Abstract:
Systems and methods for a permeable pavement system are described. The permeable pavement system includes blocks designed to facilitate water seepage between the blocks and to permit water storage within the blocks. The blocks may be cabled together to create paving units that facilitate installation and maintenance of the pavement system. The permeable pavement system provides improved management of stormwater, reducing runoff and facilitating infiltration of stormwater into the subgrade below the paving system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 12/014,325, filed Jan. 15, 2008, the entire contents of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates in general to the field of paving systems. More particularly, the present invention relates to a modular, permeable paving system. Specifically, a preferred embodiment of the present invention relates to a permeable paving system utilizing paving units made from blocks cabled together and providing fluid storage within the blocks. 
         [0004]    2. Discussion of the Related Art 
         [0005]    As is known to those skilled in the art, paving systems historically create a surface impervious to rain. The water that falls on the paved surface runs off the edge of the paving surface rather than being absorbed into the ground beneath the paved surface. It is recognized that an increasing number of paved surfaces and the subsequent stormwater runoff from these paved surfaces contributes to lowered water tables and rising stream levels. Thus, it is a previously recognized problem with paving systems that stormwater runoff needs to be managed. 
         [0006]    Historically, it was known in the prior art to manage stormwater using a curb and gutter system to guide the stormwater into sewer systems. More recently the stormwater has been guided into detention basins to allow the water to be absorbed closer to the paved surface. Needless to say, it is desirable to provide a permeable pavement system allowing the stormwater to drain through the paving system and to be absorbed into the ground under the paving system, minimizing the need for any additional stormwater management system. 
         [0007]    However, such a permeable pavement system has not been fully realized without incurring various disadvantages. For example, U.S. Pat. No. 5,797,698 and U.S. Pat. No. 6,939,077 disclose paving elements designed to allow water to drain between adjacent paving blocks. While these paver blocks, as disclosed, allow stormwater to drain down the sides of the block, they are still susceptible to one of the major drawbacks of existing permeable pavement systems: they are dependent on the aggregate interlock and aggregate subgrade and the underlying soil for infiltration. Sandy or rocky soils have more cracks and fissures that allow the water to filter into and away from the surface, but heavy, clay soils do not drain quickly and require a longer retention time prior to the water entering the soil. 
         [0008]    Another previously recognized approach to solving the problem of being dependent on the subgrade and soil for infiltration involves the use of underground storage systems. These storage systems are made of plastic and have several feet of aggregate dumped on top of them. A disadvantage of this approach is the inability to clean out the underground storage systems once they are filled with sedimentation and particulates from stormwater runoff. Therefore, a preferred solution will manage the stormwater runoff to improve infiltration of the water into any type of soil and, if it becomes necessary, will allow for sedimentation to be cleaned out from the water storage system. 
       SUMMARY AND OBJECTS OF THE INVENTION 
       [0009]    Consistent with the foregoing and in accordance with the invention as embodied and broadly described herein, a paver block and a permeable pavement system are disclosed in suitable detail to enable one of ordinary skill in the art to make and use the invention. 
         [0010]    In basic form, the invention is a permeable paving system made up of interlocking blocks. These blocks and multiple blocks may be installed as a mat. The blocks are designed to facilitate water drainage down the sides of the block. In addition, the blocks include a storage cavity storing fluid within the block. This results in a permeable paving system that provides for stormwater storage within the paving system unlike conventional paving systems. 
         [0011]    In one embodiment of the invention, a block includes an upper surface and a lower surface opposite the upper surface. The upper and lower surfaces are connected by a plurality of sides. At least one of the sides includes a drainage spacer that extends along at least a portion of the side. At least one of the lower surface and the plurality of sides has a cavity at least partially enclosed by the block. The cavity allows fluid to be stored within the block, and the volume of the cavity is at least two percent of the volume of the block. 
         [0012]    In another embodiment of the invention, the cavity extends along the lower surface of the block. The width of the cavity is between 25 and 60 percent of the width of the lower surface, and the height of the cavity is between 25 and 60 percent of the height of one of the sides of the block. 
         [0013]    In still another embodiment, the cavity extends along one of the sides of the block. The height of the cavity is between 25 and 50 percent of the height of one of the sides, and the width of the cavity is between 20 and 50 percent of the width of the upper surface of the block. 
