Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     None 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates in general to regulating the level of groundwater in the fields of an agricultural operation and, more particularly, wherein the level of the groundwater in the field is automatically regulated according to contemporaneous and local groundwater levels as well as manually actuated downstream control mechanisms. 
     2. Description of the Prior Art 
     It is known in the art to use a variety of machines and apparatuses to increase or decrease moisture in the soil used for agrarian purposes. Some of these machines include the use of aquifers, irrigation ditches and canals, use of overhead sprinkler irrigation, terracing for directing the flow of water while maintaining top soil and some moisture in the soil on a hill, and the laying of underground tile lines into which water will drain and flow away from the field. 
     Tile lines, effective for routing excess water from the soil, have heretofore typically served that singular purpose. Unfortunately, when moisture levels in the season result in a need for more water in the soil, the tile lines typically continue to drain without means to control or adjust the flow. In this manner, efficient water removal by the lines can be detrimental to the crop either by depriving the plants of moisture or by allowing nitrates, phosphates and other nutrients used by plants to flow out of the soil before sufficient time has passed to allow them to break down naturally. This means that ponds and streams are often polluted by these nutrients. 
     As an improvement over uncontrolled tile lines, drainage systems have been developed that include the use of flow control regulators in the lines in such a way as to manage and regulate the moisture level in the soil. The management is typically based upon seasonal needs and is provided via water level control structures or groundwater control systems. Two types of groundwater control systems are described in U.S. Pat. Nos. 6,715,508 to Schafer et al., issued Apr. 6, 2004, and 6,786, 234 to Schafer et al., issued Sep. 7, 2004. 
     Although water drainage systems that include timer control regulators are a vast improvement over uncontrolled systems, they operate in essentially the same manner regardless of the type of weather that has occurred and the amount of groundwater in the soil. 
     SUMMARY OF THE INVENTION 
     The present invention is referred to as a Watergate and provides an apparatus and a system for controlling and regulating the level of groundwater in an agricultural field that involves the use of a buried tile line in said field to drain water therefrom, a preferably manually or automatically operated control stand, typically positioned at or near the discharge end of the system, and one or more novel automatic water flow regulators located in the tile line for controlling the flow of water therethrough in conjunction with said control stand. 
     In a preferred embodiment of the apparatus and system of the present invention, the automatic water flow regulator is opened or closed based on the amount of water in the tile line proximate said regulator. The present invention is designed to provide a groundwater control system that is actuated in response to the volume of water present in the system, provides increased water and nutrient availability to increase yield, disrupts the preferential flow of chemicals and fertilizers and minimizes outflow. 
     It is also advantageous to have regulators that are fully automatic and do not require active management, and regulators that are completely buried in the field, thereby eliminating the problem of having to farm around such apparatuses or those control or access portions of such devices that emerge above the surface of a field. It is also an object of the present invention to provide a system capable of providing infinitely variable water table levels. 
     The foregoing and other advantages of the present invention will appear from the following description. In the description, reference is made to the accompanying drawings, which form a part hereof, and in which there is shown by illustration and not of limitation a specific system and method in which the invention may be embodied. Such embodiments do not represent the full scope of the invention, but rather the invention may be employed in a variety of other embodiments and reference is made to the claims herein for interpreting the breadth of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagrammatical view of an agricultural field having various components of a groundwater control apparatus and system of the present invention that are located in the field; 
         FIG. 2  is a perspective, partial cutaway view of a conventional control stand; 
         FIG. 3  is a perspective, partial cutaway view of a preferred embodiment of a groundwater control apparatus of the present invention in an opened position; 
         FIG. 4  is a perspective, partial cutaway view of the groundwater control apparatus of  FIG. 3  in a closed position; 
         FIG. 5  is a top, partial cutaway view of the groundwater control apparatus of  FIG. 3  in a closed position; 
         FIG. 6  is a side, partial cutaway view of the groundwater control apparatus of  FIG. 3  in a closed position; 
         FIG. 7  is a top, partial cutaway view of the groundwater control apparatus of  FIG. 3  in an opened position; and 
         FIG. 8  is a side, partial cutaway view of the groundwater control apparatus of  FIG. 3  in an opened position; 
         FIG. 9  is a cutaway view similar to that of  FIG. 6 , but modified to include rib structures; and 
         FIG. 10  is an enlarged partial view of a selected part of the control apparatus as indicated in  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is adapted to provide an apparatus and a system for regulating the level of groundwater in an agricultural field according to the amount of water present in the system. Consequently, the system and method of the present invention may be advantageously employed to reduce, maintain or accumulate the amount of groundwater according to simultaneous needs for the planting and harvesting of crops in the field as well as regulating the flow of water from a field when it is contaminated with impurities. For example, during the growing months it is desirable to keep the water table high in the soil so that nutrients, phosphates and nitrates will not be lost through unnecessary or excessive drainage. The present invention also allows for the addition of water to the field by sub-irrigation. Additional water and nutrients may help improve the effectiveness of riparian vegetation buffers by enhancing plant density and growth. 
