NL2024264B1

NL2024264B1 - Urban artificial wetland and method for building such an urban artificial wetland.

Info

Publication number: NL2024264B1
Application number: NL2024264A
Authority: NL
Inventors: Mirthe Snoek Cornelia; Jonathan Kok Willem
Original assignee: Univ Delft Tech
Priority date: 2019-11-19
Filing date: 2019-11-19
Publication date: 2021-08-18
Also published as: WO2021099488A1; EP4062000A1

Abstract

Artificial wetland 1 for storing a water volume in a water buffer delimited by a liner 4. A liner 5 mount region 41 of the liner is connected to an edge element 8. The edge element 8 comprises a T-shaped base element 2 and a U-shaped upper element 3. The base element 2 is formed by a base body 20 and an upstanding barrier member 24. The upper element 3 has a bottom portion with a bottom recess 330 which fits on the base element 2. In an assembled condition of the edge element 8, the liner mount region 41 is folded over the barrier member 10 24 and covered by the upper element 3. The attachment of the liner 4 to the edge element 8 is beneficial because of its firmness without necessitating additional fasteners, its shielded arrangement and smooth outer appearance. The artificial wetland is beneficial in an urban environment. 15 Fig. 3

Description

P34284NLO0/KHO Title: Urban artificial wetland and method for building such an urban artificial wetland.

The present invention relates to an urban water management system, in particular a containment system, more in particular a constructed wetland basin, also called an artificial wetland.

Urban water management systems in delta cities are in need of change due to climate change, expecting more rainfall, more extreme rainfall and more dry periods. Sewage systems cannot cope with the larger amounts of rain. More rainwater is to be contained in cities temporary or for a longer period to enable reuse. In addition to the sewage system a large variety of different water management systems are being added to the urban water management system: constructed wetlands, retention ponds, water squares, raingardens, infiltration strips, SUDs, bioswales, bio-filters, etc. CN108793604 A discloses a sewage and rainwater treatment system for colleges and universities. The system sequentially includes a regulation pool, a vertical flow artificial wetland, a first ecological-based artificial wetland, an ecological gravel bed, a second ecological-based artificial wetland, a disinfection tank and a water outlet tank according to a water treatment order. Every adjacent two are connected through a sewage pipe. The vertical flow artificial wetland and a bed body of the ecological gravel bed are rectangular, two corresponding sides of the bed body are respectively provided with a water distribution channel and a water collecting channel which have rectangular cross sections, the middle of the bed body is provided with an overflow channel perpendicular to the water distribution channel, and retaining walls are distributed on the remaining two sides; water distributing pipes are distributed evenly on the vertical flow artificial wetland and the upper portion of the bed body of the ecological gravel bed, and water collecting pipes are distributed on the lower portions of the water distributing pipes. The water distributing pipes are longitudinally connected with ventilating pipes. According to the sewage and rainwater treatment system for colleges and universities, the recycling of washing sewage and rainwater of the colleges and universities is achieved, and the sewage recycling rate is improved. CN108862846A discloses an urban rainwater management and treatment method. The method comprises the following steps of treatment by a pre-treatment unit: water is subjected to interception, filtration and adsorption and absorption of suspension and matter and contaminants in water through an inlet filter and a peripheral filter; treatment by a wetland

2. unit: pre-treated water enters a wetland unit through a water inlet flow guide pipe; suspension matter and contaminants in the water are intercepted and absorbed through filling material compositions in the wetland module; when the water flow rate is high, the water enters the wetland unit and a discharge unit through a bypass system; control discharge by a discharge unit: after the treatment by the wetland unit, discharge and flow rate regulation are performed through a water outlet guide pipe; the water enters the discharge concentration pool through the water outlet guide pipe; after the water is filtered in the discharge concentration pool, the water is discharged from the system through a water outlet pipe. The method has the advantages that the operation and the maintenance are simple and convenient; the bypass pipeline is used; the adaptation capability of the rainstorm season is enhanced; the artificial wetland is used; the overland flow is treated; meanwhile, the municipal greening is considered at the same time.

US7.510.649 discloses an artificial wetland which has a basin forming a treatment unit which is operatively connected to a tank by an inflow control device. The treatment unit is comprised of a liner which fits a contour of a depression in perimeter dikes and treatment unit bottom.

A drawback of this artificial wetland is that it lacks a secure attachment of the liner at an edge region.

US2019136651 discloses a modular fluid containment system which has wall segments that are joint at angled corners to form a closed wall. A membrane spans the closed wall and is connected to the closed wall with membrane attachment members.

A drawback of this fluid containment system is that the attachment of the membrane by the attachment members to the wall segments is labour-intensive. Additionally, the attachment members are visual from the outside which makes the containment structure and attractive to be used in an urban environment.

The general object of the present invention is to at least partially eliminate the above mentioned drawbacks and/or to provide a usable alternative. More specific, it is an object of the invention to provide a secure attachment of a liner of an artificial wetland which artificial wetland is suitable to be used in an urban environment in which a smooth outer appearance is required.

According to a first aspect of the invention, this object is achieved by an artificial wetland according to claim 1.

-3- The artificial wetland is arranged to contain a water volume in a buffer volume. The artificial wetland delimits the buffer volume which is suitable for storing the water volume. The buffer volume may be closed along its circumference, but may also be locally open for allowing an outflow of water. The buffer volume may for example be elongated like a trench in which the water volume may flow away in a longitudinal direction. The artificial wetland comprises at least one base element. The base element is adapted to be placed on an underground. The base element has a base body. The base body has a ground face at a bottom size for a placement of the base body on the underground. The base body has a support face at a top side for supporting a structure. The artificial wetland further comprises at least one upper element. The upper element is configured to be placed on the base element. The upper element has a bottom portion which is adapted to be placed on top of the base element. The bottom portion has a bottom face at a bottom side. The bottom face is adapted to be placed on the support face of the base element. Further, the artificial wetland comprises a liner for defining the buffer volume of the artificial wetland. The liner can be used to cover a deepened portion in the underground to provide the buffer volume. The liner defines the buffer volume of the artificial wetland. The liner comprises a sheet-shaped liner body. The liner has a liner mount region for connecting the liner to an edge element. The edge element for connecting the liner is formed by a combination of at least one base element and an upper element. The edge element is configured to delimit the buffer volume of the artificial wetland from a surrounding environment. The upper element is stacked on the at least one base element, wherein the liner mount region is placed in between the upper element and the at least one base element. Preferably, the upper element is positioned in a staggered manner across neighbouring base elements.

To obtain a secure attachment of the liner, the base element comprises an upstanding barrier member. The barrier member is plate-shaped. The barrier member extends away from the support face to a predetermined height, in particular of at least 10 cm. The height of the barrier member determines a certain maximum surface level of the water volume in the buffer volume.

-4- The upper element has a bottom portion with a barrier recess which fits across the barrier member of the base element. Seen in a cross section, the bottom portion is U-shaped. The barrier recess extends from a first end face to a second end face along the bottom face of the upper element. In the assembled condition, the liner mount region is positioned in between the base element and the upper element. The liner mount region extends in between the barrier member and the barrier recess. The liner mount region of the liner extends across the barrier member and is covered by the upper element. By placing the liner across the barrier member, a watertight barrier is obtained to a height level of the barrier member. Herewith, a water buffer may be obtained which allows a surface level of the water volume above ground level. The water buffer may obtain an increased capacity. The upper element which covers the liner mount region is beneficial in an urban environment, because it protects the liner from being damaged by vandalism. The covering by the upper element protects the connection of the liner from impact or tearing but also from UV-light or other degradation of the material. The covering hides the liner connection from sight to improve or adapt looks in public space. Additionally, the covering by the upper element of the liner mount region hides the attachment from view and provides a smooth finishing of the edge region of the artificial wetland which is appreciated by the public in an urban environment.

In an embodiment of the artificial wetland according to the invention, the barrier member is integrally formed with the base body of the base element. The barrier member and the base body form a one-piece item. Preferably, the base element is T-shaped in which the barrier member is centrally positioned on the base body. Preferably, the height of the barrier member substantially equals a width of the base body. Preferably, the base element has an elongated base body. Preferably, the barrier member extends along a whole length of the base body. Both the barrier member and the base body are preferably made of concrete to provide a prefab article. The construction of watertight containers may become a lot more faster, easier and more accurate to install, because of the use of prefab elements. Prefab elements are easy to transport, less work on site resulting in less hindrance in cities. A fixation of the prefab elements may be temporary (not poured in concrete) to allow a quick inspection, cleaning or replacement.

In an embodiment of the artificial wetland according to the invention, the barrier member has a converging shape in a direction away from the support face of the base body. Preferably, the barrier recess of the upper element has a corresponding converging shape. In particular,

-5- the barrier recess of the upper element is delimited by opposite positioned recess sidewalls which are converging in a direction to a top face of the upper body. The converging shaped barrier member has a barrier base and a barrier top which barrier base is wider than the barrier top. Preferably, the barrier top is truncated, such that the liner mount region gradually crosses across the barrier member. Preferably, the barrier top is surrounded to prevent sharp edges engaging the liner mount region. Preferably, the barrier member has a trapezoidal shape. Preferably, an angle in between a side face of the barrier member and the support face is at least 95°. The converging shape of the barrier member is beneficial in preventing damage to the liner mount region when placing the upper element onto the base element, because due to the converging shape the liner mount region is firmly engaged by the upper element at only final stage of the movement when the upper element nearly contacts the support face of the base element.

The artificial wetland according to the invention is advantageous, because the barrier member allows a water level in the buffer volume of the wetland above ground level. In an urban environment, the artificial wetland may look like a pond. The base element can be placed at ground level on the underground aside the buffer volume. The base element may be placed on a stable bed of the underground. The stable bed may be provided by poured concrete.

The barrier member extends above ground level to form a border between a water volume in the buffer volume of the artificial wetland and a surrounding environment. A higher water level above ground level provides an increase in buffer volume. A higher water level even allows a buffer volume bottom laying flush with ground level.

In another arrangement of the artificial wetland according to the invention, the edge element may have a top face laying flush with ground level. This alignment of the edge element allows a rainwater run-off from a surrounding environment, in particular a paving, to the buffer volume of the artificial wetland.

In an embodiment of the artificial wetland according to the invention, the artificial wetland comprises a supply system for supplying water to the buffer volume of the wetland. In particular, the supply system comprises a drainage conduit for supplying ground water to the buffer volume. More in particular, the supply system comprises a pump for actively supplying the ground water to the buffer volume. The drainage conduit extends through the liner. The liner preferably comprises a liner seal for sealing the drainage conduit, such that a backflow of rainwater out of the buffer volume is prevented.

-6- In an embodiment of the artificial wetland according to the invention, the upper element may comprise an upper portion which is configured to increase a functionality of the edge element. The upper portion may for example be configured as a channel module as described hereafter. The upper portion may comprise a connector, in particular at least one thread holes, for mounting an edge element accessory, like a fence. The upper portion may for example comprise a seat to allow a person to sit down on the edge element close to the artificial wetland. Further, the invention relates to an edge element suitable to be used to provide an artificial wetland according to the invention. The edge element comprises T-shaped base element and an upper element to be placed on top of the base element. The base element comprises a base body and an upstanding barrier member extending from the support face of the base body. The upper element comprises a U-shaped bottom portion including a barrier recess. The barrier recess is configured to cover the barrier member and a liner mount region extending across the barrier member when the upper element is stacked on the base element. Advantageously, additional fasteners to attach the liner to the edge element may be superfluous as a weight of the upper element surface to clamp the liner. Further, in the first aspect, the invention relates to a method for providing an artificial wetland.

