Abstract: A dynamically deployable, low visibility pneumatic cofferdam for flood mitigation is disclosed. The cofferdam includes a first planar component, a second planar component, an inflatable hermetic airbag sandwiched therebetween, and connection members attached to the first planar component, a second planar component to form a cofferdam unit. The connection members are adjustable to apply and maintain a desired amount of pressure on the airbag to enable a watertight seal to be formed. The cofferdam units may be sized and designed to sealingly mate adjacent cofferdam units in a variety of configurations to form watertight seals. The cofferdam units may also be sized and designed to attach to seawalls, flood walls, sidewalks, or other infrastructure. When in a deployed state, the height of the cofferdam may be adjusted to a desired height to provide flood mitigation. When in an undeployed state, the cofferdam remains in a substantially flat and unobtrusive position.

Abstract: The invention provides a method for preventing super large-scale floods and debris flows. First, the scale corresponding to certain standard floods in the watershed is evaluated based on field investigations and historical data. Second, the design standards of the system are chosen based on the prevention of super large-scale floods, and the design standard of critical control engineering is further determined. Finally, the design methods of check dams with different functional zones are proposed according to the design standards of critical control engineering. The invention allows part of the key control dam to fail under safe operating conditions of the entire system by increasing the cross-sectional areas and the flow discharges. The unbroken foundation of the dam can effectively control the channel entrainment and regulate the cross-sectional discharge. The design is helpful in mitigating giant floods and debris flows, thus protecting downstream infrastructures.

Abstract: The absorption device includes a hydrophilic powder and a casing which is permeable to a liquid, the casing being composed of an upper layer which is superimposed on a lower layer, the lower and upper layers being connected to each other by strong connections which delimit a confinement zone for the hydrophilic powder in the casing. Advantageously, the lower and upper layers are connected to each other by first weak connections. The first weak connections delimit a plurality of adjacent cells in the confinement zone, each cell enclosing a quantity of hydrophilic powder sufficient to bring about the breakage of the first weak connections which delimit the cell when the hydrophilic powder absorbs a liquid.

Abstract: An erosion prevention system, a cell assembly and a kit of parts for such a system, and methods of making and installing such an erosion prevention system is disclosed. A cell assembly (2501) may comprise a plurality of cells (2520a, 2520b, 2520c) for containment of rock pieces, each cell having a bottom, sides/ends and a top each formed from wire mesh. A continuous length of wire mesh may wrap around and defines the upper, lower (2502) and end faces (2503a, 2503b) of the cell assembly (2501), the ends of the length being fastened together at an overlapping join positioned on the upper and/or end of the cell assembly. The continuous length of chain-link wire mesh may extend beyond at least one side face (2503d) of the cell assembly, thereby being configured to overlap at least a portion of the lower, upper and end faces of a corresponding second cell assembly when positioned side by side. The wire mesh may be chain-link wire mesh.

Abstract: Flexible containment tubes form sections of a dike for fluid containment. For example, multiple vinyl-coated polyester tubes with a 19-inch diameter may be filled with water and stacked on top of each other to create a temporary diversion dike. Multiple sections of dike may be abutted together to form longer sections of dike. A vapor barrier or plastic membrane may wrap over dike sections and/or weaved through the flexible containment tubes as they are placed prior to filling. Configurations of the vapor barrier and associated anchoring mechanisms improve the utility of dike sections by reducing hydrostatic pressure of contained fluid on the dike, harnessing the weight of fluid columns, and mitigating seepage through the dike sections.

Abstract: A method and a device for laying down and sealingly anchoring a waterproofing liner of a synthetic material, on a surface of a hydraulic work, by a plurality of anchoring assemblies each including a lower and an upper metal sections configured with a raised part and side sloping walls, wherein the lower metal section bar has a set of anchoring holes at a plurality of axially spaced anchoring zones; the surface of the hydraulic work is marked with a set of reference marks at a plurality of fastening zones, corresponding to the set of anchoring holes of the lower section bar; each lower section bar is fastened to the hydraulic work by anchoring devices threaded into an anchoring hole of a respective anchoring zone of the lower section bar, and into a perforation of the hydraulic work provided at one of the set of reference marks at each fastening zone.

