A technique for aiding an underground communications cable installer in the installation such cable in underground utilities neighborhoods. The technique manages the problem presented by a surface-visible, underground-pathway obstruction such as a sidewalk, which lies across the path of installation. The technique, or method, is useful with any kind of cable, such as fiberoptic cable or copper wire cable. Hydraulic water pressure is applied through a biased, flexible conduit to erode a pathway under the obstruction from ground surface on one side to ground surface on the opposite side of the obstruction, thereby forming a tunnel under the obstruction through which the cable can be easily pulled. In alternative embodiments, the cable can be inserted directly into and through the conduit while it is underground, the conduit then acting as a sleeve for the cable which is subsequently removed prior to burying the cable in a trench dug from street-located handhole to house. Special apparatus connects a water hose to the flexible conduit (PVC plastic) to provide watertight operation while allowing manual flow control.

BACKGROUND 
     It is not uncommon today to find residential neighborhoods which have underground utilities, in addition to the usual underground water/sewer service. In these neighborhoods, the electric, gas, and communication services (telephone, fax, cable television, Internet, etc.) are all installed underground, and there are no upright power poles to be seen. There are advantages to underground utility services. For example, in high wind storms, or ice storms, in an underground utility neighborhood, there are no power poles or wires subject to high wind and/or ice damage and/or collapse. 
     In these neighborhoods, when a new communication cable is to be connected, for example, to a particular residence, that cable is buried in a trench in the ground typically between a “hand-hole” located near the street and the particular residence to which the cable is to be connected. The depth of the trench is typically seven inches, or so. Obviously, buried cable installation is not limited to single family dwellings and it can be applied to apartment buildings as well as to non-residential buildings such as industrial buildings. 
     These trenches are usually dug by hand, at least for individual residences. In the course of digging these trenches for cable installation, such as fiber optic cable or copper-wire cable installation, it is not unusual to be confronted with an immovable obstacle such as a concrete sidewalk, a stone wall, a series of large rocks in the nature of a wall, decorative landscape concrete edgings, etc. These are problematic situations that slow down any underground installation process, and the cable installer must come up with a “work-around” (or, more precisely, a “work-under”) solution to the obstacle problem. There is a need for an easily applied and effective solution to this underground-pathway obstruction problem and the disclosed subject matter of the instant application teaches and claims such a solution. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic top view of an exemplary surface-visible, underground-pathway-obstruction such as a sidewalk with a flexible conduit positioned there-under; 
         FIG. 2  is a schematic elevation front view of an exemplary cross-section of the sidewalk of  FIG. 1 , with a flexible conduit positioned there-under; 
         FIG. 3  is a functional block diagram of an exemplary system for configuring a pathway under a surface-visible, underground-pathway-obstruction; 
         FIG. 4  is an exemplary schematic diagram of the hose to conduit adapter of  FIG. 3   
         FIG. 5  is a flowchart depicting an exemplary method of fiberoptic or other cable underground installation; and 
         FIG. 6  is an exemplary schematic diagram showing how fiberoptic cable can be lashed for pulling it through a resultant tunnel fashioned under a ground surface obstruction. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In this description, the same reference numeral in different Figs. is referring to the same entity. Reference numerals of each Fig. start with the same number as the number of that Fig. For example,  FIG. 3  has numerals in the “300” category and  FIG. 4  has numerals in the “400” category, etc. Thus, if discussing an entity in a Fig. having a particular reference numeral not starting with the same number as that Fig. one can easily refer back to the appropriate Fig. 
     Exemplary embodiments include system and method for facilitating underground installation of communication cable such as fiberoptic cable or copper wire cable. If an obstruction, such as a sidewalk, is encountered crossing paths with an intended trench path in which communication cable is intended to be buried, the systems and methods permit the erosion, or washing-away, or loosening-up, of soil underneath the sidewalk, along an intended underground route, through which the communication cable is passed. 
     In other words, a trench may first be hand-formed starting from the location of a communication signal source, such as, for example, a hand-hole located at the street in front of a residence, to the first-encountered side of the sidewalk obstruction. The trench is continued from the other side of the sidewalk obstruction to the residence. Applicant's erosion, or hydraulic-pressure, technique, whereby the soil is loosened under the sidewalk along a particular underground route, permits the communication cable to be easily fed under the sidewalk through that loosened-up, or eroded, underground route or tunnel from the formed trench on one side of the sidewalk to the formed trench on the other side of the sidewalk. There is no requirement that the trench be formed prior to the underground route or pathway under the sidewalk, and the underground pathway can be formed first. 
