| 摘要 |
PURPOSE:To permit measurement of accurate water levels in plural places without the need for any special boring, by opening the lower position of a manhole, inserting a perforated pipe into the subsoil in the outside part of the manhole and detecting the oozing state of the ground water into the perforated pipe. CONSTITUTION:A hole is drilled in a concrete wall 2 in the lowest possible position of a manhole 1. A perforated pipe 4 is inserted into the subsoil 3 in the outside part of the manhole 1 through said hole. A removable cap 9 is held put on the opening end on the manhole side of the pipe 4. In the stage of measurement, the operator removes the cap 9, fits a transparent vinyl pipe 10 into the pipe 10 to form a U-pipe 11 and observes the water level in the pipe 10 visually. |