The method comprises the step of placing a liner on an underground to delimit a buffer volume. In a step in preparation, the underground may be stabilised, for example by providing a sand layer. In a step of the method, a plurality of base elements is provided. The base elements are placed in an array. In particular, the base elements are placed around the liner to completely circumvent the buffer volume. Each base element has a barrier member which is upwardly directed. The liner has a liner mount region which is in a step of the method placed over the barrier member. In a next step, an upper element is placed onto the base element, such that the liner mount region becomes situated in between the base element and the upper element. The base element and upper element together form an edge element of the artificial wetland. The built edge elements delimit the buffer volume from a surrounding environment. The placement of the upper elements onto the base elements serve to connect the liner mount region and provide a watertight border. The method may save construction time and costs. The method may be independent of a clamping fixating or use of adhesives to make a watertight edge element. A simple raise of the watertight liner, followed by a cover to protect and hide the liner may suffice. Less manual labour is involved.

-7- Due to the presence of the edge elements, each artificial wetland is scalable to a particular environment. The flexible liner and modular edge elements may cope with irregular subsidence. A scalable way of customizing the wetland to a particular assignment is by use of a flexible liner. The liner is scalable in length and width and will move alongside subsidence, particularly important in urban delta areas. The scalability and modularity of the artificial wetland allow for a flexible design to fit in an existing urban space. The liner is scalable in length and width and is framed by the modular edge elements (base element: raiser and upper element: cover), of which different sizes and configurations are possible.

The method of the invention is further beneficial in that it allows a building of different arrangements of an artificial wetland. An artificial wetland may be built as a semi-above- ground container with raised edges out of prefab elements for urban applications. A raise of contained material may be beneficial, e.g. closer to sight and decrease the depth to be dug. Or make waterlevel equal to ground level. Also in- and outlets do not have to be dug as deep.

Thus according to the first aspect of the invention an artificial wetland and a method for building such an artificial wetland is provided for storing a water volume in a water buffer delimited by a liner. A liner mount region of the liner is connected to an edge element. The edge element comprises a T-shaped base element and a U-shaped upper element. The base element is formed by a base body and an upstanding barrier member. The upper element has a bottom portion with a bottom recess which fits on the base element. In an assembled condition of the edge element, the liner mount region is folded over the barrier member and covered by the upper element. The attachment of the liner to the edge element is beneficial because of its firmness without necessitating additional fasteners, its shielded arrangement inside the edge element and smooth outer appearance. For this, the artificial wetland is especially beneficial in an urban environment as an urban artificial wetland, in particular in use as an urban water management system, e.g. for storing and/or distributing rainwater. According to another aspect of the invention, the described structure of the edge element for connecting a liner may also be relevant to other urban containing functions where (contaminated) water/soil is retained: gas stations, heavily used roads, highways or parking places, industrial areas, etc. A constructed basin may be formed as a fountain, pool, pond et cetera.

According to a second aspect of the invention, the invention relates to a ground barrier substructure and method for building the ground barrier substructure.

-8- EP0.578.445 discloses a drainage system, comprising a U-shaped channel module, a waterproof membrane, and a membrane drain module. The channel module comprises inwardly facing spaced recesses in each side wall thereof, adapted to receive a locking bar. In an assembled state, the membrane is interposed between the channel module and the drain module. On the top side of the drain module, a cover is seated. This cover is held in position by means of a locking bolt. The bolt is threaded, and on one side a locking bar can be secured to it. By bringing the locking bar in engagement with the corresponding recesses in the channel modules and threading the bolt, the drainage system is secured and the waterproof membrane is clamped between the channel module and the drain module.

A drawback of this known drainage system is that the attachment of the membrane to the channel and the drain module may damage the membrane or the membrane may loosen when the membrane is getting tensioned. Another drawback is that the attachment of the membrane requires special attention of an installer to obtain a proper placement of the membrane in between the drain and channel modules. US2011/0192097 discloses an attachment of a geogrid to a wall. The wall is a retaining wall which includes a geogrid to stabilise or retain soil or other materials adjacent the wall. The geogrid is coupled in between an upper block and a lower block of the wall. Friction between the geogrid and a lower block, in between the geogrid and the upper block holds the geogrid to the wall. Each block includes a top surface that includes a plurality of bosses, and a bottom surface that includes a groove. When the block is placed on another similar block such that the bottom surface of the block and a top surface of the similar block oppose each other to form an interface region, the groove holds the plurality of bosses. The force generated by friction between the geogrid and the block is increased by the combination of the bosses and the groove of the blocks. A drawback of this geogrid attachment is that this attachment is not sufficient robust over a long time span.

The general object of the invention according to the second aspect is to at least partially eliminate the above mentioned drawbacks and/or to provide a usable alternative. More specific, it is an object of the invention according to the second aspect to provide a more reliable and secure attachment of a liner of a ground barrier substructure.

According to the invention according to the second aspect, this object is achieved by a ground barrier substructure according to clause 1.

-9- The ground barrier substructure comprises at least one base element. The base element is adapted to be placed on an underground. At a bottom side, the base element has a ground face. At a top side, the base element has a support face for supporting an upper element.

The ground barrier substructure comprises at least one upper element. The upper element is adapted to be placed on top of the base element. At a bottom side, the upper element has a bottom face. The bottom face is adapted to be placed on the support face of the base element.

The ground barrier substructure further comprises a liner. The liner is arranged for covering soil. In an embodiment, the liner may be arranged as a ground cover to prevent soil contamination. In an embodiment, the liner may be arranged as a water buffer, a ground reservoir, to contain a ground material for collecting and discharging drained water, in particular surface water, more in particular rainwater and groundwater. The liner has a sheet shaped liner body. The liner has a liner mount region for mounting the liner to an assembly of the base and upper element, in which the liner mount region is placed in between the base and upper element.

The ground barrier substructure according to the second aspect of the invention is improved in that the substructure further comprises at least one insert. The insert serves for positioning the upper element on the base element. The bottom face of the upper element comprises a bottom recess for receiving the insert. The liner mount region of the liner comprises at least one liner hole. The liner hole is positioned at the liner mount region in correspondence with a position of an insert on the base element in an assembled condition of the substructure. The liner hole is sized in correspondence with an outer contour of the insert. Herewith, the liner hole is adapted to allow the insert to be inserted through the at least one liner hole.

The ground barrier substructure according to the second aspect of the invention may provide various benefits.

A major advantage is provided in that instead of a friction based clamping as seen in the known drainage system above, the invention provides a form closure in between the liner and an assembly of the base and upper element. The insert in between the base and upper element extends through the liner hole and prevents a shifting away of the liner. The liner is locked in position by the at least one insert. Already during initial steps of a method of building the ground barrier substructure, a liner hole can be laid over an insert, and the insert prevents the liner from shifting away from the base element. The liner can be placed quickly and is

-10- kept in position.

The liner can be locked in position without a need of a mechanical operatable fastener, like a bolt or clamp.

Advantageously, the liner remains in position when spreading the liner over an underground in an initial step and the liner remains in position during subsequent steps of the method.

A sliding movement of the liner with respect to the assembly of the base and upper element is restricted by the at least one insert Herewith, the liner is reliable and secure connectable to the assembly of the base and upper element.

The ground barrier substructure can be arranged to provide a ground barrier to prevent underground contamination, e.g. at a petrol station or a waste depot.

The ground barrier substructure may be arranged as an infrastructural substructure.

The ground barrier substructure may be arranged as a drainage system, also called an urban wet land, for collecting and discharging water in a ground reservoir formed by the liner.

In particular, the liner is a foil or a fabric.

The liner may be a geo-textile.

The liner may be a permeable or impermeable liner in dependence of the technical requirements of the ground barrier substructure in a certain application.

In an embodiment of the ground barrier substructure according to the second aspect of the invention, the liner mount region comprises a pattern of liner holes.

The pattern includes a first and second liner hole.

The pattern of liner holes may include liner holes which are all equally spaced and equally sized.

Such a pattern of liner holes which correspond with a same configuration of a pattern of inserts which may allow multiple placements of an upper element onto a base element.

Preferably, the pattern of liner holes is configured in correspondence with a pattern of inserts which restricts possible placements of the upper element onto the base element.

More preferably, the pattern of inserts determines only a single placement of an upper element onto a base element.

In an embodiment of the ground barrier substructure according to the second aspect of the invention, the first and second liner hole of the pattern of liner holes differ from each other.

The first liner hole may be larger than the second liner hole or may differ in shape in that it has a different outer contour.

The pattern of liner holes correspond with a pattern of inserts present on a base element.

The pattern of inserts may include differently shaped or sized inserts which differences serve to provide a predetermined placement of the upper element onto the base element.

Herewith, advantageously, the pattern of liner holes is adapted to be compatible with the assembly of the base and upper element.

-11- In an embodiment of the ground barrier substructure according to the second aspect of the invention, the substructure is provided with a pattern of inserts including at least a first insert and a second insert.

Preferably, the base element is provided with separate inserts which are, in particularmanually, removable from the base element.

The first and second insert are different from each other, ie. in shape or size.

For example, the first insert may have a larger width than second insert.

A complementary upper element is provided which has a mating first and second bottom recess.

The first and second bottom recess of the upper element correspond in geometry with respectively the first and second insert.

Advantageously, the difference in inserts on the base element restrict possible placements of the upper element on the base element, preferably to just a single placement.

In an embodiment of the ground barrier substructure according to the second aspect of the invention, the pattern of inserts is arranged to obtain an overlapping placement of an upper element above two adjacently positioned base elements.

Preferably, a single opportunity for a placement of the upper element onto the base element is provided by the pattern of inserts which results in the overlapping placement.

The upper element fits only at a predetermined position of the upper element with respect to the base element.

For example, a large first insert at a left sided region of the support face of a base element and a small second insert at a right sided region of the support face may provide the overlapping placement.

Herewith, a spatial positioning of the inserts at the support face or variety in geometry of the inserts within the pattern and corresponding mating bottom recesses of the upper element may prevent a stacking of gaps being present in between adjacently positioned base and upper elements.

Advantageously, the overlapping placement of the upper element with respect to the base element increases a robustness of the substructure which further contributes to a secure and reliable placement of the liner.

In an embodiment of the ground barrier substructure according to the second aspect of the invention, the at least one insert is a removable insert.

The insert may be a separate item which is removable from the base element and upper element.

The base element may comprise at least one base recess for receiving the at least one insert.

Herewith, the support face of the base element can be configured without protrusions which may provide benefits during transport of the base elements.

Another advantage is that separate inserts can be easily replaced in case that an insert is damaged.

Particularly, a base recess may have a certain depth which determines how far an insert protrudes above the support surface of the base element of the placement of the insert into the base recess.

