McMahon & Mann prepared calculations, design plans, and specifications for a shoring system to accommodate the replacement of a 122-foot-long section of sewer on the Buffalo Psychiatric Center’s campus. The sewer crosses under a concrete steam tunnel that needed to be maintained and protected throughout construction. To accomplish this, the contractor installed the replacement sewer by horizontally jacking it below the steam tunnel. This method requires two excavations, one for a jacking pit and the other for a receiving pit, at each terminus of the sewer.

The jacking and receiving pits were each approximately 22 feet deep. Due to the depth, the shoring required bracing. The design included a plan, cross sections, connection details, and construction sequencing.

The design was successful in meeting the contractor’s needs for safety, the sewer designer’s requirements for installation, and the owner’s need to protect the existing utilities.