The invention relates to a system for draining water from a land surface which is covered by a waterproof membrane. 5 Such systems are known from the state of the art, for instance for application in sports areas, tennis courts, etc. Examples thereof are described in the German Patent DE 465,166 and in the European Patent Application EP 0072559• In all these systems the waterproof membrane comprises a foil of plastic material, whereby separate drainage gutters

10 or drainage tubes are used to receive water from this foil and to drain said water. In all these prior art systems the foil is furthermore covered with a top layer of soil, which may have a thickness of some tenths of centimetres and which gives the area the appearance of a tennis court, a football field or something like that.

15 In the German Patent DE 465,166 no further special measures are taken to obtain a watertight connection between the membrane and the drainage tubes. Therefor part of the water flowing along the waterproof membrane will not be received in the gutter but will penetrate into the ground. Furthermore, the prior art gutters are made in situ from stone

20 or concrete and are therewith expensive and not relocatable.

In the European Application EP 0072 559 there is no separate gutter. In stead, the gutter is formed by positioning the marginal section of the membrane in a gutter-shaped trench or excavation, which is made specially for that purpose. Because in that way the gutter

25 lining is made from the marginal section of the membrane itself, this membrane should be relatively thick and stiff for that purpose to maintain its shape during further use and to assure a certain degree of form stability. However, thick and stiff membranes are hard to handle especially when it comes to covering a preshaped land area with a

30 relatively broad length of such a membrane. Besides of that it seems practically impossible to use this last-mentioned method for obtaining a long gutter with a length of several hundreds meters which has a continuous fall of for instance a few centimetres per hundred meter gutter length.

35 n plant growing farms, in which plants, shrubs, trees, etc. are ψ grown outside in pots or in other containers rainwater and sprinkle water which is not absorbed by the plants or by the soil in the pots or containers will reach the underlying soil and will penetrate therein.

That will convert the soil in a muddy substance, especially in case of heavy rainfall or plenty of sprinkling water, detoriating the working conditions for the grower. A more serious disadvantage resides in the fact that in general nutricients, pesticides or other substances will be added to the sprinkling water. These additives will penetrate into the soil and will accumulate therein forming a potential environmental hazard.

Experiments are carried out momentarily with land surfaces which are covered by a waterproof membrane such as a plastic web or foil. Thereby first of all the land surface ^* is preshaped to form a slightly inclined ramp or slope such that rainwater or sprinkle water ^* (together with eventual additives) , which falls on the membrane, will flow in a natural manner in the desired direction to the margin of the membrane where the water is received in a gutter. Through this gutter the water may for instance flow into an accumulation reservoir. In such systems the membrane is not covered by an other layer of soil such as in the above-mentioned state of the art, but forms as such the top layer which directly receives and drains rainwater and sprinkle water to the gutter system. During the practical realization of such a system various problems are encountered. Dependent on the form and the material of the gutter it appeared to be more or less difficult to obtain in a simple manner a watertight connection between the margin of the membrane and the gutter in such a manner that in principle all the water, which falls on the membrane and flows along the membrane in the direction of the gutter, will indeed be drained into the gutter. However, with reference to the above-mentioned environmental hazard caused by the accumulation of pesticides and nutricients into the earth, a reliable and easy to make watertight transition between the membrane margin and the gutter, assuring that all water flowing along the membrane will reach the gutter and in principle no water will penetrate into the ground, is of outmost importance.

The construction of the gutter should be easy and quick. Therefor generally available cheap but reliable materials are preferred in stead of concrete or stone gutter elements such as known from the prior art. The used membranes, especially embodied as monolayers or multilayers of a suitable plastic material, are preferably selected so strong and thick that it is possible to walk upon and to drive over it

with light conveying materials, such as wheelbarrows, etc. However'„ ΏΈL the other hand to improve the handling of the membrane and to reduce, the. pure material costs the membrane is selected so thin and light of ^' weight that, if no further measures are taken, the membrane can be lifted off ^' and blown away easily by the wind. That has to be prevented.

An object of the invention is now to eliminate these disad¬ vantages and to provide a system which assures in a cheap and efficient manner the drainage of water from a land surface which is covered by a waterproof membrane. In this respect the invention now provides a system for draining a land surface which is covered by a waterproof membrane, whereby tubular gutters are installed in trenches in the land surface adjacent to the margins of the waterproof membrane and whereby the land surface is slightly sloped such that water falling onto the membrane will flow in a natural manner in the direction of a gutter, each tubular gutter being assembled from one or more interconnected tubes each comprising one or more aligned apertures in the upwards directed wall section, whereby the marginal section of the membrane adjacent to said aligned ^* row of apertures in the tubular gutter wall is attached to the tubular gutter by suitable means such that water flowing along the membrane will be received in said gutter.