         [0014]    In another embodiment, the upper surface joins the plurality of sides at a rounded edge, and the angle, alpha (α), between at least one of the sides and a vertical plane is less than about five degrees. In yet another embodiment, the cavity of the block is arched, and in still another embodiment, the cavity of the block has sufficient volume to store at least an inch of rain that falls on the upper surface of the block. 
         [0015]    In one embodiment, the block includes an upper surface and a lower surface opposite the upper surface. The upper and lower surfaces are connected by a plurality of sides. At least one of the sides includes a drainage spacer that extends along at least a portion of the side. A first side of the block contains at least one aperture and a second, opposing side contains at least one aperture. Each of the apertures on the first side has a corresponding aperture on the second side and a fluid passage is defined between each of the corresponding apertures. The volume of the at least one fluid passage is at least two percent of the volume of the block and allows fluid storage within the block. 
         [0016]    In still another embodiment of the invention, a permeable pavement system includes a plurality of blocks. Each of the plurality of blocks may be, but is not limited to, one of the embodiments of blocks described above. A cable runs through a plurality of ducts. Each duct is contained within one of the plurality of blocks. The cable-connected blocks may then be installed as a single paving unit. 
         [0017]    According to yet another embodiment of the invention, a permeable paving system includes a plurality of paving units, and each paving unit includes a plurality of blocks. Each block includes a pair of ducts, extending through the block, and a storage cavity. The paving unit also includes a plurality of cables having a first end and a second end. The first end of each cable is inserted through one of the ducts of the multiple blocks, joining the multiple blocks, until the majority of each cable is contained within the multiple blocks. In one embodiment, the first end of each cable is looped back and secured to the cable to form a first lifting loop, and the second end of each cable is looped back and secured to the cable to form a second lifting loop. 
         [0018]    In another embodiment, two cables are connected to provide a singular cable and lifting loop. The cables are preferably extend a foot or two beyond the side of the block and are crimped together to form a singular loop with metal crimps. 
         [0019]    In another aspect of the invention, a first duct of the pair of ducts is proximate to a first side of the block, and a second duct of the pair of ducts is proximate to a second side of the block. Each cable is inserted alternately through a first duct and a second duct of successive blocks. In still another aspect of the invention, each block has a first end a second end opposite the first end. The first end of each block has a first non-planar geometric surface, and the second end of each block has a second non-planar geometric surface complementary to the first non-planar geometric surface such that the first end and the second end restrict lateral movement between adjacent blocks. 
         [0020]    According to yet another aspect of the invention, the permeable paving system further includes at least two paving units and a plurality of lock blocks. Each paving unit has a first end, a second end, and a width, and each lock block has a depth and a width. The width of each lock block is generally uniform and less than the width of the paving unit. One end of one of the two paving units is opposed to one end of the other of the at least two paving units and spaced apart by the depth of the lock block. Each of the lock blocks is placed adjacent to another of the lock blocks between the two paving units. 
         [0021]    In still another aspect of the invention, each of the lock blocks is substantially the same as each of the plurality of blocks in the paving unit. For each of the plurality of blocks and each of the lock blocks, an upper surface is closed and a lower surface includes the storage cavity. The storage cavity is an arched channel extending along the depth of the block, and the first lifting loop and the second lifting loop of the opposed paving units are configured to fit within the storage cavity of one of the lock blocks. Each of the lock blocks adjacent to one of the paving units may be removed such that the paving unit may be lifted from the paving system to allow the cavities of each of the plurality of blocks to be cleaned. The paving units may be reinserted into the paving system and each of the lock blocks reinstalled. 
         [0022]    In yet another aspect of the invention, the permeable pavement system further includes a subgrade extending substantially beneath each of the paving units. The cavities in the plurality of blocks have sufficient volume to store at least one inch of rain, which falls on an upper surface of each of the plurality of blocks and which subsequently filters into the subgrade. 
         [0023]    In yet another embodiment of the invention, a permeable pavement system includes at least two paving units. Each paving unit has a first end, a second end opposite the first end, a plurality of blocks, and a plurality of cables joining the plurality of blocks. Each of the plurality of cables is terminated at a first lifting loop at the first end of the paving unit and a second lifting loop at the second end of the paving unit. 
