Baltimore Siphon Rehabilitation: Changing Conditions, Dynamic Solutions

The Baltimore Siphon project for the city of Baltimore required the assessment of the Horner’s Lane Siphon, a 3-barrel concrete encased siphon (1–24 inch and 2–36 inch) built in 1931. Sewage was reported leaking from a crack in one of the pipes and discharging into the stream. The city’s goals for the project were threefold: (1) immediate repair: seal the crack on the 24-inch siphon pipe to stop the sewage leak, (2) short-term repair: re-support the siphon pipes, as the stream had incised so much that the pipes were exposed, with no soil supporting them, and (3) long-term repair: develop a long-term solution to repair/rehabilitate the exposed siphon pipes and restore the stream. This paper describes the process used to develop the immediate, short-term, and long-term repair solutions, and it also discusses how to deal with a new emergency situation when trying to correct an existing emergency.