitation and clear up.

A significant advantage of traditional sandbags is that their construction, typically of hessian, is biodegradable and that the contents can simply be returned to where they have been dug up in the case of soil or in the case of sand similarly disposed of with minimal enviionmental consequence. However, the in situ hydrated sandbags are more difficult to dispose of. The hydrated material is typically chosen from a polyacrylate or similar polymer which has relatively pooi biodegradation and cannot be ieadily disposed of. Similarly sacking material other than cofton or hessian and similar materials will similarly not readily biodegrade or become assimilated into the environment on a reasonable timescale. There is therefore a need for an improved flood control system which facilitates subsequent clean-up and disposal.

The present invention in its various aspects is as set out in the appended claims.

In one aspect the present invention provides an improved sandbag for use in flood management. By a sandbag is meant a bag or sack suitable for use in the manner of a traditional sandbag, rather than a bag containing sand as such.

The flood containment sack or sandbag, as it will now be ieferied to, of the piesent invention comprises a nonwoven high density polyethylene fabric formed into an open sack for sealing or into sealed sack of predetermined contents, having heat sealed seams and being, when flattened, a rectangular stiucture complising iespectively a sealable or sealed inner volume and an outer surface exposed the environment wherein the outer surface preferably complises a plurality of attachment points for a tethel and the inner volume complises any predetermined contents comprising a water adsorbent, water-insoluble material capable of absorbing more than 10 times its own weight in water and retaining that water.

It has being found that the use of a nonwoven high density polyethylene (HDPE) fabric overcomes several of the disadvantages of known synthetic sandbags. First, the combination of high density polyethylene in a nonwoven structure provides a ielatively high degree of friction between sandbags in the presence of water. In contrast a woven structure intrinsically comprises directions in which the degree of friction is lower, critically with polyethylene and polypropylene structures, for example when the forces involved line up with the direction of the warp or weft. Whilst this may be addressed by using a diagonal weave relative to the main geometry of the sandbag users of sandbags in an emergency situation are unlikely to have the time and presence of mind to avoid sandbags being aligned in directions which can still give rise to low friction. In addition polyethylene and polypropylene woven structures typically comprise flat strands and these have particularly low levels of friction but are nevertheless preferentially chosen due to their low cost and high strength. However, a specification of a nonwoven, preferably spun bond, high density polyethylene or polypropylene fabric having a thickness in the range 0.075mm minimum to, 0.380 maximum has been found to give a combination of strength and flexibility for the construction of the sandbags of the present invention. The spun bond can be thermally bonded or needle punched fabrics. Thermal bonding is preferred for temporary structures and needle punched for longer term structures later consolidated by the growth of vegetation before fibre dispersal. The above thickness range is in the context of a fabric density in the range of 0.80 to 0.96 g/cm3 which typically gives a tensile strength of 7-20 N/mm. A preferred fabric density is 0.94 g/cm3.

This above parameters alone or preferably together have been found to provide an optimal strength/flexibility compromise for this intended use. Specifically, providing a strong bag is self-evidently useful. But providing strength at the expense of flexibility means that the bags will not fit effectively together and deform under normally applied forces so as to provide an effective barrier to water. Equally, very high flexibility provides undue deformation and often weakness of a bag, which in the context of a bag filled by hydration of material by water adsorption and of a relatively low density difference between the bag and the water that is being resisted this is also undesirable as bags may simply extrude themselves from a wall.

Similarly, a further factor which is helpful is the thickness of the constituent polypropylene or polyethylene fibres. To fine a fibre gives rise to a very smooth surface and hence low friction but provides excellent retention of water adsorbent material. To coarse a fibre gives rise to a coarse surface that may effectively interlock but provides relatively large pores such that retention of water absorbent material can be poor. Hence it is been found that an optimum linear mass density of fibers of Sto 20, preferably 10-15 denier provides the best results.

Polyethylene or polypropylene is used, preferably polypropylene due to its chemical resistance and better aggregation of the properties considered above. This material may preferably contain 2 to 3 per cent carbon black or titanium dioxide for ultraviolet light resistance but also since visual opacity of the fabric appears to facilitate better manual handling so as to more effectively place sandbags in a structure to be created.

Whilst the aforementioned fabric structure is generally very effective, whether used with a conventional sand or soil filling and whether this is supplemented by a water adsorbent material or replaced by a water adsorbent material it has been found capable of further improvement.

