Patent Publication Number: US-8992115-B2

Title: Surface drainage system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 13/592,742 entitled SURFACE DRAINAGE SYSTEM filed Aug. 23, 2012, which is a continuation of U.S. patent application Ser. No. 13/026,064 entitled SURFACE DRAINAGE SYSTEM flied Feb. 11, 2011, which is a continuation of U.S. patent application Ser. No. 11/903,085 entitled SURFACE DRAINAGE SYSTEM filed Sep. 20, 2007. 
    
    
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
     Not Applicable 
     BACKGROUND 
     1. Technical Field 
     The present invention relates generally to concrete structures and related construction methods, and more particularly, to surface drainage systems. 
     2. Background 
     Drainage systems are typically incorporated into paved streets, parking lots, airport runways, taxiways and ramps, driveways, and other like surfaces where surface water presents a substantial hazard. Such systems are configured to channel excess rain and ground water from the surface, and are typically comprised of conduits embedded beneath the surface to be drained. The conduit may form a part of a larger network of storm drains, which may transport water to a processing plant prior to discharge, directly discharge into a canal, river, lake, or the ocean, or discharge into small and localized dry wells. 
     Typically, conduits utilized in conventional surface drainage systems are elongate troughs with U-shaped or V-shaped cross sections. The conduits are disposed within the pavement in a manner that the open top is contiguous with the pavement surface. In order to facilitate gravitational flow, the pavement surface may be slightly sloped. It is understood that the conduits may be defined by the pavement material itself, such as where the pavement material is poured around a form that is later removed. The conduit thus corresponds to the shape of the form. Production of these types of conduits is expensive and time-consuming because of the need to install and remove the forms over extended periods of time. Alternatively, conduits may be stand-alone components constructed of metal, plastic, or other resilient material that are installed into the pavement. These open top conduits are difficult to install because they must be supported in a desired position while the pavement material is poured, particularly in such a position that the open top is flush with the pavement surface. To the extent that support members are utilized to maintain the desired position of the conduit, such components become permanently embedded within the pavement, thereby increasing costs. 
     Due to the wide open top of conventional drain conduits, grates are fitted thereon to prevent large debris from entering the conduit, to prevent injuries to pedestrians, and to prevent damage to vehicular traffic traveling over the conduit, while still allowing the excess surface water to pass. The grates are generally large and heavy because of the need to support the high load imposed by the traffic. As such, the grates tend to be unsightly and difficult to remove when the inside of the conduit needs to be cleaned. Along these lines, the grates often clog with debris that is likewise difficult to remove. Regardless of being able to support the load of vehicular traffic, the grates are hazardous to pedestrians, particularly to those wearing pointed-heel shoes or open-toe shoes. The heels may become wedged between the grates and cause the person to trip and fall. Or, a person&#39;s toes may also become trapped and likewise result in a fall, or worse, toe breakage. 
     As an alternative to using grates to cover the wide open tops of conventional drain conduits, slotted drains have been contemplated. Slotted drains generally consist of cylindrical pipes embedded beneath the surface, with relatively narrow slots or throats extending upwardly from the pipe to the surface. Thus, it is unnecessary to install a grate over the slots. Despite the small width of the slots, the conduit along which the water is carried to the outlet is large, so large volumes of water can be channeled away from the surface. Because of the specialized construction, slotted drains tend to be expensive. Due to the differences in the coefficient of thermal expansion between the slotted drains and the surrounding concrete, cracking of the concrete is a common problem. Especially problematic are parts of the paving that must conform to the diminutive subparts of the slotted drain, such as the throat and the lip of the opening. In environments where frequent freezing and thawing occur, this problem is further compounded. Furthermore, the above-described problems related to installation and particularly the problems of keeping the openings of the conduit flush with the pavement surface still remain. Support mechanisms added to alleviate the aforementioned problems further add to the cost of the slotted drains. In addition to the need for the surfaces surrounding the conduit openings/slots to be slanted, the conduit itself must be slanted to facilitate the flow of water. Accordingly, the difficulty associated with properly aligning the opening of the slotted drain with the pavement surface is multiplied. 
     Therefore, there is a need in the art for a surface drainage system that has minimal peripheral components such as throats, supports, and the like. There is also a need in the art for surface drainage systems that reduce dangers to pedestrians, and are visually attractive. There is also a need in the art for a method of constructing a surface drainage system that minimizes repeated alignment corrections, and generally simplifies the procedure. 
