WOODS TRUNK COLLAPSE LESSONS LEARNED IN EMERGENCY DESIGN & CONSTRUCTION

In late summer of 2005 the Bureau of Environmental Services got its first looks at a 30” brick pipeline that had been spitting bricks. The results were scary. A section of the brick pipe was collapsed down to 9” high. Flow was running outside of the pipe and could be seen through the space in between the bricks. The City immediately issued an emergency contract to make repairs before complete collapse of the sewer pipe.As the details of the pipe were uncovered, we found it originally was built in a ravine in 1893, then buried with up to 50 feet of fill, after which buildings, two highways, and several arterial streets were constructed. The City Engineer's anxiety level rose when eminent collapse was considered. The pipe conveyed combined sanitary and storm flows of up to 18,000 gallons per minute on a seven percent slope when it was raining.The City could not wait to finish a detailed design for replacement of the problem sewer, a process that normally takes up to 18 months. This necessitated a series of emergency contracts, during one of the wettest winters on record. The project competed for pumps and piping resources with the Hurricane Katrina relief efforts. It resulted in spending millions, at a time when City construction project costs were under political scrutiny.This paper will discuss the lessons learned: contracting, problem solving, constructing, and interacting with the public/political system on this challenging project.