Alternatively, a base recess may extend through the base element, such that after placement of an insert into the base

-12- recess, the insert may extend through the base element into the underground below the base element. In an embodiment of the ground barrier substructure according to the second aspect of the invention, the at least one insert is integral with the base element. The at least one insert is incorporated in the base element. The at least one insert and the base element form a one piece item. Advantageously, an incorporation of the at least one insert in the base element may simplify and reduce operational steps in a method of building the ground barrier substructure.

In an embodiment of the ground barrier substructure according to the invention, the at least one insert is block shaped. The block shaped insert comprises an insert top face, and four circumventing planar insert side face. If embodied as a separate item apart from the base element, the insert further has an insert bottom face. Preferably, in an assembled condition of the insert and the base element, at least one side face is a right angled side face. The side face of the insert is oriented in perpendicular with the support face of the base element. Advantageously, a block shape of an insert allows a distribution of tension forces to prevent peak stresses and a resulting damage to a liner. Advantageously, the right angled side face of the insert prevents an upwards movement, a whipping up, of the liner over the insert when the liner is tensioned.

In an alternative embodiment of the ground barrier substructure according to the second aspect of the invention the at least one insert is pin shaped, in which the insert is called a locking pin. The locking pin may include a circumventing sideface with a right angled insert side face section. The right angled insert side face section is right angled with respect to a below positioned support face and prevents an upwards movement or slipping of the liner over the insert.

Preferably, the insert includes at least one upwardly inclined side face which contributes to a quick and easy placement of the liner and an alignment in placing an upper element on the base element. The at least one side face of the insert is inclined towards the top face at a top angle e.g. about 30°.

In an embodiment of the ground barrier substructure according to the second aspect of invention, the at least one liner hole has a straight liner hole edge. Preferably, the at least one liner hole has a rectangular shape. In the assembled condition of the substructure, the straight liner hole edge mates with a straight insert side face. Advantageously, tension forces

-13- acting on the liner may be equally distributed over the insert sidewall and a rupture of the liner at a location of a liner hole may be prevented. Preferably, the base element is a base plate. The base element may form a foundation or anchoring. The base element is preferably plate shaped to provide a required ground support to the substructure. In particular, the base plate has a support face which is larger than a surface area of the bottom face of the upper element. Several upper elements may be placed on a single base element. Besides providing a support for an upper element, the support face of the base element may be sufficient large for further supporting other items, e.g.

pavements, cable gutters, ground level urban furniture etc.

In an embodiment of the ground barrier substructure according to the second aspect of the invention, the base element comprises a plastic or concrete body. The base element may comprise a polystyrene body. The base element may comprise a grid body. The base element may comprises a grid body filled with a cured substance, like cement, to form a closed reinforced plate.

Each upper element comprises a first and a second end face. The substructure can be built by placing end faces of adjacently positioned upper elements against each other.

In an embodiment of the ground barrier substructure according to the second aspect of the invention, the first and second end face of an upper element are in parallel with each other. Preferably, the first and second end face are inclined with respect to the bottom face of the upper element. Preferably, the first and second end face are inclined at an inclination angle of atleast 5°, e.g. of about 20°. The ground barrier substructure is mountable by mating an end face of a first upper element to an end face of a second upper element. Due to the inclination of the end faces, the upper elements become locked in an upwards direction. Herewith, a stable substructure can be built.

In an embodiment of the ground barrier substructure according to the second aspect of the invention, the first and second end face of an upper element are inclined with respect to each other and oriented at an inclination angle of at least 5°, e.g. of about 20°. The first and second end face are oriented non-parallel with respect to each other. The ground barrier substructure can be built by placing several types of upper elements adjacent each other. At least a first and second type of upper elements are provided to build the substructure. A first type upper element is provided to be positioned adjacent the second type upper element, such that the end faces of the adjacently positioned upper elements mate to each other. Advantageously,

-14 - the inclined end faces may provide an upwards lockage of an upper element, which contributes to a more reliable and secure placement of the liner and upper element. In an embodiment of the ground barrier substructure according to the second aspect of the invention, each end face comprises a lock member. The lock member serves to prevent a lateral movement of adjacently positioned upper elements. Preferably, the lock member is a first lock member which is one of a pair of complementary lock members, ie. a first and second lock member. The lock members may be co-operating male and female features, e.g. a recess cut and a complementary projection. Adjacently positioned upper elements engage with each other by the lock members to prevent a relative lateral movement of an upper element. Advantageously, after placement of the upper elements, the pair of complementary lock members provide a form closure in a lateral direction in between the adjacent positioned upper elements which means that additional clamping means or fasteners are redundant. The lateral form closure allows a quick mounting of the substructure.

In an embodiment of the ground barrier substructure according to the second aspect of the invention, the lock member further comprises a hook shaped member, a hook member, to prevent a relative axial movement of two adjacently positioned upper elements. The hook member provides a hooking engagement in between two upper elements, such that two abutting end faces cannot move away from each other. In an embodiment of the ground barrier substructure according to the second aspect of the invention, the lock member comprises a seal. Preferably, the seal is a ring shaped. The seal may be embedded in the recess cut.

Thus, according to the second aspect of the invention a ground barrier substructure is provided for arranging a soil cover with a liner. The sub-structure comprises at least one base element with a support face and a ground face and at least one upper element adapted to be placed on top of the base element, wherein the upper element has a bottom face, which bottom face is adapted to be placed on the support face of the base element. The substructure further comprises at least one insert for positioning the upper element onto the base element, wherein the bottom face of the upper element comprises a bottom recess for receiving the insert. The liner comprises has a liner mount region. The liner mount region comprises a liner hole to allow the insert to be inserted through the at least one liner hole.

Herewith, the liner is reliable mounted in between the base and upper element.

-15- Further, the second aspect of the invention relates to a method for building a ground barrier substructure according to the invention. In a step of the method a ground barrier substructure according to the invention is provided which comprises at least one base element, at least one upper element and a liner. At least one insert is provided which may be integral with the base element or maybe a separate item. In the method, the base element including the at least one insert is placed at an underground. A liner mount region of the liner is placed across the base element. A protruding insert is inserted through a liner hole. Subsequently, the upper element is placed on the base element. Herewith, the substructure can be obtained in carrying out just a few steps. By using a liner with at least one liner hole and placing the liner hole over the protruding insert, advantageously, the liner is quickly and stably placed in position. Embodiments of the second aspect of the invention are described by the following clauses:

1. Ground barrier substructure (1) for arranging a soil cover, comprising: - at least one base element (2) adapted to be placed on an underground, wherein the base element comprises a support face (22) at a top side and a ground face (21) at a bottom side; - at least one upper element (3) adapted to be placed on top of the base element (2), wherein the upper element has a bottom face (33) at a bottom side, which bottom face is adapted to be placed on the support face of the base element; and - a liner (4) for covering soil, which liner comprises a sheet shaped liner body (40) including a liner mount region (41), characterised in that the substructure further comprises - at least one insert (5) for positioning the upper element on the base element, wherein the bottom face of the upper element comprises a bottom recess (331) for receiving the insert; and wherein the liner mount region (41) comprises at least one liner hole (42), which liner hole is adapted to allow the insert (5) - in an assembled condition of the substructure - to be inserted through the at least one liner hole (42).

2. Ground barrier substructure according to clause 1, wherein the liner mount region comprises a pattern of liner holes which is configured in correspondence of a pattern of inserts which pattern restricts possible positions of the upper element onto the base element.

3. Ground barrier substructure according to clause 2, wherein— in the assembled condition - each base element is provided with a pattern of inserts including at least a first insert and a second insert, which first and second insert are different with respect to each other, and wherein the upper element has a first bottom recess and a second bottom recess,

- 16 - wherein said first and second bottom recess respectively mate with the first or the second insert to obtain a predetermined position of the upper element onto the base element.

4. Ground barrier substructure according to clause 2 or 3, wherein the pattern of inserts provide an overlapping placement of an upper element onto adjacent positioned base elements.

5. Ground barrier substructure according to any of the preceding clauses, wherein the at least one insert is integral with the base element.

6. Ground barrier substructure according to any of the preceding clauses, wherein the at least one insert is block shaped, having an insert top face, and four planar insert side faces, wherein at least one side face is arranged at a right angle with respect to the support face of the base element in the assembled condition of the substructure.

7. Ground barrier substructure according to any of the preceding clauses, wherein the at least one liner hole has a straight liner hole edge.

8. Ground barrier substructure according to any of the preceding clauses, wherein at least one side face of the insert is inclined towards the top face at a top angle.

9. Ground barrier substructure according to any of the preceding clauses, wherein the upper element comprises a first and second end face which are inclined with respect to the bottom face and oriented at an inclination angle.

10. Ground barrier substructure according to clause 9, wherein the substructure is mountable by adjacently positioning a first and second type of upper elements which include each end faces which are inclined with respect to each other, such that adjacently positioned end faces mate with each other.

11. Ground barrier substructure according to any of the preceding clauses, wherein each end face comprises a first lock member for preventing a lateral movement of adjacently positioned upper elements, which lock member is one of a pair of complementary lock members, ie. a first and second lock member, e.g. a recess cut or a complementary projection, such that said adjacently positioned upper elements laterally engage with each other.

-17 -

12. Ground barrier substructure according to any of the preceding clauses, wherein the lock member further comprises a hook member for preventing an axial movement of two adjacently pasitioned upper elements with respect to each other. 13 Ground barrier substructure according to any of the preceding clauses, wherein the lock member comprises a seal.

14. Method for building a ground barrier substructure comprising the steps of: - providing a ground barrier substructure according to any of the preceding claims comprising at least one base element including at least one insert, at least one upper element and a liner; - placing the base element including the at least one insert at an underground; - placing a liner mount region of the liner across the base element; - inserting the insert through a liner hole; and - placing the upper element on the base element.

15. Method according to clause 14 further comprising a step of placing at least one removable insert into a base recess of the base element. According to a third aspect of the invention, the invention relates to a drainage system and method for building the drainage system. EP 0.578.445 discloses a drainage system comprising a U-shaped channel module at a bottom region, a waterproof membrane, and an open-top drain module at a top region. The drainage system is defined by a network of interconnected channel modules. The configuration of the network depends on the lie of the land to be drained and the rate at which water must be removed. Grid covers are secured to the upper side of the drain modules to enable an entry of water into the drainage system. An additional water entry is obtained by the membrane. The waterproof membrane forms a surface to collect water. The membrane is laid adjacent to the drainage channels and clamped in between the drain and channel module. Cut edges of the membrane overlap the edges of the sidewalls of the channel module. Collected water at the surface of the waterproof member flows under gravity through openings into the channel module. These openings are formed by a crenelated bottom surface of at least one sidewall of the drain module. Herewith, water is collected in the channel module to be discharged via the network of channel modules.

-18- A drawback of such a known drainage system is that the drainage system has a limited discharge capacity which makes the drainage system vulnerable to an overload. In particular, such a drainage system of interconnected channels is problematic in an urban environment, in which rainwater has to be quickly transferred from roofs and streets via the drainage system to a water buffer at a central point. Nowadays, extreme weather conditions bringing heavy rainfalls occur more often and further raise technical requirements to a drainage system in an urban environment. The general object of a third aspect of the invention is to at least partially eliminate the above mentioned drawbacks and/or to provide a usable alternative. More specific, it is an object of the invention to provide a drainage system formed by a network of interconnectable channel modules which provides an increased discharge capacity. More specific, it is an object of the invention to provide a drainage system including a filtering capacity.

