Low Overhead Secant Piles Drilled from within a Shaft-Video

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Video Summary

A Detroit sewer collapse created a surface sinkhole and forced nearby residents to evacuate. Years later, the water department commissioned a slip-lining project to prevent future failures. Schnabel built a circular secant-pile access shaft about 50 feet deep, stepping it over the existing sewer and extending below groundwater to contain soil and water.<br /><br />The site was tightly constrained by nearby power lines, leaving only a six-foot window for lifting equipment. Crews dismantled a 200,000-pound drill rig, lowered it into the shaft with a 400-ton crane, and reassembled it in the confined space—during icy winter conditions. With no room for loaders or other machinery, workers removed spoil by hand and used a crane to handle steel and casing. Concrete was pumped through a hard line, with tremie placement required in water-bearing sand.<br /><br />The difficult setup slowed mobilization and production substantially, but enabled safe access for the sewer’s repair.

Keywords

Detroit sewer collapse

sinkhole evacuation

slip-lining project

secant-pile access shaft

confined-space construction