         [0024]    In still another aspect of the invention, the permeable paving system further includes a plurality of lock blocks. Each lock block is configured to be placed between one of the first end and the second end of a first paving unit and one of the first end and the second end of a second paving unit. Each of the lock blocks may be substantially the same as each of the plurality of blocks in the paving units. 
         [0025]    According to another aspect of the invention, the permeable paving system further includes a subgrade extending under each of the paving units. The subgrade may include between 6 inches (15.2 cm) and 11 inches (28.9 cm) of stone. A first layer of the subgrade may include stone less than 1 inch (2.5 cm) in diameter and a second layer of the subgrade may include stone greater than 1 inch (2.5 cm) in diameter. 
         [0026]    In yet another aspect of the invention, each of the blocks includes a closed upper surface and a lower surface having a channel extending along the depth of the block. Each of the blocks may include at least one drainage spacer protruding from a first side and a second side opposite the first side. Each drainage spacer extends along a portion of the height of each side. The channels in the plurality of blocks have sufficient volume to store at least one inch of rain, which falls on the upper surface of each of the plurality of blocks, within the paving unit such that the water filters into a subgrade. 
         [0027]    In still another embodiment of the invention, a permeable paving system includes a subgrade, a plurality of paving units, and a plurality of cables. The subgrade includes between about 5 inches (12.7 cm) and 11 inches (28.9 cm) of stone. The plurality of paving units is configured to be placed on the subgrade and each paving unit includes a plurality of blocks. Each block includes a lower surface, an upper surface opposite the lower surface, a first side wall extending between the lower surface and the upper surface, a second side wall opposite the first side wall and extending between the lower surface and the upper surface, a first end extending between the lower surface and the upper surface, a second end opposite the first end and extending between the lower surface and the upper surface, a pair of ducts extending through the block between the first end and the second end, a storage cavity extending along the lower surface between the first end and the second end, and a pair of spacers protruding from each of the first and the second side wall. The plurality of cables has a first end and a second end. The first end of each cable is inserted through one of the ducts of multiple blocks until the majority of each cable is contained within the multiple blocks. The first end of each cable is looped back and secured to the cable to form a first lifting loop, and the second end of each cable is looped back and secured to the cable to form a second lifting loop. 
         [0028]    These and other aspects and objects of the present invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following description, while indicating preferred embodiments of the present invention, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    A clear conception of the advantages and features constituting the present invention, and of the construction and operation of typical mechanisms provided with the present invention, will become more readily apparent by referring to the exemplary, and therefore non-limiting, embodiments illustrated in the drawings accompanying and forming a part of this specification, wherein like reference numerals designate the same elements in the several views, and in which: 
           [0030]      FIG. 1  is a top view of one embodiment of a block incorporated into the paving system according to the present invention; 
           [0031]      FIG. 2  is a sectional view taken along  2 - 2  of  FIG. 1 ; 
           [0032]      FIG. 3  is an end view of the embodiment of the block of  FIG. 1 ; 
           [0033]      FIG. 4  is a side view of the embodiment of the block of  FIG. 1 ; 
           [0034]      FIG. 5  is an end view of another embodiment of a block incorporated into the paving system according to the present invention; 
           [0035]      FIG. 6  is a top view of another embodiment of a block incorporated into the paving system according to the present invention; 
           [0036]      FIG. 7  is a sectional view taken along  7 - 7  of  FIG. 6 ; 
           [0037]      FIG. 8  is an end view of the embodiment of the block of  FIG. 6 ; 
           [0038]      FIG. 9  is a right side view of the embodiment of the block of  FIG. 6 ; 
           [0039]      FIG. 10  is a left side view of the embodiment of the block of  FIG. 6 ; 
           [0040]      FIG. 11  is a top view of one embodiment of a paving unit incorporated into the paving system according to the present invention; 
           [0041]      FIG. 12  is a sectional view taken along  12 - 12  of  FIG. 11 ; 
           [0042]      FIG. 13  is a top view of one embodiment of the present invention; 
           [0043]      FIG. 14  is a bottom view of a joint connecting two paving units according to the embodiment shown in  FIG. 13 ; 
           [0044]      FIG. 15  is a sectional view taken along  15 - 15  of  FIG. 14 ; 
           [0045]      FIG. 16  is a partial bottom view of another embodiment of a paving unit incorporated into the paving system according to the present invention; 
           [0046]      FIG. 17  is a sectional view of a paving unit as shown in  FIG. 16  being positioned end-to-end to another paving unit as shown in  FIG. 16 ; 
           [0047]      FIG. 18  is a partial bottom view of the two paving units shown in  FIG. 17  without a lock block inserted; 
           [0048]      FIG. 19  is a partial sectional view of the two paving units shown in  FIG. 17  without a lock block inserted; 
           [0049]      FIG. 20  is a partial bottom view of the two paving units shown in  FIG. 17  with a lock block inserted; 
           [0050]      FIG. 21  is a partial sectional view of the two paving units shown in  FIG. 17  with a lock block inserted; 
           [0051]      FIG. 22  is an exemplary embodiment of lifting a paving unit; and 
           [0052]      FIG. 23  shows a perspective view of another embodiment of the present invention. 
