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  • Whitemarsh Run Stream Restoration

Whitemarsh Run Stream Restoration

Straughan developed an innovative design for the Maryland Transportation Authority at a former sand and gravel mining location to provide fish passage across a 5-foot vertical barrier and minimize additional sediment loss at a third-order Coastal Plain stream. Channel and floodplain improvements were proposed as mitigation for unavoidable wetland and stream impacts associated with construction of 11 miles of I-95 Express Toll Lanes. Field measurements and modeling efforts indicated any stream restoration efforts would be constrained by highly erosive storm velocities through an undersized bridge culvert, high bedload sediment, an adjacent roadway prone to flooding, reduced baseflows due to catchment urbanization, a limited footprint due to adjacent properties, and nearby concrete waste and diesel-fuel contamination.

Analyses that supported the design included discharge and sediment rating curves developed through storm velocity and bedload measurements, stream, groundwater, and rain gage installations, ground-penetrating radar, and HEC-RAS, iSURF (A Mixed-Size Sediment Transport Tool), and BSTEM (Bank Stability and Toe Erosion Model) modeling. A 1400 LF riffle grade control will provide the minimum flow depths and maximum velocities at baseflow for the weakeast anadromous and resident fish while remaining stable at all stormflows. Straughan designed targeted bank stabilization along the 2-mile reach to limit sediment yield and promote native landscaping. Straughan also supported the acquisition of 187 acres of floodplain and upland forest, wetland enhancement and vernal pool construction, and invasive species eradication on site.