According to the third aspect of the invention, this object is achieved by a modular drainage system for discharging water. In particular, the drainage system is an urban drainage system for transferring water to a discharge location, e.g. to a location with a water reservoir.

The drainage system comprises a drainage channel. The drainage channel is arranged to transfer water from a first location to a second location. The first location may be close to a roof or pavement to allow run-off water to enter the drainage system by gravity. The second location may comprise a rainwater reservoir.

The drainage system is modular in that the drainage channel of the drainage system is mountable by interconnecting a plurality of channel modules which then form a network. Each channel module comprises a hollow inner space. The hollow inner space forms a drainage channel portion. The drainage channel portion has a channel bottom to conduct water. The drainage channel portion has open channel ends to transfer water to a next drainage channel portion in the network.

Each channel module has a longitudinal channel body. Particularly, the channel body is block shaped. The channel body has a bottom face to be directed to an underground in an installation of the drainage system. The channel body has a top face to be directed upwards in an installation of the drainage system. The top face may be an open top face, e.g. covered by a grid. Further, seen along its circumference, the channel body has a left and right side face and a first and second end face. The end faces define a longitudinal or axial direction.

-19- The end faces are configured to mate adjacently positioned channel modules with each other, such that the open channel ends of the channel modules become in a fluid communication. Preferably, the end faces are inclined with respect to the longitudinal direction. Said drainage channel is formed by fluidly connecting the adjacently positioned drainage channel portions to each other.

At least one channel module of the drainage system comprises an inlet. The inlet is arranged to allow an entry of water into the drainage channel portion of the channel module. The inlet is positioned at an upper region of the channel body and in fluid communication with the hollow inner space, such that water may enter the drainage channel portion of the channel module under gravity. The inlet may be provided by an opening at the top face of the channel body, e.g. by openings of a cover grid, or by openings in a sidewall of the channel body, like the crenelated openings in EP 0.578.445. In a variant, the inlet may be provided by a separate piece which may be coupled to an end face of a channel module, e.g. to connect the channel module to a downpipe. According to the third aspect of the invention, an improvement is provided in that at least one channel module of the drainage system comprises at least one outlet. The outlet is directed in a lateral direction with respect to the longitudinal direction which longitudinal direction is defined by the end faces of the channel body. The outlet is positioned at a lower region of the channel body and in fluid communication with the hollow inner space to allow an exit of water by gravity out of the drainage channel portion to an exterior of the channel body. Particularly, the outlet is in fluid communication with the channel bottom to let a flow of water discharge from the channel module.

Herewith, a flow of water may pass through the open channel ends in a longitudinal direction to transfer the water through the drainage channel to another location. Additionally, water may pass in the lateral direction through the at least one outlet to discharge a flow of the water to an underground around the drainage system. Water is transferred but also discharged to the underground around the channel module via the outlet. The outlet provides a lateral discharge of water from the drainage system, such that not all water needs to be transferred to the other location. Advantageously, a drain capacity of the drainage system is increased by the discharge which is especially beneficial in an urban environment. Due to the lateral discharge via the at least one outlet, the drainage system according to the invention is less vulnerable to an overload. Instead of transferring all collected water from roofs and streets through the drainage channel towards a water buffer or central water discharge, the water is at least partially absorbed into the underground around the drainage system.

-20- In an embodiment of the drainage system according to the third aspect of the invention, the network of interconnected channel modules comprises a total amount of channel modules in which at least 20%, in particular at least 50%, is provided with at least one outlet. Herewith, a substantial discharge of water to an underground can be obtained.

In an embodiment of the drainage system according to the third aspect of the invention, the outlet of the channel module comprises an opening in a bottom, right or left sided sidewall of the channel body. Particularly, the opening is a through hole, more in particular a through drill hole, which extends through the bottom or sidewall. In a variant, the channel module may be manufactured in a mould and the outlet may be an moulded opening.

In an embodiment of the drainage system according to the third aspect of the invention, the at least one outlet comprises an exterior outlet opening at the bottom face and/or at at least one of the left and right side face. The outlet extends from the channel bottom to the outlet opening at an outer face of the channel body. Preferably, the exterior outlet opening is arranged for coupling a drain pipe. The drain pipe extends the outlet of the channel module into the underground, such that a flow of water is discharged deeper into the ground. This may advantageously further increase a discharge capacity of the drainage system.

In an embodiment of the drainage system according to the third aspect of the invention, at least one outlet comprises a stopper for selectively opening or closing the at least one outlet of a channel module. The stopper fits tightly to the outlet opening to close the outlet. The stopper may be a removable stopper, which is removable by an installer when building the drainage system, such that an outlet of a channel module may be opened or closed if desired.

The stopper may be an adjustable stopper for adjusting a size of the outlet opening, such that a flow of discharged water is controllable. Herewith, the drainage system is easily adjustable to an occurring situation.

In an embodiment of the drainage system according to the third aspect of the invention, the drainage system further comprises a water buffer including a liner and a drainpipe. The assembly of the liner and the drainpipe in an underground forms the water buffer.

The liner comprises a sheet shaped liner body. The liner may be a foil, in particular a plastic foil, or a fabric, in particular a geo textile material. The liner may be a permeable liner which may serve as a sieve to prevent soil contamination. The liner is preferably an impermeable liner to form a watertight closure in the underground.

-21- The liner is arranged to be laid in the underground.

The water buffer is created by digging a deepened portion in an underground.

After digging the deepened portion, the liner may be spread over the deepened portion to cover the soil, and the drainpipe is also placed in the deepened portion.

Preferably, the drainpipe is placed above the liner.

The assembly of the underground placed liner and drainpipe form the water buffer.

Water may enter the buffer at an upper region of the buffer and is discharged via the drainpipe at a lower region of the buffer.

Preferably, after placement of the liner and the drainpipe, the deepened portion is filled up with a ground material.

The liner in the underground encloses a buffer volume.

Preferably, the buffer volume is at least partially filled up with a rough-granulated material, like a layer of gravel, to increase a quick absorbance capacity of the water buffer.

Preferably the buffer volume is at least partially filled up with a fine-granulated material, like a layer of sand, to provide a filter in the water buffer.

The fine-granulated material may filter contaminations from water, like rainwater, ground- or surface water, sinking down in the water buffer.

Herewith, the drainage system further serves as a bio-filter for filtering introduced water.

Further, the third aspect of the invention relates to a channel module for building a drainage system comprising a drainage channel.

Each channel module comprises a drainage channel portion.

The drainage channel is mountable by interconnecting a plurality of such channel modules.

The channel module according to the third aspect of the invention comprises hollow inner space which forms the drainage channel portion.

The hollow inner space has a bottom which forms a channel bottom.

The channel module has a longitudinal channel body.

In particular, the channel body is block shaped.

The channel body includes a bottom face, a top face, a left side face, a right side face and a first and second end face.

The end faces define a length direction of the channel body.

Each of the end faces includes an open channel end of the drainage channel portion.

The end faces of the channel body are configured to fit to each other.

By aligning the channel bodies, the open channel ends at the end faces mate which each other, such that the drainage channel portions of each channel body form the drainage channel of the drainage system.

According to the third aspect of the invention, the channel module is improved by a provision of an outlet.

The channel module comprises an outlet.

The outlet is positioned at a lower region of the channel body.

The outlet is in fluid commutation with the drainage channel portion to allow an exit of water away from the drainage channel portion to an exterior.

The

22. outlet is directed in a lateral direction. The lateral direction is a transversal, in particular a perpendicular, direction with respect to the length direction of the channel body. From an operational point of view, the outlet may be horizontally directed. Preferably, the outlet is directed in a downwardly inclined lateral direction. Preferably, the outlet has an exterior outlet opening which is positioned flush or below a channel bottom of the drainage channel. Further, the third aspect of the invention relates to a method for building a drainage system and/or a bio-filter. In the method, use is made of a drainage system according to the invention. The method comprises a step of providing a drainage system according to the invention. The drainage system may be embodied as described in this application and as illustrated in the drawings. In a step of the method, the drainage system is assembled by interconnecting a plurality of channel modules at ground level. The channel modules are placed in such a way that water may enter the channel modules by gravity. In a step of the method, the channel modules are fluidly connected to a water supply. The water supply may for example be formed by a pavement or street gutter adjacently positioned to the channel modules. The channel modules are placed at a location such that in operation water enters the drainage system. At least one of the channel modules is arranged to provide a lateral discharge of water. In a step of the method, the underground is prepared to receive a flow of laterally discharged water by providing a water accumulator. The water accumulator may be formed by a free exposing surface area or an underground build water reservoir. Free exposing means that an underground is unpaved at ground level. Laterally discharged water may flood over the surface area. Water may be collected or charged to a particular location, or water may penetrate the underground after a while.

In a preferred embodiment of the method according to the third aspect of the invention, the method comprises a step of lowering the interconnected channel modules with respect to ground level, such that at least one outlet is positioned below ground level in the underground. The lowering of the channel modules to position and outlet opening below ground level prevents a flooding at ground level and contributes to a quick absorbance of the discharged water in the underground. Preferably, in a step of the method, the at least one outlet is connected to a drainpipe extending in the underground. Connecting a drain pipe to the outlet of the channel module may further improve an absorbance of water into the underground.

In an embodiment of the method according to the third aspect of the invention, the method further comprises a step of excavating a deepened portion in an underground whereafter the deepened portion is filled with a ground material. The filled deepened portion forms a buffer

-23. volume to collect water from the drainage system. The ground material is selected to replace present underground material at a location of the drainage system to improve an absorbance of water. Preferably, to provide a bio-filter, the ground material comprises at least partially a fine-granulated ground material, like a sand layer, to provide a filter. Preferably, the ground material comprises at least 50% of fine-granulated ground material. Discharged water which lowers through the buffer volume is filtered by the fine-granulated ground material. In an embodiment of the method according to the third aspect of the invention, the method comprises a step of placing a plurality of base elements at ground level at a top region of the deepened portion. In the channel modules and providing at least one insert protruding from the base element. The at least one insert may be a separate item which may be connected to the base element in a separate step of the method. The at least one insert may be incorporated in the base element, such that the at least one insert is in position after a placement of the base element on the underground. In a step of the method, the deepened portion is covered by a liner. The liner is spread out over the deepened portion and covers soil at a bottom of the deepened portion. The liner has a liner mount region which is provided with at least one liner hole. In particular, the liner mount region is provided at a contour of the liner, such that the liner mount region is positioned at ground level along a circumference of the deepened portion. In a step of the method, the at least one liner hole is placed over de at least one insert. Now, the insert protrudes through the at least one liner hole. The liner is held in position by the insert which is fixed to the base plate. In a next step, at least one drainpipe is placed across the liner. The at least one drainpipe preferably extends substantially horizontal. The drainpipe is arranged to discharge water from a lower region of the buffer volume. Preferably, the drainpipe is placed above the liner. In particular, the drainpipe may extend through the liner. Embodiments according to the third aspect of the invention are described by the following clauses:

1. Modular drainage system (1) for discharging water which drainage system (1) comprises a drainage channel (C) for transferring water which drainage channel (C) is formed by a network of interconnected channel modules (3), wherein each channel module (3) comprises a hollow inner space (35) which forms a drainage channel portion (C') with a channel bottom and open channel ends, wherein each channel module (3) has a longitudinal channel body (30) including a bottom face (33), a top face (34), a left side face (36), a right side face (37), a first end face (311) and a second end face (312) which end faces (311, 312) are configured to mate adjacently

-24- positioned channel modules (3) with each other to form said drainage channel (C) by fluidly connecting the open channel ends of drainage channel portions (C’), wherein at least one channel module (3) comprises an inlet (301) which inlet (301) is positioned at an upper region of the channel body (30) and in fluid communication with the hollow inner space (35) to allow an entry of water by gravity into the drainage channel portion (CY, and wherein at least one channel module (30) comprises an outlet (302) which is directed in a lateral direction and which outlet (302) is positioned at a lower region of the channel body (30) and in fluid communication with the hollow inner space (35) to allow an exit of water by gravity out of the drainage channel portion (C').

