Culver-Goodman Tunnel Dropshaft Exit Conduit Model Studies

The City of Rochester plans to excavate the Culver-Goodman tunnel and connect it to the existing Cross-Irondequoit tunnel through a control structure. Several dropshafts will convey the effluent from surface collection facilities to the storage and conveyance tunnel. The function of these dropshafts is to transport the water from one elevation and energy level to a lower elevation and energy level and, in the process, to dissipate energy and remove the entrained air. The term "dropshaft" is sometimes used collectively to include the various components of the structure. Conduits at or near the ground surface collect the water and convey it to an elbow which deflects the flow about 90 degrees into the vertical drop shaft. The vertical shaft is divided by a slotted wall which separates the falling water-air mixture and the released air returning to the surface. In the elbow and vertical shaft the falling water entrains considerable amounts of air and gains kinetic energy. The vertical shaft terminates in a sump, which is a large excavated and lined chamber. The purpose of the sump is to dissipate some of the energy, to remove and co~lect the entrained air, and to direct the water at a reduced velocity into the exit conduit. The sloping roof of the sump guides the collected air back to the vent side of the vertical shaft. A portion of the rising air is drawn through the slots in the divider wall and re-· entrained in the falling water; the excess air returns to the surface. The exit conduit conveys the water into the tunnel. A typical model including all of these components