Specifically, and especially when relatively low density fillings are used, such as a water adsorbent material, the low density of the bags relative to water requires their overall usage to be optimised for best effect. In a first instance the weight of the bags may be supplemented by the inclusion of a metal, ball bearings, such as stainless steel may be chosen. However the preferred choice is aluminium. Despite its low density aluminium particularly in a seawater environment has a relatively short life in the order of weeks such that subsequent disposal is not a problem.

In a second instance, the bags may be provided with a plurality of attachment points for the attachment of one bag to another. Whilst these may be provided in a number of ways it has generally been found that tying with lanyards whether with or without auxiliary features such as loops is generally ineffective in flood management, particularly in emergencies. Tying effective knots in synthetic ropes, which tend to have low friction requires skill and knowledge and furthermore emergency situations including flooding often leave tired operatives with a cold and numb hands and unable to tie effective knots even if they are able. The present invention therefore preferably also includes attachment points using the known hook and loop system. Even then it has been found that hooks and loops of a height around 2mm to 3mm are required. A preferred form of hook and loop fastener is that to US Military Specification A-A 551 26B Rev 2006. Coarser fixtures can snag clothing and fine is generally not as effective in actual practice, such as due to the ingress of sand and the like into the fasteners. The attachment points may be interlinked by corresponding (i.e. hook for loop etc.) separately provided tethers. In practice these are best provided as an attached tether between 2 attachment points on a bag, the length of the tether been such that the tether lies flat on the back when stretch between 2 attachment points of an unfilled bag. This has the advantage that when the bag fills the tethers distort the bag and an operative tends

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to automatically remove the tether at one end to facilitate bag filling or bag expansion. This naturally leads to a loose tether which is more or less automatically used by an operative, simply to get it out of the way, to attach it to another attachment point when placing the bag.

Often this attachment point is chosen on another bag automatically strengthening the structure. This has the strong advantage that in an emergency situation it is not necessary to instruct operatives as to the configuration of the tethers and the attachment points as described above automatically give rise to a beneficial behavior.

It is also been found that an optimum tether length is around one third the length of a rectangular sack. For example, optical measurements appear to be in the region of separately. The tether length to sack ration is 1/3rd length of overall sack length. For example on a standard 450mm length rectangular sack the tether length would be 150mm.

this given that the attachment points are placed no more than half the length of the tether in from the edge of a sack, as measured in unfilled form.

The preferred dimensions of the attachment points are 70mm wide squares. Tethers are preferably as wide as the attachment points. It is also been found that preferable attachment is by box stitch with vertical centre stitch for patches. This is because should the attachment points be put under too much stress they can detach by ripping of the stitches. In contrast, if the attachment points are welded than the bag itself rips and the low density of the filling, particularly if a water adsorbent material is used, means that the material rapidly flows out and the bag may collapse.

The attachment points are preferably 3 in number. The attachment points are preferably deployed with 2 adjacent corners on a short side of the bag's rectangle and a third attachment point midway between adjacent corners on a further short side of the rectangle remote from the first side. The attachment points are preferably all on one side of a bag as viewed in an un-deployed state as a flat rectangle.

Using the above arrangement it is possible to consolidate the sandbags in horizontal and vertical directions. A particular advantage of providing the separate tethers is that they may be readily used to allow the units to be anchored to physical structures or a deployed grid system.

When the sandbags of the present invention are used with a water adsorbent material then any of the conventional materials used for this purpose may be chosen.

When sandba9s of the present invention are used with a water adsorbent material then the bags are normally provided sealed with the water absorbent material contained within the sealed bag.

However, it has been found optimal when using water absorbent material to provide the sacks with an inner and an outer skin. Both of those skins preferably being in the form of a fabric as previously described, this provides for ease of construction and, additionally, unlike known bags of that structure, convenient means for attaching the inner back to the outer bag, such as by the use of a common welded seam of an inner and outer polyethylene bag may be used.

When used with water adsorbent material the inner sack preferably contains a specific blend of cioss-linked polyacrylic polymers in two foims. The fiist is a small giain <125pm polymer commonly none as SAP (super absorbent polymer), the second polymer is a starch coated granular polymer with a larger grain size <250pm. These polymers offer a combined highly effective rapid absorption of water and other fluids even under high salinity conditions e.g. sea water. The small giain rapidly absorbs the main watel body and cleates the barriei in situ, whilst the larger starch coated polymer absorbs at a slower rate absorbing much of the duty water and contaminants, this synchronized appioach is unique in watei control systems of this nature.

