Towing of First Dam Segment for Braddock Dam Past
Pittsburgh, PA
The BSCE team of experienced structural, geotechnical and construction engineers while working with Ben C. Gerwick, Inc and the Pittsburgh District of the U.S. Army Corps of Engineers developed and pioneered the use of off-site prefabrication and overwater installation of large precast concrete elements for locks and dams. This technique, using lift-in or float-in methods is referred to as "In-the-Wet" construction. The float-in method for dam construction was first utilized in 1998 by the Corps of Engineers for constructing a 720-ft long replacement navigation dam for Dam 2 on the Monongahela River at Braddock, Pennsylvania, eleven miles upstream from Pittsburgh. This project was highly successful and proved the effectiveness of this new construction method.
The design for this new dam was based on the use of innovative "In-the-Wet" construction techniques to achieve cost and time savings, minimize disruption to navigation, and improve quality. Historically, navigation structures in the United States have been built by installing large circular sheet pile cofferdams in the river that allow large areas of the river bottom to be dried up, thereby allowing the lock or dam to be built in the dry.

Itaipu Dam Under Construction
This "In-the-Dry" method has been successful in the past, but suffers from a number of drawbacks, while "In-the-Wet" construction offers the potential for:
  • Less disruption to river navigation and river flow
  • Lower cost of construction through the elimination of conventional large sheet pile cofferdams and site dewatering
  • Shorter construction time by allowing concurrent construction of dam segments and dam foundations
  • Less environmental impact by reducing dredging and elimination of site dewatering
  • Higher quality by allowing the use of precast concrete produced in a controlled on shore environment

Itaipu Dam Interior View
BSCE's services related to locks and dams include:
  • Detail Design of Locks and Dams
  • Feasibility Studies for Use of Float-In Technology for the Construction of Locks and Dams
  • Temporary Cofferdam Design
  • Dewatering and Seepage Analysis
  • Design of Dewatering Systems
  • Detail Design of Positioning, Ballasting, Landing, and Leveling System for Installation
  • Detail Design of Foundation Systems Including Cut-Off Walls
  • Constructability Reviews
  • Value Engineering Studies


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