     BRIEF SUMMARY 
     In accordance with one embodiment of the present invention, there is provided a surface drainage structure formed above a subgrade. The structure may include an elongate drain conduit disposed partially within the subgrade. The elongate drain conduit may define at least one drain slot extending through a wall thereof. Further, the structure may include a pavement layer with an exposed top surface. The pavement layer may define a drainage channel extending from the top surface, and may further be in fluid communication with the drain slot of the elongate drain pipe. 
     According to another aspect of the present invention, there is provided a method of forming a surface drainage structure over a subgrade. The method may commence with forming a receiving trench in the subgrade, followed by placing an elongate conduit in the receiving trench. Thereafter, the method may continue with forming a pavement layer on the subgrade and over the elongate drain. After curing, the method may include cutting an upper channel into the pavement layer along the axis of the elongate drain. The upper channel may have a first depth. The method in accordance with one aspect of the present invention may conclude with cutting a first lower channel and a first drain slot in the elongate conduit. The first lower channel may extend from the first depth to the elongate drain conduit. 
     The present invention will be best understood by reference to the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which: 
         FIG. 1  is a perspective view of a surface drainage system in accordance with an aspect of the present invention including an elongate conduit disposed within a pavement layer; 
         FIG. 2  is a cross-sectional view of the surface drainage system taken along axis  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the surface drainage system taken along axis  3 - 3  of  FIG. 1 ; 
         FIG. 4  is a flowchart depicting the method of constructing the surface drainage structure in accordance with an aspect of the present invention; and 
         FIGS. 5   a - 5   e  are perspective views of the surface drainage systems in various stages of completion as per the method of constructing the surface drainage structure. 
     
    
    
     Common reference numerals are used throughout the drawings and the detailed description to indicate the same elements. 
     DETAILED DESCRIPTION 
     The detailed description set forth below in connection with the appended drawings is intended as a description of the presently preferred embodiment of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. It is understood that the use of relational terms such as first and second, top and bottom, and the like are used solely to distinguish one from another entity without necessarily requiring or implying any actual such relationship or order between such entities. 
     With reference to  FIG. 1 , a surface drainage structure  10  in accordance with one aspect of the present invention is formed above a subgrade  12 . The subgrade  12  generally refers to the foundation or the native ground underneath a pavement structure. Typically, the subgrade  12  is compacted to eliminate soft spots, with some of the topsoil and any vegetation present thereon being removed. The subgrade  12  may be stabilized with additional materials such as concrete, aggregate, and so forth. 
     With further reference to  FIG. 3 , the surface drainage structure  10  includes an elongate drain conduit  14  that is disposed partially within the subgrade  12 . In one embodiment, the elongate drain conduit  14  is a pipe with a hollow cylindrical configuration having an upper half  15   a  and a lower half  15   b  separated by an intersecting plane  15 . Further, the elongate drain conduit  14  is comprised of a conduit wall  16 . The elongate drain conduit  14  has a longitudinal axis  17 . The pipe may be constructed of any suitably resilient non-corrosive material such as acrylonitrile butadiene styrene (ABS) or polyvinyl chloride (PVC) plastics, though any other suitable material such as concrete, galvanized steel or copper may be readily substituted. As will be appreciated by one of ordinary skill in the art, ABS and PVC have desirable weather resistance characteristics, and retains its rigidness over a wide range of temperatures. It is understood that the thickness of the conduit wall  16  and the diameter of the elongate drain conduit  14  may be varied as well. Along these lines, the internal and external shapes of the elongate drain conduit  14  may be varied, and no particular shape, size, or material is deemed to be limiting. As a general matter, the diameter of the elongate drain conduit  14  should be large enough such that it is capable of handling a peak volume of water anticipated for a given application. For example, the diameter of the elongate drain conduit  14  in low precipitation areas may have smaller diameters, while in high precipitation areas the elongate drain conduit  14  may have larger diameters to accommodate a higher volume of water. 