Abstract: A system and method to create or elevate a berm of a liquid retention facility by placement of lightweight fill material anchored by an impervious liner material(s). The impervious liner material is integral to a water retention system such as a containment system of a retention pond. The system and method can also be used to elevate the liquid retention height of a levee in combination with impervious liner retention material. By constructing the berm system on an existing levee, the effective height of the levee can be increased. The lightweight fill material provides the shape of the berm or levee extension. The liquid impervious liner material provides a watertight surface, the media for joining of the lightweight fill material, and the anchoring of the lightweight fill material to the existing berm or levee structure.

Abstract: A lightweight concrete composition is mixed from cement, sand, water, and organic material, and placed on an area of soil, proximal a body of water, to protect the soil from erosion and the like due to water action. Preferably, the organic material comes from the area in which the soil is being stabilized, and may include soil, leafy matter, and ground up wood, forming a particulate organic material. Preferably, the final density of the resulting lightweight concrete composition is greater than the density of the water in the body of water, and less than the density of the soil being stabilized. A representative density range is between 62.43 pounds per cubic foot and 100.00 pounds per cubic foot.

Abstract: An apparatus, system, and method for creating a flood barrier by use of an open-top fabric bag device or series of connected bag devices that can be filled with materials to create the barrier. Each bag has a bottom panel, a front panel, a back panel, a four-sided neck, an opening in the neck, and lifting loops at the neck for lifting the bag. The bottom panel may contain a closable aperture formed by a front bottom panel overlapping a back bottom panel underneath the back bottom panel and secured by a fastening device to releasably secure the aperture. When the bag is full of materials and is lifted at the neck loops, the aperture opens and the contents are released and remain in place as the bag is lifted and removed and is available for re-use.

Abstract: A floodwall system comprises a plurality of wall panels detachably attached to a plurality of columns that are anchored to the ground. The plurality of wall panels include a plurality of chambers that receive water through perforations to increase the mass of these wall panels.

Abstract: An apparatus for filling joints in precast concrete structures includes a core that has exceptionally low creep and conforms to ASTM D 1752 made of controlled particle size composites of recycled cellular rubber and plastic materials in the form of a rectangular slab. Holes are drilled through a central area and countersink recesses are formed around the holes. An outer coating of a thermoplastic polyurethane/polyurea elastomer system of a thickness of 0.075 inch covers the slab and countersink recesses. The coated core is abrasion and UV resistant while having the creep characteristics needed to make a dam expansion joint filler.

Abstract: In an embodiment, a water containment barrier may include a hollow body at least partially defined by a front wall, a back wall, a top portion, a bottom portion, a first end, and a second end. An external support system may be connected to the front wall of the hollow body. The external support system may include an upper cross member, a lower cross member, a first side member generally extending between the upper and lower cross members, and a second side member generally opposite the first side member. The external support system may be configured to at least partially reinforce the front wall against internal forces and/or external forces exerted on the front wall. The barrier may also include an elongated foot member attached to the bottom portion.

Abstract: A liquid containment berm and its method of creation, assembly and use, wherein the berm has one or more interior seal members, a floor member and an outer wall member created by applying an expandable foam polymer along a desired retention or flow control pathway, the foam polymer expanding to form the liquid impermeable outer wall member. The berm is assembled and installed on site about a liquid container.

Abstract: A modular liquid dam comprising a plurality of individual elongated members or segments that can be assembled in an end-to-end relationship to form a temporary liquid retainer or diverter on a substrate surface. The dam members are provided with one or more longitudinal bores or passages that reduce the amount of material in each member, thereby reducing manufacturing costs. The bores may extend completely through the dam member, may be internal bores closed off at each end, or may be bore segments intermittently spaced within the dam member. Intermittent bore segments provide internal bridging structures to increase the structural integrity of the dam member.

Abstract: A modular liquid dam comprising a plurality of individual elongated members or segments that can be assembled in an end-to-end relationship to form a temporary retainer or diverter on a substrate surface. The dam members are provided with a magnetic connection system having a magnet disposed within or exposed on the end of at least one adjacent dam member, the other adjacent dam member having a second magnet or metal member disposed within or exposed on its end, such that when the two dam members are abutted, the magnetic connection system maintains the dam members in abutting relationship. Structural mating members providing a mechanical or frictional fit may also be provided in the ends of the dam members to further enhance the connection in conjunction with the magnetic connection mechanism.