       FIG. 1  is a schematic top view of a surface-visible, underground-pathway-obstruction such as a sidewalk with a flexible conduit positioned there-under according to an exemplary embodiment. Sidewalk  101  represents a surface-visible obstruction to a trench (trench not shown in this Fig.). In other words, sidewalk  101  prevents a continuous trench, approximately 6-12 inches deep, from being dug, usually by hand using shovels or similar tools, from one side, e.g., side “A” of sidewalk  101  to side “B” thereof. 
     Flexible conduit identified as  102 ( a ) and  102 ( b ) is a continuous conduit with sections  102 ( a ) lying on top of the ground, one section on either side of the sidewalk, and with sections  102 ( b ) lying under the ground and depicted in dashed-line-format. Sections  102 ( b ) also pass underneath sidewalk  101 . Therefore, locations  103  and  104  signify the two places where above-ground conduit section  102 ( a ) transitions to below ground conduit section  102 ( b ). This depicts the conduit after it has been passed under the sidewalk. 
     Referring to  FIG. 2 , a schematic elevation front view of a cross-section of the sidewalk  101  of  FIG. 1  is shown, exposing flexible conduit  102  which is positioned there-under according to an exemplary embodiment. Sidewalk  101  is shown as partially submerged below ground surface  201  into underground  202 . Output end P of flexible conduit  102  is shown at the right of the drawing, the opposite end of the conduit being its input end. Input and output ends of the conduit are used in reference to inflow and outflow, respectively, of water therethrough, to be described below. Water flow direction  205  is shown. 
       FIG. 3  is a functional block diagram of a system for configuring a pathway under a surface-visible, underground-pathway-obstruction in accordance with according to an exemplary embodiment. A source of water pressure  301  is shown at the left of  FIG. 3 . This source can come from a home water supply which, in turn, receives water from a public source such as a municipal reservoir or from a private water source such as a well drilled on the property of that home. 
     The source of the water is not of particular significance, but the pressure of the water that is applied is relevant to their operational success. In other words, well-water pressure may be insufficient to allow efficient operation. But that pressure can be boosted by a mechanism (not shown) similar to that used for power-washing outdoor decks, house siding, etc., if needed. Typical water pressure from municipal supplies is generally adequate, but that pressure can also be increased by the same mechanism noted herein, if needed. The pressure needed for proper operation of embodiments disclosed herein is a function of the compactness of the soil to be eroded—the more compacted the soil such as hard clay, the more pressure required. 
     Water pressure source  301  is connected to a typical garden hose  302 , which homeowners use for lawn-watering and other similar chores. The other end of that hose is connected to a hose-to-conduit-adapter  303  (hereinafter “adapter  303 ”). Adapter  303  connects to conduit  304  and forms a water-proof interface between the garden hose and conduit  304 . Adapter  303  can be constructed from standard metal plumbing and/or plastic plumbing hardware. Adapter  303  can include a shutoff valve to be used by a cable installer to turn on/off water flow there-through. 
     Detail of adapter  303  is shown in  FIG. 4  which is an exemplary schematic diagram of the hose to conduit adapter of  FIG. 3 . Adapter  303  has typical garden hose coupling  401  on its left side for normal coupling to a standard garden hose. Adapter has compression fitting  402  on its right side, to properly engage and make water tight the interface between itself and flexible conduit  304 . In addition adapter  303  has valve  403 , manually adjustable, to control water flow and shut-off such flow if need be. 
     Returning to  FIG. 3 , conduit  304  may be formed from a flexible plastic tube having inner diameter similar to, or typically less than, the inner diameter of the garden hose to which it is attached by adapter  303 . Conduit  304  is formed in a manner that gives it a permanent bias or curve; in other words, if lying flat on the ground without external constraint imposed on the conduit, it can assume a curve in the manner shown. In addition, other conduits can be brought to a job-site and made available for use by a cable installer, these other conduits having a more severe curve-bias, even to the extent that the conduit is “coiled.” These various strengths of bias or curvature can be useful in different applications as a function of ground soil density actually encountered at a particular job site, distance to be traversed underground, and other factors. In other words, for a short underground distance, compared to the distance of a sidewalk width, and in a highly compacted soil, it may be advantageous to try a tightly-coiled conduit to achieve an underground path consistent with the size of the barrier in its path, as shall be more fully described below. The output end P of the conduit can be tipped with a rim of hard metal such as steel, and the rim can have a sharp cusp formed into it, the cusp pointing in the direction of water flow, to facilitate operation. 
