Patent Publication Number: US-11644144-B2

Title: Pig launch and recovery apparatus and pig therefor

Description:
FIELD OF THE INVENTION 
     The present invention relates to a method and equipment for inspecting, cleaning and maintaining a water main or other type of piping system, and in particular, to a pig launch and recovery apparatus and pig therefor, and a method of inspecting, cleaning and maintaining a section of water main between hydrants using the pig and pig launch and recovery apparatus under system pressure and using a circulating flushing flow. 
     BACKGROUND OF THE INVENTION 
     Almost all water providers are required to have their water mains large enough to provide a sufficient flow for fire suppression. This means that the flow rate or velocities in the large mains during normal use are reduced significantly, allowing particulates that are suspended in the water to settle to the bottom of the pipe and also substances such as iron, manganese, bio-film, etc. to adhere to the inside surfaces of the pipe. After a length, of time the settled particulates and substances, etc. build up and, if there are any surges in the system, the particulates and substances, etc. are stirred up and thereby increase the turbidity in the water. To address this issue and minimize the potential turbidity in the water, the piping system may be flushed periodically from hydrants and blow-offs located throughout the system. However, this method wastes millions of gallons of water each year, may cause property damage, flood streets causing traffic problems, and is usually performed at night to avoid the public eye, making the flushing procedure costly. 
     In addition to the above problems, new regulations require that the water be de-chlorinated before it is allowed to drain into any storm drainage system. A NPDES (National Pollutant Discharge Elimination System) permit is required and containment systems need to be in place to protect against washing silt and other materials into the storm drains. 
     From time to time, it is necessary to flush water systems which deliver potable tap water. This is especially the case with newly installed water mains. Before water passing through a water main can be used for drinking water purposes, it is necessary to thoroughly flush the mains with tap water. In order to maintain water quality, it is also necessary, from time to time, to flush local tap water delivery systems such as neighborhood and subdivision tap water systems. 
     Generally, discharges from potable water systems result from overflow, flushing, disinfection, hydrostatic testing, mechanical cleaning or dewatering of vessels or structures used to store or convey potable water. This frequently includes fire hydrant flushing in which high velocity streams are generated on the order of 2,000 gallons per minute for a period of 10-15 minutes. By periodically testing fire hydrants (fire flow testing), it can be determined if sufficient water is available in the system for firefighting purposes. 
     Potable tap water usually contains residual chlorine. The Federal Clean Water Act and state agency regulations regarding discharges of potable water, require that total maximum daily amount of residual chlorine must be less than 0.1 mg/liter. At levels higher than 0.1 mg/liter, aquatic life is endangered and fish kills can occur. Since potable tap water and water discharged from fire hydrants are typically chlorinated, heavy discharges of this water will adversely affect aquatic life unless the amount of residual chlorine is reduced to less than 0.1 mg/liter. In the past, this was either not done or, when attempted, was done by injecting sodium sulfite into the discharge stream. This is a difficult process to perform and monitor because it is necessary to dispense sodium sulfite in controlled amounts according to the volume of water being treated. If there is too much sodium sulfite, it can itself cause pollution problems by interfering with pH levels and if the amount is insufficient, there will be excessive residual chlorine. It has been found that the injection approach requires not only highly skilled personnel, but extensive training. Moreover, the end result is unpredictable. Thus, while some attempts have been made at improving water main flushing systems, the real problems of water waste and water quality still remain to be addressed. 
     The above-discussed issues may be compounded during “pigging” operations. Pigging in the context of pipelines refers to the practice of using devices known as “pigs” to perform various maintenance operations. This normally cannot be done without stopping the flow of the product in the pipeline (usually oil and gas), or most often when used in water pipes, only after the pipeline is drained. These operations include but are not limited to cleaning, videoing/inspecting, GIS (locating), and leak detection from inside the pipeline. 