     The subgrade  12  defines a trench  18 , within which the elongate drain conduit  14  is placed. The trench  18  may be sloped relative to a ground axis  20 , such that the elongate drain conduit  14  placed therein is likewise sloped. It is understood that such a sloped configuration facilitates the gravitational flow of rain water and the like upon entering the elongate conduit  14 . The elongate drain conduit  14  is cast into position with a setting  22  disposed within, and along the entire length of, the trench  18 . The setting  22  is molded at least partially around the elongate drain conduit  14 . More specifically, in a preferred embodiment of the present invention, the setting  22  is molded around about the lower half  15   a  of the elongate drain conduit  14 . The setting  18  may be either dry pack concrete or wet concrete, and one may be readily substituted for the other. As understood in the art, dry pack refers zero slump concrete that is tamped against a rigid mold until it is densely compacted, and compared to wet concrete, utilizes significantly less water. Alternatively, or in addition to the setting  18 , the elongate drain conduit  14  may be held by various support members such as stakes and the like that are driven into the subgrade  12 . 
     With reference to  FIGS. 1 ,  2 , and  3 , the elongate drain conduit  14  defines one or more drain slots  24  that extend through the conduit wall  16 . More specifically, the upper half  15   a  of the elongate drain conduit  14  defines the drain slots  24 , which are aligned with the longitudinal axis  17 . According to one preferred embodiment, the drain slots  24  are formed in the conduit wall  16  such that it defines a perpendicular relationship between the intersecting plane  15 . However, it will be appreciated by one of ordinary skill in the art that the drain slots  24  may be formed to define alternative angles with respect to the intersecting plane  15 . It is understood that separate drain slots  24  are disposed along the elongate drain conduit  14  in a spaced relationship so as to prevent the same from collapsing under stress imparted to the pavement that is transferred to the elongate drain conduit  14 , as well as under the weight of the pavement layer  26 . In this regard, the structural integrity of the elongate conduit  14  is retained, and the drain slots  24  are prevented from closing shut. The width of the drain slots  24  may also be limited to further reduce incidences of stress-related damage to the elongate conduit  14 , since the wider the drain slot  24 , the weaker the elongate drain conduit  14 . 
     In accordance with another aspect of the present invention, the surface drainage structure  10  includes a pavement layer  26 . The pavement layer  26  defines an exposed top surface  28 , and a bottom surface  30  that is adjacent to and is coterminous with the subgrade  12 . It is understood that the pavement layer  26  is comprised of conventional concrete or asphalt concrete, though any other suitable pavement material may be readily substituted without departing from the scope of the present invention. 
     The pavement layer  26  also defines a drainage channel  32  that extends from the top surface  28 , and is in fluid communication with the drain slot  24  of the elongate drain pipe  14 . More particularly, according to one preferred embodiment of the present invention, the drainage channel  32  is defined by a first portion  34  that extends from the top surface  28  to a first depth d as delineated by a plateau line  35 . Additionally, the drainage channel  32  is defined by a second portion  36  that extends from the first depth d to the elongate drain conduit  14 . Generally, the depth d of the first portion  34  is approximately a third of a depth D of the pavement layer  26 , though such dimensions may be varied. It is contemplated that the first portion  34  and the second portion  36  are contiguous, and collectively define the drainage channel  32 . The width of the drainage channel  32  may be varied according to the needs of a particular application, and generally depends on the peak volume of water that is anticipated to be drained through the surface drainage structure  10 . As indicated above, the drainage volume capabilities of the surface drainage structure  10  is related to the diameter of the elongate drain conduit  14 . Accordingly, the width of the drainage channel  32  is matched such that the volume of water passing in the aggregate therethrough is substantially equivalent to the volume of water passing through the elongate drain conduit  14 , in order to prevent flooding of the top surface  28 . It will be appreciated by one of ordinary skill in the art that the width of the drainage channel  32  may be limited for the particular safety needs of a given application. For example, areas with anticipated high pedestrian traffic should have the width minimized to avoid injury. On the other hand, areas anticipated to have primarily vehicular traffic may have slightly larger widths because vehicle tires would be able to traverse the drainage channel  32  without the risk of becoming trapped, while there is a need for increased drainage capacity. 
     The first portion  34  extends substantially along the length of the elongate drain conduit  14  and is coplanar with the longitudinal axis  17 , that is, the pavement layer  26  defines a slot that traverses the top surface  28 . However, the first portion  34  need not extend the entire length of the surface drainage structure  10 , and the drainage slot  24 , particularly the first portion  34  thereof, may be segregated into different segments as desired. It will be appreciated that the first portion  34  serves as an initial entry point for water on the top surface  28 . Along these lines, it is also contemplated that the top surface  28  is slanted towards the drainage channel  32 , such that water flows thereto with gravitational force. 
