The Chelmsford Stormwater Management Master Plan (SWMMP) captures the town’s current stormwater management efforts and operations, federal stormwater permit compliance requirements, needed drainage infrastructure repairs, and culminates in a capital improvement plan for the next 21 years. Weston & Sampson developed the SWMMP after completing a condition assessment of a substantial portion of the town’s stormwater system and developing recommendations for improvements. Over 15 miles of streams and drainage features were inspected, assessed, and identified for improvements and repairs. Hundreds of culverts were also inspected, documented, and identified on the capital improvements list. All of the recommendations were prioritized based on the risk and consequence of failure to ensure that the town’s available resources are allocated efficiently and effectively. Given the town’s stormwater management goals, five types of projects were considered: stream maintenance, culvert rehabilitation or replacement, localized flood mitigation, federal permit compliance, and green infrastructure retrofits.
During the field investigation, Weston & Sampson’s crews walked more than 15 miles of streams, documenting and geolocating erosion, sedimentation, and infrastructure condition. The team subsequently worked with the town to build a comprehensive database of information to support future maintenance tracking. Areas known to flood based on the town’s Hazard Mitigation Plan, resident survey, and town staff input were investigated for opportunities to install green infrastructure and upsize stormwater assets, such as culverts and drainage piping. Municipally owned properties that had large amounts of impervious areas and were large enough parcels to support green infrastructure retrofits were also assessed as candidates to implement stormwater best management practices, reducing pollutant loading in impaired subbasins or in wellhead protection areas. Lastly, the project team reviewed bylaws, regulations, and standard operating procedures to meet MS4 requirements. Stakeholders and residents were engaged through standing monthly meetings with the Stormwater Master Plan Advisory Committee. Many of the project tasks complemented or directly met MS4 requirements.
The Chelmsford SWMMP document is a compilation of all recommendations into a capital improvement plan that leverages stormwater enterprise funds to address years of maintenance and capital improvements backlog. The Plan itself is a public-facing, visually appealing, and easy-to-understand report, which can be utilized as a tool to engage the community in further discussions on stormwater management.