     Briefly, in operation, an underground cable installation team may have certain team members who are responsible for digging the above-referenced trench and for traversing any ground surface obstacles that are encountered. When encountering an obstruction, e.g., a sidewalk, one of these team members, an installer, after connecting flexible conduit to a water supply, can grab flexible conduit  304  and press the sharp metal rim into the soil at one side of the sidewalk. The water can then be turned-on, allowing a pressure stream of water to be applied against the ground surface. Simultaneously, a steady force is applied by the installer to the flexible conduit, pushing against the soil. The conduit, thereby, follows the direction of the water stream which is eroding, or loosening, the soil in its path. 
     An experienced installer can guide, wiggle, push and/or orient the flexible conduit, thereby working the metal-rimmed output end of the conduit through the soaked underground soil until the metal rim pops-up through the ground surface on the opposite side of the sidewalk. Another variable under control of the installer is the water pressure, which can be increased/decreased to achieve the desired result. In the event that the flexible conduit passes under the sidewalk, but does not emerge on its own, the installer can always dig a hole on the opposite side of the sidewalk at the approximate place where the emergence was expected, and capture the conduit by that technique, as a last resort. 
       FIG. 5  is a flowchart depicting the above-described method or technique of fiberoptic cable underground installation in more detail. In act  501 , the installer attaches water hose  302  to source of water pressure  301 . In act  502 , the installer attaches flexible conduit  304  to the hose via adapter  303 . In act  503 , the installer presses the flexible conduit output and, in particular embodiments, the hard metal rim attached to the conduit output, against ground surface  201  nearby sidewalk  101 . In act  504 , someone opens a water flow valve, either at the dwelling on the property from which the water is supplied, or at the adapter  303 , or both, to cause water flow through conduit  304  to penetrate the ground at the place where it is being pressed by the conduit output P. 
     In act  505 , the installer works the conduit under the obstruction with intentions of achieving an emergence on the other side of the obstruction  101 . In question box  506 , the query is made: has the conduit emerged? If not, another question box  507  answers the question: is progress being made? If yes, a return to question box  506  occurs to query the emergence of the conduit end. But, if not, the algorithmic process moves to act  508  which allows, if needed, a pressure adjustment to the water supply; the flow can be increased by opening the garden hose to fully-open and/or a pressure washing apparatus (not shown) can be connected to the garden hose upstream from adapter  303  to radically increase available water pressure to loosen heavily compacted underground soil. After that, acts  505  and  506  are repeated to see if the conduit emerges. 
     If conduit  304  does emerge on the other side of the obstruction, then in act  509  one end of the fiber optic cable (or other telecommunications cable) that is being installed on this property is tied or lashed to the output end of the flexible conduit. In act  510 , the installer pulls the conduit back out of the underground passage in the opposite direction from that in which it was inserted, thereby dragging the fiber optic cable into and through the underground tunnel or passage to the other side of the obstruction. Thus, the cable is now traversed under the obstruction and it can then be detached from the conduit. In act  511 , the cable can then be pulled thereunder to whatever length is needed to make the appropriate optical or electrical connection from hand-hole to dwelling structure. If a trench has been dug, the cable is then appropriately buried in the trench, and if not, the trench is then dug at that time with cable burial following. 
       FIG. 6  is a schematic diagram showing how fiberoptic cable can be lashed/tied for underground installation, in accordance with the description of the previous paragraph.  FIG. 6  shows a portion of conduit  304  near its output end P, after it has emerged from underground per the discussion above. Fiber optic cable  601  is shown physically attached to conduit  304  by lashing or tie  603 . Lashing  603  can be a twist wire-tie or made from nylon cord or from any other strong, suitable material. In addition, conduit  304  can be grooved near end P on its outer circumferential surface to form a frictional surface or a detent to facilitate the binding between the conduit and the cable. Alternatively, an adhesive tape, such as electrical insulating tape can be wound around the cable and conduit, tightly, to enable the pull-through operation to properly conclude. In this instance the direction of pull-through is direction  602  as shown in  FIG. 6 . 
     In the preceding specification, various preferred embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the invention as set forth in the claims that follow. For example, in a first alternative technique, a fiberoptic or other cable can be attached to the flexible conduit at the adapter end, instead of at the conduit's output end, after removing the adapter, and the conduit can be pulled out of the underground tunnel in the same direction in which it was inserted, thereby dragging the fiberoptic cable behind it into and through the tunnel. In another alternative technique, where a copper-wire cable is being installed, after removal of the conduit from the hose-to-conduit-adapter  303 , that cable can be inserted directly into and through the conduit itself, before the conduit is removed from its above and below ground position; after emergence of the copper wire cable, the conduit sleeve can then be pulled out of the ground, leaving the cable in proper place. Accordingly, the specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.