     The second portion  36  is also coplanar with the longitudinal axis  17 , and as indicated above, extends from the first depth d or plateau line  35  to the elongate drain conduit  14 . It is understood that there may be one or more second portions  36 , each of which are in a spaced relationship with respect to the others. The length l of the second portion  36  is less than the length of the first portion  34 , which is typically the length of the entire pavement layer  26 . The second portion  36  has a widened top end  36   a  adjacent to the first portion  34 , and a narrowed bottom end  36   b  adjacent to the drain slot  24 . The length of bottom end  36   b  is understood to be substantially equivalent to, and in alignment with, the drain slots  24 . As indicated above, the drain slots  24  may be spaced to prevent the elongate drain conduit  14  from collapsing. It is for similar reasons that the second portion  36  of the drainage channel  32  does not extend the entire length of the surface drainage structure  10 . Reinforcement segments  37  between the second portions  36  of the drainage channel  32  prevent the pavement layer  26  from collapsing and obstructing the flow of water therethrough. 
     Alternatively, the drainage channel  32  may be said to be defined by a left side surface  38 , an opposed right side surface  40 , and a channel surface  42 . The channel surface  42  has a flat segment  44  that is parallel to the top surface  28 , and an inclined segment  46 . The inclined segment  46  connects the flat segment  44  to the conduit wall  16 . According to one preferred embodiment of the present invention, the inclined segment  46  may have an arcuate shape, for reasons that will become more apparent below. However, it will be understood by one of ordinary skill in the art that any other suitable shape may be substituted, for example, a straight line. Along these lines, the segments of the conduit wall  16  that define the drain slots  24 , i.e., that part of the conduit wall  16  between an outer surface  16   a  and an inner surface  16   b , may be similarly arcuate in shape. 
     As explained above, the width of the drain slots  24  may be limited to strengthen the elongate drain conduit  14 . To further improve the structural integrity of the elongate drain conduit  14 , there is at least one support member  48  mounted transversely to the longitudinal axis  17 . The support members  48  are anchored within the pavement layer  26 , and thus extend into the same. More particularly, the support members  48  are inserted through the upper half  15   a  of the elongate drain conduit  14  and fixed to the conduit wall  16 . According to one preferred embodiment shown in  FIG. 1 , the support members  48  may be screws or other like fasteners inserted through opposed sides of the elongate drain conduit  14  and extend into the interior of the same. Alternatively, as shown in  FIG. 3 , the support members  48  may be unitary structures that extend through the interior of the elongate drain conduit  14 . It is contemplated that the support members  48  function to anchor the elongate drain conduit  14  in the pavement layer  26 , as well as brace the elongate conduit  14  to increase resistance to the compressive forces imparted thereon. In this regard, larger width drain slots  24  may be utilized, increasing the water discharge capacity of the surface drainage structure  10 . 
     Based on the description above, it will be understood that the surface drainage structure  10  collects water on the top surface  28 , and channels it to a different location. More particularly, the top surface  28 , with its slanted surface, directs water to the drainage channel  32 . The first portion  34  serves as a collection basin, and in order to minimize the volume of standing water on the top surface  28  at any given point, it extends along the entire length of surface drainage structure  10 . As water is collected in the first portion  34 , the water is channeled into the second portion  36 , which is in fluid communication with the elongate drain conduit  14  via the drain slots  24  formed thereon. It is understood that the elongate drain conduit  14  may be connected to other underground conduits such as larger storm drain pipes and the like. It is also contemplated that the drainage channel  32  be configured in such a manner so as to enhance the visual appearance of the surface drainage structure  10 . More specifically, the elongate drain conduit  14  may be positioned in various geometric configurations, with corresponding drain channels  32  defining a desired pattern or design on the top surface  28 . 
     According to another aspect of the present invention, a method of forming the surface drainage structure  10  over the subgrade  12  is described in the flowchart of  FIG. 4  and the sequential illustrations of the drainage structure  10  being formed as shown in  FIGS. 5   a - e . The method begins with the step  100  of forming the receiving trench  18 , and otherwise preparing the subgrade  12  as explained above. As shown in  FIG. 5   a , the subgrade  12  has a quadrilateral configuration and is generally defined by a front side  50  and an opposed back side  52 , and by a left side  54  and an opposed right side  56 . The trench extends from the left side  54  to the right side  56 , and has an axis that is substantially parallel to the front and back sides  50 ,  52 . As explained briefly above, the receiving trench  18  has a semicircular cross section. As also explained above, the receiving trench  18  may be formed with a slant relative to the plane of the subgrade  12  to facilitate the flow of water. 