     Water industry personnel have been looking for ways to perform pigging without having to either dig up the water main, depressurize the main, impact the customer, or waste the water. Video pigs are normally cameras attached to a push-thru cable and most cleaning pigs are normally attached to pull-thru cables. In each case, the pipes are cut into to create launch and recovery stations. Moreover, pigging potable water pipes that carry drinking water has been performed since pipelines were created; but the one issue all pigging services have in common is that they always must depressurize the water main to insert the pig. Once the pigging was completed, the water main still needs to be flushed to waste before it can be put back into service, thus prolonging the downtime of the water main, as well as wasting water. Even more problematic, it has been shown that once a main is de-pressurized, it is more susceptible to leaks in the future. 
     Video camera pig systems normally use an umbilical cable, which limits travel to the amount of cable on hand, while others are configured as free-flowing pigs inside the pipe. Similarly, geographic information system (GIS) pigs and leak detection pigs may also be configured as free-flowing pigs inside the pipe. As a result, each of these system require launch and recovery points, depend on existing distribution flows inside the mains and can only be recovered by opening a fire hydrant and wasting water (additional water is then wasted to flush the main when completed). Moreover, commercial servicers typically offer only one of these above services, meaning that multiple servicers are needed depending upon the type of service requested. A further drawback to these systems is that the pigs can become lost within the pipe system, and because water distribution mains are installed on almost every street in every city, a grid of loops and dead-ends is created that is not conducive to installing entry and exit points for traditional pigs. 
     What is needed is a system for periodically inspecting, cleaning and maintaining water mains or other piping systems that does not require depressurization of the main, wasting the water, or dumping water containing chemicals and pipe sediments into the environment. The present invention addresses these needs as well as other needs. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, a pig launch and recovery apparatus for use with a water supply system having a plurality of sections including water mains, pipes, hydrants and valves is provided. The apparatus comprises a flow tube having a first flow end configured to couple with a recirculating unit including a pump, an opposing second flow end configured to mount to a hydrant, and a main flow valve located therebetween. The apparatus further includes a launch and recovery tube having a first launch end fluidly coupled to the flow tube between the first flow end and the main flow valve, and a second launch end fluidly coupled to the flow tube between the main flow valve and the second flow end. The launch and recovery tube may also include a first valve proximate the first launch end, a second valve proximate the second launch end, and a tube access door located therebetween. The second launch end may also be coupled to the flow tube at an angle relative to a longitudinal axis of the flow tube, wherein the angle is about 45 degrees in one example. The flow tube also includes an angled screen configured to form a secondary fluid pathway with the second launch end of the launch and recovery tube, and the launch and recovery tube may further include a bleed valve located between the first valve and the second valve. 
     In a further aspect of the present invention, a closed conduit system for use in a water supply system having a plurality of sections including water mains, pipes, hydrants and valves is provided. The system may comprise a recirculating unit including at least one pump and at least one filter. The system further includes a first pig launch and recovery apparatus comprising a flow tube having a first flow end configured to fluidly couple with the recirculating unit, an opposing second flow end configured to be fluidly coupled to a first hydrant, and a main flow valve located therebetween. The first pig launch and recovery apparatus further includes a launch and recovery tube having a first launch end fluidly coupled to the flow tube between the first flow end and the main flow valve, and a second launch end fluidly coupled to the flow tube between the main flow valve and the second flow end. The system further includes a second pig launch and recovery apparatus comprising a flow tube having a first flow end configured to fluidly couple with the recirculating unit, an opposing second flow end configured to be fluidly coupled to a second hydrant, and a main flow valve located therebetween. The second pig launch and recovery apparatus further includes a launch and recovery tube having a first launch end fluidly coupled to the flow tube between the first flow end and the main flow valve, and a second launch end fluidly coupled to the flow tube between the main flow valve and the second flow end. An isolated section of the water supply system is defined between the first hydrant and the second hydrant, and the recirculating unit, the first pig launch and recovery apparatus, the second pig launch and recovery apparatus and the isolated section form a closed recirculating fluid circuit. 
     The closed conduit system may further comprise a pig configured to be loaded into the launch and recovery tube of the first pig launch and recovery apparatus, travel through the isolated section of the water supply system, and be retrieved at the launch and recovery tube of the second pig launch and recovery apparatus. The pig may include one or more of a camera, a global positioning sensor, a scrubber, a battery and a light. The recirculating unit may be mounted on a vehicle, such as a large bobtail truck, semi-truck/trailer or a trailer. 
