- 1 ARTIFICIAL GRASS SYSTEM The present invention relates to an artificial 5 (sometimes referred to in the industry as "synthetic") grass system that has a capability to drain, and in one embodiment, capture and store, rainwater that falls on the surface of the system. 10 The present invention relates particularly, although by no means exclusively, to an artificial grass system that can be used for recreational playing fields for sports, such as cricket, hockey, soccer, rugby, and football, that are exposed to the elements all of the time 15 or for part of the time in the case of playing fields in stadiums that have roofs that can be opened and closed. The present invention also relates to a recreational playing field for sports, such as cricket, 20 hockey, soccer, rugby, and football, that includes such an artificial grass system. The present invention also relates to a method of constructing such an artificial grass system. 25 According to the present invention there is provided an artificial grass system that comprises: (a) a layer of artificial grass on an area of ground; and 30 (b) a shock absorption element beneath the artificial grass layer that allows water to flow through the layer and is adapted to absorb impact of players and/or equipment on the artificial grass layer, the shock absorption element formed from a shock absorbing material 35 and including voids that promote shock absorption; and (c) a water collection element beneath the shock absorption element for directing downwardly flowing 5978763_1 (GHMatters) P81810.AU.2 PETAK 21/11/14 - 2 rainwater therethrough; and (d) at least one layer of permeable material beneath the water collection element. 5 According to the present invention there is also provided an artificial grass system that comprises: (a) a layer of artificial grass on an area of ground; (b) a shock absorption element beneath the 10 artificial grass layer that allows water to flow through the layer and is adapted to absorb impact of players and/or equipment on the artificial grass layer, the shock absorption element formed from a shock absorbing material and including voids that promote shock absorption; 15 (c) a water collection element beneath the shock absorption element for directing downwardly flowing rainwater therethrough; (d) at least one layer of permeable material beneath the water collection element; and 20 (e) optionally, at least one underground water storage tank for storing rainwater that falls on the artificial grass layer and flows downwardly through the artificial grass layer. 25 Accordingly, there is provided in one embodiment an artificial grass system that includes: (a) a layer of artificial grass on an area of ground; and 30 (b) at least one underground water storage tank for storing rainwater that falls on the artificial grass layer and flows downwardly through the artificial grass layer. 35 The above-described artificial grass system makes it possible to harvest and store for use (as required) a 5978763_1 (GHMatters) P81810.AU.2 PETAK 21/11/14 - 3 substantial part, if not all, of the rainwater that falls on the artificial grass surface. Artificial grass does not retain water - consequently substantially all, if not all, of the rainwater that falls on the artificial grass 5 flows downwardly through the grass layer and is potentially available for harvesting and subsequent use. Hence, in a situation in which the artificial grass system forms a recreational playing field, the invention can harvest water for use beneficially, for example for 10 watering and thereby maintaining gardens or natural grass recreational playing fields in the general area of the artificial grass playing field and/or for other end use applications. 15 The artificial grass may be any suitable artificial grass for a given end use activity, such as cricket and/or football. The artificial grass system may comprise a water 20 collection element between the artificial grass layer and the water storage tank that extends below at least a substantial section of the area of the artificial grass layer and is adapted to direct downwardly flowing rainwater to flow into the water storage tank. In this 25 regard, it is relevant to note that in many applications of the artificial grass system of the present invention the artificial grass layer may have a substantially larger surface area, i.e. footprint, than that of the water storage tank. The water collection layer is necessary in 30 such situations to direct downwardly flowing rainwater to the water storage tank for collection and storage in the tank. The water collection element may comprise a 35 plurality of water flow passages that can receive water that flows downwardly onto the element and can direct the water to the water storage tank or be otherwise formed to 5978763_1 (GHMatters) P81810.AU.2 PETAK 21/11/14 - 4 direct water that contacts the water collection element into the water storage tank. The artificial grass system may comprise a shock 5 absorption element between the artificial grass layer and the water storage tank that allows water to flow through the element and is adapted to absorb impact energy of players to minimise impact injuries to players. 