Climate Ready South Boston
Our latest report, Coastal Resilience Solutions for South Boston, presents near-term strategies as well as a long-term vision for the neighborhood. We want to reduce risk due to sea level rise and coastal flooding in South Boston.
This report is the City’s second local climate resilience plan that presents district-scale climate adaptation solutions. The first was Coastal Resilience Solutions for East Boston and Charlestown.
Coastal Resilience Solutions
The image shows near-term and long-term ideas that would protect Fort Point Channel. All images are courtesy of Halvorson Design Partnership.
The gradations of blue in the map show how the 1-percent annual chance flood probability changes in South Boston through time. The colors do not indicate depth of flooding. Arrows indicate key flood pathways.
The near-term implementation period consists of actions that should be initiated now, and completed by 2025. These actions address the most urgent flood pathways associated with current flood risk along Fort Point Channel and Seaport Boulevard.
The 100-Acre Master Plan area and adjacent parcels need near-term action. Flood risk is expected to increase along the channel, and there are opportunities to partner with property owners and others to incrementally implement solutions. Near-term actions range from $3 to $16 million depending on design, and consist of berms and open park space. The area of the Arcade requires a more detailed engineering analysis to assess the structural integrity of the buildings and the flood protection solution that would be most appropriate.
The preferred option for Fort Point Channel is adding flood protection through expanded open space along the perimeter of the Channel.
Near-term coastal flood protection can be completed in steps in the most urgent areas for action along Seaport Boulevard. The cost to complete a flood barrier along Seaport Boulevard between the World Trade Center and Dry Dock 4 is between $19 million and $22 million. Floodproofing the Fish Pier would add an additional $29 million to $33 million. Near-term improvements could prevent tens of millions of dollars in direct physical damage and displacement costs. Earthen berms or floodwalls designed and constructed in the mid-term could be raised in the long-term as sea level rises.
Proposed actions include a flood wall that may be integrated with the harborwalk, floodproofing of existing structures, and a berm that could be part of future open space improvements.
Mid-term strategies extend north from the 100-Acre Master Plan to Martin’s Park and south to the base of the east side of Fort Point Channel. Shoreline strategies include earthen berms and open park space. Along the existing Harborwalk, options include incorporating building structures into the line of defense or building new barriers in the water. Bridge guardrails along the proposed alignment would be converted to floodwalls. The many stormwater outfall pipes along the channel will require flap gates. These solutions range in cost from $56 to $73 million.
Design concepts use both planned development as well as opportunities for recreation to increase flood protection along Fort Point Channel.
The Seaport Boulevard area is significantly space constrained between the existing waterfront and the roadway. We examined two alignment options for this area: flood protection along the existing shoreline, and flood protection out into the water. Both alternatives propose a minimum of 15 feet NAVD88 as the design elevation and could be adapted to higher design elevations.
The Harborwalk along Seaport Boulevard could be adapted for flood protection. Higher elevations could be adapted with creative additions and expansions of the Harborwalk.
Two of four alignments examined along the South Boston Waterfront are recommended to move forward for further evaluation. These are Option A, which is aligned with the existing shoreline, and Option B, which expands available space for flood protection by adding fill in the marina. At the 1-percent annual chance elevation with 9 inches of sea level rise, Option A or B will protect 250 people and avoid $85 million in direct physical damages and displacement costs. At higher flood depths, South Boston Waterfront could still flood from Fort Point Channel, Seaport Boulevard, Raymond L. Flynn Marine Park, and Reserved Channel if action is not taken to reduce risk in those areas.
We examined two alignment alternatives for the Raymond L. Flynn Marine Park and Reserved Channel. Option A provides flood protection along the perimeter of the Raymond L. Flynn Marine Park, and Option B aligns flood protection along interior roadways. Option B would require floodproofing for many structures, as well as other actions to protect access and egress. Option A is recommended for further evaluation.
Option A provides flood protection along the perimeter of the Raymond L. Flynn Marine Park and Reserved Channel.
We examined two alternatives. Option A is aligned with the perimeter of the neighborhood along Pleasure Bay, and involves floodwall or raised Harborwalk along Day Boulevard and the beaches. Option B is characterized by coastal restoration and inland flood protection, and involves beach nourishment and elevation of park space along Farragut Road. Both options are recommended for further evaluation.
Coastal adaptations would include elevating the Harborwalk along its current path or routing the line of protection down the right-of-way of Day Boulevard and Columbia Road. It also would include converting the concrete wall along the southern edge of the Conley Terminal to a flood wall.
In the long-term, earlier strategies can be further enhanced through expanded Harborwalk, possible increased fill and enhanced park space along the Channel, long-term flood protection measures to the Arcade, and other improvements that increase the overall flood protection, social, and recreational benefits within the area. Such additional enhancements may cost around $49 million.
The Flynn Cruiseport Boston at the Black Falcon Terminal is at lower risk, though may require more site specific flood-risk evaluation.
We’re working with a design team to find solutions for coastal flooding in South Boston. We asked people in South Boston for their thoughts about this project through a community survey.