A major highlight of the meeting was the in-depth presentation by the Department of Public Works and Kleinfelder and Company, which delved into a comprehensive watershed analysis of three critical areas in Chelmsford: the Evergreen Street area, Blackbrook, and Deep Brook. The presentation aimed to address flood risks and propose mitigation strategies using sophisticated hydrologic and hydraulic models. These models simulated flood scenarios during significant storm events, providing a detailed understanding of the current and future risks, especially considering the impact of climate change.

The analysis revealed that the Evergreen Street area was particularly susceptible to flooding, with drainage issues exacerbated by a problematic culvert under Route 3. Three mitigation alternatives were presented to address the flooding: creating a new outfall, implementing subsurface storage, and constructing a vegetated swale. All options showed potential in reducing flood volumes by over 80%, with the first alternative being the most cost-effective. However, the need for coordination with private property owners, such as Market Basket, was emphasized due to required access for implementing the latter options.

In the Blackbrook area, undersized culverts and topography increased flood risks. The presentation outlined three alternatives, with the first focusing on culvert upsizing and others on redirecting flow. Although these alternatives aimed to mitigate flooding, concerns about potential permitting challenges were raised due to the area’s wetland designation.

For Deep Brook, the analysis identified critical hydraulic restrictions, with a combined approach of culvert upsizing and active control at Swain’s Pond offering nearly 90% flood reduction. Coordination with the Massachusetts Department of Transportation was deemed critical for the project’s success, given the complexities of timing and utilities.

The meeting also addressed tree management near a historic fire tower on Robin Hill. Concern was raised about trees obstructing radio communications critical for fire detection. With approximately 30 trees identified as problematic, the discussion focused on whether to top or remove these trees to restore the tower’s functionality. The ecological impact of tree removal and the potential for replanting shorter trees were key considerations, with the commission expressing the need for input from a tree warden and a plans for replanting.

Additionally, the commission tackled the proposal for a stormwater cleanup policy. The commission highlighted the need for a flexible approach, allowing an agent to handle minor issues directly without formal permits, while balancing wetland preservation and flood prevention.