       
    
    
       [0053]    In describing the preferred embodiments of the invention which are illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific terms so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. For example, the word “connected”, “attached”, or terms similar thereto are often used. They are not limited to direct connection but include connection through other elements where such connection is recognized as being equivalent by those skilled in the art. 
       DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0054]    Specific embodiments of the present invention will now be further described by the following, non-limiting examples which will serve to illustrate various features of significance. The examples are intended merely to facilitate an understanding of ways in which the present invention may be practiced and to further enable those of skill in the art to practice the present invention. Accordingly, the examples should not be construed as limiting the scope of the present invention. 
         [0055]    Turning initially to  FIGS. 1-4 , one embodiment of a block  20  used in a permeable pavement or permeable paving system  100  is illustrated. The block  20  is generally comprised of an upper surface  25 , a lower surface  30 , a first side wall, or side,  35   a , a second side wall, or side,  35   b , a first end  37   a , a second end  37   b , and a cavity  40 . It is contemplated that the block  20 , for example, a paver block, could be of any shape known to one of ordinary skill in the art, including, but not limited to, a square, a rectangle, and a hexagon. As illustrated in  FIG. 1 , the paver block  20  has two generally flat sides,  35   a  and  35   b , and two stepped ends,  37   a  and  37   b . Additionally, the paver block  20 , may be manufactured in a variety of heights, H 1 , widths, W 1 , and depths, D 1 . Preferably, the range of dimensions for the paver block  20  is from 9 to 15 inches (22.9 to 38.1 cm) wide, 9 to 15 inches (22.9 to 38.1 cm) deep, and 4 to 7 inches (10.2 to 17.8 cm) high. In one embodiment, the block is about 12 inches (30.5 cm) wide, 12 inches (30.5 cm) deep and 5 inches (12.7 cm) high. The paver block may be manufactured out of any material known to one of ordinary skill in the art, but is preferably a concrete block. At least one drainage spacer  45  extends at least partially along one of the sides,  35   a  or  35   b , of the paver block  20 . As illustrated in  FIGS. 1 and 4 , two drainage spacers  45  may extend vertically along the entire height, H 1 , of one of the sides,  35   a  or  35   b , of the paver block  20 . In addition, at least one, and preferably all, of edges  50  between the upper surface  25  and each of the sides,  35   a  and  35   b , and each of the ends,  37   a  and  37   b , will be rounded, creating seepage down the block. 
         [0056]    When used in a permeable pavement or permeable paving system  100 , multiple paver blocks  20  may be installed as a single paving unit  115  to increase the speed and efficiency of installation. To permit installation as a single paving unit  115 , each paver block  20  includes holes or ducts  110  passing through the paver block  20 . Each duct  110  is sized to allow a cable  105  to pass therethrough, and is preferably about one inch in diameter. In addition, the ends,  37   a  and  37   b , of the blocks through which the ducts  110  pass will have some angle, alpha (α), between the end,  37   a  or  37   b , and a vertical plane. It is desirable to minimize this angle as much as possible; however, the angle provides flexibility between blocks in a paving unit  115 . It is desirable to keep this angle, alpha (α), at about 3 degrees and preferably between 1 and 5 degrees. See, for example,  FIG. 4 . 