     In still another aspect of the present invention, a method for pigging a section of a water supply system having a plurality of sections including water mains, pipes, hydrants and valves is provided. The method comprises the steps of connecting a first pig launch and recovery apparatus to the first hydrant; connecting a second pig launch and recovery apparatus to the second hydrant; connecting a recirculating unit to the first and second pig launch and recovery apparatuses to create a closed recirculating fluid circuit; isolating a section of a water supply system between a first hydrant and a second hydrant; loading a pig in the first pig launch and recovery apparatus; pumping water through the closed recirculating fluid circuit to drive the pig from the first pig launch and recovery apparatus to the second pig launch and recovery apparatus; and removing the pig from the second pig launch and recovery apparatus. 
     Each of the first pig launch and recovery apparatus and the second pig launch and recovery apparatus comprise a flow tube having a first flow end configured to fluidly couple with a recirculating unit including a pump, an opposing second flow end configured to be fluidly coupled to the respective first or second hydrant, and a main flow valve located between the first flow end and the second flow end; and a launch and recovery tube having a first launch end fluidly coupled to the flow tube between the first flow end and the main flow valve, and a second launch end fluidly coupled to the flow tube between the main flow valve and the second flow end. The pig may include one or more of a camera, a global positioning sensor, a scrubber, a battery and a light. The recirculating unit may be mounted on a vehicle, such as a large bobtail truck, semi-truck/trailer or a trailer. 
     In yet another aspect of the present invention, a pig apparatus for use with a water supply system having a plurality of sections including water mains, pipes, hydrants and valves is provided. The pig apparatus comprises a riser includes a first end and a second end. The pig apparatus also includes a drogue chute including a webbing canopy connected to the first end of the riser through at least two suspension lines, and a pig load connected to the second end of the riser. The pig load may include one or more of a camera, a global positioning sensor, a scrubber, a battery and a light. In one aspect, the pig apparatus may further include a plurality of stabilizer guides coupled with the pig load. At least one pivoting mount may be connected to the pig load, wherein the plurality of stabilizer guides are coupled to the pig load using the at least one pivoting mount. In another aspect, the pig load may include a scrubber, wherein the scrubber includes a scrubber body having an outer surface, and wherein a plurality of spring wire brushes extend radially outwardly from the outer surface of the scrubber body. The plurality of spring wire brushes may collectively define a scrubbing unit having a first diameter that is greater than a second diameter of a water main that the pig apparatus is configured to be positioned within. 
     Additional objects, advantages and novel features of the present invention will be set forth in part in the description which follows, and will in part become apparent to those in the practice of the invention, when considered with the attached figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other details of the invention will be described in connection with the accompanying drawing, which is furnished only by way of illustration and not in limitation of the invention, and in which drawing: 
         FIG.  1    is a top plan view of a pig launch and recovery apparatus in accordance with an aspect of the invention; 
         FIG.  1 A  is a top plan view of an alternative pig launch and recovery apparatus in accordance with an aspect of the invention; 
         FIG.  2    is a schematic view of a closed conduit system for a municipal water supply system employing a pair of pig launch and recovery apparatuses in accordance with another aspect of the invention; 
         FIG.  2 A  is a schematic view of a closed conduit system for a private fire water supply system employing a pair of pig launch and recovery apparatuses in accordance with another aspect of the invention; 
         FIG.  3    is a top plan view of an embodiment of a pig for use within a water supply system; and 
         FIG.  4    is a top plan view of an additional embodiment of a pig for use within a water supply system. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in the drawings, with initial reference to  FIG.  1   , a pig launch and recovery apparatus for use with a water supply system is generally indicated by reference number  100 . Pig launch and recovery apparatus  100  includes a linear flow tube  102  having a first flow end  104  and a second flow end  106 . First flow end  104  includes a fitting  108  that is configured to be coupled to a recirculating unit  218 , while second flow end  106  includes a fitting  110  that is configured to mount pig launch and recovery apparatus  100  to a hydrant  112  (see  FIG.  2   ). Further, main flow valve  114  is located between first flow end  104  and second flow end  106 , and operates to control the flow rate of water passing through flow tube  102 . 