10 The shock absorbing element may be formed from a shock absorbing material. The shock absorption element may allow water to flow downwardly through the element. 15 The shock absorption element may allow water to flow downwardly and laterally through the element. The shock absorption element may be between the 20 artificial grass layer and the water collection layer. The shock absorption element may be made from a permeable material that allows rainwater to flow through the material. 25 The shock absorption element may be formed with passageways that allow rainwater to flow through the material. 30 The shock absorption element may have a shape that promotes shock absorption. For example, the shock absorption element may comprise voids that promote shock absorption. 35 By way of further example, the shock absorption element may comprise an upper wall and a plurality of side 5978763_1 (GHMatters) P81810.AU.2 PETAK 21/11/14 - 5 walls that extend downwardly from the upper wall and a plurality of open voids defined by the upper wall and the side walls. 5 The shock absorption element may be formed from a shock absorbing material, such as rubber or an ethylene vinyl acetate (EVA). The water storage tank may be located below a 10 section of the layer of artificial grass. The water storage tank may also be located away from the area of ground on which the layer of artificial grass is located. There may be situations in which it is 15 not possible to locate the water storage tank below the artificial grass layer and locating the tank away from the area of ground may be necessary. The water storage tank may comprise a framework 20 that defines a water storage chamber and an outer liner of a water impermeable material. The framework may comprise a base and sides. 25 The liner may be positioned under the base and extend up the sides of the framework. The artificial grass system may comprise a filter element above the water storage tank to prevent 30 contaminants, such as animal faecal matter, entering the water storage tank. The purpose of the filter element is to remove impurities that may significantly limit subsequent use of the water in the water storage tank. 35 The artificial grass system may comprise a water impermeable liner, for example defined by a plastic material membrane, below the water storage tank. The 5978763_1 (GHMatters) P81810.AU.2 PETAK 21/11/14 - 6 purpose of the water impermeable liner is to at least partially close the system. More particularly, the artificial grass system 5 may be a completely closed system so that there is no loss of water from the system into the surrounding ground. The artificial grass system may comprise a water distribution system for distributing water in the water 10 storage tank to end-use applications for the water. Also disclosed herein is an artificial grass system that comprises: 15 (a) a layer of artificial grass on an area of ground; and (b) a shock absorption element beneath the artificial grass layer that allows water to flow through 20 the layer and is adapted to absorb impact of players and/or equipment on the artificial grass layer. The shock absorbing element may be formed from a shock absorbing material. 25 The shock absorption element may allow water to flow downwardly through the element. The shock absorption element may allow water to 30 flow downwardly and laterally through the element. The shock absorption element may be made from a permeable material that allows rainwater to flow through the material. 35 The shock absorption element may be formed with passageways that allow rainwater to flow through the 5978763_1 (GHMatters) P81810.AU.2 PETAK 21/11/14 -7 material. The shock absorption element may have a shape that promotes shock absorption. 5 For example, the shock absorption element may comprise voids that promote shock absorption. By way of further example, the shock absorption 10 element may comprise an upper wall and a plurality of side walls that extend downwardly from the upper wall and a plurality of open voids defined by the upper wall and the side walls. 15 The shock absorption element may be formed from a shock absorbing material, such as rubber or an ethylene vinyl acetate (EVA). According to the present invention there is also 20 provided a recreational playing field for sports, such as cricket, hockey, soccer, rugby and football, that comprises the above-described artificial grass system. In a situation in which the artificial grass 25 system covers the whole of the playing field, the water storage tank may be adapted to store at least 2 million litres of water. According to the present invention there is also 30 provided a method of constructing the artificial grass system, as described above, on an area of ground which comprises: (a) excavating the area of ground; (b) locating a water collection element in the 35 excavating area, the water collection element being adapted for directing water downwardly flowing rainwater therethrough; 5978763_1 (GHMatters) P81810.AU.2 PETAK 21/11/14 - 8 (c) locating a shock absorption element above the water collection element, the shock absorption element being adapted to allow water to flow through the layer and to absorb impact of players and/or equipment on artificial 5 grass ultimately laid on the element; and (d) laying artificial grass on the area of ground. Also disclosed herein is a method of constructing an 10 artificial grass system on an area of ground that comprises: (a) excavating the area of ground; 15 (b) locating at least one water storage tank in the excavated area; and (c) laying artificial grass on the area of ground. 