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BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates generally to appurtenances for potable water supply systems and, more particularly, is concerned with a dead end potable water main chlorine residual stabilization system. 
     Description of the Related Art 
     Devices relevant to the present invention have been described in the related art, however, none of the related art devices disclose the unique features of the present invention. 
     In U.S. Pat. No. 6,062,259 dated May 16, 2000, Poirier disclosed a method and apparatus for preventing water from stagnating in branches of a municipal water supply system, however, Poirier is different from the present invention in that, as a minimum, it has no solar panel for supplying energy and no computer for controlling the pump. In U.S. Pat. No. 5,921,270 dated Jul. 13, 1999, McCarty disclosed an automatic flush system for water lines. In U.S. Pat. No. 6,635,172 dated Oct. 21, 2003, Newman disclosed an apparatus for the enhancement of water quality in a subterranean pressurized water distribution system. In U.S. Pat. No. 6,880,566, dated Apr. 19, 2005, Newman disclosed an apparatus for the enhancement of water quality in a subterranean pressurized water distribution system. In U.S. Pat. No. 6,948,512 dated Sep. 27, 2005, McKeague disclosed a flushing attachment for a hydrant. In U.S. Pat. No. 8,733,390 dated May 27, 2014, McKeague disclosed an automatic flushing device for municipal water systems. 
     While these devices may be suitable for the purposes for which they were designed, they would not be as suitable for the purposes of the present invention as hereinafter described. As will be shown by way of explanation and drawings, the present invention works in a novel manner and differently from the related art. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention discloses an environmentally friendly system for automatically and remotely maintaining legally required healthy and acceptable levels of chlorine residual in the dead end branches of potable water mains so as to protect the users from high levels of coliform organisms by recirculation of the stagnant dead end water back to a flowing water main. A pump circulates stagnant water from near the end of the dead end water main back through a tube to a water main having flowing water therein. Thus, stagnant water is evacuated from the problematic dead end branch of the water main back to the flowing water main which, due to fluid dynamics, causes fresh water from the flowing water main to replace the stagnant water as fresh water is circulated back to the area of the dead end water main. The present invention uses a remote photovoltaic solar array mounted on a stanchion as its source of power which is electrically connected to a watertight vault housing a lithium ion battery pack, programmable logic controller (PLC), pump, power cables, flow meter, and test port all designed for being accessible from the surface of the ground for service and/or repair. The pump assembly is controlled by a PLC control panel set to send power from the solar array to the battery pack for recharge, wherein the battery level triggers/actuates the PLC controller to sequence the timer to power the pump which is on a variable timed schedule determined by the dead end pipe size, length and ambient conditions so as to maintain the proper level of chlorine residual. 
     An object of the present invention is to prevent water in dead end branch water mains from becoming stagnant due to depletion of the residual chlorine caused by dissipation or chloramines decay. A further object of the present invention is to circulate water from a dead end branch water main back to a flowing water main so that the water is refreshed with high chlorine residual water from the flowing water main. A further object of the present invention is to provide a system which can be used to retrofit existing water supply systems having dead end branch water mains commonly found in municipal and rural water supply/distribution systems. A further object of the present invention is to provide a system which is self-contained and can be successfully operated without access to the public power grid wherein the system receives its only source of required energy from a photovoltaic solar panel. A further object of the present invention is to provide a system which can be easily installed requiring only minimal training to a utility operator or contractor. A further object of the present invention is to provide a system which can be easily operated by a user. A further object of the present invention is to provide a system which can be relatively inexpensively operated and maintained. 
     The foregoing and other objects and advantages will appear from the description to follow. In the description reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. In the accompanying drawings, like reference characters designate the same or similar parts throughout the several views. 
     The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the invention may be more fully understood, it will now be described, by way of example, with reference to the accompanying drawings in which: 
         FIG. 1  is a perspective view of the present invention. 
         FIG. 2  is a side elevation view of the present invention. 
         FIG. 3  is a side elevation view of portions of the present invention. 
     
    
    
     LIST OF REFERENCE NUMERALS 
     With regard to reference numerals used, the following numbering is used throughout the drawings.