     Pig launch and recovery apparatus  100  further includes a launch and recovery tube  116  having a first launch end  118  and a second launch end  120 . First launch end  118  is coupled in fluid communication with flow tube  102  between first flow end  104  and main flow valve  114 , while second launch end  120  is coupled in fluid communication with flow tube  102  between second flow end  106  and main flow valve  114 . Launch and recovery tube  116  also includes a first valve  122  proximate first launch end  118 , and a second valve  124  that is located proximate second launch end  120 . A tube access door  126  is located between first and second valve  122 ,  124 . In accordance with an aspect of the present invention, tube access door  126  is configured to allow a pig to be inserted into and removed from launch and recovery tube  116 , such as, but not limited to, pigs  130   a ,  130   b  shown in  FIGS.  3  and  4   , as will be discussed in greater detail below. To allow a user of apparatus  100  to see if pig  130   a ,  103   b  is located in launch and recovery tube  116 , tube access door  126  may be constructed of a transparent, or translucent material, with non-limiting examples including poly(methyl methacrylate) (PMMA), polycarbonate, polyvinyl chloride and similar materials. Launch and recovery tube  116  may also include a bleed valve  128  to relief pressure within launch and recovery tube  116  during insertion and removal of pig  130   a ,  130   b  through tube access door  126 . 
     As seen in  FIG.  1   , launch and recovery tube  116  may include a first portion  116 ′ which may be generally parallel to the longitudinal axis L of flow tube  102  and a second portion  116 ″ which has a longitudinal axis L′ disposed at an angle A relative to axis L. Angle A may be any suitable angle, and in accordance with one aspect of the present invention, may be between about 40 degrees and 50 degrees, and more particularly about 45 degrees. Flow tube  102  may further include an angled screen  132  configured to be disposed at angle A relative to axis L and coincide with an inner sidewall  134  of second portion  116 ″. Screen  132  includes a plurality of through-holes which allow water to travel through flow tube  102  while defining a secondary fluid pathway  136  which directs pig  130   a ,  130   b  into or out of launch and recovery tube  116  as will be discussed in greater detail below. It should be understood that other types of guiding mechanisms may be used in addition to or instead of screen  132  to guide pig  130   a ,  130   b  from recovery tube into flow tube  102 . 
     Turning now to  FIG.  1 A , an alternative pig launch and recovery apparatus for use with a water supply system is generally indicated by reference number  100   x . Pig launch and recovery apparatus  100   x  is similar to pig launch and recovery apparatus  100  described above in all respects except for modifications to launch and recovery tube  116   x . As seen in  FIG.  1 A , launch and recovery tube  116   x  may include a first portion  116   x′  which may be generally parallel to the longitudinal axis L of flow tube  102   x  and a second portion  116   x″  which has a longitudinal axis L′ disposed at an angle A relative to axis L. Angle A may be any suitable angle, and in accordance with one aspect of the present invention, may be between about 40 degrees and 50 degrees, and more particularly about 45 degrees. Flow tube  102   x  may further include an angled screen  132   x  configured to be disposed at angle A relative to axis L and coincide with an inner sidewall  134   x  of second portion  116   x ″. Screen  132   x  includes a plurality of through-holes which allow water to travel through flow tube  102   x  while defining a secondary fluid pathway  136   x  which directs pig  130   a ,  130   b  into or out of launch and recovery tube  116   x . It should be understood that other types of guiding mechanisms may be used in addition to or instead of screen  132   x  to guide pig  130   a ,  130   b  from recovery tube into flow tube  102   x.    