         [0057]    Referring next to  FIGS. 6-10 , another embodiment of a paver block  20  used in the permeable paving system  100  is illustrated. The paver block  20  is generally comprised of an upper surface  25 , a lower surface  30 , a first side  35   a , a second side  35   b , a first end  37   a , a second end  37   b , and a cavity  40 . The paver block  20  has two flat sides,  35   a  and  35   b , and two stepped ends,  37   a  and  37   b . It is contemplated that each of the ends,  37   a  and  37   b , may have various non-planar, geometric configurations other than the stepped end such that when placed next to each other, the first end  37   a  and the second end  37   b  restrict lateral movement between adjacent blocks. The paver block  20 , may be manufactured in a variety of heights, H 1 , widths, W 1 , and depths, D 1 . The illustrated embodiment of the paver block  20  is about 11.8 inches (30 cm) wide, 11.8 inches (30 cm) deep and 5.6 inches (14.2 cm) high. A pair of drainage spacers  45  protrudes from and extends at least partially along each of the flat sides,  35   a  or  35   b , of the paver block  20 . Further, the drainage spacers  45  on a first flat side  35   a  are laterally aligned such that they are offset from the drainage spacers  45  on a second flat side  35   b . Thus, when two paver blocks  20  are placed adjacent to each other, the drainage spacers  45  on the first flat side  35   a  of the first paver block  20  engage the second flat side  35   b  of the second paver block  20 . Similarly, the drainage spacers  45  on the second flat side  35   a  of the second paver block  20  engage the first flat side  35   b  of the first paver block  20 . The drainage spacers  45  may be manufactured in a variety of heights, H 4 , widths, W 4 , and depths, D 4 . Preferably, the range of dimensions for the drainage spacers  45  is from ⅛ to 2 inches (0.3 to 5.1 cm) wide, 1/16 to ½ inches (0.2 to 1.3 cm) deep, and from one-half the height, H 1 , of the paver block  20  to the entire height, H 1  of the paver block. The drainage spacers  45  of the illustrated embodiment are about 1 inch (2.5 cm) wide, ⅜ inches (1.0 cm) deep, and about 80 percent of the height, H 1 , of the paver block  20 . 
         [0058]    Each paver block  20  also includes ducts  110  passing from the first end  37   a  to the second end  37   b  of the paver block  20 . Each duct  110  is sized to allow a cable  105  to pass therethrough and may have any suitable cross-section. As illustrated in  FIG. 8 , an upper portion  112  of the duct  110  may be curved and a lower surface  114  of the duct  110  may be planar. Referring to  FIGS. 9 and 10 , the ends,  37   a  and  37   b , of the blocks through which the ducts  110  pass will have some angle, alpha (α), between the end,  37   a  or  37   b , and a vertical plane. It is desirable to minimize this angle as much as possible; however, the angle provides flexibility between blocks in a paving unit  115 . It is desirable to keep this angle, alpha (α), at about 3 degrees and preferably between 1 and 5 degrees. 
         [0059]    Referring next to  FIGS. 3 and 8 , a cavity  40  allows fluid storage within the paver block  20  and is configured to contain stormwater that has drained down the paver block  20 . The cavity  40  may be partially or wholly defined by the paver block  20 . The cavity  40  may be designed in a wide variety of shapes and sizes to allow for fluid storage within the paver block  20 . In the illustrated embodiment, the cavity  40  is an arch extending along the entire depth, D 1 , of the bottom surface  30 . Another embodiment of the cavity  40  is shown in  FIG. 5  wherein the cavity  40  is a fluid passage  65  extending entirely through the paver block  20 . A further embodiment of the cavity  40 , not illustrated, may include multiple fluid passages  65  extending through the paver block  20 . Still another embodiment of the cavity  40 , not illustrated, may be an arch extending along one or both of the sides,  35   a  and  35   b , of the paver block. The afore-mentioned examples disclose several embodiments for the cavity  40 , but the structure of the cavity  40  could be any shape or size capable of storing fluid within the block such as, but not limited to, a square, rectangular, or triangular cavity extending across the bottom, side, or through the paver block  20 . The cavity  40  extends generally along the center line of the block  20  defining, at least in part, a first and second generally planar portion of the lower surface  114  extending along the cavity  40  and between each of the first side  35   a  and the second side  35   b , respectively, of the block  20 . Because the width of the cavity  40  may vary between about 25 to about 60 percent of the width of the lower surface  114 , the first and second planar portions of the lower surface  114  may conversely define between about 40 and 75 percent of the lower surface  114 . In one preferred embodiment, the cavity  40  is an arched channel having a radius of about 3.3 inches (8.5 cm) and a height of about 2.6 inches (6.5 cm) as shown in  FIG. 8 . 
