edges 38 at any point along axis body axis 30 may generally be described as lying on an a circle indicated whimsically by broken line 44 see fig2 circle 44 has its smallest diameter at about front end 32 of body 22 this smallest diameter must be smaller than the inside diameter of pipe 35 to allow edges protrusions 36 to penetrate therein generally circle 44 may have a smallest diameter between about one half and three quarters of the inside diameter of pipe 35 sloping portion 40 of edge 38 may extend from about first end 32 along first cylindrical portion 24 and frustro conical portion 28 to a point 46 on edge 38 point 48 may be generally aligned with junction 48 between cylindrical portion 26 and frustro conical portion 28 straight portion 42 of edge 38 extends partially along cylindrical portion 26 ending at point 50 circle 44 has its maximum diameter between point 46 and point 50 as will be explained below the location of point 50 is determined primarily by the construction details of body 22 straight portion 42 may extend completely along cylindrical body portion 26 the maximum diameter of circle 44 must be greater than the diameter of cylindrical portion 26 so that protrusions 36 may extend radially outward therefrom body 22 is preferably constructed such that it does not have moving or removably attached parts which may come into forceful contact with existing pipe 35 or surrounding earth 50 in which it is buried cylindrical portion 24 includes a first hollow cylindrical member or pipe 29 pipe 29 may be made from seamless stainless steel tube having a wall thickness of about three eighths of one inch cylindrical portion 26 includes a second.