Seattle City Light last week used an innovative approach to installing conduit for new fiber optic cables in a utility tunnel under Portage Bay. The flooded tunnel, built decades ago, would normally have to be pumped dry for maintenance work which now triggers expensive environmental disposal of water and sentiments at a cost of $500,000. The new approach? Scuba divers. From City Light:
Instead, City Light hired the dive team to help install the conduits while the tunnel remained flooded. The dive team guided a pull rope and the conduit through the tunnel while City Light crews fed the conduit from large rolls on one side of the Ship Canal and used a winch to pull the conduit to the other side. That approach cost less than $20,000.
City Light crews will come back later to install the fiber optic cable. The cable will provide a dedicated data link for City Light and enhance reliability. Three other data lines City Light uses are carried on overhead wires and shared with other city departments. Large construction projects can interrupt service on some of those overhead wires.
Tunnel under Portage Bay? Who knew? Perhaps scuba-geared bikes and pedestrians could use it to cross 520?