Coastal Resilience Solutions for Downtown Boston and North End
The “Coastal Resilience Solutions for Downtown Boston and the North End” is a $200 to $300 million dollar, 50-year plan to protect the Boston waterfront, including Downtown, the North End, and the eastern edge of the city’s West End. The plan aims to protect these neighborhoods from a hundred-year flood on top of a 40 inch rise in sea levels by late this century. The integrated plan relies on a combination of natural (green infrastructure) defenses, breakwaters, seawalls, harbor walks, and raised land to protect the waterfront and inland areas from increases in coastal flooding and sea level rise.
Boston’s resilience plan is aimed at reducing flood risks that includes the areas of Rowes Wharf in Downtown, the Wharf District, North End waterfront, and the eastern part of the West End, but not including the New Charles River Dam. The estimated sea-level rise scenario used to develop the plan assumed 9 inches by 2030, 21 inches by 2050, and 36 inches (approximately 1 meter) by 2070. The scenario, which is referred to as the “40 inches scenario,” includes the one in one-hundred year event (a storm that has a 1% chance of happening a year), on top of the sea-level rise projections. The plan also allows for the possibility that sea-level rise will exceed 40 inches this century.
The resilience plan proposes an integrated coastal defense system, including specific options that provide protection from flooding caused by sea-level rise and more intense coastal storms. The defense system outlined by in the plan includes combinations of:
- green infrastructure (living shorelines)
- offshore breakwater structures
- raising land such Puopolo Park in the North End
- building and raising hard structures such as elevated waterfronts, harbor walks, seawalls and bulkheads, and
- where necessary, to provide additional defense against elevated flood risks, raised roadways, intersections, and bike paths.
The plan incorporates parks and bikeways and maximizes public access to the city’s waterfront. Private property owners will need to take additional actions to protect their properties. Specific actions are included to defend against the “40 inch scenario,” but provisions are made to put in more protections, should sea level rise exceed that scenario.
There are three time frames for implementing the specific components of the plan:
- Near-term out to 2030. These include immediate measures to address current flood risks.
- Mid-term actions out to about the 2040s.
- Long-term measures out from 2050 to 2070 and beyond.
Capital costs are estimated to be between $189 and $315 million, with estimated annual maintenance costs $3 to $5 million. The plan reports that net benefits over its lifetime (applying discount rates of 3% and 7%) will be $2 to $6 billion.
The Downtown and North End plan builds on detailed technical reviews of existing infrastructure and flood risks, soil conditions, location of tunnels and utilities, and consideration of municipal, state, and federal laws, rules and regulations.
Stakeholders including property owners, neighborhood groups, state and federal agencies, and others were involved in developing the plan. Two open houses were held for the public to provide input. The stakeholders strongly preferred a combination of effectiveness, adaptability, feasibility, and consideration of environmental impacts in deciding on options for protecting the waterfront. Other criteria for examining coastal defense options included design life and adaptability, social impact, equity (including impacts on vulnerable communities and equitable access to the waterfront), and creation of value (including consideration of the value created by investments and opportunities to attract funding).
The Downtown and North End plan is part of the “Climate Ready Boston” planning efforts and complements the city’s Climate Action Plan that will reduce greenhouse gas emissions. The plan was issued by the City of Boston and the Barr Foundation.
Publication Date: September 2020
- City of Boston, Massachusetts
- Adaptation plan