Abstract: A drainage channel includes a first sidewall provided with a first rail member extending along a longitudinal axis of the drainage channel. A second sidewall extends along the longitudinal axis of the drainage channel with the first and second sidewalls at least partially defining an interior area of the drainage channel. A first locking insert is at least partially positioned within a first rail opening of the first rail member, with the first locking insert including a first insert opening. Further examples include methods of making a drainage channel.

Abstract: An object of the present invention is to provide methods for laying a waterproofing layer which may be used for forming the bottom and the walls of depositing sites so as to comply, both in literal and in substantial terms, with the legal requirements. The aim is also to provide durable waterproof barriers which have a high mechanical strength, without discontinuity.

Abstract: In an embodiment, a water management barrier may include a hollow body at least partially defined by a front wall, a back wall, a top portion, a bottom portion, a first end, and a second end. The front wall may include a plurality of raised portions spaced from each other and extending substantially between the top portion and the bottom portion. The raised portions may at least partially define a plurality of channels extending substantially between said top portion and said bottom portion. The raised portions and/or the channels may be configured to help the front wall resist deformation due to one or more forces being exerted on the front wall. The barrier may also include an elongated connection member connection to the first end and a connection recess formed in the second end. The barrier may also include an elongated foot member attached to the bottom portion.

Abstract: The present invention is directed to a unique, elongated sandbag for use as the bottom layer(s) in a sandbag barrier wall and a kit containing such an elongated sandbag as well as a sufficient number of other, shorter, sandbags for forming a barrier wall for an opening, such as a doorway.

Abstract: A rapidly assembled debris flow sediment storage dam and a construction method are provided. The sediment storage dam has a main dam body with multiple prefabricated reinforced concrete rectangular boxes linked by vertical and horizontal connections. The top surface of each rectangular box is open, and the other five surfaces of the rectangular box are closed. Soil is used to fill each rectangular box. The main dam body is assembled above dam body foundations. Dam abutment foundations of the sediment storage dam and the inside slope of the dam body are filled with cement-laid stone masonry or concrete, while the top surface of the dam crest is also sealed using cement-laid stone masonry or concrete.

Abstract: A flood protection bag system includes a troughlike structure having longitudinally-extending sidewalls and a bottom wall connected therebetween, along with one or more internal walls, the internal walls serving to divide the troughlike structure into a plurality of bag chambers. The longitudinally-extending sidewalls are continuous and seamless between the ends of the troughlike structure, and the bag system can be made of a plastic such as polypropylene. In one embodiment, the bag system may be implemented in conjunction with other such bag system(s). Also, in one embodiment, a frame structure is employed to support the bag chamber(s) during filling thereof with sand or other filling material, in a manner whereby tension is applied to each of the corners of the given bag chamber being filled. Further, in one embodiment, the bag chambers are covered by way of a bag top that is openable or removable relative to the bag system.

Abstract: A flood barrier comprises hollow self-filling units (10, 12, 14, 16) placed end-to-end and connected at their ends by downwardly tapered bilobal (46) keys inserted into sockets (26, 28) at the ends of the units, wherein the keys incorporate concrete or other ballast for negative buoyancy.

Abstract: The proposed advanced multi-level protective system comprises two types of barriers, harmoniously complementing to each other: a portable barrier for the protection of individual houses at the height of the floods up to 0.8-0.9 meters, and more powerful protective quick-installable barriers, suitable for mechanized installation and resistant to higher water flows up to 1.2-2 meters. The proposed advanced protective system comprises a number of additional means capable of weakening against dangerous natural processes that give rise strong water flows, and these means can weaken these flows and increase the efficiency of proposed protective barriers.

Abstract: Slurry walls and methods of using those slurry walls to seal unlined solar ponds are provided. The slurry walls are formed from a mixture comprising clay and cement in water. A trench is keyed into the dike surrounding the solar pond, down to a geotechnically predetermined level. The slurry is deposited into the trench and allowed to harden, after which it is covered with a membrane or other covering. The inventive slurry walls reduce, and preferably prevent, leakage of water from the solar pond.