2. Drainage system according to clause 1, wherein the network of interconnected channel modules comprises a total amount of channel modules in which at least 20% of the channel modules is provided with at least one outlet.

3. Drainage system according to clause 1 or 2, wherein the outlet (302) comprises an exterior outlet opening at the bottom face (33) or one of the side faces (36, 37) of the channel module.

4 Drainage system according to any of the preceding clauses, wherein the outlet comprises a stopper for selectively opening or closing the outlet.

5. Drainage system according to clause 3 or 4, wherein the exterior outlet opening is arranged for coupling a drainpipe.

6. Drainage system according to any of the preceding clauses, wherein the drainage system further comprises a water buffer (P) including a liner {4} and a drainpipe (D), wherein the water buffer (P) has a buffer volume which is enclosed by the liner (4).

7. Drainage system according to clause 6, wherein the buffer volume of the water buffer (P) which is enclosed by the liner (4) comprises at least partially a rough-granulated material for absorbing introduced water.

8. Drainage system according to clause 6 or 7, wherein the buffer volume of the water buffer (P) which is enclosed by the liner (4) comprises at least partially, preferably for at least 50%, a fine-granulated material for filtering introduced water.

- 25.

9. Channel module (3) for building a drainage system (1) comprising a drainage channel (C) which is mountable by interconnecting a plurality of such channel modules (3}, wherein the channel module (3) comprises a hollow inner space (35) which forms a drainage channel portion (C') with a channel bottom (cb) and open channel ends, wherein the channel module (3) has a longitudinal channel body (30) including a bottom face (33), a top face (34), a left side face (36), a right side face (37), a first end face (311) and a second end face (312) which end faces (311, 312) are configured to mate adjacently positioned channel modules (3) with each other to form said drainage channel (C) by fluidly connecting the open channel ends of drainage channel portions (C’), wherein the channel module (30) comprises an outlet (302) which is directed in a lateral direction and which outlet (302) is positioned at a lower region of the channel body (30) and in fluid communication with the hollow inner space (35) to allow an exit of water by gravity out of the drainage channel portion (C').

10. Method for building a drainage system to discharge water, wherein use is made of a drainage system according to any of the clauses 1-8, wherein the method comprises the following steps: - interconnecting a plurality of channel modules (3) at ground level (GL) to assemble the drainage system (1); - fluidly connecting the drainage system (1) to a water supply, e.g. a pavement, such that in operation water enters the drainage system under gravity; - providing a water accumulator for receiving laterally discharged water from at least one outlet of a channel module of the drainage system.

11. Method according to clause 10, wherein the method comprises a step of lowering the channel modules (3) with respect to the ground level (GL), such that at least one outlet (302) is positioned below ground level (GL) in an underground {U}.

12. Method according to clause 10 or 11, wherein the method further comprises a step of: - excavating a deepened portion {P) in an underground (U); and - filling the deepened portion (P) with a ground material to provide a buffer volume, wherein the ground material comprises at least partially, preferably at least 50%, of a fine-granulated material for filtering water.

13. Method according to clause 11 or 12, further comprising a step of: - placing a plurality of base elements (2) at a top region of the deepened portion (P) for supporting the channel modules (3);

- 26 - - providing at least one insert (5) protruding from the base element (2); - covering the deepened portion (P) by a liner (4) for enclosing the buffer volume; - placing at least one liner hole (42) positioned in a liner mount region (41) across the at least one insert (5); and - placing at least one drainpipe (D) over the liner (4) for discharging water from the buffer volume. Aspects and embodiments according to the invention are further described by the detailed description and the accompanying drawings.

The invention will be explained in more detail with reference to the appended drawings. The drawings show a practical embodiment according to the invention, which may not be interpreted as limiting the scope of the invention, in which: Fig. 1 shows an artificial wetland according to the invention including an underground liner which is at ground level attached to a circumventing array of edge elements; Fig. 2 shows a cross-sectional view of the artificial wetland of in fig. 1; Fig. 3 shows a cross-sectional view of an edge element of the artificial wetland of fig. 1; Fig. 4 shows a cross-sectional view of the artificial wetland in which a water volume is provided with a surface level above ground level; Fig. 5 shows the artificial wetland including a drainage system including a pump for supplying groundwater to the artificial wetland; Fig. 6 shows the artificial wetland in which the water volume has a surface level below ground level for a rainwater run-off to the artificial wetland, Fig. 7 shows the artificial wetland arranged to allow a rising of a surface level of the water volume above ground level; Fig. 8 shows another possible application of the structure of the artificial wetland to form a ground barrier substructure; Figs. 9A and 9B schematically show a transversal, respectively a longitudinal cross- sectional view of an embodiment of the ground barrier substructure; Fig. 9C shows in a cross sectional view a channel module in further detail including an outlet for discharging water to the underground; Fig. 9D shows in a cross sectional view a street which is at both sides provided with elevated sidewalks. Fig. 10 schematically shows a top view of an embodiment of a liner of the ground barrier substructure;

-27- Figs. 11A — 11D schematically show a top view and a side view of a first and second embodiment of a base element of the ground barrier substructure; Figs. 12A — 12E schematically show an isometric, respectively a top, a front, a side, and a bottom view of a first embodiment of an upper element of the ground barrier substructure; Figs. 13A — 13C schematically show an isometric, respectively, a side, and a bottom view of a second embodiment of an upper element of the ground barrier substructure; Fig. 13D schematically shows the first embodiment of an upper element and the second embodiment of an upper element, in an assembled condition; Figs. 14A — 14D schematically show an isometric, respectively a top, a side, and a bottom view of a third embodiment of an upper element of the ground barrier substructure; Fig. 15 schematically shows a top view of an embodiment of the ground barrier substructure; Fig. 16 schematically shows different steps of a method to provide the ground barrier substructure.

Identical reference signs are used in the drawings to indicate identical or functionally similar components. To facilitate comprehension of this description, clauses and of the claims the words vertical, horizontal, bottom side, top side, longitudinal, cross-sectional etc. are used with reference to gravity and are used in a non-limiting way. Specific features may also be considered apart from the shown embodiment and may be taken into account in a broader context as a delimiting feature, not only for the shown embodiment but as a common feature for all embodiments falling within the scope of the appended claims.

Fig. 1 shows an artificial wetland 1 according to the invention. The artificial wetland 1 is arranged for containing a water volume in a buffer volume. The artificial wetland 1 comprises an array of edge elements 8 for securing a liner 4. The liner 4 is placed in a deepened portion P in an underground U to delimit an inner volume, the so-called buffer volume, to contain the water volume. At its circumference, the liner 4 has a liner mount region 41 which is attached to a plurality of edge elements 8. Fig. 2 shows a cross-sectional view of the artificial wetland 1. An edge structure is provided by an array of edge elements 8. An edge element 8 is formed by a stacking of an upper element 3 on a base element 2. The base elements 2 are placed on the underground U. In a staggered manner, the upper elements 3 are placed on the base elements 2. The liner mount

-28- region 41 is attached to the edge element 8 by clamping the liner mount region 41 in between the upper element 3 and the base elements 2. Fig. 3 shows the edge element 8 in further detail. The edge element 8 is formed by placing an upper element 3 on an base element 2 while holding the liner mount region 41 in between the upper and base element. The base element 2 has a plate-shaped base body 20. In the cross-sectional view, the base element 2 is T-shaped. The base element 2 comprises a barrier member 24. The barrier member 24 is integrally formed with the base body 20. The barrier member 24 may be a metal plate moulded together with the base body 20. Preferably, the barrier member 24 is made of concrete and forms an integral part of the base body 20. Here, the barrier member 24 is centrally positioned on a top surface of the base body 20. The top surface of the base body 20 forms a support face 22 for supporting the upper element 3. The base body 20 has a support face 22 at both sides of the barrier member 24. Further, the base body 20 comprises a ground face 21 at a bottom side for placing the base element 2 on the underground U. The upper element 3 has an upper body 30. The upper body 30 has a top face 34 at a top side and a bottom face 33 at a bottom side. The bottom face 33 is adapted to be placed on the support faces 22 of the base element 2. As shown in the cross-sectional view of fig. 3, the bottom portion of the upper element 3 is U- shaped. The upper body 30 has a portion which forms a U-bridge and downwardly extending portions which each form a U-leg. In between the U-legs, the upper element 3 has an open groove which forms a bottom recess 331 for receiving the barrier member 24. The bottom recess extends across a whole length of the upper element 3. The bottom recess 331 extends from a first end face 311 to a second end face 312 of the upper body 30.

The bottom recess is shaped in correspondence with a shape of the barrier member 24. The bottom recess is delimited by opposite positioned sidewalls. The sidewalls are converging in a direction to the top face 34. The barrier member 24 of the base element has a corresponding converging shape in upwards direction. The converging shape of the barrier member 24 and bottom recess 331 is beneficial when placing the upper element on top of the base element whilst the liner mount region 41 is placed across the barrier member 24. Due to a narrowing of the bottom recess, only at an end of a movement when placing the upper

-29. element, the liner 4 is engaged.

Herewith, the converging shape of the bottom recess 331 may prevent a damage to the liner 4 when stacking the upper element onto the base element.

Fig. 4 shows an embodiment of the artificial wetland 1 in which the contained water volume has a surface level SL which is above ground level GL.

The base elements 2 can directly be placed onto the underground U.

As shown here, the underground U may first be locally stabilised before placement of the base element 2. The underground U can for example be stabilised by a volume of concrete.

The base body 20 has a support face 22 which is laying flush with ground level GL.

The barrier member 24 extends in upwards direction and its height above the support face 22 determines a maximum permissible surface level SL in a buffer volume of the artificial wetland 1. Exceeding this maximum surface level SL may cause water leakages through the edge elements 8. Fig. 5 shows an embodiment of the artificial wetland 1 which includes a bio-filter BF.

The bio-

filter may comprise a macrophyte.

A macrophyte is an aquatic plant that grows in or near water and is either emergent, submergent, or floating.

Further, the artificial wetland 1 comprises a supply system 9 for supplying groundwater to the buffer volume of the wetland.

The supply system 9 comprises at least one drainage conduit 80 and a pump 91 for pumping groundwater to the buffer volume.

The artificial wetland 1 is configured for receiving water from its environment and for containing the water in the buffer volume.

The upstanding barrier member 24 along the whole circumference of the buffer volume prevents water to flow back to street level.

