material layer by layer while each of the layers surrounding tubular section 5 is carefully and tightly compacted both the small diameter of tubular section 5 and the absence at this stage of frame 1 facilitates compacting all around said section at this stage the upper extremity of tubular section 5 extends above the final level of street foundation 4 in order both that the frame 1 can be properly positioned and that no granular material will find its way into tubular section 5 once street foundation 4 has been well compacted a small excavation in accordance with the dimensions of frame 1 and the slope of inclined external wall 2 is made manually around tubular section 5 so that frame 1 can be set into position as frame 1 is being set into the aforedescribed small excavation up to the level of the first layer of pavement 7 the upper portion of tubular section 5 slides inside lower portion 3 once frame 1 has been properly embedded with external inclined wall 2 resting upon street foundation 4 the upper extremity of tubular section 5 is cut below the lower limit of inclined internal wall 10 so as not to impede the flow of runoff water the first layer of pavement 7 is laid down.