Abstract: Dams are a useful source of energy. An embodiment of a dam according to the present invention includes precast segments configured to be coupled together to form a dam optionally used to generate energy. An embodiment includes encasing an existing dam structure using interconnected precast segments. An underpinning system may penetrate the existing dam structure and be employed to assist in maintaining position of the dam or segmental components. A further embodiment includes encasing a main energy generation component using interconnected precast segments formed from a composite material including electrically conducting fibers, an electric circuit configured to measure and report the electrical resistance using a transmitter or transceiver to a dam stress/strain monitoring server. The electrical circuit may be powered directly or indirectly by available power supplied by the main energy generation component.

Abstract: A liquid containment berm and its method of creation, assembly and use, wherein the berm has one or more interior seal members, a floor member and an outer wall member created by applying an expandable foam polymer along a desired retention or flow control pathway, the foam polymer expanding to form the liquid impermeable outer wall member. The berm is assembled and installed on site about a liquid container.

Abstract: Dams are a useful source of energy. An embodiment of a dam according to the present invention includes precast segments configured to be coupled together to form a dam optionally used to generate energy. An embodiment includes a spillway extender to prevent upstream or downstream erosion of a riverbed at the dam. An underpinning system may be employed to assist in maintaining position of the dam or segmental components. Solar panel energy generation systems and battery storage may be associated with the segmental dam to store energy and, optionally, produce auxiliary power for subsystems associated with the dam, such as for supporting automated spillway control gate level control or automated gearing system control to control a gear ratio associated with rotating or other moving parts used to convert kinetic energy of water into electrical energy.

Abstract: Embodiments disclosed herein relate to barriers for managing and/or controlling water. In an embodiment, a barrier may include a hollow body at least partially defined by a front wall, a back wall, a top portion and a bottom portion. An elongated connection member may be connected to the first end. The connection member may have a tapered free end portion substantially adjacent said top portion and a lower free end portion substantially adjacent said bottom portion of said hollow body such that the connection member virtually extends the entire length of the first end. A connection recess may be formed in the second end. The connection recess may be sized and configured to generally correspond to at least a portion of the connection member. The barrier may further include a foot member attached to the bottom portion, and a fill port and a drain port in fluid communication with the hollow body.

Abstract: A process for grouting a super-thin curtain with polymer, includes: forming a series of V-shaped injecting holes by direct pushing method using a special drilling tool along a dam or dike axis spacedly at a predetermined distance; and injecting a two-component polymer composition into each of the holes, wherein the mixed polymer material expends and coagulates under chemical reaction to form a series of super-thin curtain segments, and the curtain segments connect with each other end to end to form a continuous and impermeable polymer curtain.

Abstract: The water barrier is comprised of a number of interconnected modules, that contain expansive material (such as polymer powder). Each module has inlets that allow rising water to enter the interior volume of the module so that it inflates from a flattened configuration to a four sided shape. The shape is wedge shaped and the modules are alternated so that the narrow end of the module is toward the rising water on one module and the wide end is next to the rising water on the adjacent module, so that pressure from the rising water is transferred to adjacent modules from module to module and ultimately to an anchoring system.

Abstract: A levee and barrier module for fluid control and containment is provided including an outer module shell and a module-to-module connection system to attach adjacent outer shells. The outer module shell is formed by opposing side walls and two opposing end walls and is configured to enclose or support filler material. The outer module shell defines a top aperture and a bottom aperture. The bottom aperture allows filler material communication with the earth below the module. The top aperture allows filler material to be added to the module, as well as visual observation of, and maintenance of, the amount of contained filler material. A presented application is directed to protecting pipelines and to allowing pipeline integration or association with levees.

Abstract: The present disclosure generally relates to a polymeric cellular confinement system which can be filled with soil, concrete, aggregate, earth materials, and the like. More specifically, the present disclosure concerns a cellular confinement system characterized by improved durability against damage generated by UV light, humidity, and aggressive soils, or combinations thereof.

Abstract: Slurry walls and methods of using those slurry walls to seal unlined solar ponds are provided. The slurry walls are formed from a mixture comprising clay and cement in water. A trench is keyed into the dike surrounding the solar pond, down to a geotechnically predetermined level. The slurry is deposited into the trench and allowed to harden, after which it is covered with a membrane or other covering. The inventive slurry walls reduce, and preferably prevent, leakage of water from the solar pond.

