Big Ridge #5 Pump Station Improvements

Problem

The City of Chattanooga’s Big Ridge #5 Pump Station required several significant upgrades, however, the site of the existing pump station was prone to subsidence (the gradual sinking of the ground). Constructing a new pump station adjacent to the existing one was the best option, but one of the biggest challenges was the limited space for installation. CTI decided to go with vertical tunneling using liner plates. This method required much less space than conventional methods. The plan was to horizontally tunnel from the new wetwell to the existing wetwell and connect the two.

Solution

Improvements include the construction of a new pump station adjacent to the existing station with a pumping capacity of 825 gpm per pump, conversion of the existing wetwell into a large manhole, installation of a new 12-inch-diameter gravity sewer connector line between the existing and new wetwells, and installation of other miscellaneous components.

Project Elements

• Replacement of existing 8-foot-diameter precast concrete wetwell top slab and access hatch
• Installation of three new 8-inch-diameter drop piping in existing wetwell and an inline grinder in the existing wetwell at the inlet of the connecting gravity sewer between the existing and new wetwells
• Replacement of existing flow meter

CTI Services

• Evaluation
• Design
• Bidding and Award
• Construction Administration
• Coordination of Surveying and Geotechnical services with outside firms