Stormwater Infrastructure Improvement Plan

The City of Newton has dedicated significant resources over the past 20 years to improve their stormwater collection system. These efforts were leveraged to develop a comprehensive Stormwater Infrastructure Improvement Plan (SIIP) that would guide Newton’s efforts to modernize its stormwater collection system. Weston & Sampson developed a multi-year capital improvement plan for the city’s stormwater system, enabling them to plan and prioritize stormwater projects, obtain the funding necessary to complete the work, help protect flood-prone areas, improve water quality, and comply with the extensive requirements of the 2016 MS4 General Permit. The initial phases of SIIP development included:

• Compilation and review of information about the city’s stormwater system, including sampling data; drainage system inspection, operation and maintenance (O&M) data; locations of prior drainage system improvements; proposed stormwater conveyance projects; 2003 MS4 General Permit compliance data, including best management practices (BMPs); and information regarding flooding areas and streams in need of maintenance
• Field data collection to supplement and enhance available historical data, including performing a walking survey to document stream conditions, the structural condition of culverts, and evaluate flooding locations

Our team created GIS maps to display the collected data and generated projects to include the following:

• BMPs for compliance with the 2016 MS4 General Permit’s six minimum control measures and the Charles River total maximum daily loads (TMDLs) for phosphorous and pathogens, including the development of a phosphorus control plan
• Inspection and rehabilitation of stormwater infrastructure (e.g., culverts, pipes,  stream channels)
• Design of improvements to alleviate localized flooding problems

We developed rating criteria and project grouping alternatives for each project. The rating system served as the basis for prioritizing projects and developing the plan. We developed planning-level costs for each project that included all components of the 2016 MS4 General Permit. As part of the SIIP development process, we worked in partnership with the city’s Stormwater Steering Committee, which included members from the Board of Aldermen, the Public Facilities Committee, and key city staff. We developed a multi-year SIIP and presented it to the Board of Aldermen to help the city efficiently invest in infrastructure improvements to meet its stormwater needs over the next 20 years.

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