Hot Strip Mill (HSM) Scale Pit

GEI provided the geotechnical engineering and the design of a 150-foot- diameter, 100-foot-deep reinforced concrete cofferdam for use as a water cutoff and structural support of excavation at a large steel plant in Calvert, Alabama.

A water processing facility will be constructed inside of the concrete diaphragm structure. A detailed 3-D geotechnical and structural analysis was performed to generate the load conditions and structurally design the wall. The reinforced concrete structure was installed using the slurry wall construction technique. GEI also performed a detailed geotechnical and structural analysis, and design of a cap beam and a permanent mat slab at the base of the structure. The mat slab is supported by permanent tiedowns.

Design and construction challenges included:

• Running sands
• Application of large surcharges and unbalanced excavations on the outside of the wall
• Wall penetrations for a flume tunnel
• Control of groundwater pressures at the base of the excavation

GEI’s scope of work for the project included the evaluation of geotechnical information, the 3-D analysis of the structure, the structural design of the diaphragm and baseslab structures, the generation of dewatering, diaphragm wall, and tiedown specifications, the generation and oversight of a wall and slab monitoring system, and construction oversight and consultation.