During this construction, there was a possibility that an underground connecting passage & a foundation pile for the Tokyo Metro Marunouchi Line were left on the pipeline. Since the place where the foundation piles & left is a road in the center of the city with heavy traffic & the depth of the pipeline is very deep, it was necessary to give due consideration to safety. In the actual construction, there were no piles, but liner plate reinforced ring 6 steps of the reception shaft, 5 H-beams (150 mm), & 1 m of manhole RC wall were cut.