     Thereafter, per step  102  and as shown in  FIG. 5   b , the method continues with placing the elongate drain conduit  14  in the receiving trench  18 . The elongate drain conduit  14  is positioned such that the longitudinal axis  17  thereof is coaxial with the axis of the receiving trench  18 . Optionally, the trench  18  may be partially filled with a setting material such as dry pack or wet concrete, with the elongate drain conduit  14  being held therein. Generally, the elongate drain conduit  14  is positioned at approximately three to four inches below the subgrade  12 . As indicated above, the elongate drain conduit  14  may include the support members  48  that are mounted transversely thereto. Before the step  102  of placing the elongate drain conduit  14  in the trench  18 , the elongate drain conduit  14  may be fitted with the support members  48 . In accordance with one preferred embodiment, the support members  48  are not embedded within the subgrade  12 . At this time, the elongate drain conduit  14  may be connected to additional conduits as described above. 
     According to step  104  and as shown in  FIG. 5   c , the pavement layer  26  is formed on the subgrade  12  and over the elongate drain conduit  14 . A series of forms  58   a - d  having a set depth are arranged in a quadrilateral configuration in alignment with the front side  50 , the right side  56 , the back side  52 , and the left side  54 , respectively, to define a structure space  60 . The forms  58   a - d  are typically wooden beams having particular dimensions, and are anchored to the subgrade  12  via stakes and the like. In one preferred embodiment, the pavement layer  26  is comprised of concrete, so wet concrete is poured into the structure space  60 . Upon curing the concrete, the forms  58   a - d  may be removed. Alternative pavement construction and finishing techniques are known in the art, however, and any such alternative may be readily substituted without departing from the scope of the present invention. 
     With reference to the partially completed surface drainage structure  10  shown in  FIG. 5   d  and according to step  106 , the method continues with cutting an upper channel  62  into the pavement layer  26 . The upper channel  62 , also referred to herein as the first portion  34  of the drainage channel  32 , is cut along the longitudinal axis  17  to the first depth d. In order to determine the proper cut, a line is drawn or otherwise inscribed on the top surface  28  between the endpoints of the elongate drain conduit  14 . As indicated above, the first depth d is approximately one-third the total depth D of the pavement layer  26 . In a preferred embodiment of the present invention, a rotary saw  66  may be utilized, though any other type of saw may be substituted. As understood, the width of the drainage channel  32  is determined by the thickness of the blade of the rotary saw  66 . It will be appreciated that the speed at which the rotary saw  66  is operated is dependent on the material of the elongate drain conduit  14 , and one of ordinary skill in the art will be able to determine the proper speed based on the selected material. 
     With reference to  FIG. 5   c  and the flowchart of  FIG. 3 , the method may conclude with a step  108  of cutting a first lower channel  64  and a first drain slot  65  on the elongate drain conduit  14 . The first lower channel  64 , otherwise referred to herein as the second portion  36  of the drainage channel  32 , extends from the first depth d to the elongate drain conduit  14 . Preferably, the cutting in step  108  is accomplished with the rotary concrete saw  66 . The saw  66  is ratcheted along the upper channel  62 , to cut out the first lower channel  64  and to punch through the elongate conduit  14 . In other words, the first lower channel  64  and the first drain slot  65  are vertically cut. As indicated above, with reference to  FIG. 2 , the inclined segment  46  in the second portion  36  or the lower channel  64  is arcuate, which is in conformance with the rotary saw  66 . Along these lines, the width of the drain slot  24  and the drainage channel  32  is determined by the width of blade of the saw  66 . 
     As understood, multiple lower channels  64  and drain slots  24  may be cut, each being spaced apart from the others. In further detail as illustrated in  FIG. 5   e , the method may also include the step of cutting a second lower channel  68  and a second drain slot  69  in the elongate drain conduit  14 . The second lower channel  68  and the second drain slot  69  are in a spaced relation with respect to the first lower channel  64  and the first drain slot  65 . 
     The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.