20 Also disclosed herein is a method of constructing an artificial grass system on an area of ground that comprises: 25 (a) excavating the area of ground; (b) locating a shock absorption element in the excavated area, the element being adapted to allow water to flow through the layer and to absorb impact of players 30 and/or equipment on artificial grass ultimately laid on the element; and (c) laying artificial grass on the area of ground. 35 The present invention is described further by way of example with reference to the accompanying drawings, of 5978763_1 (GHMatters) P81810.AU.2 PETAK 21/11/14 -9 which: Figure 1 is a partially cut-away perspective view of one embodiment of an artificial grass system in 5 accordance with the present invention; Figure 2 is a vertical cross-section that further illustrates the artificial grass system shown in the Figures; 10 Figure 3 is another vertical cross-section that further illustrates the artificial grass system shown in the Figures; 15 Figure 4 is a top plan view of a section of the shock pad layer of the artificial grass system shown in the Figures; Figure 5 is a side view of the long side of the 20 shock pad layer shown in Figure 4; and Figure 6 is a side view of the short side of the shock pad layer shown in Figure 4. 25 The Figures illustrate one embodiment of an artificial grass system in accordance with the present invention that forms a playing surface of a recreational playing field for sports, such as cricket, soccer, hockey, rugby, and football, that is exposed to the elements all 30 of the time or for part of the time as is the case of playing fields in stadiums that have roofs that can be opened and closed. With reference to Figures 1 to 3, the artificial 35 grass system is constructed by excavating a suitable area to form the playing field and the below-ground elements of the artificial grass system and then positioning the 5978763_1 (GHMatters) P81810.AU.2 PETAK 21/11/14 - 10 following elements in the order set out below into the excavated area to form the artificial grass system: (a) a water impermeable liner 3, for example in 5 the form of a plastic membrane 3 that is impermeable to water, that is located on the base and sides of the excavation (see Figure 3) and is designed to close the system and retain water in the system, for example for environmental reasons; 10 (b) a layer 5 of permeable material, typically a 150 mm layer of washed river sand or crushed glass, on top of the membrane 3; 15 (c) a layer 7 of a geotextile material or other suitable that filters contaminants, such as animal faecal matter, (d) at least one underground water storage 20 chamber 9 for storing rainwater that falls on the artificial grass layer system and flows downwardly through the system - the chamber is defined by a framework of milk crates stacked on top of each other, although it is emphasised that this is only one of a number of options 25 for the framework; (e) a layer 11 of a geotextile material or other suitable material that extends over the upper wall of the chamber 9 and filters contaminants, such as animal 30 faecal matter, and purifies the water flowing into the chamber 9; (f) a layer 15 of permeable material, typically a 300 mm layer of washed river sand or crushed glass that 35 filters contaminants, such as animal faecal matter, and purifies the water flowing downwardly; 5978763_1 (GHMatters) P81810.AU.2 PETAK 21/11/14 - 11 (g) a layer 17 of a geotextile material or other suitable material that filters contaminants, such as animal faecal matter, and purifies the water flowing downwardly; 5 (h) a water collection element 19 that extends substantially under the whole of the footprint of the playing field and directs downwardly flowing water to the water storage chamber 9 for collection and storage in the 10 chamber - typically, the layer has a 1*-3* fall to the water storage chamber 9 footprint - the cross-section shown in Figure 3 shows that the water storage tank does not extend below the whole of the surface of the layer of artificial grass and, as a consequence, the water 15 collection layer is necessary and important in such situations to maximise the harvesting of rainwater from the whole of the surface of the layer of artificial grass; (i) a layer 21 of a geotextile material or 20 other suitable material that filters contaminants, such as animal faecal matter, and purifies the water flowing downwardly; (j) a shock absorption element 23 shown in more 25 detail in Figures 4 to 6 that is adapted to absorb impact of players to minimise impact injuries to players; (k) a layer 25 of a geotextile material or other suitable material that filters contaminants, such as 30 animal faecal matter, and purifies the water flowing downwardly; and (1) a layer 27 of artificial grass that forms the playing surface of the field. 