Town public‑works staff presented the South Street water‑main replacement project to the Select Board on March 11 and described related stormwater work that will add best‑management practices (BMPs) to help meet the town’s NPDES phosphorus‑removal obligations.

Public‑works staff said the water‑main replacement creates an opportunity to add infiltration‑based BMPs — structures designed to slow, infiltrate and settle stormwater before it reaches wetlands and the Charles River — in multiple locations along South Street. Staff said two of the proposed BMPs will conflict with existing trees and two trees sit within the right‑of‑way in locations where water‑main excavation would effectively destroy their root systems; leaving those trees would likely result in the trees failing in coming years.

Tree removal and replacement

The project team reported 15 trees are proposed for removal; they said only three of the 15 are in good condition. Staff presented a replacement plan that calls for two replacement trees for every tree removed (a 2:1 replacement ratio), totaling 30 replacement trees. Because some locations are narrow or otherwise unsuitable for immediate replanting, staff said replacements may be planted in other locations around town after consultation with residents and the Forestry Division.

BMPs and water quality goals

Project engineers described infiltration trenches and concrete stormwater structures that will capture runoff, allow suspended solids to settle and discharge overflow into perforated pipes so water can infiltrate and reduce phosphorus loads that would otherwise enter resource areas. Staff said additional drainage upgrades are needed because of prior flooding on South Street and limited green space to meet treatment goals.

Process and outreach

Public Works said the project is entering design stages and the tree warden will be the Select Board’s representative at the Scenic Byway Act review at the Planning Board. Staff said they have met with Conservation Commission and will meet with neighbors to coordinate final tree placement, species selection and a planting plan in the coming spring. The board and staff discussed tree caliper and planting stock; staff said they will evaluate nursery resources and consider planting locations across town if on‑street caliper replacements are infeasible.

Next steps

Staff will continue design and permitting, coordinate with Park and Forestry to identify replacement locations and species, and schedule a Planning Board Scenic Byway review. The Select Board requested clear public communications explaining why individual trees are removed and how the 2:1 replacement and planting schedule will be implemented.