Abstract: A flood barrier comprises a plurality of panels attached together. A gasket runs continuously around the exterior periphery of each panel. When a panel is attached to an adjacent panel, the said gasket is compressed and the panels together form a watertight joint. Elongated members are attached to each panel to provide support. The bottom surface of the panel, together with the said gasket, is pressed against the ground from the weight of the floodwater and that of the panel itself. Sandbags and/or weights may be used to assist in pressing the said gasket against the ground as needed. This forms a watertight joint between the bottom surface of the panels and the ground. The attachment of a plurality of said panels together form a flood barrier. Most panels are flat panels and some are angled panels. The flat panels and angled panels can be assembled on site to surround a house or a building to form a barrier against flooding.

Abstract: The present disclosure generally relates to a polymeric cellular confinement system which can be filled with soil, concrete, aggregate, earth materials, and the like. More specifically, the present disclosure concerns a cellular confinement system characterized by improved durability against damage generated by UV light, humidity, and aggressive soils, or combinations thereof.

Abstract: A modular-unit floodwall system is disclosed. The system includes modular floodwall units configured for holding water and connecting and sealing devices for connecting the units together to form a barrier against floodwater. A method of constructing such a floodwall is also disclosed.

Abstract: A barrier panel system and a method of installing the barrier panel system is provided. The barrier panel system includes a barrier panel having a top and a bottom. The panel includes at least one channel extending from the top to the bottom of the barrier panel. A removable jet assembly unit can be connected to the panel within the channel. The removable jet assembly unit includes at least one cutter tool pipe which is connected to a jet head and at least one vacuum manifold. The jet head at the bottom of the cutter tool pipe delivers and directs the pressurized stream to transform the ground material into a form which is easily removable by a vacuum connected to the vacuum manifold. As the vacuum removes the ground matter, an opening is formed in the ground allowing the panel to sink. The barrier panel also includes interlocking features on the sides allowing them to be easily attached to one another horizontally to form an interconnected barrier wall system.

Abstract: The present invention is a silt fence installer of unique design wherein the frame is angular rather than longitudinal and the fabric chute assembly is oriented parallel with the angular frame. This arrangement results in an installer with a generally perpendicular trailing edge, a fabric chute assembly with a closed leading edge and no need for hinged relationship between the sidewalls, and simple fabric threading with a single directional turn of the fabric. Further, the angular frame results in a shorter installer able to be more responsive to turns. In addition, the invention includes a sliding offset hitch wherein a silt fence installer may be adjusted laterally by hand due to strategic placement of rollers.

Abstract: The present disclosure generally relates to a polymeric cellular confinement system which can be filled with soil, concrete, aggregate, earth materials, and the like. More specifically, the present disclosure concerns a cellular confinement system characterized by improved durability against damage generated by UV light, humidity, and aggressive soils, or combinations thereof.

Abstract: A secondary containment system for an above-ground petroleum storage tank includes a berm rising above the ground surrounding the tank and spaced apart from the tank for defining a petroleum retention basin about the tank. An impermeable liner covers the ground between the tank and the berm. At least one drain is formed through the liner and into the underlying ground. A hydrocarbon sensor monitors the presence of petroleum in the drain. A control device responds to the presence of petroleum in the drain by closing a containment valve to prevent discharge of petroleum from the basin. An indicator device provides at least one of an audible and visible signal indicating that petroleum is sensed in the drain.

Abstract: A secondary containment system for an above-ground petroleum storage tank includes a berm rising above the ground surrounding the tank and spaced apart from the tank for defining a petroleum retention basin about the tank. An impermeable liner covers the ground between the tank and the berm. At least one drain is formed through the liner and into the underlying ground. A hydrocarbon sensor monitors the presence of petroleum in the drain. A control device responds to the presence of petroleum in the drain by closing a containment valve to prevent discharge of petroleum from the basin. An indicator device provides at least one of an audible and visible signal indicating that petroleum is sensed in the drain.

Abstract: In accordance with at least one methodology of the present disclosure, an excavating machine (e.g., excavator, backhoe, bulldozer, etc.) moves an excavating apparatus (e.g., a bucket, blade, etc.) such that the excavating apparatus skims the underwater surface of a beach close to the shoreline to gather sand thereby forming a shallow trench in such surface. The depth of trench is small so that the effects of the sand removal to the contour of the beach is quickly compensated by the wave action of the ocean. Although the depth of the removed layer of sand is small, a significant amount of sand can be gathered by continuing the skimming operation over a much longer horizontal distance relative to the vertical depth of the removed sand. Moreover, by repeating the skimming operation along a shoreline, large amounts of sand can be gathered from the underwater surface of a beach close to the shoreline without a significant prolonged impact to the beach's underwater surface contour.