35 In effect, the liner 3, the layer 5 of permeable material, the layer 7 geotextile material, the water 5978763_1 (GHMatters) P81810.AU.2 PETAK 21/11/14 - 12 storage chamber 9, the layer 11 of geotextile material, and the layer 15 of permeable material define an assembly of a water storage tank and a filter system for filtering water flowing into the tank. 5 The artificial grass system also comprises a water distribution system (not shown) that comprises, by way of example, water pipes (not shown) and pumps (not shown) that can distribute water from the water storage 10 tank 9 to gardens or natural grass playing fields or other end-use applications in the vicinity of the artificial grass playing field. By way of example only, the total excavation 15 depth is approximately 1.4 m and the water storage tank has a 3 million litre capacity. Typically, the dimensions of the tank are: 80 m long, 46 m wide and 0.88 m deep. With reference to Figures 4 to 6, the shock 20 absorption element 23 for this embodiment of the present invention comprises a plurality of mats 31 that are laid on the surface of the geotextile layer 21 to form a continuous element 23. Each mat 31 is made from a shock absorbing material such a rubber or an EVA that is moulded 25 into a shape that promotes shock absorption. Specifically, each mat 31 comprises voids that promote shock absorption. More specifically, each mat 31 comprises a combination of a moulded shock absorbing material structure that includes voids, whereby the 30 combination of the properties of the material and the shape of the mats (including the voids) promotes shock absorption. With particular reference to Figures 4 to 6, each mat 31 comprises an upper wall 33 and a plurality of downwardly depending side walls 35 and a plurality of open 35 voids 37 defined by the upper wall 33 and the side walls 35. 5978763_1 (GHMatters) P81810.AU.2 PETAK 21/11/14 - 13 The above-described artificial grass system is an effective system for collecting rainwater that falls on the artificial grass layer 27 so that the water can be used as required beneficially and does not simply drain 5 away. Many modifications may be made to the present invention as described above without departing from the spirit and scope of the invention. 10 By way of example, whilst the embodiment of the artificial grass system is described with reference to the Figures in the context of use for recreational playing fields for playing sports, such as cricket, soccer, 15 hockey, rugby and football, the present invention is not so limited and extends to other uses of artificial grass systems, such as artificial lawn areas in garden settings. By way of further example, whilst the embodiment 20 of the artificial grass system is described with reference to the Figures comprises a water storage tank, the present invention is not so limited and extends to systems that do not include tanks and do not otherwise harvest water. In particular, the present invention also includes 25 embodiments that are based on the combination of a shock absorption element (such as the element 23 in the Figures) and an artificial grass layer (such as the layer 27 in the Figures). 30 By way of further example, whilst the embodiment of the artificial grass system is described with reference to the Figures in the context of a single water storage tank, the present invention is not so limited and extends to the use of a plurality of such tanks positioned under 35 the artificial grass. By way of further example, whilst the embodiment 5978763_1 (GHMatters) P81810.AU.2 PETAK 21/11/14 - 14 of the artificial grass system described with reference to the Figures comprises a single water storage tank located below the artificial grass layer 27, the present invention is not so limited and extends to arrangements in which the 5 water storage tank is located outside the area covered by the artificial grass layer 27. As discussed above, this may be appropriate in a number of situations, for example, where there are constraints on excavating in the ground on which the artificial grass layer 27 is required. 10 By way of further example, whilst the embodiment of the artificial grass system described with reference to the Figures comprises harvesting rainwater that flows onto and through the artificial grass layer 27, the present 15 invention is not so limited and extends to harvesting rainwater from a range of urban surfaces, such as roofs of buildings and carparks, and from stormwater systems. Specifically, in addition to being a range to receive rainwater flowing downwardly through the artificial grass 20 layer 27, the water storage tank may also be connected to harvest water from these urban surfaces and stormwater systems. 5978763_1 (GHMatters) P81810.AU.2 PETAK 21/11/14