     In contrast to maintaining a high water table during the growing months, the water table should be significantly lowered prior to harvest to allow access to the field and to minimize compaction of the soil by large harvesting equipment. This is also true for the time period prior to and during planting to allow the soil to warm and encourage root growth and, again, to allow access to the field. 
     During times of heavy rainfall, the present invention can also be employed to reduce the amount of drainage from the field to prevent nutrients, phosphates, nitrates and other constituents i.e. pesticides and herbicides, from being carried away by the drainage of excess water from the field. Reduction of downstream flooding and reduction of the volume of water flow from the field extends the time frame over which subsurface waters are released into wetlands to allow time for the biological process that occurs in a wetland to more fully treat or purify the water passing through said wetland. Accordingly, the present invention is adapted to automatically respond to local groundwater conditions such as the water table level of the field or the amount of impurities in the water table and can take seasonal needs into account in doing so in order to automatically manage water drainage from the field. 
     Referring now to the drawings and with reference first to  FIG. 1 , a diagram of an agricultural field is shown generally at  10 . Although only one field  10  is illustrated in  FIG. 1 , it is contemplated that the system and method of the present invention can be readily employed for providing water drainage control of numerous different fields. While the illustrative embodiment is depicted to address drainage of groundwater in an agricultural field, persons skilled in the art will appreciate that the apparatus and system may be used to regulate the flow of any fluid in any suitable environment or fluid system. 
     With respect to  FIG. 1 , agricultural field  10  has a buried groundwater drainage tile line  12  that runs down grade from highest point  14  of field  10  and terminates at its lowest point  16 . Line  12  need not be inclined at the same or similar slope as field  10  so long it generally tracks the grade of field  10  and permits gravity drainage therefrom. That section of line  12  proximate lowest point  16  of field  10  is characterized by a conventional control stand  18 , which may be one of any number of types known in the art. As shown in  FIG. 2 , control stand  18  is preferably manually operable (but may also be automatic) such that one or more physical barriers  20  may be cumulatively applied to the interior  22  of control stand  18 —e.g., by sliding them in from above—to restrict water flow out of line  12 . By way of example only, physical barriers  20  may be planks or stop logs. Thus, the control stand  18  is capable of infinite variability, has two way telemetry, can monitor, measure, and record rainfall, water levels and water flows to help quantify the reduction of outflow of a managed drainage system compared to the outflow of an unmanaged drainage system to facilitate water quality trading and to determine eco services benefits. One such control stand is Agri Drain Corporation&#39;s Inline Water Level Control Structure™ (A GRI  D RAIN  C ORPORATION ; Adair, Iowa). 
     Turning back to  FIG. 1 , line  12  is further characterized by at least one automatic water flow regulator  24  in fluid connection therewith. Ordinarily, in order to achieve optimal regulation, a plurality of automatic water flow regulators  24  will be provided along the length of tile line  12  such that one regulator  24  is provided for every foot or so of vertical incline of field  10 . For example, if the change in elevation between lowest point  16  of field  10  and highest point  14  of field  10  is roughly three (3) feet, a first regulator  26  is provided along line  12  beneath that area of field  10  that is approximately one foot in elevation above lowest point  16 , a second regulator  28  is provided further along line  12  beneath that area of field  10  that is approximately two feet in elevation above lowest point  16 , and a third regulator  30  is provided further along line  12  beneath that area of field  10  that is approximately three feet in elevation above lowest point  16 . 
     It will be appreciated that this one-foot vertical spacing convention of regulators  24  may vary to accommodate surface or sub-surface features or obstacles, and that the stated spacing is for exemplary purposes only. In some instances, it may be desirable to locate regulator  24  slightly upstream or downstream of a branch line (not shown) attached to tile line  12  at a point at or near the one-foot vertical increment of field  10 . Deviating from the one-foot vertical spacing convention may result in a watertable directly above the subject regulator  24  that is slightly higher or lower than intended. Any such variance can be corrected by locating the next upstream regulator  24  at an elevation that relates back to the one-foot vertical spacing relative to the lowest point  16  of field  10 . In other words, variances in individual vertical spacing may be corrected by having the average intervals of each regulator  24  close or equal to one foot. 
