Pump Station Slipform - Atlanta, Ga.
City of Atlanta
The South River Tunnel project was a joint venture between Ibberson, Kiewit and Western Summit for the City of Atlanta, Georgia, and its effort to upgrade the water/wastewater infrastructure of that area. The project included the construction of a new underground pump station shaft which would have a finished diameter of 50 feet high and over 175 feet deep.
The project team determined early on that slipforming was the preferred method of construction to line the excavated shaft with a 3-foot-thick (nominal) reinforced concrete wall. Slipforming would offer many benefits to the project including shaving several months off of the construction schedule for the pump station. Other benefits included the added safety of a full, custom-engineered work platform as well as the quality associated with a monolithic concrete pour without the need for costly construction joints and water stop.
The slipform was suspended by strand jacks mounted on a structural steel head frame located over the shaft. This system allowed the use of the suspended platform multiple times, opposed to the one-time-only upward movement of a conventional slipform, resulting in our ability to:
We started pouring concrete at 7:50 a.m. on a Tuesday and finished pouring at 11:55 p.m. on Saturday of the same week. We poured 175 vertical feet of shaft wall in 112 hours (an average of just less than 19 inches of vertical wall poured every hour). In those 112 hours, we placed over 4,700 cubic yards of concrete.
This successful project was completed on budget as well as realizing a savings of several months on the construction schedule