These precast concrete products include stormwater detention vaults, catch basins, and manholes. Founded in 1917, the company manufactures pre-cast concrete pipe, culverts, boxes, manholes and arches. Vertical pipes, usually made of precast concrete, called manholes, connect the mains to the surface. It is the system of pipes, chambers, manholes, etc. Buried tanks and manholes may float in the liquefied soil due to buoyancy. The army was kept under withering machine gun fire from the manholes of the tunnels. The manholes were later welded shut. There are two diameter manholes in the top of the containment vessel. Access for cleaning and repairs was through manholes at distances. Manholes fitted to them allowed regular internal inspection. The Buchan trap is normally found in the bottom of manholes or drop-shafts. Later, smoke emerged from the ends of the tunnel and from several manholes. Manholes provided access to parts that were covered. He would conduct measurements and was prepared to climb into street manholes to do so. Even the Con Ed men were shooting me from down in their manholes.