Abstract: A fluent material confinement system configured to receive a granular fluent material to form a temporary barrier structure is disclosed, wherein the fluent material confinement system includes a plurality strips, the plurality of strips including a plurality of lengthwise strips and a plurality of widthwise strips coupled with each other to define a plurality of open cells, wherein the plurality of lengthwise strips includes at least one wider lengthwise strip configured to extend into cells of a next-lowest fluent material confinement system when the fluent material confinement system is stacked on the next-lowest fluent material confinement system, and a stacking error indicator associated with the wider lengthwise strip, wherein the stacking error indicator is configured to be effective in low visibility conditions to indicate to a user a location of an error in stacking of the fluent material confinement system on the next-lowest fluent material confinement system.

Abstract: The disclosure shows an apparatus and a method for containing a spill of petroleum product. The inventive apparatus and method each include the assembly pliable building blocks of a generally rectangular shape that surrounds an internal void. The blocks form a wall by stacking successive horizontal rows of building blocks such that the respective internal voids vertically align, thereby forming adjacent columnar voids within the wall. The columnar voids are then filled with an adsorbent material that will cling to the petroleum product.

Abstract: A portable dike and floatation device having a lower partition including a water inlet and an upper partition attached to the lower partition. The lower partition is water-fillable via the water inlet. The upper partition includes an air inlet for inflating the upper partition. The lower partition forms a triangular prism having a floor and two sides. The upper partition has two lobes, the lobes cover the two sides, the lobes have a triangular prism shape, and wherein the inner and upper partition forms a square prism shape when the lower partition and the upper partition inflate. At least one support member is positioned within the portable dike and floatation device to provide added rigidity to the portable dike and floatation device.

Abstract: A trussed embankment dam and wall structure includes a cantilever structure group and a rod member group, and each cantilever structure of the cantilever structure group includes an anchor supporting pillar and a multidirectional connecting board. The lower portion of the anchor supporting pillar is built at a stratum or foundation to support the cantilever structure, and the upper portion of the anchor supporting pillar installs a multidirectional connecting board to a trussed joint structure. After a force is exerted to a rod member of the invention, the force is acted onto the joints of the cantilever structure and transmitted by other rod members. Therefore, each cantilever structure maximizes the supporting effect and provides a dispersive supporting type structure. Unlike the centralized supporting type truss structure, the invention uses the hollow portion of the structure and the malleability of components to create landscapes, fill soil and plant vegetation.

Abstract: A portable, inflatable flood wall is characterized by a sheet of synthetic plastic material which is folded back on itself to define a chamber between bottom, rear and front portions of the sheet and within which at least one inflatable bladder is secured. When the bladder is inflated, the rear portion of the sheet is erected to a vertical position which prevents water from passing beyond the sheet. The front portion preferably contains a plurality of openings to allow water to enter the chamber. The weight of the water on the bottom portion of the sheet serves to hold the wall in place. A plurality of such walls may be connected in end-to-end relation to construct a wall of a desired length.

Abstract: A machine which provides high quality, strong, relatively low-cost silt fencing in the proximity of the location of use of the produced silt fencing. It is within the scope of this invention to assemble material different from the material used for creation of “silt fencing”, which “fence” may be useful in different manner and be incorporated for different purpose than the purpose of silt fence.

Abstract: A bag made from a length of material (10) divided into a series of three or more substantially equal sized sections (12, 14, 16, 18, 20). Every other section is filled with sand (14, 18), or other particulate material and there is an unfilled section (12, 20) at each end.

Abstract: A reconfigurable barrier system (10) includes a plurality of support units (100) spaced one from the other, with each support unit (100) having at least one engagement section (110) defining an elongate channel (112). System (10) further includes at least one retention unit (200) that is substantially impervious to liquid, and is supported to extend between a pair of support units (100). Each retention unit (200) is formed with a pair of opposed engagement portions (212) which slidably engage respective ones of the support unit channels (112). Each retention unit (200) is also formed with a seal portion (220) that extends along a longitudinal edge of at least an intermediate portion (214) between the engagement portions (212). A barrier section (15) is defined by each pair of support units (100) and the at least one retention unit (200) supported thereby.