         [0060]    The paver block  20  is designed to balance fluid storage and structural integrity. Preferably, the volume of the cavity  40  allows for at least the first inch (2.5 cm) of stormwater that falls on the top surface  25  of the paver block  20  to be stored within the cavity  40  of the paver block  20 . This stored water subsequently filters out of the cavity  40  into the aggregate subgrade  135  and soil below the paving system  100 . 
         [0061]    Referring next to  FIGS. 11 and 12 , a paving unit  115  is constructed by passing multiple cables  105  through multiple paver blocks  20 . As illustrated, each paver block  20  may have a first duct  111  positioned proximate to the first side  35   a  and a second duct  113  proximate to the second side  35   b . The cable  105  may be inserted alternately through a first duct  111  and a second duct  113  of successive blocks. Optionally, the cable  105  may be inserted exclusively through either the first duct  111  or the second duct  113  of each block  20 . It is contemplated that the cable  105  may be, but is not limited to, one of the following materials: polyester, stainless steel, and galvanized steel. The resulting paving defines a first side  116 , a second side  118 , a first end  117 , and a second end  119 . 
         [0062]    According to one embodiment of the invention, illustrated in  FIGS. 11 and 13 , the cable  105  may protrude a short distance beyond the end of the last block  20  and loop back through the blocks  20  to create a lifting loop  107  at the end of each paving unit  115 . According to another embodiment of the invention, each cable  105  may terminate after passing through a single set of aligned ducts  110 . A first lifting loop  107  may be formed by looping back one end of the cable  105  and securing it to itself by any suitable device, such as a ferrule, clamp, or clip. A second lifting loop  107  may similarly be formed by looping back the other end of the cable  105  and securing it to itself. 
         [0063]    In another embodiment, two cables are preferably connected to provide a singular cable and lifting loop. The cables preferably extend a foot or two beyond the side of the block and are crimped together to form a singular loop with metal crimps. In order to maximize cable movement when placing the paving unit  115 , there are no washers or spacers provided between the end of the cable loop and the block and the crimps are far enough away to minimize interference. Once the unit is set in place, the singular cable is used to tighten the individual blocks within unit up. The cable is then folded over under the cavity of the last blocks in the unit. The cable is preferably made of a polyester for strength and integrity. 
         [0064]    It is contemplated that the paving unit  115  will be of varying widths, W 3 , and lengths, L, to accommodate the desired application, including, but not limited to, pathways, driveways, parking lots, and roads. Preferably, the paving unit  115  is about 8 feet (2.4 m) wide and may extend from 8 to 60 feet (2.4 to 18.3 m) in length. Based on its application, the paver block  20  may accommodate either pedestrian or vehicular traffic. The paver block  20  is preferably designed to accommodate a load of up to 4000 pounds per square inch (19.2 newton per square centimeter). 
         [0065]    Referring next to  FIG. 13 , multiple paving units may be installed adjacent to each other. Because the cable  105  is inserted in an alternating fashion between the first duct  111  and the second duct  113  of successive blocks  20 , a staggered edge forms along the paving unit  115 . As a first paving unit  115  and a second paving unit  115  are installed adjacent to each other, the paver blocks  20  along the side of the second paving unit  115  are positioned such that they interweave with the blocks  20  along the side of the first paving unit  115  in a “zippered” fashion, creating a continuous paved surface. In addition, the outer row of the ducts  110  along each edge of the paving units  115  may be left open during initial assembly because a cable  105  inserted in this row would alternately pass through a duct  110  and open space. However, once adjacent paving units  115  have been installed, the outer row of ducts  110  of one paving unit  115  align with the outer row of ducts  110  of the other paving unit  115 . Optionally, an interlocking cable  120  may, therefore, be passed through the two paving units, securing the first paving unit  115  to the second paving unit  115 . 
