Goal of the plan is to determine climate factors that impact the city today and in the future
The Strawberry Brook watershed in coastal Lynn, Massachusetts has a long history of stormwater flooding, exacerbated by tidal flooding, which is expected to worsen with more intense precipitation and sea level rise projected to occur due to climate change. Once an open, winding system, the brook is now hidden underground and frequently overflows into nearby homes and businesses. Using grant funds from the State of Massachusetts Municipal Vulnerability Preparedness (MVP) Program, the City of Lynn retained Weston & Sampson to prepare a Strawberry Brook Resilient Stormwater Management and Implementation Plan. The goal of the Plan was to determine the climate factors that impact the City today and in the future, identify opportunities for nature-based and green infrastructure (GI) solutions within the watershed, and provide a prioritized list of evaluated and implementable projects to help minimize future flooding.
We implemented a field data collection program to minimize current data gaps and validate the City’s current GIS information. This included a bathymetric survey of several ponds in the watershed as well as manhole and sewer TV inspections. We performed climate projection modeling to allow us to predict future climate rainfall for multiple design storm events. We developed a stormwater model to identify potential flood-prone areas and evaluate the potential benefit of various green and gray stormwater management practices under both existing and future climate conditions. Based on this data, we modeled a total of 24 scenarios to illustrate the effectiveness of a variety of GI techniques which use native vegetation, soils, and other natural processes to reduce flooding and improve water quality. We also conducted an urban heat island assessment and conducted open, two-way public communication efforts with local organizations to achieve public engagement throughout the City, including in Spanish to accommodate the great diversity in Lynn.
Our investigation identified over 230 potential GI components grouped into 23 individual projects, organized into an easy to read and understand table, along with a relative price comparison for each project. We illustrated each project’s overall effectiveness at alleviating urban infrastructure stresses and function during various designed storm events and evaluated their impact to the urban environment. Out of the 23 potential projects, we identified 10 prioritized actions that represent projects that create the greatest impact in terms of flood risk reduction, reducing flooding times, and reducing urban heat. They also prioritized water quality improvements and creation of better, healthier public spaces. The integration of nature-based solutions into the City’s existing drainage system will create a more resilient infrastructure that can accommodate future climate, social, and environmental challenges.
- Field data collection to fill data gaps
- Thorough stormwater modeling
- Flood reduction
- Urban heat island assessment
- Integration of nature-based solutions into existing drainage system
- Green infrastructure