As shown, the drainage conduit 90 penetrates through the liner 4. The liner 4 comprises a liner seal 49 for sealing the drainage conduit.

The seal 49 prevents an outflow of water from the buffer volume and prevents a rising of a groundwater level around the buffer volume.

Fig. 8 shows an embodiment of the artificial wetland 1 which is configured for receiving rainwater run-off from an adjacently arranged paving.

Here, a paving comprising tiles T is laying flush with the top face 34 of the edge element 8. The edge element 8 serves as a gutter.

As indicated by an arrow, rainwater enters the buffer volume of the artificial wetland 1 from the top face 34 of the edge element 8. The liner 4 extends through the underground to the edge element 8 across the barrier member 24 and forms a barrier for the water volume in the buffer volume to prevent an outflow of water to the underground U surrounding the wetland.

Herewith, a ground water level GWL may remain stable and within permissible levels.

-30- Fig. 7 shows an embodiment of the artificial wetland 1. Here, the artificial wetland 1 is arranged as a pond. A water level of the pond may vary and rise above ground level GL. The predetermined height of the barrier member 24 and the relative height level of the base element 2 determines a maximum permissible surface level SL of the water volume of the wetland. Fig. 8 shows a ground barrier structure which is similar to the structure of the shown artificial wetland. Here, another beneficial appliance of the edge elements 8 is illustrated. A paving is provided at both sides of the edge element 8. The edge elements 8 are used to form a ground barrier structure for containing a soil volume and to prevent contaminations from flowing out the soil volume. The upstanding barrier member 24 and the crossing liner mount region 41 of the liner 4 forms a barrier to prevent contaminations to escape from the soil volume delimited by the liner 4.

Figures 9A, 9B and 15 schematically show a ground barrier substructure, in particular an artificial wetland 1, for arranging a soil cover, in its assembled condition. Soil is covered to form a ground barrier. Soil may be covered by a liner which may be positioned close to ground level GL, e.g. just below a pavement to prevent soil contamination. A liner may be used to form a water buffer, e.g. for buffering ground- or surface water. As shown in the figures 9A and 9B, a liner is positioned at a certain depth in an underground to form a run-off water buffer in a deepened portion P. Urban run-off water, like rainwater from streets and roofs, can be guided and collected in the water buffer. Such a water buffer may also be called an urban wet land.

Figure 15 shows a top view of the artificial wetland. Figure 9A shows a cross sectional view of the ground barrier substructure along line | as illustrated in Figure 15; Figure SA shows a cross-sectional view of the ground barrier substructure in a length direction along line Il in Figure 15.

The ground barrier substructure comprises a base element 2. The base element 2 is placed on an underground U as shown in Figure 9B. The underground U comprises a sand layer to stably support the base element 2. Different embodiments of the base element 2 will be described below with reference to Figure 11A — 11D.

The ground barrier substructure further comprises at least one upper element 3 that is placeable on top of the base element 2. The upper element 3 is adapted to be stably placed on top of the base element 2. Various embodiments of the upper element 3 which are formed

-31- as a channel module of a modular drainage system will be described below with reference to Figures 12, 13, and 14. The ground barrier substructure may comprise a liner 4 for covering soil.

In Figures 9A and 9B, the liner is laid at a certain depth in an underground to provide the rainwater buffer P.

The configuration of the liner 4 to obtain a secure and quick connection to the upper element 3 will be described below with reference to Figure 10. As can be seen in Figures 9A and 9B and in further detail in Figure SC, the ground barrier substructure further comprises at least one insert 5 for positioning the upper element 3 on the base element 2. A bottom face of the upper element 3 comprises a bottom recess for receiving the insert 5. According to the first aspect of the invention, a barrier member 24 is provided which has a barrier height to allow a certain surface level in the buffer volume of the wetland.

According to a second aspect of the invention, and insert 5 is provided.

The insert 5 has another technical function and is configured to position the upper element 3 on the base element 2. In comparison with figures 1-8 and according to another aspect of the invention, the liner 4 may comprise a liner hole that allows the insert 5 to be inserted through the liner hole in the assembled condition of the substructure.

In an embodiment of an edge element 8, the base element to may comprise both a barrier member 24 and at least one insert 5 in which the barrier member 24 provides a watertight border and in which the at least one insert 5 contributes to a robustness of the liner connection.

Shown in Figures 9A and 9B, is a liner 4 that extends from the left upper element 3 to the right upper element 3, to define a rainwater buffer in a deepened portion P for collecting rainwater.

The liner 4 is placed in the underground U at a depth of at least 1.0m.

The liner 4 is laid in a parabolic shaped deepened portion.

The liner 4 encloses a buffer volume.

The buffer volume is filled with a ground material, like sand, clay etc.

Preferably, the buffer volume is filled up for at least 50% with a filter material, a fine-granulated material, like sand of filtering introduced water, in particular surface water or rainwater.

A buffer including a filter material may also be called a bio-filter.

Preferably, the remaining buffer volume is filled up with at least partially a rough-granulated material for quickly absorbing introduced water.

Some vegetation may be provided on top of the buffer volume at ground level GL.

Further shown in Figures 9A and 9B are upper elements 3 that have different shapes.

The upper element is an infrastructural element.

The upper element is arranged for infrastructures.

One upper element 3 in Figure 9A at a left side is modelled as a bench,

-32- another upper element 3 at a right side in Figure 9B is modelled as a curb stone. Many other shapes for the upper element 3 are foreseen, e.g. gutter-stones, separation bands etc. In Figure 9A, the base element 2 is substantially aligned with a ground level GL of the environment, while in Figure 9B the base element 2 is arranged below the ground level GL. Both embodiments are possible, depending on the specific envisioned application of the ground barrier substructure. It may alternatively even be possible to arranged the base element 2 above ground level GL.

Figure 9C shows in a cross sectional view the upper element 3 as shown in Figure 9B in further detail. Here, the upper element is a channel module 3. The channel module 3 has a channel body 30. The channel body 30 is positioned in a lowered position with respect to ground level GL. The channel body 30 has a hollow inner space which forms a drainage channel portion C’. A drainage channel C can be formed by interconnecting a plurality of channel bodies.

Rainwater may enter the channel module via an open channel end. At an extreme end of the drainage system, a separate inlet piece may be coupled to the open channel end of the channel module. The inlet may e.g. be formed by a rain pipe coupling piece. Here, the channel body 30 has incorporated at least one inlet 301 to allow rainwater entering a hollow inner space of the channel module. The at least one inlet 301 is integral with the channel body 30.

An inlet 301 is provided at a side wall of the channel body 30 which allows an entry of rainwater flooding at ground level GL, e.g. discharged from a pavement. As shown, as an alternative or in addition, an inlet 301 may be provided at a top wall of the channel body 30, e.g. by providing a grid, to allow an entry of rainwater into the channel module from above. The at least one inlet 301 is positioned at an upper region of the channel body 30 which allows an entrance of rainwater by gravity.

Fig. 9D shows a street in a cross sectional view which street is at both sides provided with elevated sidewalks. The street and sidewalks are paved with tiles T. The street has a pervious street pavement to allow water to flow into the ground through the street pavement into the underground U’ below the street pavement.

A liner 4 is placed under the street pavement. The liner 4 covers the underground U and extends across the whole width of the street. The liner 4 below the street is connected to a

-33- channel module 3 which is placed along a side of the street. The channel module 3 comprises a top-up channel module 3’ which is placed on top of the channel body 30. The channel body 30 has a hollow inner space 35 which forms a drainage channel portion C. The channel body 30 has an inlet 301 at a top face to allow a drain of water from the top-up channel module 3’ into the drainage channel portion C. Water which originates from the sidewalk pavement and/or street aside the top-up module may first enter the top-up channel module 3’, whereafter the water drains into the lower positioned channel body 30. Further, the channel body 30 has an inlet 301 at a lateral side face which is in fluid communication with a ground volume on top of the liner 4 below the street. Water can be drained from the ground volume to the channel body 30 through the inlet 301 as the lateral side face. The inlets are positioned at an upper region of the channel body 32 drain water by gravity. The sidewalk in the left-sided view of the drawing is paved on top of an underground water buffer, also called a bio-filter. The bio-filter BF is formed by a deepening P in the underground U. The deepening P is filled with a volume of material which forms a filter volume for filtering water that lowers into the ground. The bio-filter BF has a filter volume which is here delimited by a liner 4 at a certain depth of at least 1m in the underground U. The liner 4 separates the bio-filter BF from the underground U. Preferably, the liner 4 is an impermeable liner and a drainpipe D is provided at a bottom region of the bio-filter to drain water away. The filter volume contains a fine-granulated material FM which serves to filter water which lowers through the filter volume. The fine-granulated material FM forms a layer of the filter volume. Further, the filter volume comprises a rough-granulated material RM to enhance an absorption of water. The rough-granulated material forms a layer of the filter volume which is here positioned below the layer of fine-granulated material.

Channel modules 3 are placed at both sides of the street and a separate the street from the sidewalks. The channel modules 3 are placed on top of basic elements 2. According to an aspect of the invention, a modular drainage system comprising a plurality of channel modules may be improved by providing at least one channel module which includes an outlet for a lateral discharge of rainwater to an underground U. Fig. 9C and Fig. 12A, 13A show such an outlet 302 in further detail. The outlet 302 provides a discharge of a flow of rainwater in a lateral direction of the channel body 30. The outlet 302 provides a fluid communication between an exterior and the drainage channel portion C’ of the channel body

30. The outlet 302 is positioned at a lower region of the channel body 30 to allow an exit of a flow of rainwater under gravity.

-34-

LINER Shown in Figure 10 is a liner 4 for covering soil to form a ground barrier. The liner 4 maybe an impermeable liner to form a water buffer. In other applications, the liner 4 may be a permeable liner, e.g. to serve as an underground barrier to sieve contaminations.

The liner 4 comprises a sheet shaped liner body 40, including a liner mount region 41. The liner mount region 41 comprises liner holes 42, 432, 433, arranged in a pattern 43. The pattern of liner holes 43 matches with a pattern of inserts 5 arranged on the base element 2, as will be explained below in further detail with reference to Figure 7.

As visible in Figure 10, the liner mount region 41 may comprise a pattern 43 of liner holes 431, 432, 433. In Figure 10, one row of liner holes 42 is provided in the liner mount region 41, but in relation to Figure 15 it will be shown that there may be multiple rows of liner holes 42 forming a pattern 43.

Further visible in Figure 10 is that some of the liner holes 42 can have a shape that is different from other liner hole 42. More in particular, a first liner hole 433 is differently shaped than a second 432 and third 431 liner hole.

