The western shore of Hart-Miller Island’s (HMI) south cell in Baltimore County is an unarmored shoreline comprised of a 43-acre tidal island that was formerly two (2) separate islands (Hart and Miller Islands) northeast of Edgemere, MD. HMI currently operates as a dredged material containment facility as well as Hart Miller Island State Park. Straughan assessed shoreline erosion issues and recommended solutions for long-term stability to the Maryland Port Administration (MPA) so that MPA can plan for restoration/stabilization prior to a future property transfer to the Maryland DNR. Straughan was responsible for assessment of the existing shoreline and review of the historical evolution of the shoreline to propose restoration and stabilization alternatives. Straughan quantified construction costs and TMDL/MS4 credit available for each design alternative.
Straughan provided a comprehensive field assessment report, linking accelerated erosion to loss of barrier islands along the maximum fetch. We recommended five design alternatives for shoreline stabilization and erosion control to help provide long-term stabilization of the shoreline. Alternatives included offshore breakwaters, sill and tidal marsh, beach nourishment, and emerging technology/proprietary solutions to reduce risk at lower cost (Atlantic Reefmaker). The offshore breakwaters were designed to promote landward sand accretion, which would help to naturally restore shoreline lost to erosion and provide protection from wave action. The hybrid design solution included the installation of living shorelines, which was a tidal marsh with a stone sill structure protecting the marsh toe. This would help to establish a shallow water habitat that enhances the shoreline while addressing the need for stabilization and erosion control. We also proposed the use of Atlantic Reefmaker structures to mimic the wave attenuation of the former barrier islands similar to a groin structure. Each design alternative included detailed descriptions of expected maintenance, including invasive species control and a breakdown of construction costs. Straughan prepared TMDL/MS4 nutrient load reduction and equivalent impervious acre credits using the Recommendations of the Expert Panel to Define Removal Rates for Shoreline Management Projects and MDE’s Accounting for Stormwater Wasteload Allocations and Impervious Acres Treated. The project is complete and was submitted to MES in April 2020. Final review of alternatives with MPA and MD DNR is pending.