     The third regulator  30  may, but need not, be located directly beneath highest point  14 . Each regulator  24  services a corresponding surface area of field  10 , and that portion of line  12  generally upstream therefrom. For example, it will be appreciated by persons skilled in the art that the surface area of field  10  serviced by third regulator  30 , as shown in  FIG. 1 , will include highest point  14 . 
     Turning to  FIG. 3 , each automatic water flow regulator  24  comprises an elongate, housing  32 , an upstream end  34 , a downstream end  36  and there are connecting portions  31  and  33  extending outwardly from the upstream and downstream ends  34 ,  36  respectively that are both cylindrically shaped and sized to receive a portion of the tile line  12  (see  FIG. 1 ). Housing  32  is preferably cylindrically shaped with a diameter of approximately 12 inches, but may be any shape or diameter. Preferably, the upper housing portion has at least one air vent (not shown) to prevent air compression within housing  32  during operation of regulator  24 . Each of upstream end  34  and downstream end  36  defines an aperture  35 ,  37 , respectively, adapted to be in fluid connection with line  12  via connecting means that are well known in the art. Water flow through the line  12  is controlled by the regulator  24  by means of a water actuated float assembly that acts to open and close regulator  24  in response to the amount of water in the field  10  as will now be described. 
     Disposed within housing  32  is a longitudinal frame rail  38  that serves as an upper attachment means having an upstream end  40  and a downstream end  42 , wherein “upstream” and “downstream” refer to the relative orientation of rail  38  within housing  32 . Rail  38  is secured at its upstream end  40  to the inside face  43  of the housing upstream end  34 . 
     Also disposed within housing  32  is a hinge  44  having a first end  46  pivotably attached to one or both sides of upstream end  40  of rail  38 , and a second end  48  securely attached near the upper edge of a closure  50 . Alternatively, and perhaps depending on the construction of hinge  44 , first end  46  of hinge  44  may be attached to upstream end  34  of housing  32  proximate, and on one or both sides of, rail  38 . 
     The closure  50  comprises a generally flat surface that—in a closed condition—is held against the housing upstream end face  43  to fully cover aperture  35  at the interface between upstream end  34  of housing  32  and connecting portion  31 . The perimeter of closure  50  may be fitted with a sealing member  52  such as a gasket to form a better seal with upstream end  34  of housing  32 . Alternatively, rather than using the sealing member  52 , it has been found to be preferable to employ circular rib structures on the closure  50  and the upstream end face  43  to prevent the closure  50  from vibrating or chattering when it is in a partially opened condition as will now be described. 
     Referring to  FIGS. 9 and 10 , the regulator  24  has a modified closure  50 ′ and an upstream end face  43 ′ to provide circular rib structures thereon. Such rib structures are relatively shallow as indicated in  FIG. 10  showing the closure  50 ′ having an upstream facing rib  51  disposed about the circumference of the closure  50 ′ and the upstream end face  43 ′ having a downstream facing rib  45  disposed about the periphery of the aperture  35 . The closure rib  51  is approximately 0.035″ high and extends toward the end face  43 ′ to restrict water flow and equalize water pressure when the regulator  24  is partially open. The end face rib  45  is approximately 0.045″ high and provides a circular contact surface between the closure  50 ′ and the end face  43 ′ to establish a passive seal therebetween. 
     Water tightness of the seal between closure  50  and aperture  35  may vary, but it is anticipated that the seal will not be fully watertight, particularly when line  12  upstream from regulator  24  is under approximately one foot of head pressure or more. Persons skilled in the art will appreciate that one vertical foot of water produces approximately 0.433 pounds of pressure per square inch on the closure  50 . When exposed to increased head pressures, closure  50  will open at least partially. Even under diminished head pressure, flow through aperture  35  and into regulator  24  at a rate of two (2) gallons per minute, more or less, may be expected. 