The liner holes 42 visible in Figure 10 have at least one straight liner hole edge. More in particular, the at least one liner hole has a rectangular shape. In an assembled condition, visible in Figures 9A and 9B, the liner 4 is arranged between a bottom face 33 of the upper element 3 and a support face 22 of the base element 2. The insert 5 is inserted through a liner hole 42, such that the liner 4 is locked in position in between the upper element 3 and the base element 2. A form closure in between the liner 4 and the base element is obtained which prevents a lateral movement of the liner. It is not needed to clamp the liner 4 between the upper element 3 and the base element 2, or to provide a compressive force that presses the upper element 3 on the base element 2 to prevent movement of the liner 4. According to the invention, the movement of the liner 4 is simply restricted by arranging an insert 5 through a liner hole 42. BASE ELEMENT / INSERT Shown in Figures 11A — 11D are a first 2.1 and a second 2.2 embodiment of the base element 2. The base elements 2.1, 2.2 comprise a base body 20, a support face 21 at a top side and a ground face 22 at a bottom side. The support face 21 is configured to support an upper element 3 when the ground barrier substructure is in its assembled condition, while the

-35- ground face 22 is adapted to stably place the base element on the underground U in the assembled condition.

Showen in Figures 11A and 11B is an elongate base element 2.1, while Figures 11C and 11D show a base element corner piece 2.2.

The base element 2 may comprise a concrete body. In alternative embodiments, the base element 2 may comprise a polystyrene body or comprise a grid body, in particular a plastic grid body.

Further visible in the embodiments of Figures 11A — 11D are insert bodies 50, 60, 70, here integral with the base element 2. Each insert body 50, 60, 70 has a top face 55, 65, 75, and first 51, 61, 71, second 52, 62, 72, third 53, 63, 73, and fourth 54, 64, 74 circumventing planar insert side faces.

Each insert body 50, 60, 70 in the embodiments of Figures 11A — 11D is substantially block- shaped, at least when seen in the top view of Figures 11A and 11C. The insert body 70 of Figure 11D is also block-shaped in a side view thereof.

Further visible in Figure 11A — 11D is that at least one of the side faces 51, 61, 71 of the insert bodies 50, 60, 70 is arranged at a right angle with respect to the base body 20. In an assembled condition, this side face 52, 62, 72 is preferably arranged substantially vertical, as is visible in Figures 9A and 9B, although it is observed that the side faces are not numbered there. The substantially vertical extending side face 52,62, 72 advantageously further prevents an upcrawling of a liner 4.

At least a second side face 51, 61 of an insert body 50, 60 may be inclined towards the top face 55, 65 at a top angle q, although embodiments of an insert body 70 are conceivable where all side faces 71, 72, 73, 74 are at a right angle with respect to the base body 20, as visible in Figure 11D.

Further visible in Figures 11A and 11C is that a first insert body 50 may have different dimensions than a second insert body 60, which in turn may have different dimensions than a third insert body 70. Seen from above, the inserts differ in cross section. For example, the first insert body 50 may have a larger insert width than the second insert body 60, or vice versa. In the specific embodiment of Figure 11A, the second insert 60 has an insert width that is approximately 2 times the width of the first insert 50.

-36- Shown in Figure 11D is that some of the insert bodies 50, 60, 70 are integral with the base element 2, while one insert, 70, is formed as a separate piece that is arranged in a base recess 23 in the base element body 20.

The base plate 2 as shown in Figures 11A and 11C thus is provided with a first 50 and a second 60 insert that are differently shaped with respect to each other. As will be explained below, the upper element 3 may advantageously have a first bottom recess and a second bottom recess, the geometry of the inserts 50, 60, 70 corresponding to the geometry of the bottom recess, such that, in the assembled condition, the upper elements 3 can be placed on the base plate 2 in only one manner.

UPPER ELEMENTS Figures 12A — 12E, 13A — 13C, and 14A — 14D schematically show respectively a first embodiment of a first upper element 3.1, a second upper element 3.2 and a third upper element 3.3 of the ground barrier substructure according to the invention. Here, the upper elements are embodied as channel modules of a drainage system. The drainage system is modular in that a drainage channel C is obtainable by interconnecting the channel modules. The first upper element 3.1 may be denoted as a first type elongate upper element, the second upper element 3.2 may be denoted as a second type elongate upper element, and the third upper element 3.3 may be denoted as a third type corner piece upper element. How these different upper elements 3.1, 3.2, 3.3 advantageously cooperate, is described below with reference to Figure 15.

The upper elements 3.1, 3.2, 3.3 are block shaped. Each upper element comprises a top face 34, a bottom face 33, two end faces 31,32, and a left and right lateral side face 36, 37. A longitudinal or axial direction is defined in a direction from one end face to the opposite end face. Here, the upper elements are slightly tapered in upwards direction, whichis in a direction from the bottom to the top face. Both the end and lateral side faces taper in the upwards direction.

In the embodiments shown, the upper elements 3.1, 3.2, 3.3 have a hollow inner space 35, e.g. as a drainage channel portion C’, or a cable passageway, although an upper element

3.1, 3.2, 3.3 may also be massive, e.g. as a curb stone, as shown in Fig. 9A. It is conceivable that after placement the hollow inner space 35 can be filled with a medium, to make the upper element 3.1 heavier and to stabilize it. The upper element may have a weight less than 25kg which allow a manual placement by a single person without a machine.

-37- As shown in Fig. 12A and 13A, the channel module 3 comprises an outlet 302 (also shown in fig. 9C). The outlet 302 is formed by a through hole in a sidewall of the channel body 30. The outlet 302 allows a lateral discharge of rainwater from the hollow inner space 35. The outlet extends from the hollow inner space 35, which forms the drainage channel portion C’, to the side face 37. The outlet 302 has a first outlet opening at the drainage channel portion C’ which is positioned close to or preferably adjacent with a channel bottom cb, such that rainwater inside the drainage channel portion C’ will flow under gravity through the outlet 302. The outlet 302 has a second outlet opening at a lateral side face 36, 37 of the channel body 30 to allow a lateral discharge of rainwater. Herewith, besides a transfer of rainwater through the open channel ends at the end faces, a discharge flow of rainwater is provided by the outlet 302 of the channel module. By interconnecting channel modules, wherein at least one channel module has such a lateral outlet 302, a drainage system may be provided with an increased drain capacity.

As clearly visible in Figures 12A, 12E, 13A, and 13C the bottom face 33 of the first upper element 3.1 and the second upper element 3.2 comprise several differently shaped bottom recesses 331, 332, 333. As an example, it may be possible that a first bottom recess 331 is sized to house a first insert body 50 with a particular geometry, while another, second, bottom recess 332, having a different shape than the first bottom recess 331, is not sized to allow the insertion of an insert body 50, 80, 70, while a third bottom recess 333, having yet another geometry than the other bottom recesses 331, 332, is sized to house a second insert body 60, different from the first insert body 50. Each bottom recess mates with a particular insert. The bottom faces 33 at the bottom side of the upper elements 3 are adapted to be placed on the support face 22 of the base element 2.

Visible in Figure 12C, 14C are the end faces 311, 312 of the first 3.1 and third 3.3 upper element. As indicated, the end faces 311, 312 may be oriented non-parallel with respect to each other, for example at an inclination angle with respect to the vertical orientation.

Inthe embodiments of Figure 12C and 14B, the top face 34 of the element 3.1, 3.3 is smaller than the bottom face 33, the end faces 311, 312 being inclined towards the top face 34.

The upper elements 3.1, 3.3 further comprise a lock member 32, having a recess cut 321. A lock member 32 is positioned at each end face. As will be described later with reference to Figure 13D, the lock member 32 is adapted to be coupled with a complementary lock member 32 provided on another upper element. The lock member 32 of the first upper element 3.1 may be a male lock member 32 which is complementary to a female lock member 32 of the

-38- second upper element 3.2 or vice versa. The locking members prevent a lateral movement of adjacently positioned upper elements. The locking members provide a lateral engagement of the adjacently positioned upper elements with each other. The first 311 and second 312 end faces of the same upper element 3.1, 3.3, in the embodiments shown, each comprise the same type of lock member 38 at each end face, which is here a female lock member, a recess cut 381. Further visible in Figure 12C, near the bottom of the end faces, are hook recesses 381 of hook members 38. The hook recesses 381 are adapted to be coupled with hook projections of a hook member 38 provided on another embodiment of an upper element, as will later be described with reference to Figure 13D. The hooking of the hook members 38 prevents an axial movement of two adjacently positioned upper elements 3 with respect to each other. Figures 13A — 13C schematically show an embodiment of a second upper element 3.2 of the ground barrier substructure according to the invention. Visible in Figure 13B are the end faces 311, 312 of the second type upper element 3.2. As indicated, the end faces 311, 312 may be oriented non-parallel with respect to each other, for example at an inclination angle y with respect to the vertical orientation. In the embodiment of Figure 13B the top face 34 of the element 3.2 is wider than the bottom face 33, the end faces 311, 312 being inclined away from the top face 34. In a conceivable embodiment of the ground barrier substructure according to the invention, the angle B of the end faces 31 of the first upper element 3.1 is substantially the same as the angle y of the end faces 31 of the second upper element 3.2. The upper element 3.2 as shown in Figures 13A — 13C further comprise a lock member 32, having a recess projection 322. As will be described later with reference to Figure 13D, the lock member 32 is adapted to be coupled with a recess cut of a lock member 32 provided on a first upper element 3.1 or a third element 3.3. The first 311 and second 312 end faces of the second upper element 3.2, in the embodiments shown, each comprise the same type of lock member 38: a recess projection 382.

Further visible in Figure 13B, near the bottom of the end faces, are hook projections 382 of hook members 38. The hook projections 382 are adapted to be coupled with hook recesses 381 of a hook member 38 provided on a first upper element 3.1 or a third upper element 3.3, as will later be described with reference to Figure 5D.

Further visible in Figure 13B is a seal 39, arranged near the outermost side of the projection 322 on the end faces 311, 312. The seal 39 at the end faces 311, 312 provides a watertight connection in between two interconnected channel modules 3.

-39- Where the end faces 31 of the longitudinal upper elements 3.1, 3.2 are arranged at opposite sides of the upper element 3, the end faces 311, 312 of the corner piece upper element 3.3 are arranged at adjacent sides. Shown above is a connection between two longitudinal upper elements 3.1, 3.2. In a similar way, an longitudinal upper element 3.1, 3.2 may be connected to a corner piece upper element 3.3, or two corner piece upper elements 3.3 may be connected. This can be achieved either with the locking members 32, and/or with the hooking members 38.

Shown in Figure 13D are a first upper element 3.1 and a second upper element 3.2, positioned adjacent each other, in an assembled condition. The hook projection 382 of hook member 38 on the second upper element 3.2 hooks into the hook recess 381 of the hook member 33. Further, the projection 322 of the lock member 32 on the second upper element

3.2 is interlocks with the recess cut 321 of the lock member 32 on the first upper element 3.1. This interlocking of the lock members 32 on the adjacently positioned first 3.1 and second 3.2 elements prevents a lateral movement of the upper elements 3.1, 3.2 with respect to each other, laterally engaging them. By also hooking the first 3.1 and 3.2 upper elements into each other, an axial movement of the adjacently positioned upper elements 3.1, 3.2 is further prevented.

The seal 39, arranged at the outermost side of the end face 31 of the second upper element

3.2 is compressed by this locking and hooking connection, advantageously providing a watertight seal between the end faces 311 of the first upper element 3.1 and the end face 312 of the second element 3.2.

ASSEMBLED ARTIFICIAL WETLAND Shown in Figure 15 is an embodiment of an artificial wetland in an assembled condition. Shown are four base element corner pieces 2.2, and two elongate base elements 2.1 The base elements 2.1, 2.2 are coupled to each other and form a rectangular drainage system, having a deepened portion P for drainage in a middle region.

