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The Atlanta Water Supply Program included an approximately 5-mile long, 12.5-foot diameter, finished TBM water conveyance and storage tunnel connecting the Bellwood Quarry to the Hemphill Pump Station and the Chattahoochee River. Delivered under a CMAR contract, the tunnel originates at the Bellwood Quarry site via portal launch, continues to the Hemphill Pump Station, and terminates at the Clayton site—increasing Atlanta’s water storage capacity from a 4-day to a 40-day supply.
The Bellwood site includes four shafts ranging in depths from 200 to 400 feet with 20- to 30-foot diameters and finished with reinforced cast-in-place concrete, placed both top-down and bottom-up, with associated hand-mined adits connecting the shafts to the quarry.
At the Hemphill site, tunnel connections include five, 9.5-foot diameter, blind-drilled pump shafts lined with steel casing.
At the Clayton site, a 30-foot diameter by 350-foot-deep shaft served as the exit location for the TBM.
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