     Further disposed within housing  32 , as shown best in  FIGS. 6 and 8 , is an articulated, elongate lever arm  54  having a first end  56  proximate closure  50 , a roughly centrally located joint  58 , and a second end  60  proximate downstream end  42  of rail  38 . In a preferred embodiment illustrated in  FIGS. 5 and 6 , that portion of lever arm  54  between first end  56  and joint  58  is a unitary, rigid member  62 , while that portion of lever arm  54  between joint  58  and second end  60  comprises two symmetric and parallel rigid members  64 ,  66 . Unitary member  62  comprises an upstream end  68  and a downstream end  70 ; symmetric members  64 ,  66  each comprise upstream ends  72 ,  74  and downstream ends  76 ,  78 , respectively. “Upstream” and “downstream” in this context again refer to the relative orientation of lever arm  54  within housing  32 . 
     Upstream end  68  of unitary member  62  is pivotably and roughly centrally attached to closure  50 . Downstream end  70  of unitary member  62  is pivotably attached about joint  58 . Upstream ends  72 ,  74  of members  64 ,  66  are also pivotably attached about joint  58 . Downstream ends  76 ,  78  of members  64 ,  66  are pivotably attached to opposite sides of downstream end  42  of rail  38 . 
     Housing  32 , rail  38 , closure  50  and articulated lever arm  54  may be made of any suitable rigid material, but are preferably made of rigid poly vinyl chloride (PVC) or a similar material. 
     Turning to  FIGS. 5-8 , joint  58  is depicted. In a preferred embodiment, joint  58  comprises a pivot pin  80  that passes through the downstream end  70  of unitary member  62 , and the upstream ends  72 ,  74  of members  64 ,  66 . Pivot pin  80  also passes through a pair of spacer bushings  82 ,  84  on either side of members  64 ,  66  and through a pair of parallel, symmetric vertical supports  86 ,  88 . Vertical supports  86 ,  88  are preferably rectangular in shape and rigid in construction. 
     As shown in  FIGS. 3-5 , attached to vertical supports  86 ,  88  are float members  90 ,  92 , respectively. Float members  90 ,  92  are blocks that are generally smaller than, and do not extend beyond the outer perimeter of, vertical supports  86 ,  88 . Float members  90 ,  92  are preferably constructed of a lightweight, resilient and buoyant material such as foam or other polystyrene product. 
     It will be appreciated by those skilled in the art that automatic water flow regulator  24  functions substantially as follows. In a state of rest, illustrated in FIGS.  3  and  8 —e.g., where no buoyant forces are exerted upward on float members  90 ,  92 , such as where there is little or no water downstream of regulator  24  in line  12 , closure  50  does not form a seal over aperture  35  and regulator  24  is in the “open” position. Hence, water in tile line  12  upstream of regulator  24  will flow uninhibited through upstream end  34 , through housing  32 , and out through downstream end  36 . This open position is also achieved when the head pressure upstream of regulator  24  exceeds approximately one foot, as described above. 
     As housing  32  fills with water, such as where the amount of water in line  12  downstream from regulator  24  is increased, buoyant forces will be exerted upward on float member  90 ,  92 , thereby causing joint  58  to pivot upward about pivot pin  80 . The action of joint  58  upon closure  50  is accomplished via unitary member  62  of articulated lever arm  54 . Upstream end  68  of unitary member  62  pivots about its point of attachment with closure  50 , thereby forcing closure  50  against upstream end  34  about hinge  44 . Parallel, symmetric members  64 ,  66  of articulated lever arm  54  pivot about rail  38  in response to the upward action of joint  58 . This results in regulator  24  being in a “closed” position, illustrated in  FIGS. 4-6 . In quantitative terms, regulator  24  will close when the vertical depth of water within housing  32  meets or exceeds approximately eight to nine (8-9) inches. 
     Referring back to  FIG. 1 , a system of flow regulation along line  12  incorporates at least one regulator  24  with control stand  18 . It will be understood by those skilled in the art that the flow of water along line  12  is restricted by the installation of additional barriers  20  to the interior chamber  22  of control stand  18  as indicated in  FIG. 2 . This results in decreased throughput along line  12 . Upstream from control stand  18  along line  12  is regulator  24 . When regulator  24  is in the closed position, it may be inferred that the amount of water downstream has resulted in water collecting in regulator  24 . This would be advantageous, for example, during a period of heavy rainfall. When regulators  24  are closed, they temporarily block water flow through line  12  in order to prevent excess water drainage from the field following the application of fertilizers or pesticides to the field to prevent the runoff thereof. 
     Thus, the present invention provides a novel and unique means for regulating the level of groundwater in an agricultural field according to selected criteria. Although the control system and method of the present invention has been described with respect to a preferred embodiment, it should be understood that such embodiment may be altered without avoiding the true spirit and scope of the present invention.

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