A preferred corn-starch and polymer complexes of cross-linked carboxymethyl cellulose (CMC) -a CMC trade name is Blanose Cellulose! Carboxymethyl ether, Sodium Salt.

When an inner sack is used then sack size may be based on the maximum expansion of the outer sack and polymer increase due to elasticity, therefore the inner sack may 98% of maximum expansion dimensions of the outer sack.

As mentioned previously, the optimum configuration of a sandbag for use with features of the pieserit invention deteimined by an interplay of features. When using the pieferred materials optimal dimensions have been found to be between 400 and 500 mm in length! between 250 and 350 mm in width and thickness deteimined by stacking of the material as described unless filled with water as a material in which case a thickness of between 20mm and 60mm of evenly filled material is preferred. Most preferred being 450mm in length, 300mm in width and when tilled with water is a material of thickness 50mm.

Whilst the above considerations have been mostly considered in relation to emergency situations there is the possibility, either accidental or deliberate, to use sandbags in more permanent structures. Examples of permanent retained systems are water body embankments or coastal protection of dunes, wetlands or reed beds. In this respect the use of the tethers mentioned above can be used in order to allow units to have an overall height of up to 4 meters of wall with an acceptable degree of dimensional stability.

As mentioned above In permanent or semi-peimanent protection the membrane can be further supplemented with an inner sack containing starch polymers, organic media containing a specially formulated humis that is pre seeded with indigenous plants and grasses that will rapidly grow and offer further protection and pleasing cosmetics to the barrier system.

Specially formulated humis that is pro seeded with indigenous plants and grasses -example needed Humic Mineial Concentrate (HMC) a combination of insoluble humic acids and soluble humates, in an optimal ratio, with a pH of 6.5-7.5. Sorption on HMC combines hydrophobic interaction with covalent bonding, followed by decomposition of petroleum hydrocarbons and dechlorination and decomposition of chlorinated hydrocarbons. HMC application suppoits highei microbial activity, and increases moistule letention and fertility.

The formulated blend may also contain fulvic acid and humin. Humates naturally contain carbon and other organic stimulants as an energy souice for microbes. use a numbei of industrial materials to create the HMC these include Humi Source Plus ( Leonartdite Products LLC), Humate Ag 6 (Viresco).

By adding a specially blended mix of microbes from the archea group -specific example needed Archaebacteria (Prokaryotes) specifically Methanogenic Archaea and Halophilic Groups an alternative base for specific non water based remediation could have the archea substituted with mycorrhiza fungi specially for use in barren soil adaption and where mine tailing restoration is required.

Oil enriched bentonite clay, such as comprised primarily of sodium montmorillonite, characterized by high swelling potential and low hydraulic conductivity and enriched with a stabilized crude oil which contains butane AP 0.8-1 % by volume, n-Hexane AP 0.3-1 % by volume, Isopentane AP 0.3-1.5 % by volume and Pentane AP 1.5-2.5 % by volume may be included in the sand bag.

A further application is used in the long-term removal of heavy oils in the event of an oil spill the membrane is designed to allow heavy oils (crudes) to adhere to the outer membrane and will not pass through the unit allo'ving only water to enter and if required at maximum absorbency allow filtered' water to continue to flow through the units as an aid to important tidal activity. An important factor in many brackish water bodies. By adding a specially blended mix of microbes from the archea group with oil enriched bentonite clay to the polymers. The microbe mass rapidly increases with the heavy oil hydrocarbons as the food source. Breaking down the heavy oils on the membrane into harmless fatty acids, minerals and oxygen. The microbes will continue to breakdown the heavy oils whilst the food source is present. The constant wave action brings the spill ashore and continues to coat the membrane allowing the heavy oils to be broken down in a controlled and natural manner.

Drawings The present invention is illustrated by the following figures which are intended to be illustrative.

Figure 1 discloses, as a schematic view a cross section of a welded seam construction of a polyethylene or polypropylene bag for use in the present invention.

A top portion of the bag (12) extends to the right, the lower to the left. The dimensions characteristic for this weld shape are indicated: Dt (thickness of top membrane), Db (thickness of bottom membrane), Os (thickness off seam), Ws (width of seam), a (off-setting, dis-alignment), o (overlap). Please put some numbers on the dimensions. Db and Dt may be >2.5mm and <5mm; o >40mm and <80mm; Ws >30mm and <40mm; with a>Smm and C 20mm.

