Omaha Combined Sewer Overflow (CSO)


Omaha, Nebraska


Diaphragm Walls, Augercast Piles

subsurface conditions:

Soft clays, sands and limestone bedrock over shallow water table

size and solutions:

705 foot long, 4 foot thick diaphragm wall (56,000 square feet) to a depth of 79 feet and 9 each 2 foot diameter augercast piles to a depth of 73 feet


Owner: City of Omaha Public Works
General Contractor: Hawkins Construction
Engineer: CH2MHill

project snapshot:

As part of one of the major infrastructure projects associated with the Omaha long term CSO plan, the Missouri River Waste Water Treatment Plant needed to expand and improve on their existing facilities with allowances for an increase in combined sewage flow during wet weather. The expansion included a new chlorine contact basin located along the Missouri River. Nicholson constructed a support of excavation box for the basin, as well as deep foundation elements for the fiberglass reinforced plastic (FRP) odor control duct support system.

Omaha Combined Sewer Overflow (CSO)