Climate Modeling Supports Suffolk Downs Project, Improves Resilience

The HYM Investment Group’s (“HYM”) vision for Suffolk Downs focuses on connectivity and accessibility. Located in East Boston and Revere, this redevelopment will turn an underutilized site into a new neighborhood with an active, lively, and appropriate mix of uses, including retail, residential, office, lab, and hotel. Surrounded by several diverse water resources, the Suffolk Downs redevelopment represents a unique opportunity to prepare for predicted climate change conditions through upfront infrastructure planning.

The site is complex, with many topographic and environmental constraints. It is in a low-lying area and bounded by an active subway line, local roads, and a state highway, which are directly adjacent to tidally influenced waterways and marshland. A freshwater creek bisects the site, which is upstream from a state-owned pumping station and tide gate. As part of the state environmental review process required for the project under the Massachusetts Environmental Policy Act (MEPA), a Resiliency and Adaptation Study was completed—the first of its kind for a single development. The study aimed to understand the impacts climate change may have on this interconnected system and how the built environment affects the movement of floodwaters on- and off-site. By analyzing current and future climate conditions for rainfall and coastal flooding, the study sought to evaluate whether the development would displace floodwaters, determine if the project provided a resilient design, and recommend appropriate mitigation.

A working group with representatives from VHB, HYM, MEPA Office, Massachusetts Office of Coastal Zone Management, MA Department of Environmental Protection, MA Department of Conservation and Recreation, and the MA Transit Authority studied current sea levels and various sea level rise scenarios, using detailed hydrologic and hydraulic models to analyze data from a variety of sources. The results allowed the team to accurately simulate the flow of floodwaters under different scenarios using 2D modeling software. The dynamic United States of Army Corps of Engineers (USASE) 2D Hydraulic Engineering Center River Analysis System (HEC-RAS) model was used. The modeling analysis included riverine and coastal inputs, regional flood protection infrastructure (culverts, bridges, tide gates, and a stormwater pumping station), and the abutting communities of Revere and Boston. The team completed model runs for rainfall events coupled with various sea level and tidal conditions for current and forecasted climate and sea level conditions (mid to late century). Visualizations of possible storm events helped communicate the project’s complexities to regulators.

Figure 1. Regional Flood Modeling –  1.5-feet of Sea Level Rise and 100-Year 
Event Flow Paths​

Figure 2. Regional Flood Modeling – Existing Conditions with 1.5-feet of Sea 
Level Rise and 100-Year Storm Event

As a result of the Resiliency and Adaptation Study, HYM committed $6 million in mitigation funding to improve flood resiliency at the project site and for more than 1,000 surrounding properties. The study identified several potential flood protection measures, to be confirmed when returning to MEPA at a future development phase, including upgrading the existing state-owned pump station, constructing protective berms on the site, and installing tide gates. The study also investigated constructing an additional off-site berm along an adjacent state-owned roadway and DCR parkland to further protect the area from coastal storm surge.

Suffolk Downs is an essential project for the Boston area, providing much-needed affordable housing to the communities of Boston and Revere and significant economic development throughout the lifespan of the project. HYM continues to rely on forward-thinking principles, like the Resiliency and Adaptation Study, to effectively manage for climate change and sea-level rise.

Figure 3. Suffolk Downs Redevelopment
(Image courtesy of The HYM Investment Group)​