         [0066]    Multiple paving units  115  may also be installed in an end-to-end configuration. According to one embodiment of the invention, illustrated in  FIGS. 14 and 15 , the end loops  107  of the first paving unit  115  are tucked into the cavities  40  of the paver blocks  20  at the end of the second paving unit  115 . Likewise, the end loops  107  of the second paving unit  115  are tucked into the cavities  40  of the paver blocks  20  at the end of the first paving unit  115 . A sheath is laid into the gap between the two paving units  115 . Preferably, a very narrow veneer plastic sheath is used. Moreover, the preferred plastic sheath is only ten to twelve inches wide and eight to ten mils thick. This sheath prevents grout from entering the cavities  40  of the paver blocks  20  at the end of either paving unit  115  and additionally isolates the cables  105  from the grout. Finally, grout is poured between the two paving units  115  to form a joint  130 . The grout may be of any type known to one of skill in the art and suitable for the application, but is preferably a pervious concrete or small aggregate grout. 
         [0067]    According to another embodiment of the invention, illustrated in  FIGS. 17-21 , a second installation method is illustrated. A first paving unit  115  and a second paving unit  115  are installed in an end-to-end configuration. Due to the symmetry of the paving units  115 , a first end  117  of one paving unit  115  may be placed adjacent to either a first end  117  or a second end  119  of another paving unit  115 . The paving units  115  are spaced apart by a width substantially equal to the depth, D 1 , of one paver block  20 . The lifting loops  107  of adjacent paving units  115  are positioned on the substrate  135  such that they align with a storage cavity  40  in a subsequently inserted lock block  200 . Lock blocks  200  are inserted between the two paving units  115  to form a generally continuous surface between the two paving units  115 . According to one embodiment of the invention, each of the lock blocks  200  is substantially the same as each of the paver blocks  20  used in the paving units  115 . Optionally, the lock blocks  200  may be of any suitable form to cover the lifting loops  107  and span the distance between the two paving units  115 . 
         [0068]    Prior to installing the paving units  115 , a suitable subgrade  135  may be laid over the ground, G, on which the paving system  100  is to be installed. The thickness and/or composition of the subgrade  135  may vary according to the site requirements. According to one embodiment of the invention, a barrier layer  140 , such as a geogrid or geotextile material, may first cover the ground, G. A first layer of stone  142  covers the barrier layer  140 . The first layer of stone  142  may be between 5 and 10 inches (12.7 and 25.4 cm) thick and includes stone having a diameter of about 1 to 1 and one-half inches (2.5 to 3.8 cm). A second layer of stone  144  covers the first layer of stone  142 . The second layer of stone  144  is preferably one half inch (1.3 cm) thick and more preferably at least one inch (2.5 cm) thick, including stone having a diameter less than 1 inch (2.5 cm). 
         [0069]    Each paving unit  115  is preferably installed as a single unit. Referring to  FIG. 22 , an exemplary paving unit  115  is being lifted using a crane, but installation may be performed by any means known to one skilled in the art, such as a forklift. Further, if cleaning of the cavities  40  of the paver blocks  20  becomes necessary, the paving unit  115  may be subsequently lifted out, the cavities  40  and subgrade  135  cleaned of debris, and the paving unit  115  reinstalled. 
         [0070]    In operation, the paving units  115  are installed according to the requirements of each paving system  100 . The ground, G, of the installation site is tested to determine the appropriate composition and thickness of the subgrade  135 . After laying the subgrade  135 , the paving units  115  are installed to cover the installation site. Individual blocks  20  are inserted around the perimeter of the paving system  100  as necessary to provide a generally linear edge. Lock blocks  200  are inserted between paving units  115  to complete the surface of the paving system  100 . When rain falls on the paving system  100 , the rain runs down between the blocks  20  and is either filtered into the subgrade  135  or stored in the cavities  40  of the paving system  100  according to the capacity of the subgrade  135  and the rate of rainfall. As the rate of rainfall slows and/or stops, additional water stored in the cavities  40  of the blocks  20  is filtered into the subgrade  135 . The cavities in each of the plurality of blocks has sufficient volume to store at least one inch (2.5 cm) of rain from the upper surface of the plurality of blocks in the paving unit. 