           10  present invention     11  pump assembly     12  power assembly     13  tube insertion assembly     14  suction end assembly     15  connection assembly to flowing main     16  dead end     17  flowing main     18  circulation pump     19  lithium ion battery pack     21  pump isolation valve     22  pump inlet line     24  flow meter     25  sampling valve with vacuum breaker     26  pump discharge line     27  pump check valve     28  insertion/isolation valve     30  rigid flexible insert tubing     32  inlet of insert pipe     34  tapping saddle     38  control panel/programmable logic controller     39  power cable     40  photovoltaic solar panel     42  stanchion     43  concrete pier with mounting plate     44  ground     46  vault     48  bolt down cover with gasket seal     50  electrical connection     52  aperture     54  water tight electrical plug and bulkhead socket     56  aperture     58  water tight bulkhead fitting     64  insert/pulling cone     66  sloping head     68  wall of vault     70  tapping sleeve     71  access cover     72  45 degree lateral pipe with flanged end     74  joint     76  pump discharge line     78  dead end main       

     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following discussion describes in detail at least one embodiment of the present invention. This discussion should not be construed, however, as limiting the present invention to the particular embodiments described herein since practitioners skilled in the art will recognize numerous other embodiments as well. For a definition of the complete scope of the invention the reader is directed to the appended claims.  FIGS. 1 through 3  illustrate the present invention which disclosed a method and apparatus for automatically stabilizing the residual chlorine level of water mains containing potable water and which is generally indicated by reference number  10 . 
     Turning to  FIGS. 1 and 2 , therein is shown the present invention  10  wherein a dead end branch water main  78  has its water refreshed from a flowing water main  17  by evacuating by pumping the stagnated water from near the dead end  16  by drawing the water through the inserted rigid flexible insert tube  30  which is connected to the suction side of pump  18  of pump assembly generally indicated by reference number  11  by means of pump inlet line  22 . The water is then pumped through and then out pump discharge line  26  into the water main connection assembly generally indicated by reference number  15  which is attached to the flowing main  17  thereby causing the replacement of the stagnated water associated with the dead end  16  area of the dead end branch water main  78  with the higher chlorine residual water from the flowing water main  17 . 
       FIG. 1  shows one embodiment of a connection assembly  15  having an insertion/isolation valve  28  mounted onto a saddle-type connector or tapping saddle  34  for connection to flowing water main  17 .  FIG. 2  shows a second embodiment of a connection assembly  15  having the insertion/isolation valve  28  attached to or bolted to a sleeve-type connector being a stainless steel or like tapping sleeve  70  for connection to flowing water main  17 . 
     Suction end assembly generally indicated by reference number  14  is attached to the distal end of the rigid flexible insert tubing  30  which is inserted through the dead end main  78  having an inlet  32  on its distal end. The suction end assembly  14  includes an insert/pulling cone  64  attached near the distal end of insert tubing  30 . The insert/pulling cone  64  has a sloping head or face  66  thereon so that the insert/pulling cone can be slidably inserted through the dead end water main  78  without hanging up or catching on any build up, edge or seam as might occur, e.g., at a joint  74  as a result of joining together pipe sections of the dead end water main. The purpose of the sloping head  66  is to allow the insert/pulling cone  64  to easily pass through the interior of the dead end branch water main  78 . 
     Tube insertion assembly generally indicated by reference number  13  enables the rigid flexible insert tubing  30  to be inserted into the dead end main  78  and be isolated for service and testing without valving off or otherwise isolating the dead end main  78 .  FIG. 1  shows one embodiment of a tube insertion assembly  13  having an insertion/isolation valve  28  mounted onto a saddle-type connector or tapping saddle  34  so that the valve  28  is angled with respect to the dead end main  78 .  FIG. 2  shows another embodiment of a tube insertion assembly  13  having the insertion/isolation valve  28  attached to a 45 degree flanged lateral pipe  72  which is attached to a sleeve-type connector being a stainless steel or like tapping sleeve  70  interconnecting the dead end branch main  78  to the pump assembly  11 . Access cover  71  is also provided on tapping sleeve  70 .  FIG. 3  shows a more detailed view of the tube insertion assembly  13  and connection assembly  15 . 
     Pump assembly  11  connects to tube insertion assembly  13  via pump inlet line  22  passing through vault wall  68  through aperture  56  sealed from ground water with water tight bulkhead fitting  58  and then to isolation valve  21 . A pump check valve  27  is connected to the suction side of pump  18  which pump then discharges through pump discharge line  76  to flow meter  24  and then through a second pump isolation valve  21  and then the pump discharge is piped through vault wall  68  using aperture  56  and sealed from ground water by bulkhead fitting  58 . A sampling valve with vacuum breaker  25  is also provided. Pump  18  is controlled by the computer in the PLC control panel  38  and powered by lithium ion battery pack  19  which receives electrical power from power cable  39  passing through vault wall  68  using aperture  52  and seal  54 . Power cable  39  is connected to power assembly  12 . Vault  46  is expected to be water tight having a bolt-down cover with gasket seal  48  thereon which is expected to be accessible from above ground  44 . 