The preferred form of seam is an extrusion fillet seam, both dual weld and extruded weld seams may be used. As mentioned previously the preferred material is a non-woven polyethylene or polypropylene.

All parts are constructed from the same basic chemical material, either polyethylene or polypropylene.

Figure 2 shows a plan view of a sandbag (10) of the present invention, having welds 20 and sealable joins 22, attachment points 30 and tether 40 having end attachment portions 42 and 44.

Figure 3 shows, A, a simplified drawing of a flood control assembly of units (10, b) with tethers (40,a) applied to a face (b), a is removable but the bond is strong enough to remain in place. A permanent secured anchor point can be supplied on (b) that is easily attached to (d), d is a movable tethering point that easily attaches to c securing a number of units (b) to each other to create secured barrier systems.

In a further aspect a system of recovery of sand bags of the invention, when using a water adsorbent polymer is provided.

Once the used flood prevention device is no longer required, the inner sack is injected with a very high saline based fluid; this is delivered via a needle device or in larger units by way of an outer tube through which the fluid can be directed. Within a few moments of the high saline fluid being introduced to the polymer inner pack the osmotic pressure is greatly changed and the retained fluid will be released. The released water will be either collected in a temporary berm or pumped away safely form location.

Claims (10)

1. Claims, 1. An article for use in the manner of a sandbag for flood prevention, the article consisting of a bag or sealed bag of generally rectangular dimensions; being constructed from nonwoven polyethylene or polypropylene fabric; having welded seams to form the bag; and if a sealed bag subsequently, welded to seal contents in the bag.2. The article of claim 1 wherein the construction is of nonwoven high-density polyethylene.
2. 2. The article of claim 1 or claim 2 wherein the fabric is made from polymer strands of 10 to denier.
3. 3. The article of any of claims ito 3 when the fabric is of thickness in the range 0.075mm to 0.380 and having a density in the range 0.80 to 0.96 gtcm3.
4. 4. The article of any preceding claim wherein the bag is a sealed bag and the bag is partially filled with a highly water adsorbent polymer before sealing.
5. 5. The article of claim 4 wherein the bag filling also comprises plant seeds.
6. 6. The article of claim 4 wherein the bag filling comprises montomorilinite clay.
7. 7. The article of any preceding claim wherein a number of attachment points are provided being one of a hook or loop component of a and hook and loop connector.
8. 8. A kit of parts comprising an article as defined in claim 7 and being an unsealed bag, in combination with an elongate tether, the tether being attached by means of corresponding hook or loop connector at a first end to a first of said attachment points and at the other end of the tether to by a further corresponding hook or loop connector to a second, remote, one of said attachment points, the tether being linear between said attachment points when both article and tether are laid flat.
9. 9. The kit of claim 8 wherein the tether and attachment points are configured so that filling the bag fully is constrained by remaining attachment of one or other end of said tether.
10. 10. The article as defined in figure 3 and in the associated description.Amended claims have been filed as follows:-Claims, 1. An article for use in the manner of a sandbag for flood prevention, the article consisting of a bag or sealed bag of substantially rectangular dimensions; being constructed from nonwoven polyethylene or polypropylene fabric; having welded seams to form the bag; and if a sealed bag subsequently, welded to seal contents in the bag wherein a number of attachment points are provided being one of a hook or loop component of a and hook and loop connector.2. The article of claim 1 wherein the construction is of nonwoven high-density polyethylene.3. The article of claim 1 or claim 2 wherein the fabric is made from polymer strands of 10 to denier.4. The article of any of claims ito 3 when the fabric is of thickness in the range 0.075mm to 0.380 and having a density in the range 0.80 to 0.96 g/cm3.0 5. The article of any preceding claim wherein the bag is a sealed bag and the bag is partially 0 filled with a highly water adsorbent polymer before sealing. r6. The article of claim 5 wherein the bag filling also comprises plant seeds.7. The article of claim 5 wherein the bag filling comprises montomorilinite clay.8. A kit of parts comprising an article as defined in claim 1 and being an unsealed bag, in combination with an elongate tether, the tether being attached by means of corresponding hook or loop connector at a first end to a first of said attachment points and at the other end of the tether to by a further corresponding hook or loop connector to a second, remote, one of said attachment points, the tether being linear between said attachment points when both article and tether are laid flat.9. The kit of claim 8 wherein the tether and attachment points are configured so that filling the bag fully is constrained by remaining attachment of one or other end of said tether.10. The article as defined in figure 3 and in the associated description.