     Launch and recovery tube  116   x  has a first launch end  118   x  and a second launch end  120   x . First launch end  118   x  is coupled in fluid communication with flow tube  102   x  via a flow conduit  119   x  located between first flow end  104   x  and main flow valve  114   x . Second launch end  120   x  is coupled in fluid communication with flow tube  102   x  as described above. Flow conduit  119   x  includes a first valve  122   x  while a second valve  124   x  that is located proximate second launch end  120   x . Terminal end  118   x′  of first launch end  118   x  is capped by a tube access plug  126   x . In accordance with an aspect of the present invention, plug  126   x  is a threaded coupling including a tube fitting  126   x′  and cap  126   x ″. By way of example and without limitation thereto, tube fitting  126   x′  may be a Storz adapter while cap  126   x″  is a corresponding Storz cap. Plug  126   x  is configured to allow pig  130   a ,  120   b  to be inserted into and removed from launch and recovery tube  116   x  after closing of first valve  122   x  and second valve  124   x . (Ttube access door  126  and tube access plug  126   x  may be collectively and interchangeably referred to as a tube access apparatus). Launch and recovery tube  116   x  may also include a bleed valve  128   x  to relief pressure within launch and recovery tube  116   x  during insertion and removal of pig  130   a ,  130   b.    
     Turning now to  FIGS.  2  and  2 A , in accordance with a further aspect of the present invention, a closed conduit system  200  conducts a flow of water (flow direction indicated by arrows) between a first point, e.g., first hydrant  202  and a second point, e.g., second hydrant  204  in a water supply system  201 . Water mains  206 ,  208 ,  210  and valves  212  and trunk pipes  214 ,  216  are connected to hydrants  202 ,  204 . As shown in  FIG.  2 A , water main  206  is a private fire water main receiving water from a municipal water main  207 . A back flow preventer  209  may be placed along trunk pipe  217  to prevent water from private water main  206  from entering the municipal water supply in municipal water main  207 . With continued reference to  FIGS.  2  and  2 A , closed system  200  conducts the flow of water out of the water supply system  201  at first hydrant  202 , through a recirculating unit  218  and returns the flow of water back into water supply system  201  at second hydrant  204 . Recirculating unit  218  includes at least one pump  220  to pump the flow of water through closed conduit system  200 . 
     Closed conduit system  200  may further include a pair of pig launch and recovery apparatuses  100   a  and  100   b . It should be noted that while shown and described as including pig launch and recovery apparatuses  100   a  and  100   b , one or both of pig launch and recovery apparatuses  100   a  and  100   b  may be swapped with a respective pig launch and recovery apparatus  100   x  as shown and described above with regard to  FIG.  1 A  with equal effect. First pig launch and recovery apparatus  100   a  may be coupled to first hydrant  202  at second flow end  106   a  while first flow end  104   a  is coupled to recirculating unit  218  via a hose  222  or other type of conduit. Second pig launch and recovery apparatus  100   b  may be coupled to second hydrant  204  at second flow end  106   b  while first flow end  104   b  is coupled to recirculating unit  218  via a hose  224  or other type of conduit. In this manner, water main  206 , trunk pipes  214 ,  216 , recirculating unit  218 , hydrants  202 ,  204 , pig launch and recovery apparatuses  100   a ,  100   b  and hoses  222 ,  224  create a closed recirculating fluid circuit  226  whereby all of the flow of water taken from water supply system  201  is returned to the water supply system and no water is wasted or run off into the environment. It should be further noted that pig lunch and recovery apparatuses  110   a ,  100   b , ( 100   x ) and recirculating unit  218  are coupled inline and pressurized via the water supply system prior to isolation of water main  206  and trunk pipes  214 ,  216  (i.e. prior to closing of all valves  212 ). Pump  220  is then powered so as to generate and controlled flow of the isolated, pressurized water within closed recirculating fluid circuit  226 . 
     In a further aspect of the present invention, recirculating unit  218  may also include one or more in-line filter units  228  to receive the flow of water from water supply system  201  within closed recirculating fluid circuit  226 . Filter unit  228  may be a particulate filter or a granular activated charcoal (carbon) filter (GAC filter), and multiple filter units  228  may be serially connected, connected in parallel, or independently turned on and off as desired, within closed recirculating fluid circuit  226 , as needed. In this manner, the one or more filter units  228  may filter and/or adsorb the undesirable particulates or other matter from the water so that water main  206  of water supply system  201  is cleaned between the hydrants  202  and  204 . All of the flow of water taken from water supply system  201  is returned to water supply system  201  free of all the undesirable matter and no water is wasted or discharged into the environment. 
