Topic Area: 11c. Strategies to Mitigate Climate Change Impacts

Formatted Title:

Remediation of the Mystic River Boathouse Park Shoreline Parcel

Background/Objectives:

The Mystic River Boathouse Park Project parcel, a 1.4-acre public accessway to the Mystic River, in the historic Mythic borough of Stonington, Connecticut, is impacted with various contaminants including volatile organic compounds, petroleum, polycyclic aromatic hydrocarbons and metals from historic use of the property primarily from coal ash deposition.

The planned redevelopment of the historic parcel into a modern public access way to the Mystic River for non-motorized watercraft and pedestrians utilizing public funds necessitates the remediation of the impacted soil on the parcel for safety and resilience purposes.

Approach/Activities:

Environmental investigations have shown the property including portions extending to below the mean high tideline of this coastal property along the Mystic River to be impacted with various contaminants that exceed State of Connecticut cleanup criteria and indicate a hazard to the public due to the potential for exposure through direct contact with soil. Public Brownfields funding has been secured by the Town of Stonington, Connecticut, for the remediation and redevelopment of this parcel. Remediation of the parcel will take advantage of allowable exemptions to the State cleanup regulations that allow for impacted soil to remain in place with the construction of a proper barrier separating the public from the impacted soil. Stakeholders evaluated various remedial alternatives and settled on the construction of a clean fill soil cap and living shoreline features. The clean fill cap will take the form of a Licensed Environmental Professional Approved Engineered Control and will consist of varying thicknesses of clean fill placed above a demarcation barrier. The clean fill will be completed with various surface features including buildings, parking areas, grassy areas, landscaped areas and walking paths. Disturbance of the cap will be addressed by an institutional control that will prohibit disturbance of the surface features.

Living shoreline features are planned for the intertidal portion of the perimeter of the property to and protect the shoreline from coastal erosive forces such as wave action, current, and wake. A siting analysis was performed to determine the viable site-specific shoreline protection measures subject to sea level rise, tidal range, storm surge, wave action, boat wakes, currents and ice. The selected living shoreline design consists of a Marsh Sill rock structures and associated mussel socks, coir matting, marine plants and log protection uniquely situated within the critical tidal range. The living portion of the features, the mussel socks and marine vegetation is designed to migrate with anticipated sea level rise and allow the living shoreline to provide resiliency both currently and in the future.

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Dustin Byttautas