Hydraulic/Scour Analysis

DTC was responsible for hydraulic sizing and scour assessment for this major movable span bridge replacement project, directly on Niantic Bay. Hydraulic sizing considered both inland and tidal flooding events through the 500 year level. Scour assessment was performed utilizing HEC-18 and included analysis for a wide range of inland and tidal flooding events to determine the most critical event from a scour perspective. Foundation design including pile embedment lengths for the final bridge design was determined based on this analysis work.


DTC was responsible for preparation of application forms and all supporting information as well as general coordination on State and Federal Environmental permits for the project. Permits required for this federal project include CT DEP Federal Coastal Consistency Permit, CT DEP 401 Water Quality Certification, and US Army Corps of Engineers Individual 404 Permit. Proposed improvements effecting the environment included shifting of nearly two miles of main line Amtrak rail line, installation of a new 370’+ movable span bridge, and over 75,000 cy of sand fill for beach nourishment. The presence of a state designated threatened plant species within the area of impact, added additional complexity to the permitting process.