Cofferdams

A Sample of successful projects cofferdams

PCI has extensive experience in the design and construction of cofferdams in various soil types and rock formations   PCI has delivered design-build solutions for circular cofferdams up to 140 ft in diameter with concrete rings and rectangle cofferdams up to 25 feet deep.  PCI has also installed cofferdams in the middle of medium-sized rivers for bridge construction work.

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US-30 Bridge, Tama County, Iowa

PCI was the General Contractor on the IDOT US-30 Bridge project.  In order to construct the bridge stems, PCI and Ground Improvement Engineering (GIE) designed a cofferdam system consisting of interlocking sheet piles.  The cofferdams allowed for the construction below the adjacent stream level.  PCI constructed the 4-span, 458 ft by 40 ft pretensioned, prestressed concrete bridge for the future four-lane highway expansion.  PCI also performed the stream reshaping work.

cofferdam plus piles

McCollister Blvd. over Iowa River

PCI self-performed the grading and bridge work for the new McCollister Bridge.  The bridge was a 3-span prestressed concrete beam bridge and was 393 ft long by 57.5 ft wide.  The substructure was overbuilt to accommodate the future four-lane expansion of McCollister Blvd. PCI installed sheet piles to build a cofferdam in the river to construct the bridge piers.  The interior struts were floated to the cofferdam on barges and (52) steel H-piles were driven within the cofferdam to provide foundation support for the bridge.  PCI floated center span beams across the Iowa River on a barge and tug setup.  PCI placed (24) 130 foot long Prestressed Concrete Beams over the Iowa River.  PCI placed the 800 cubic yard bridge deck in 10 hours using two concrete pump trucks.  PCI’s contract with the city was in excess of $6 million dollars and was intended to take 200 working days.  The contract was completed ahead of schedule with minimal extra work orders. 

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Bluff Street Lift Station

Construction of the new Bluff Street Lift Station in Cedar Falls required shoring and excavation for a 40-ft-deep cut next to two streams.  The rock excavation required blasting, and during the process, voids in the existing rock were discovered that caused water to flood the cofferdam on many occasions.  PCI workers and divers placed sandbags at the locations of the voids in the cofferdam and the voids were injected with concrete and flowable fill.  PCI used 2,600 cubic yards of concrete and 500,000 lbs of rebar to construct the lift station.  PCI also placed the slide gates, automatic bar screen, stairs, ladders, pumps, and overhead crane - and connected a 54-inch active sewer line to the lift station.