Grafton has repeatedly faced flooding from the Park River. After back-to-back flooding events in 2013, the effort to provide flood protection to the city was reinitiated. Barr facilitated a value engineering workshop to kick off the design phase, which resulted in changes to key hydraulic structures that ultimately reduced the anticipated project cost while improving functionality.
Barr designed the diversion inlet and outlet using unsteady HEC-RAS modeling and 2D modeling to identify areas that may require erosion protection measures or grading modifications. We also designed a pile-founded gated-control structure and cantilevered sheetpile to connect the tie-back levee across the river. The control structure will regulate flow through town and into the bypass channel. Geotechnical investigations were conducted to determine levee and bypass channel geometry, evaluate overbuilds to account for long-term settlement, determine materials likely to be encountered in excavations, and recommend structural features.
Barr developed the individual Section 404 permit application, including a wetland mitigation plan for 12.4 acres of unavoidable wetland impacts. We also used 2D hydraulic modeling to support the environmental impact review. Barr distinguished between regions within the inundated area where fish passage was feasible and where it was not. The modeling demonstrated that the project allowed for fish passage up through the design event with minor modifications to operating procedures.
Vice President Civil Engineer
Senior Geotechnical Engineer
Senior Structural Engineer
Water Resources Specialist