H&H is the lead designer on the $70M Design-Build Westchester County Bridge Replacement Project which replaces three existing bridges (two Saw Mill River Parkway bridges and one East 3rd Street over the Hutchinson River Parkway bridge) with new widened and lengthened structures, reconstructs approaches and adjacent roadways, and relocates the river.

H&H obtained the HEC-RAS geometric model from the previously-studied streams, performed a supplemental survey, and adapted the HEC-RAS geometries to model existing and proposed conditions. H&H verified and refined the hydrologic model design storm results and updated Hutchinson River tidal tailwater elevations to match current FEMA studies and observations. 1D hydraulic model (HEC-RAS) computations were used for floodplain management studies and environmental compliance, as well as for scour evaluation (HEC-18), scour countermeasure design (HEC-23) and AASHTO extreme event design parameters.

Flood profile simulations, detailed scour analysis, and estimates for general scour and local scour at piers and abutments utilizing FHWA and NYSDOT guidance were completed, and scour risk along river bank retaining wall for Hutchinson River Parkway was evaluated. Stormwater management engineers designed water quality treatment devices to treat the water quality stormwater runoff, prepared streambank stabilization plans for all three bridges, and relocated the Hutchinson River channel. Other work included preparing detailed hydraulics and drainage design reports, as well as roadway, drainage, utility, work zone traffic control, erosion, and sediment control plans. H&H hydraulic engineers coordinated with geotechnical and structural engineers to design scour countermeasures at the proposed piers and abutments.