     Provision of pig launch and recovery apparatuses  100   a  and  100   b  allows for controlled introduction and removal of one or more pigs (e.g., pigs  130   a ,  130   b ) depending upon the service needed/requested. As will be described in greater detail below, a pig may be equipped with one or more of a camera, a global positioning system (GPS) sensor, a scrubber, a battery and a light, such as an LED. In this manner, closed conduit system  200  can efficiently perform a number of services, including flow rate testing, flushing, scrubbing, disinfecting, videoing, global information system (GIS) visualization, leak detection using a single system without requiring depressurization of the water main or wasting of hundreds or thousands of gallons of water. 
     With reference to  FIGS.  3  and  4   , pigs  130   a ,  130   b  may generally include a drogue chute  250  having a webbing canopy  252  connected to a first end  254  of riser  256  using two or more suspension lines  258 . Second end  260  of riser  256  is coupled to a pig load  262 . With reference to pig  130   a  shown in  FIG.  3   , the second end  260  of riser  256  may be connected to pig load  262  using two connectors  261  that are attached to opposite front corners thereof. 
     As shown in  FIG.  3   , pig  130   a  may include a pig load  262   a  having a camera  264  and one or more lights  266  housed within a camera case  268  to enable visual inspection of the interior of water main  206  and trunk pipes  214 ,  216 . In one aspect of the invention, lights  266  are light emitting diodes (LEDs) used to illuminate the pipe walls. A battery  270  is coupled to camera case  268  so as to provide electrical power to camera  264  and lights  266 . Battery  270  may be included within camera case  268  or may be housed with a battery case  272 . Battery case  272  may be rigidly of flexibly connected to camera case  268 . In one aspect of the invention, battery case  272  is moveably or flexibly coupled to camera case  268  to allow pig load  262   a  to bend or flex when encountering a curve or turning corners as pig  130   a  passes through closed recirculating fluid circuit  226 . 
     As further seen in  FIG.  3   , camera case  268  may further include a plurality of stabilizer guides  274  configured to center pig load  262   a  within water main  206  and trunk pipes  214 ,  216 . Stabilizer guides  274  may be mounted to camera case  268  using respective pivoting mounts  276  located adjacent to opposite front corners thereof. Stabilizer guides  274  may be elongated wire members that extend the length of pig load  262 . Distal ends of each stabilizer guide  274  may have a ball  275  coupled thereto. Pivoting mounts  276  allow pig load  262   a  to rotate within, and stay positioned within, stabilizer guides  274  so that pig load  262   a  maintains it centered orientation as pig  130   a  travels around curves or bends or has its flow reversed in the event that pig  130   a  becomes stuck or lodged within water main  206  or trunk pipe  214 ,  216 . In one example, there may be two stabilizer guides  274   a ,  274   b  extending from one pivoting mount  276   a , and two stabilizer guides  274   c ,  274   d  extending from another pivoting mount  276   b . Stabilizer guides  274   a ,  274   b  may extend to one side of pig load  262  and below pig load  262 , respectively. Stabilizer guides  274   c ,  274   d  may extend to the other side of pig load  262  and above pig load  262 , respectively. In this respect, stabilizer guides  274   a - d  surround pig load  262  and operate to position pig load  262  generally in the middle or central location as it travels through the pipe. 
     Turning now to  FIG.  4   , an alternative or additional pig  130   b  includes a pig load  262   b  comprising one or more scrubbers  278  coupled to second end  260  of riser  256 . Scrubbers  278  may include a plurality of spring wire brushes  280  extending radially outwardly from an outer surface of a scrubber body  282 . In accordance with an aspect of the present invention, a diameter D of scrubber  278  may be slightly larger than a diameter of the largest pipe comprising the water main  206  and trunk pipes  214 ,  216 . In this manner, brushes  280  may flex within water main  206  and trunk pipes  214 ,  216  such that wire ends  284  scour the inner surface of the pipes, thereby dislodging materials affixed to the inner walls of water main  206  and trunk pipes  214 ,  216 . Pig load  262   b  may also include a tracking device  286  (e.g., a GPS sensor) to locate and track the position of pig  130   b  within closed recirculating fluid circuit  226 . 