         [0071]    The paving unit  115 , after having been installed, may require occasional cleaning. The paving system  100  is configured such that each of the lock blocks  200  along one end of a paving unit  115  may be removed, allowing the paving unit  115  to be subsequently lifted as a single unit and to allow cleaning of the cavities  40  of the blocks  20 , as necessary. Any debris or particulate present on the surface of the subgrade  135  may similarly be removed. Once the cleaning is complete, the steps may be reversed. The paving unit  115  is reinstalled and each of the lock blocks  200  reinserted. Optionally, access to the cavities  40  may be provided from one end of the paving system  100  and the blocks  20  may be cleaned while the paving units  115  remain installed. 
         [0072]    Turning now to  FIG. 23 , another embodiment of the inventive block is shown. Block  320  may also be used in a permeable pavement or permeable paving system  100  (not shown). The block  320  has an upper surface  325 , a lower surface  330 , a first side wall, or side,  335   a , a second side wall, or side,  335   b , a first end  337   a , a second end  337   b , and a cavity  340 . As illustrated, the paver block  320  has two generally flat sides,  335   a  and  335   b , and two ends,  337   a  and  337   b , that have a stepped structure. In this embodiment, the stepped sides protrude more than the embodiment described above. This helps the block have a more tightly fitting interconnection with similarly-shaped adjacent blocks. A pair of drainage spacers  345   a ,  345   b  preferably extend almost all of the height along both of the sides  335   a  and  335   b  of the paver block  320  from surface  325  to surface  330 . All of edges, e.g.,  350   a  and  350   b  between the upper surface  325  and each of the sides,  335   a  and  335   b , and each of the ends,  337   a  and  337   b , will be rounded, creating seepage down the block. Further, upper portion  338  of end  337   a  is angled slightly inwardly relative to lower portion  329  of side  337   a . End  337   b  may be similarly constructed. At least two ducts  351 ,  352  are provided for receiving attachment cables. Finally, the lower surface  330  preferably has two feet  355  and  357  which come into contact with the aggregate on the ground. The feet  355  and  357  are separated by the cavity  340  which forms water drainage channel  365 . 
         [0073]    In one preferred embodiment, a mix used to construct a paving unit made up of about 125 blocks includes about: 
         [0074]    700 LBS CEMENT 
         [0075]    2875 LBS LIMESTONE 
         [0076]    2475 LBS C. SAND 
         [0077]    11 OZ PLP (PLASTICIZER—Acme) 
         [0078]    16 OZ BF3 (DENSIFIER/PLASICIZER—Essroc) 
         [0079]    It should be noted that the invention can be utilized with existing permeable and non-permeable paving systems. For example, it is possible to install a subgrade  135  in or next to an existing concrete or asphalt parking lot. A paving unit  115 , sized appropriately, may then be placed on the subgrade  135 . Alternately, the subgrade  135  and paving unit  115  may be laid down first. Appropriate spacers and/or screens are placed along each end of the paving unit  115  to prevent concrete or asphalt, being laid adjacent to the paving unit  115 , from entering the cavities  40 , fluid passages  65 , or ducts  110  of the paving unit  115  as the concrete or asphalt is poured into the surrounding area. 
         [0080]    It has been noted that the construction of the block and cavity minimize the puddling of water on the block. Further, ice melts faster off of the inventive block than it does off a conventional surface, again, because of the construction and makeup of the inventive block. Finally, paving projects can be completed much more rapidly and consistently than poured concrete projects or those accomplished with asphalt because of the construction of the block and the paving unit. 
         [0081]    Although the best mode contemplated by the inventors of carrying out the present invention is disclosed above, practice of the present invention is not limited thereto. It will be manifest that various additions, modifications, and rearrangements of the features of the present invention may be made without deviating from the spirit and scope of the underlying inventive concept. 
         [0082]    For example, individual components of the disclosed block and paving unit need not be formed in the disclosed shapes, or assembled in the disclosed configuration, but could be provided in virtually any shape, so as to provide a paver block/unit with the novel features, e.g., a cavity capable of storing fluid. Furthermore, all the disclosed features of each disclosed embodiment can be combined with, or substituted for, the disclosed features of every other disclosed embodiment except where such features are mutually exclusive. 
         [0083]    It is intended that the appended claims cover all such additions, modifications, and rearrangements. Expedient embodiments of the present invention are differentiated by the appended claims.