     Systems power is supplied by power assembly generally indicated by reference number  12  including solar panel  40  serving as the power source disposed on a stanchion  42  and mounted into the ground  44  using a concrete pier with mounting plate  43 . The electrical cable  39  attaches to and passes through the wall  68  of vault  46  via aperture  52  and water tight plug  54 . Miscellaneous electrical  50  connects control panel  38  to the battery pack  19  and pump  18 . 
     Turning to  FIG. 3 , shows a more detailed view of the tube insertion assembly  13  and connection assembly  15  as previously disclosed relative to  FIGS. 1 and 2 . The tapping sleeve inlet  70  is provided for receiving insertion tubing  30  in its interior wherein flanged insert valve  28  and an insertable flexible rigid tube  30  is disposed at an angle of about 30-45 degrees with respect to the centerline of water main  78 , the angle being effectively sized to allow for insertion into and retrofitting of an existing underground water supply system so as to ease the installation of tube  30  into water main  78 . 
     The vault  46  and cover  48  are expected to be made of concrete, cement, fiberglass, or the like, the material being suitable for installation in remote areas, as would be done in the standard manner by one skilled in the art. 
     The present invention  10  is expected to be installed on existing municipal or rural potable water distribution systems. The steps of the installation process are as follows: 1) locate the dead end water main segments  78  of the water system and measure back to the source main  17  to establish the length of insert tube  30 ; 2) valve off dead end section and excavate the end  16 ; 3) install tapping sleeve/saddle  34 ,  70  and insertion valve  28  and tap flowing water main for pump discharge piping  26 ; 4) install tapping sleeve/saddle  34 ,  70  to tap dead end water main  78  for circulator tube  30 ; 5) through the sleeve opening of dead end main  78  insert cone  64  and circulator tube  30  and push to the pre-measured end (note, if the dead end is longer than 200 feet or there is interior pipe corrosion this operation may require using a push rod to assist the insertion and some installations may require a second tapping sleeve installed near the source main and the insert be pulled in via poly rope floated down to the first tapping sleeve at the dead end; 6) install flanged valve  28  and pump inlet pipe  26  and backfill allowing for vault  46 ; 7) set vault  46  and connect pipes  22 ,  26  to prospective bulkhead fittings  58  and complete backfill; 8) excavate for stanchion base and pour concrete pier with conduit embedded and stainless steel mounting studs; 9) set stanchion  42  and solar panel  40 ; 10) trench in power cable and connect to vault plug  54  and solar plug jack at array and charge battery pack; 11) test for chlorine and determine dead-end volume for PLC programming pump controller clock and start system; 12) check meter located in vault to confirm operation and take water sample for testing residual chlorine; 13) in four hours check meter for gallons moved and retest chlorine residual; 14) recheck every 24 hours for the first three days and then weekly thereafter. 
     To retrofit the present invention  10  to an existing water supply system the insert/pulling cone  64  having its sloped face  66  is crucial because the outlet  32  could snag on the internal joint seams  74  and formations inside the dead end water main  78 . Also, the flanged insert valve  28  is attached at about a 30-45 degree angle with respect to the dead end main  78  so as to allow the pump inlet tube  22  and insertable flexible rigid tube  30  to be pushed, pulled, or slidably inserted into the existing underground dead end water main  78  which may be several feet, e.g., 3-6 feet, below the surface of the ground  44 . 
     The present invention  10  is designed for installation and operation in remote areas and is designed to require low maintenance and to have a low operating cost. Therefore, the programmable logic controller  38  is expected to be programmed so as to operate the pump  18  only during periods of time when there is enough available solar energy to do so or when the batteries are sufficiently charged to do so; at other times the pump is expected to be off. It is believed that this operating regimen will allow for the present invention  10  to operate at minimum costs.

Summary:
System and method for automatically and remotely maintaining acceptable levels of chlorine residual in the dead end branches of potable water mains so as to protect the users from high levels of coliform organisms by pumping stagnant water from the dead end branch back to a flowing water main. A solar panel serves as the source of power with batteries being used to store energy. A water circulation pump evacuates water through an insertable rigid flexible tubing from a point near the distal end of the dead end branch to the nearest flowing water main. A programmable logic controller is used to operate the pump during periods of time when there is enough available solar energy or when the batteries are sufficiently charged.