The apertures in the tube wall can have an elongated shape with the longest dimension in the length direction of the tube. However, it is also possible to make one single aperture in the tube in the form of an elongated slit.

For attaching the marginal section of the membrane to the wall of the tube various alternatives are conceivable. According to one embodiment the marginal section of the membrane is attached to the wall of the tubular gutter by means of an adhesive. According to another embodiment the marginal section of the membrane is attached to the wall of the tubular gutter by means of a melting process whereby the membrane and the wall of the tubular gutter are locally heated to above the weakening temperature.

According to a further embodiment the marginal section of the membrane is attached to the wall of the tubular gutter by means of mechanical fasteners such as screws or rivets.

According to a preferred embodiment the marginal section of the membrane is folded around the edge of the respective aperture ED the

tubular wall whereafter the membrane is attached to the tubular wall by clamping means.

Preferably t the tubular gutter is made from PVC-tubes or other suitable tubes, which are known to the expert in this field, in which tubes the desired apertures are made. In that case standard auxiliary means and standard coupling means can be applied for interconnecting a number of tubes into a longer tubular gutter system. Furthermore standard bends, knees, etc. can be applied and the connection of the tubular gutter system to a further drainage channel for further transporting the accumulated water does not give any problem.

To assure a correct positioning of the gutter system, especially with respect to the gradual an continuous fall of the gutter it is preferred that the tubular gutters are supported by foundation piles. More specifically the tubular gutters are attached to said foundation piles by means of screws or nails extending through a predrilled hole in the lower wall of the tube whereby additional measures are taken to prevent leakage of water through said predrilled hole.

Furthermore in case the tubular gutter is assembled from two or more interconnected tubes it is preferred that a coupling sleeve is used receiving the end sections of both tubes to be interconnected, whereby a water blocking non solid material such as a greasy or jelly substance is used to obtain a water tight connection between the sleeve and the end of a tube.

The invention will be explained in more detail with reference to the attached drawings.

Figure 1 illustrates a cross section through a system comprising a tubular gutter connected to the edge of a membrane.

Figure 2 illustrates a system in which the tubular gutter is con¬ nected to two membranes at both sides of the gutter. Figure a illustrates a first embodiment of a tubular gutter for application in a system according to the invention.

Figure 3B illustrates a second embodiment of a tubular gutter for application in a system according to the invention.

Figure 30 illustrates a third embodiment of a tubular gutter for application in a system according to the invention.

Figure 3D illustrates a third embodiment of a tubular gutter for application in a system according to the invention.

Figure 3E illustrates a third embodiment of a tubular gutter for

application in a system according to the invention.

Figure 4 illustrates in a more detailed manner an embodiment of the clamping means for attaching the membrane to the edge of the tubular gutter. Figure 5 illustrates in a perspective view more details of the manner in which the foil is clamped around the tubular gutter, assuming that the tubular gutter has the embodiment as illustrated in figure 3A or 3B.

Figure 6 illustrates the use of adhesive to attach the marginal section of the membrane to the tubular gutter.

Figure ~ illustrates the use of mechanical fastening means such as screws or rivets to attach the marginal section of the membrane to the tubular gutter.

Figure 8 illustrates the application of separate bridge parts for fixing the edges of the tubular gutter, especially in case the tubular gutter is embodied as illustrated in figure 3C.

Figure 9A illustrates a coupling between two tubes.

Figure 9A illustrates another coupling between two tubes.

Figure 1 illustrates a cross section through a soil layer 10, of which the upper side is at least partly covered by a waterproof membrane 12. On top of the membrane 12 potted plants can be positioned as is illustrated schematically by the pots 8a .... 8d. Before the membrane 12 is laid out, the upper side of the bottom layer 10 is shaped into such a sloping configuration that rainwater or sprinkling water, which falls onto the membrane 12, will be drained into the direction of a gutter 14.

The gutter 14 is almost completely dug into the ground and consists of an elongated tube which comprises at the top side one or more apertures. The marginal section of the membrane 12 is folded around the edge of the tube 14 in said aperture and is attached to the edge of the tube in a way which is not illustrated in detail in this figure. More details of the tube 14 and the attachment of the membrane to the tube will be explained with reference to other figures.

As schematically indicated the tube 14 is supported by a number of foundation piles 6 to assure a correct position of the tube over a long time period. Such a pile foundation is certainly preferred in case the underground 10 has a weak, soft consistency. However, even if the underground consists for instance of sand or another relatively stable material such a foundation is very helpful in obtaining the desired

continuous fall of for -nstance only a few centimetres per 100 m length.

In the systeuβ.according to figure 1 rainwater or sprinkling water, which falls dhto/the membrane 12, will be drained to the tube 14, but rainwater which falls on the left side of the tube 14 will mainly penetrate into .the ground 10.