     In use, with reference to  FIGS.  2  and  2 A , a method for pigging a section of a water supply system comprises the steps of connecting a first pig launch and recovery apparatus is connected to the first hydrant, such as by coupling second flow end  106   a  of first pig launch and recovery apparatus  100   a  to first hydrant  202 , and connecting a second pig launch and recovery apparatus to second hydrant  204 , such as by coupling second flow end  106   b  of second pig launch and recovery apparatus  100   b  to second hydrant  204 . Recirculating unit  218  is then connected to the first and second pig launch and recovery apparatuses  100   a ,  100   b , such as via respective hoses  222 ,  224  and first flow ends  104   a ,  104   b . At this point, water may flow though closed recirculating fluid circuit  226  under water supply high pressure. Next, a section of a water supply system is isolated between the first hydrant and the second hydrant, such as by closing valves  212  to create a closed recirculating fluid circuit  226 . Thus, an isolated section of water main  206  is defined between trunk pipes  214 ,  216  and first and second hydrants  202 ,  204 . Pump  220  within recirculating unit  218  may then initiate and control flow of the pressurized water within closed recirculating fluid circuit  226 . 
     To pig the isolated section of water main  206 , with reference to  FIGS.  2 - 4   , a pig  130   a ,  130   b  is loaded into second pig launch and recovery apparatus  100   b . To load the pig, first and second valves  122   b ,  124   b  are closed and tube access door  126   b  (tube access cap  126   x ) is opened so that pig  130   a ,  130   b  can placed within first portion  116   b′  of launch and recovery tube  116   b . (Prior to opening tube access door  126   b , bleed valve  128   b  may be opened to relieve any water/air pressure within launch and recovery tube  116   b ). Once pig  130   a ,  130   b  is inserted, tube access door  126   b  is closed and first and second valves  122   b ,  124   b  are opened. Water will then flow into launch and recovery tube  116   b  and propel pig  130   a ,  130   b  out of second portion  116   b″  of launch and recovery tube  116   b , guided by screen  132 , and into closed recirculating fluid circuit  226  at second hydrant  204 . Pig  130   a ,  130   b  will then travel through trunk pipe  216 , water main  206  and trunk pipe  214  to first hydrant  202 . 
     To remove pig  130   a ,  130   b  from first pig launch and recovery apparatus  100   b , first and second valves  122   a ,  124   a  are opened and tube access door  126   a  is closed. Pig  130   a ,  130   b  exits first hydrant  202  and, through interaction with angled screen  132 , is directed into secondary fluid pathway  136   a  of second portion  116   a″  of launch and recovery tube  116   a . Once the pig is disposed in first portion  116   a ′, first and second valves  122   a ,  124   a  are closed and tube access door  126   a  is opened so that pig  130   a ,  130   b  can be extract from first pig launch and recovery apparatus  100   a . Prior to opening tube access door  126   a , bleed valve  128   a  may be opened to relieve any water/air pressure within launch and recovery tube  116   a.    
     From the above description, one skilled in the art would recognize that a variety of pigs may serially be added and removed from the system to perform multiple functions during a single operation. By way of example and without limitation thereto, closed conduit system  200  may be flushed without a pig to remove sediment collected in pipes or to test system flow rates to ensure compliance with fire protection flow requirements. Scrubber pig  130   b  may then be launched and recovered such that trunk pipes  214 ,  216  and water main  206  are scoured clean of internal build-up. Camera pig  130   a , with optional leak detection capabilities, may then be launched and recovered so that the internal surface of the pipes can be inspected and monitored for potential failure and need for replacement. GPS sensors and GIS functionality may assist in locating the exact location of a leak of weakness so that the pipe may be uncovered and repaired without requiring overly extensive digging or disruption of the surface. 
     From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the system and method. It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments of the invention may be made without departing from the scope thereof, it is also to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative and not limiting. 
     The constructions described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts and principles of the present invention. As used herein, the terms “having” and/or “including” and other terms of inclusion are terms indicative of inclusion rather than requirement. 
     While the invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof to adapt to particular situations without departing from the scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope and spirit of the appended claims.