The base elements 2.1, 2.2 each comprise multiple inserts 5, arranged in a pattern. Clearly visible in the projection of Figure 15 is that the surface area of the ground face 21 of the base elements 2 is larger than a surface area of a bottom face 33 of the upper elements 3, providing a stable basis for the upper elements 3.

Arranged on top of the base elements 2.1, 2.2 is a liner (as shown in Figure SC). The liner comprises liner holes, as shown in Figure 10, wherein the inserts are inserted through the liner holes. As such, the pattern of the liner holes in the liner corresponds to the pattern of the

- 40 - inserts 5, 6, 7 on the base elements. Arranged on top of the liner are upper elements 3.1, 3.2,

3.3, near the edge of the base elements 2.1, 2.2 facing the deepened portion P. Three different types of upper elements 3 are shown in Figure 15, although embodiments are conceivable where any number of different upper elements are used, from all similar elements, to all different shapes.

The bottom recesses 331, 332, 333 in the upper elements 3 receive an insert 5, the pattern of the inserts 5 being matched to the pattern of the bottom recesses 331, 332, 333 in the bottom faces 33 of the upper elements 3, such that the upper elements 3 can be placed on top of the base elements 2 in only one way. This ensures a stable placement of the upper elements 3. Further shown schematically in Figure 15 are the locking members 32 of the upper elements

3.1, 3.2, 3.3 that lock into each other to prevent a lateral movement of two adjacently positioned upper elements 3.1, 3.2, 3.3.

METHOD A method for the building of a ground barrier substructure, in particular an artificial wetland, according to the invention is now described with reference to Figure 16. Figure 16 shows 8 subfigures, numbered 8-1 to 8-4 from the top left to the bottom left, and 8-5 to 8-8 from the top right to the bottom right. Figure 16-1 on the top left shows a street or other public or private space as one might find outside. This existing space may serve as an initial starting point for the construction of a ground barrier substructure according to the invention. It is also possible to start with a wasteland to build a new substructure. In a first step, shown in Figure 16-2, tiles T or other ground coverings are removed from grpimd level GL at the existing space, and a deepened portion P is excavated in the underground U.

In a further, optional, step, shown in Figure 16-3, the deepened portion P is partially filled with a stabilizing underground material U’, for example a sand bed. If the underground U itself is already stable, which depends on the composition of the underground U, this step might be omitted.

In a further step, the base elements 2 are placed on the underground U, with the support face 22 arranged at the top side of the base element 2 and the ground face 21 arranged at the

-41 - bottom side of the base element 2. The base element 3 comprises inserts 5, which are here integral with the base element 2.

In an optional, non-shown, step, when the base element 2 does not yet comprise inserts 5, it is conceivable that the base body 20 comprises base at least one recess, allowing an insertion of at least one insert. Inserts are then preferably inserted into the base recesses before the upper element 3 is placed on the base element 2, as shown in Figure 16-7.

In a further step, shown in Figure 16-5, a drain pipe D is arranged along an outer edge of the base elements 2 at a bottom region of the deepened portion P. Water, or other fluids, are drained away via this drain pipe D when the ground barrier substructure according to the invention is in operation.

In a step, a liner 4 for covering soil is placed on the support face of the base element 2, wherein the liner 4 comprises a liner hole 42, said liner hole 42 being arranged around the insert 5 of the base element 2, or, alternatively formulated, the insert 5 inserted through the liner hole 42 of the liner 4. It can be observed from Figure 8-6 that the liner 4 extends outwardly with respect to the base element 2, towards the drain pipe D, to ensure that fluid is drained into the drain pipe, and is, advantageously, not drained between the base element 2 and the underground U. In an embodiment, the drain pipe D may be positioned above the liner 4, such that discharged water is ducted by the liner 4 towards the drain pipe D and subsequently drained away.

In a further step, an upper element 3 is placed on top of the base element 2, a bottom face of the upper element 3 being placed on the support face of the base element 2. The bottom face of the upper element 3 comprises a bottom recess, with is placed on the insert 5, such that the insert 5 is received in the bottom recess, an such that the upper element 3 locks the liner 4 in between the upper element 3 and the base element 2.

In afinal step, the surroundings of the ground barrier substructure are finished, for example with tiles being placed back onto the underground U, such that the tiles T are placed adjacent to the upper element 3.

Although the invention has been disclosed with reference to particular embodiments, from reading this description those of skilled in the art might appreciate a change or modification that may be possible from a technical point of view but which still do not depart from the scope of the invention as described above and claimed hereafter.

-42- It will be understood by those of skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. It is in particular possible to make modifications with respect to the illustrated embodiments which are provided as exemplary embodiments.

Modifications may be made within the teaching of the invention and without departing from the scope thereof to adapt a particular situation or material. It is noted that the term “comprising” (and grammatical variations thereof) is used in this specification in the inclusive sense of “having” or “including”, and not in the exclusive sense of “consisting only of”. Therefore, the invention is not limited to the particular embodiments disclosed and illustrated in the above detailed description, but that the invention will include all embodiments falling within the scope as described above and defined in the appended claims.

-43- List of reference numerals: 1 artificial wetland; constructed 35 hollow inner space; drainage wetland; wetland treatment system; 40 channel portion ground barrier substructure 36 left side face 37 right side face 2 base element; base plate; 38 hook member

2.1 base element type 1 381 hook cut out

2.2 base element type 2 45 382 hook projection 20 base body 39 seal 21 ground face 22 support face 4 liner; membrane 23 base recess 40 liner body 24 barrier member 50 41 liner mount region 42 liner hole 3 upper element; channel module 43 pattern of liner holes

3.1 upper element type 1 431 first liner hole

3.2 upper element type 2 432 second liner hole

3.3 upper element type 3 55 49 liner seal 30 element body; cover; channel 5 insert body; upper body 50 first insert body 301 inlet 51 first inclined side face 302 outlet 60 52 second upstanding side face 31 end face 53 third side face 311 first end face 54 forth side face 312 second end face 55 top face B inclination angle a insert top angle 7 inclination angle 65 32 lock member 6 insert 321 recess cut 60 second insert body 322 projection 61 first side face 33 bottom face 62 second side face 330 barrier recess 70 63 third side face 331 first bottom recess 64 forth side face 332 second bottom recess 65 top face 34 top face

-44 - 7 insert C’ drainage channel portion 70 third insert body cb channel bottom 71 first side face D drain pipe 72 second side face GL ground level 73 third side face 20 GWL groundwater level 74 forth side face FM fine-granulated material 75 top face P deepened portion; rainwater buffer water volume; 8 edge element SL surface level 9 supply system 25 T tile 90 drainage conduit U underground, stable bed 91 pump U’ underground layer RM rough-granulated material BF bio-filter C drainage channel

Claims

- 45. CONCLUSIONS

1. Artificial water area (1) for holding a volume of water in a buffer volume, wherein the artificial water area comprises: - at least one base element (2) which is designed to be placed on a subsoil (U), wherein the base element (2 ) has a base body (20), wherein the base body (20) has a support surface (22) on a top side and a base surface (21) on a bottom side; - at least one upper element (3) with a bottom portion adapted to be placed on top of the base element (2), the bottom portion having a lower surface (33) on a lower side, the lower surface being adapted to rest on the support surface (22 ) to be placed from the base element (2) to form an edge element (8) to limit the buffer volume of the artificial water area with respect to a surrounding environment; and - a liner (4) for defining the buffer volume, the liner (4) having a foil-shaped liner body (40) with a liner attachment region (41), - wherein the at least one base element (2) is T-shaped and has an upstanding plate-shaped limiting member (24), the limiting member (24) extending from the support surface (22) to a predetermined height to form a water barrier corresponding to a determined maximum surface level (SL) of the water volume in the buffer volume; wherein the bottom portion of the at least one upper element (3) is U-shaped, the U-shaped bottom portion forming a barrier recess (330) for receiving the limiting member (24) of the base element covered by the mounting area (41) of the liner, the barrier recess (330) extending from a first end face (311) to a second end face (312) along the lower face of the upper member; and wherein the liner attachment region (41) extends across the restriction member (24) such that the liner attachment region (41) is positioned between the base member (2) and the upper member (3).

An artificial water area according to claim 1, wherein the limiting member (24) is integrally formed with the base body (20) which is preferably produced by pouring concrete in one piece.

An artificial water area according to claim 1 or 2, wherein the basic body (20) has a length, wherein the limiting member (24) extends over the entire length of the basic body (20).

“46 -

An artificial water area according to any one of claims 1 to 3, wherein the base element (2) is T-shaped, the height of the limiting member (24) being substantially equal to the width of the base body (20).

An artificial water area according to any one of the preceding claims, wherein the delimiting member (24) has a convergent shape, in particular a trapezoid shape, in a direction away from the support surface (21) of the basic body (20).

An artificial water area according to any one of the preceding claims, wherein the base element (2) has an elongate base body (20), wherein in particular the base element (2) has the same length as the upper element (3).

An artificial water area according to any preceding claim, wherein the barrier recess (330) of the upper element (3) is defined by oppositely positioned side walls of the recess extending in a direction towards an upper surface (34) of the upper body (30) are convergent.

An artificial water area according to any one of the preceding claims, wherein the upper element comprises an upper portion with at least one connector, in particular at least one threaded hole, for attaching an upper element accessory, such as a fence or seat.

An artificial water area according to any one of the preceding claims, wherein the edge element (8), in particular at least the boundary member (24), extends above a ground level (GL) to form a watertight boundary between a surrounding environment and the water volume (P). of the artificial water area (1), such that a surface level of a water volume in the buffer volume can rise higher than ground level.

An artificial water area according to any one of the preceding claims, wherein the edge element (8) has an upper surface (34) aligned with a ground level (GL) to allow rainwater runoff from a surrounding environment, in particular an adjacent pavement, to the buffer volume. (P) of the artificial wetland (1).

An artificial water area according to any one of the preceding claims, wherein the artificial water area (1) further comprises a supply system (9) for supplying water to the buffer volume of the water area, the supply system (9) comprising a discharge conduit (90) and in in particular a pump {91) for adding groundwater to the

-47 - buffer volume, wherein in particular the liner (4) comprises a liner seal (49) for sealing the drain line (9) extending through the liner (4) such that a backflow of rainwater from the buffer volume is prevented.

An edge element (8) for an artificial water area according to any one of the preceding claims, wherein the edge element (8) comprises a T-shaped base element (2) and an upper element (3), wherein the base element comprises a base body (20) and a upright limiting member (24) extending from a support surface of the base body, and wherein the top member (3) comprises a U-shaped bottom portion with a barrier recess (330) about the limiting member (24) and a liner attachment region (41 ) which extends over the limiting member when the upper element (3) is placed on top of the base element (3) to be covered.

A method of providing an artificial water area, the method further comprising a step of: - placing a liner (4) to define a buffer volume of the artificial water area, in particular by placing the liner ( 4) in a lowered part of a substrate (U); - placing several base elements (2) with a limiting member (24) along a liner attachment area (41) of the liner (4); - positioning the liner boundary region (41) over the restriction member (24); - placing an upper element (3) on top of the base element (2) such that the liner boundary area (41) becomes situated between the base element (2) and the upper element (3).