If it is desired to drain the land at both sides of the tube 14, then one can opt for a system variant which is illustrated in figure 2. ^■ In this figure the area right of the tube 14 is covered by the membrane 12a and the area left of the tube 14 is covered by the membrane 12b. At both sides of the tubular gutter 14 potted plants 8 can be positioned, as is schematically illustrated in the figure, whereby for the sake of ^* clearness only one of the potted plants has a reference number. The edges of both membranes 12a and 12b are folded into the aperture in the tubular wall 14 and are attached to the edges of said wall by means which are also not illustrated in detail in this figure. Assuming that the slope of the area is such that all rainwater and sprinkling water which falls onto the membrane 12a or onto the membrane 12b will in a natural manner flow in the direction of the gutter 14, then this system assures that rainwater* and sprinkling water at both sides of the tube 14 will be received into said tube and will not penetrate into the soil 10. In the figures 3A, B, C, D and E a number of possible variants of tubes are illustrated!.which can be applied into a system according to figure 1 or figure 2.

The tube l4a in ^' figure 3A consists of a tube with round cross- sectional shape, preferably made of PVC or an other suitable plastic material, whereby in the upper wall of the tube a series of elongated apertures 16a, 16b, ... is made. The elongated apertures 16a, 16b, ... are in this embodiment made with semicircular end sections.

In the embodiment illustrated in figure 3B the tube.l4b also com- prises a series of elongated apertures 18a, 18b, ... which in this embodiment, however, have a rectangular shape. The fabrication of such rectangular shapes requires more effort than the fabrication of apertures with semicircular end sections as illustrated in figure 3A. However, the rectangular apertures 18a, 18b in figure 3B have the advantage that the intermediate bridges 20a, 20b, 20c have uniform dimensions and have therefore a maximum strength. These bridges are necessary to assure: that under normal use, in the conditions as illustrated in figures 1 and 2, the opposite walls of the tube are not

pressed together by the pressure in the soil at both sides of the tube. Preferably the corners of the rectangular apertures are rounded off to avoid the formation of cracks and tears.

Figure 3C illustrates an embodiment in which the tube l4c comprises one elongated slit 20c with a predetermined width. To assure that this tube maintains its shape under operative conditions notwithstanding the pressure of the surrounding soil, use will be made of bridge parts, bridging the aperture at a number of places as will be discussed in more detail hereinafter. The advantage of the embodiment of figure 3C is, that the fabrication of one elongated slit in the tube is a relatively easy mechanical operation which can be carried out in a simple manner.

Figure 3D illustrates another embodiment in which the tube l4d comprises one elongated slit 20d with a predetermined width. The upper part of the tube is flat so that the slit 20d is bounded by flat wall sections 19a and 19b which under operative conditions will extend almost horizontally, these horizontal wall sections are very suited to connect the marginal section of the membrane as will be explained in detail. Also this embodiment of the tube is preferably used in combination with bridge parts to assure that the tube maintains its shape under operative conditions notwithstanding the pressure of the surrounding soil.

The tube l4e in figure 3E consists of a tube with rectangular cross-sectional shape, preferably made of PVC or an other suitable plastic material, whereby in the upper wall of the tube a series of elongated apertures 17a, 17b, ... is made. The elongated apertures 17a, 17b, ... are in this embodiment made in the same shape as illustrated in figure 3B. However, it will be clear that various other aperture shapes are conceivable, such as rectangular apertures with semicircular end sections, one elongated slit or even a series of circular apertures. Figure 4 illustrates in more detail the way in which the marginal part of the membrane can be folded around the edge of the aperture in the tube 14 and can be attached thereto. As appears from figure 4 the marginal part of the membrane 12 is folded around the edge of the tube 14 and is clamped on it by positioning a clamping element 20 over the folded membrane section. It will be clear that the dimensions of the clamping element have to be selected such that the desired clamping action is indeed obtained.

Figure 5 illustrates in a perspective view the situation when a

tube of the-type illustrated in figure 3A is applied. Figure shows two of the apertures 16a en l6b in the tube with the intermediate connecting bridge 20a. For attaching the membrane 12 two skewed incisions are made in the marginal section of the membrane at the location of the bridge section 21a in such a manner that it is possible to fold the marginal section of the membrane around the edge of the apertures 16 and l6b, whereby at the location of the connecting bridge 20a a piece of the marginal section of the membrane remains resting onto the connecting bridge. Thereafter the elongated clamping elements 22a and 22b are attached such that the membrane 12 is ^* clamped to the tube l4a. The clamping elements 22a, 22b may consist of U-shaped profiles of aluminium or a suitable resilient plastic material. The U-shape might be rectangular such as in figure 4 is indicated, but may also comprise rounded edges. Figure 6 illustrates the use of an adhesive to obtain a proper connection between the marginal section of the membrane and the upper wall of the tube. The illustrated tube has the shape which is described with reference to figure 3D. The marginal sections of the membranes 12c and 12d are adhered to the horizontal wall sections 1 and 19b respectively by means of a layer of adhesive 17a and 17b respectively. After adhering the marginal membrane section to the tube l4d the eventual projecting part of the marginal section can be cut off as is shown for the left hand membrane ^* 12c or can be left hanging in the tube l4d as is shown for the right hand membrane 12d. Because the upper wall sections 19a and 19b are extending horizontally also the thereto adhered part of each membrane will extend horizontally avoiding thereby the formation of a slight indentation 30 as is present in the embodiment illustrated in figure 4.

Figure 7 illustrates the application of mechanical fastening means such as screws or rivets in combination with a tube of the type illustrated in figure 3E. The membrane 12e at the left hand side of the figure is attached to the tube l4e by means of a blind rivet 32. To extend the clamping action of the rivet 3 preferably a washer 3 of relatively large dimensions is used in the illustrated manner. The membrane 12f at the right hand side of the figure is fixed to the upper wall of the tube l4e by means of a screw 36 which is screwed into a predrilled hole in the wall. Preferably a relatively large washer 38 is used to extend the clamping area of the screw 36. Just as in figure 6

one has the choice between cutting of the eventual projecting part of the membrane, as is done with membrane 12e, and let the overlapping part of the membrane hang down in the tube, as is done for membrane 12f. Figure 8A illustrates the manner in which by means of separate bridge parts 24 the form stability of the tube, when using especially the embodiment l4c illustrated in figure 3C, can be assured. The way in which the membrane 12 is folded around the edge of the tube l4c and is attached thereto by means of the clamping element 22, is as such already described with reference to figure 4. After positioning the clamping strips 22 the bridge part 24 is snapped over the aperture in the tube l4c. For that purpose the bridge part 24 comprises two legs 26 (one of which is visible in the figure) , which snap around the clamping elements 22. Preferably the end sections of the bridge part resting upon the clamping means 22 are provided with a hook 28 snapping around the clamping means 22. Because of these hooks 28 the bridge part 24 assures that the tube will maintain its circular shape and will not be pressed together or will be bend open.

The central part of the bridge section 24 can have a bended shape such as illustrated in figure 8A, the radius of the bend being the same as the radius of the tube 14c, but may also be embodied as a flat sec¬ tion as illustrated in figure 8B.

The flat bridge part 24a in figure 8B is apart from the flat central section almost identical to the bridge part illustrated in figure 8A. After positioning the clamping strips 22 the bridge part 24a is snapped over the aperture in the tube l4c. For that purpose the bridge part 24a comprises two legs 26a, which snap around the clamping elements 22. Preferably the end sections of the bridge part resting upon the clamping means 22 are provided with a hook 28a snapping around the respective clamping means 22. The coupling between two tubes is illustrated in a cross- sectional view in figures 9A and 9B. The tubes l4f and l4g in figure 9A are coupled through the coupling sleeve 40. Taking into account the fact that the tubes can have a considerable length such as 5 or 10 meters it is preferred to maintain a gap between the tubes l4f and l4g as shown in figure 9 providing space for extension of the tubes as the environmental temperature rises. Because dependent of the material of the tubes the length thereof may vary with temperature preferably the tubes are not fixed to the coupling sleeve but are loosely inserted in said sleeve

whereby to obtain a watertight non leaking coupling a greasy or fatty substance is applied between the inner wall of the sleeve and the adjacent parts of the tubes l4f and l4g, which substance is indicated by 42 in figure 9- A suitable greasy substance is for instance vaseline. - In figure B the coupling sleeve 44 forms an integral part of one of the tubes l4h. Between the inner wall of the sleeve section 44 and the outer wall of the other tube l4k a sealing ring 46 of a flexible material such as rubber is installed to assure the watertightness of the connection. During installation of a system according to the invention first of all trenches are made to accommodate the tubular gutters. Thereafter a series of foundation piles is pressed with predetermined mutual distance into the ground whereby care is taken that the top surfaces of said piles together determine a slightly sloping line. Thereafter the tubes are positioned on top of the row of foundation piles whereby connections between the tubes are made as described above. Preferably the tubes are fixed to the foundation piles by suitable fastening means such as nails or screws in combination with rubber washer or other suitable means to prevent leakage. In stead of nails or screws an adhesive can be used to adhere the bottom wall of the tube to the top surface of the foundation pile.

Thereafter the remaining spaces at both sides of the tubular gutter are filled with soil and the whole terrain is preshaped such that the desired slopes are obtained. Then the membrane is rolled out and the margins thereof are fastened to the tubular gutter in the above described manner.